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Chemical denudation and hydrology near tree limit, Coast Mountains, British Columbia Gallie, Thomas Muir 1983

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CHEMICAL DENUDATION AND HYDROLOGY NEAR TREE LIMIT, COAST MOUNTAINS, BRITISH COLUMBIA by Thomas Muir G a l l i e III B.A., The U n i v e r s i t y of North C a r o l i n a at Chapel H i l l , 1974 M.Sc, The U n i v e r s i t y of Utah, 1977 THESIS SUBMITTED IN PARTIAL FULFILLMENT THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES (Department of Geography) We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA September, 1983 (c) ^ Thomas Muir Gallie III In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree a t the U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and study. I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the head of my department o r by h i s o r her r e p r e s e n t a t i v e s . I t i s understood t h a t copying or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be allowed without my w r i t t e n p e r m i s s i o n . Department o f The U n i v e r s i t y of B r i t i s h Columbia 2075 Wesbrook P l a c e Vancouver, Canada V6T 1W5 Date 1>Q S ^ f t ft® 3 i i ABSTRACT Major c a t i o n and s i l i c o n budgets from a 2.3 hectare, watershed are i n t e r p r e t e d to determine environmental f a c t o r s c o n t r o l l i n g chemical denudation r a t e s on s i l i c e o u s l i t h o l o g i e s i n the a l p i n e - s u b a l p i n e ecotone, Coast Mountains, B r i t i s h Columbia. I o n i c source areas were sought by s p a t i a l and temporal s o l u t e sampling. The data were s t r a t i f i e d by s o i l - v e g e t a t i o n complexes and components of the h y d r o l o g i c cascade. The geochemical system has two major i o n i c sources. S o i l s o l u t i o n s are sodium f a c i e s and are s t o i c h i o m e t r i c a l l y balanced with v o l c a n i c g l a s s probably because the g l a s s f r a c t i o n of v o l c a n i c ash i s the primary weathering source i n s o i l s and i s d i s s o l v i n g c o n g r u e n t l y . Streamflow i s predominantly calcium f a c i e s because bedrock i s composed of calcium-magnesium s i l i c a t e s and groundwater flow through bedrock d i s c h a r g e s to p h r e a t i c s o i l water zones. The h y d r o l o g i c system has two major components. D i r e c t stormflow i s generated by s a t u r a t i o n o v e r l a n d flow from l a r g e c o n t r i b u t i n g areas due to e x t e n s i v e s o i l w a t e r - r e p e l l e n c y . I n d i r e c t stormflow i s generated by s a t u r a t e d subsurface throughflow due, i n p a r t , to strong t e x t u r a l c o n t r a s t s among s o i l parent m a t e r i a l s . The a c t u a l basin drainage d e n s i t y i s g r e a t e r than i s apparent s u p e r f i c i a l l y because p r e f e r r e d subsurface pathways are common. Annual r u n o f f was very s i m i l a r i n the study years 1979 and 1980 (904 mm and 1027 mm r e s p e c t i v e l y ) but net major c a t i o n and s i l i c o n y i e l d s v a r i e d from 1.6 metric tons km"2 to 3.4 metric i i i tons km"2. The low 1979 y i e l d was caused by segregated ground i c e which l i m i t e d s o i l - w a t e r c o n t a c t , s o i l s o l u t i o n shunting, and groundwater flow. D i f f e r e n c e s i n denudation r a t e s between subcatchments were e q u a l l y l a r g e because of t o p o g r a p h i c a l l y induced groundwater c o n t r i b u t i o n s to streamflow. A s i m i l a r c o n c l u s i o n i s reached f o r l a r g e r adjacent watersheds. Most mass i s denuded along groundwater flowpaths i n bedrock r a t h e r than from s o i l s . Denudation from a l p i n e s u r f i c i a l m a t e r i a l s during 1980 was approximately 2 tons km"2 y r " 1 which i s an order of magnitude l e s s than expected". R e s u l t s imply that where groundwater c o n t r i b u t i o n s are not d e f i n e d , watershed experiments can produce h i g h l y b i a s e d estimates of s u r f i c i a l denudation which confound process i n t e r p r e t a t i o n s . H y d r o l o g i c pathways are more important than the inherent chemical r e a c t i v i t y of s o i l s and bedrock i n r e g u l a t i n g chemical denudation r a t e s in t h i s landscape. Runoff mechanisms p a r t i t i o n water between the s u r f a c e , s o i l and groundwater r e s e r v o i r s and c o n t r o l flowpaths, c o n t a c t - t i m e s and shunting w i t h i n each r e s e r v o i r . Biopedochemical c o n t r o l s on denudation appear to be r e l a t i v e l y l e s s important than h y d r o l o g i c c o n t r o l s because s o i l s o l u t i o n s are s i m i l a r among a l p i n e s o i l - v e g e t a t i o n a s s o c i a t i o n s . S o i l l e a c h i n g l o s s e s are small because s o i l w a t e r - r e p e l l e n c y , p r e f e r r e d subsurface pathways and the d i s c h a r g e regime l i m i t s o i l s o l u t i o n shunting. i v CONTENTS Chapter 1. O b j e c t i v e s 1 I n t r o d u c t i o n 1 Antecedent Research 5 Denudation In The C o a s t a l C o r d i l l e r a 9 D i s c u s s i o n 16 Statement Of Problem 18 O r g a n i z a t i o n 20 Chapter 2. Study Area . ... 21 L o c a t i o n 21 Climate 21 Bedrock 28 S u r f i c i a l M a t e r i a l s 30 S o i l s 31 V e g e t a t i o n 31 S o i l - V e g e t a t i o n Complexes 32 Holocene H i s t o r y 32 Chapter 3. Methods 35 Sampling Str a t e g y 35 Chemical Techniques 39 Hydrometeorological Techniques 44 Other Techniques 47 Chapter 4. Water Budgets 50 I n t r o d u c t i o n 50 Budget Equations 50 Hydrometeorologic Data 52 D a i l y D i s t r i b u t i o n Methods 55 Discharge 55 Snowmelt 56 Evapo r a t i o n 59 Evap o r a t i o n Over Vegetated Surfaces 59 Model Performance 61 Evaporation Over Snow 63 Annual Water Budgets 66 Runoff R a t i o s 66 R e s i d u a l s 72 Groundwater Losses 73 S o i l Moisture C a p a c i t y 76 Summary 81 Chapter 5. Runoff Generation 83 I n t r o d u c t i o n 83 Hydrograph A n a l y s i s 83 Flow Regime 83 Recession Limbs 85 Hydrograph Separation 89 Synopsis 92 Streamflow Processes 93 P r e c i p i t a t i o n - e x c e s s Overland Flow 94 S a t u r a t i o n Overland Flow 95 Overland Flow On B r u n i s o l s 96 Subsurface Throughflow 101 Throughflow Lenses 103 v i F i n g e r i n g 107 Throughflow Channels 108 Groundwater Flow 111 Synopsis 112 Flow Components And Runoff Mechanisms 113 Summary 115 Chapter 6. Geochemical Budgets 117 I n t r o d u c t i o n 117 D e p o s i t i o n Rates 117 Concentration-Discharge R e l a t i o n s h i p s 120 Export Rates 121 Geochemical Budgets 123 Geochemical Budgets For Subcatchments 127 Summary 130 Chapter 7. So l u t e Sources 132 I n t r o d u c t i o n 132 Na t u r a l S o l u t e P o p u l a t i o n s . 132 Subpopulation C h a r a c t e r i s t i c s 133 Hydrochemical F a c i e s 134 E v o l u t i o n Sequences 136 Sodium E v o l u t i o n Sequence 138 Synopsis 147 Calcium E v o l u t i o n Sequence 147 Calcium F a c i e s Source Areas 148 Regional Groundwater 151 L o c a l Groundwater 151 Calcium D i f f e r e n c e s Between Watersheds 153 v i i M o r p h o l o g i c a l D i f f e r e n c e s Between Watersheds 154 V e r i f i c a t i o n ...155 Groundwater Flowpaths And Mineralogy 156 Synopsis 1 58 Mixed F a c i e s S o l u t i o n s 158 Potassium Sources 159 Variance Induced By I n f i l t r a t i o n 165 Synopsis 167 S o i l S o l u t i o n D i f f e r e n c e s Between S o i l Groups 168 Summary 173 Chapter 8. Denudation 175 I n t r o d u c t i o n 175 A Conceptual Runoff Model 175 Solute Dynamics 177 Source Areas 184 Denudation Components 184 Summary 192 Chapter 9. Con c l u s i o n s 194 D i s c u s s i o n 200 References 203 Appendix A. Pe t r o g r a p h i c D e s c r i p t i o n Of L i t h o l o g i e s 217 Appendix B. Major V e g e t a t i o n A s s o c i a t i o n s 220 Appendix C. S e l e c t e d S o i l P r o f i l e D e s c r i p t i o n s 224 Appendix D. Hydrometerological Data 233 Appendix E. M i s s i n g Records 240 Appendix F. Chemical Analyses Of Water 243 v i i i ILLUSTRATIONS 1.1 A Conceptual Model Of Small Watersheds As Biogeochemical Systems 3 1.2 Annual Geochemical Denudation Rates As A Fun c t i o n Of Annual Runoff For Watersheds On G r a n i t i c L i t h o l o g i e s . .. 10 2.1 L o c a t i o n Of The Study Region In Southwestern B r i t i s h Columbia, Canada 21 2.2 L o c a t i o n Of Goat Meadows Watershed In The Study Region. 21 2.3 S o i l - v e g e t a t i o n A s s o c i a t i o n s In Goat Meadows Watershed 21 2.4 Topography And Subcatchments Within Goat Meadows Watershed 21 2.5 Mean And Extreme Snowpack Storage At T e n q u i l l e Lake Snow Course 26 2.6 Mean Monthly Temperatures At Goat Meadows And W h i s t l e r Roundhouse For The Study P e r i o d 28 2.7 Bedrock At Goat Meadows 28 3.1 Sampling S i t e s At Goat Meadows 35 4.1 D a i l y H y d r o l o g i c F l u x e s , R e s e r v o i r L e v e l s And Temperature Curves For The A b l a t i o n Season, 1979 52 4.2 D a i l y H y d r o l o g i c F l u x e s , R e s e r v o i r s L e v e l s And Temperature Curves For The A b l a t i o n Season, 1980 52 4.3 Measured Versus Modeled Pond Evaporation During 78 Days Of 1979 61 4.4 Discharge Traces For The Basin O u t l e t Weir, 1979 And 1980 70 5.1 Flow Du r a t i o n Curves For The Basin O u t l e t Weir 84 5.2 Recession Limbs From The Basin O u t l e t Weir 85 5.3 Recession Limbs When Overlapped And S y n t h e t i c Recession Limbs For Both Years 87 5.4 Method Of Hydrograph Separation Based On S y n t h e t i c Recession Limbs 89 5.5 Snowmelt Hydrographs Separated Into Flow Components On The B a s i s Of S y n t h e t i c Recession Limbs 89 5.6 Flowpaths In B r u n i s o l s 97 5.7 Runoff Source Areas 99 5.8 Schematic P a t t e r n Of Surface Detention Storage And Subsurface S a t u r a t i o n During Snowmelt 101 5.9 S p e c i f i c Discharge From A Snow Lysimeter And Two Subsurface I n t e r c e p t o r G u t t e r s At The Throughflow Zones Above The W a t e r - r e p e l l e n t Layer And Above The T i l l 104 7.1 R e l a t i v e And Absolute Abundance Of Na, Ca, K In A l l F i e l d Water Samples 134 7.2 R e l a t i v e And Absolute Abundance Of Na, Ca, K In Water Samples Along The Main Chemical Sequences 136 7.3 R e l a t i v e And Absolute Abundance Of Water S o l u b l e Na, Ca, K From M i n e r a l S o i l Horizons 139 7.4 R e l a t i v e Abundance Of Major C a t i o n s In M i n e r a l s , G l a s s , And Water Samples At Goat Meadows 141 7.5 P o s s i b l e Recharge And Discharge Zones At Goat Meadows .148 7.6 Groundwater Sampling S i t e s On Goat Meadows Ridge 151 7.7 R e l a t i v e And Absolute Abundance Of Na, Ca, K In Mixed F a c i e s Water Samples 159 7.8 R e l a t i v e And Absolute Abundance Of Water S o l u b l e Na, Ca, K From Humic S o i l Horizons 159 7.9 Temporal V a r i a b i l i t y Of C a p i l l a r y Zone S o l u t e s , 1980 ..165 8.1 C o n c e n t r a t i o n - d i s c h a r g e R e l a t i o n s h i p s At Mosquito Weir, 1 979 And 1 980 1 78 8.2 Load-discharge R e l a t i o n s h i p s At Mosquito Weir, 1979 And 1980 178 8.3 Temporal V a r i a b i l i t y Of Calcium, Sodium, And Discharge Components At The Basin O u t l e t Weir, June 1 To J u l y 1, 1980 178 8.4 R e p r e s e n t a t i v e H y s t e r e s i s At Mosquito Weir, 1980 182 TABLES 1.1 Denudation Rates On S i l i c e o u s L i t h o l o g i e s 10 2.1 Comparison Of Average To 1979 And 1980 Snowpacks 27 2.2 Summary Of S o i l And V e g e t a t i o n Groups At Goat Meadows . 32 3.1 D i s t r i b u t i o n Of S o l u t e Samples As Components Of The Hydrol o g i c Cascade 35 3.2 A n a l y t i c a l P r e c i s i o n Of S o l u t e Analyses 42 3.3 Discharge Rati n g R e l a t i o n s h i p s 47 4.1 Melt Model Performance 57 4.2 Water Budgets For Goat Meadows, 1979 And 1980 66 4.3 Rates Of Groundwater Loss Through The Pond F l o o r 73 4.4 Some I m p l i c a t i o n s Of The Assumption That A l l Re s i d u a l In The Budget Equation Is Due To Groundwater Flux 73 4.5 Some P h y s i c a l P r o p e r t i e s Of S o i l s In The Watershed That Are Relevant To Moisture C a p a c i t y 76 4.6 S o i l M o i sture Storage Estimates For The Watershed Under Average And Extreme C o n d i t i o n s 78 6.1 Goat Meadows P r e c i p i t a t i o n Chemistry 117 6.2 Examples Of P r e c i p i t a t i o n Chemistry From Mountainous S i t e s In North America 117 6.3 C o n c e n t r a t i o n - d i s c h a r g e R e l a t i o n s h i p s At The Basin O u t l e t Weir 121 6.4 Geochemical Budgets For Goat Meadows Watershed, Basin x i i 6.5 Denudation Rates For Goat Meadows Watershed, Basin O u t l e t Weir 123 6.6 Comparison Of Mean Solu t e C o n c e n t r a t i o n s At The Three Weirs Based On Simaltaneous Sampling 127 6.7 Denudation Rates And T o t a l Mass Denuded For Goat Meadows And Subcatchments Based On The Mean Of Simaltaneous Samples C o l l e c t e d At The Three Weirs, 1980 129 7.1 R e l a t i v e Abundance Of M i n e r a l s In Modern Loess Near Goat Meadows 141 7.2 Approximate Molar R a t i o s Of Elements In Bedrock, V o l c a n i c G l a s s , And Loess 141 7.3 R e l a t i v e Abundance Of C r y s t a l l i n e Clay M i n e r a l s In S o i l s 145 7.4 R e l a t i v e Molar Abundance Of Elements Denuded From Mosquito Catchment And In Bedrock And V o l c a n i c G l a s s ...156 7.5 Mean Con c e n t r a t i o n Of Water Solube S a l t s From S o i l Horizons And Variance E x p l a i n e d By S o i l Horizon 164 7.6 A n a l y s i s Of Variance In C a p i l l a r y S o i l S o l u t i o n s As A Function Of Major S o i l Group 168 8.1. Mean Co n c e n t r a t i o n Of H y d r o l o g i c Flow Components 178 8.2 Regional Denudation Estimates 184 8.3 L o c a l Denudation Estimates 184 8.4. Amount Of S o l u t e s Stored In S o i l s As Water S o l u b l e S a l t s And As D i s s o l v e d Load In S o i l S o l u t i o n s 188 8.5. Flux Rates And Storage Amounts Of S o l u t e s , 1980 188 9.1 Major Hydr o l o g i c R e s e r v o i r s In The Biogeochemical Cascade At Goat Meadows 195 x i i i ACKNOWLEDGEMENTS Th i s research was funded by N a t u r a l Sciences and En g i n e e r i n g Research C o u n c i l o p e r a t i n g grant 67-7073 to Dr. 0. Slaymaker at the Department of Geography, U n i v e r s i t y of B r i t i s h Columbia and by grants from the U n i v e r s i t y of B r i t i s h Columbia A r c t i c and A l p i n e Committee. Many people have c o n t r i b u t e d d i r e c t l y to t h i s d i s s e r t a t i o n . My s u p e r v i s o r , Dr. H. Olav Slaymaker, pr o v i d e d unwavering encouragement and advice while s h i e l d i n g me from a l l a d m i n i s t r a t i v e o b s t a c l e s . The r e s e a r c h committee, Dr. Les M. L a v k u l i c h , Dr. J . Ross Mackay, and Dr. W i l l i a m H. Mathews, were a l s o s u p p o r t i v e throughout my r e s e a r c h . R. Dan Moore, Sarah Chaney, Rod Haynes, and Gary B a r r e t t were i n v a l u a b l e f i e l d a s s i s t a n t s . Dr. H. S c h r e i e r , Dr. M. Church, and Gary B a r r e t t reviewed the manuscript and suggested important improvements. Rob R a i n b i r d and Sarah Chaney c o n t r i b u t e d to the d e s c r i p t i v e appendices. I have a l s o been helped, i n one way or another, by the f o l l o w i n g people: Dr. R.H.T. Smith, Dr. Marc B u s t i n , Pat T e t i , C a r o l e R u t t l e , A l and M a r t i S t a h l i e , Dr. B i l l Milsom, Mike P a t t e r s o n , Bev Harmon, Penny Jones, John Radke, Ben Moffat, E l l e n P e t t i c r e w , Eldon T a l b o t , Arthur and Miriam F a l l i c k , Dr. John Lowman, Dr. G.E. Rouse, Dr. Douw S t e i n , and the A r m a d i l l o s . S p e c i a l thanks go to Gary B a r r e t t f o r frequent, l i v e l y debate and to Tom and Cordtsy G a l l i e for pa t i e n c e and support. 1 Chapter 1 INTRODUCTION Denudation i s the lowering of the earth's s u r f a c e by mechanical and chemical weathering, t r a n s p o r t and e r o s i o n processes (Small, 1978). Chemical denudation i s i n i t i a t e d by aqueous d i s s o l u t i o n or a l t e r a t i o n of l i t h i c m a t e r i a l s . Primary mi n e r a l s are converted to secondary products that are more n e a r l y i n thermodynamic e q u i l i b r i u m with t h e i r immediate s u b a e r i a l environments ( K e l l e r , 1968). Some weathering products are s o l u b l e . These s o l u t e s are t r a n s p o r t e d v i a the h y d r o l o g i c system from c o n t i n e n t a l sources to oceanic s i n k s . C o n t i n e n t a l s o l u t e exports have been i n v e n t o r i e d with i n c r e a s i n g p r e c i s i o n s i n c e the l a t e 19th century (Murray, 1887; Dole and S t a b l e r , 1909; C l a r k , 1924; Conway, 1942; L i v i n g s t o n e , 1963). R i v e r s d e l i v e r more than 5 x 10 9 metric tonnes of d i s s o l v e d matter to the oceans each year ( G a r r e l s & Mackenzie, 1971). Chemical denudation i s only one of three major processes that c o n t r o l t h i s l o a d . Atmospheric d e p o s i t i o n and e v a p o r a t i v e f r a c t i o n a l c r y s t a l l i z a t i o n are a l s o i n f l u e n t i a l (Gibbs, 1970). T h i s f a c t c o m p l i c a t e s denudation s t u d i e s . C o n t i n e n t a l exports c o n t a i n s u b s t a n t i a l q u a n t i t i e s of s a l t s from the atmosphere and anions d e r i v e d from atmosphere-biosphere i n t e r a c t i o n s . A s i g n i f i c a n t and c h e m i c a l l y i n d i s t i n g u i s h a b l e q u a n t i t y of anions i s d e r i v e d from chemical weathering of carbonate t e r r a i n s . L i t h o s p h e r i c c a t i o n s and s i l i c o n c e r t a i n l y make up l e s s than f o r t y percent of d i s s o l v e d c o n t i n e n t a l exports 2 (Janda, 1971). C o n t i n e n t a l export r a t e s of ions are h i g h l y v a r i a b l e . They range from 2 tonnes km"2 y r " 1 f o r A u s t r a l i a to 42 tonnes km"2 y r " 1 f o r Europe ( G a r r e l s and Mackenzie, 1971). Important f a c t o r s causing s p a t i a l v a r i a b i l i t y of export r a t e s are the l i t h o l o g y ( G a r r e l s and Mackenzie, 1971), annual run o f f (Langbein and Dawdy, 1964; L e i f e s t e , 1974), and ecosystems of the regions from which the water d r a i n s (Douglas, 1972; V i t o u s e k and Re i n e r s , 1976). An a d d i t i o n a l but r a r e l y c i t e d f a c t o r a f f e c t i n g c o n t i n e n t a l export r a t e s may be a g r i c u l t u r a l and i n d u s t r i a l p o l l u t i o n , e s p e c i a l l y i n Europe. S p a t i a l i n t e g r a t i o n at l a r g e s c a l e s obscures causal r e l a t i o n s h i p s . R e s o l u t i o n of r a t e s and processes has improved over the past two decades by i n t e n s i v e i n t e r d i s c i p l i n a r y study of small watersheds (Hewlett et a l . , 1969; Ward, 1971; Likens et a l . , 1977). Watersheds are d e f i n a b l e c o n t r o l volumes through which mass input-output r e l a t i o n s h i p s can be measured. Mass budgets, in t u r n , provide a format f o r i n t e r r o g a t i n g i n t e r n a l mass cascades. Within a small watershed l i t h o l o g y , c l i m a t e and ecosystem can be r e l a t i v e l y c o n t r o l l e d and the watershed can be viewed as a c o n s t r a i n e d biogeochemical system. However, even in small watersheds, g e n e r a l i z a t i o n s can be e l u s i v e . I n t e r a c t i o n s among f a c t o r s are complex. The range of m a t e r i a l and geometric v a r i a b i l i t y , even on a small p o r t i o n of the e a r t h ' s s u r f a c e , i s l a r g e . Observation i s confounded by the time v a r i a n t nature of c l i m a t i c (and t e c t o n i c ) events which d r i v e n a t u r a l systems. Thus, the most robust watershed biogeochemical models are currently conceptual. For example, Bormann and Likens (1979) suggested a general model of biogeochemical fluxes for small undisturbed watersheds based simply on solute occurrences in sources and sinks (Figure 1.1). Inputs to the system occur from rock weathering and ATMOSPHERIC DEPOSITION bulk precipitation | WATERSHED BOUNDARY ORGANIC MATTER AVAILABLE NUTRIENTS ROCK AND SOIL Bound uptake Fluctuating Exchangeable weathering Bound * 1 1 | t 1 living dead biomass biomass 1 * (•aching y soil solutions 1 1 exchange sites t ••condary decomposition mineral ^ formation v-HYDROLOGIC EXPORT streamflow and groundwater Figure 1.1 A conceptual model of small watersheds as biogeochemical systems (after Likens et a l . , 1977, p. 3 and Bormann and Likens, 1979, p. 35). atmospheric deposition. The former source i s denudational, the l a t t e r source i s not. The background flux of c y c l i c s a l t s and biospheric-atmospheric products must be subtracted from the load exported in streamflow and groundwater in order to derive denudation. The remaining components are intervening sinks or storage reservoirs which regulate int e r n a l fluxes, causing lags between i n i t i a l rock weathering and eventual export. T r u d g i l l (1977) 4 c l a s s i f i e d these s i n k s a c c o r d i n g to t h e i r response time. Long term i o n i c r e s e r v e s occur as bound ions i n p l a n t and animal t i s s u e s and i n secondary s o i l m i n e r a l s . Intermediate r e s e r v e s are exchangeable ions on c l a y and humus complexes. Short term or f l u c t u a t i n g reserves are ions d i s s o l v e d i n s u r f a c e , s o i l , and groundwaters w i t h i n the catchment. The r e l a t i v e c a p a c i t i e s of these s i n k s to one another and to input/output r a t e s are important r e g u l a t o r y f a c t o r s for denudation i n time and space. Thus, without an accounting of the s t a t u s of these s t o r e s , denudation estimates from short term s t u d i e s can be m i s l e a d i n g . For example, c u r r e n t export r a t e s at Hubbard Brook Experimental F o r e s t , New Hampshire, when c o r r e c t e d f o r c y c l i c s a l t s , are estimated to be one h a l f the c u r r e n t r a t e of rock weathering because the biomass i s aggrading and s t o r i n g s o l u b l e weathering products (Likens e t . a l . , 1977). T h i s g e n e r a l l e v e l of r e s o l u t i o n ( f i g u r e 1.1) i s the aim of the c u r r e n t study. I t documents and i n t e r p r e t s geochemical budgets f o r a 2.3 hec t a r e watershed l o c a t e d on s i l i c e o u s l i t h o l o g y i n the a l p i n e - s u b a l p i n e ecotone (Love, 1970), Coast Mountains, B r i t i s h Columbia. The purpose of the resea r c h i s to i d e n t i f y environmental f a c t o r s causing s p a t i a l v a r i a b i l i t y of denudation r a t e s near t r e e l i m i t . T h i s environment i s of i n t e r e s t because i t p r o v i d e s s e v e r a l types of undisturbed, s o i l - v e g e t a t i o n systems juxtaposed w i t h i n a n i v a l c l i m a t e . The s i t e a l l o w s e f f i c i e n t study of major c o n t r o l s on chemical denudation because the c o n t r o l area i s s m a l l . Before d i s c u s s i n g the research plan i t w i l l be u s e f u l to 5 review b r i e f l y the most important denudation s t u d i e s on g r a n i t i c l i t h o l o g i e s . Supporting concepts i n the geochemistry and hydrology of s u r f i c i a l environments can be found in standard t e x t s such as G a r r e l s & C h r i s t (1965), Stumm and Morgan (1970), G a r r e l s and Mackenzie (1971), B i r k e l a n d (1974), Freeze and Cherry (1979), Drever (1982) and i n l i t e r a t u r e c i t a t i o n s by D e t h i e r (1977, p. 1-5). Antecedent Research Anders Rapp (1960) measured s o l u t e exports of 26 tonnes km"2 y r ~ 1 from Rarkevagge, i n Lappland, Sweden. The load was dominated by s u l f a t e s which Rapp i n f e r r e d were d i s s o l v e d from bedrock f r a c t u r e s i n heterogeneous l i t h o l o g i e s ( p h y l l i t i c s c h i s t s , limestone and q u a r t z i t e ) and from a m i c a - s c h i s t t i l l . Rapp a l s o presented evidence that r e g i o n a l denudation r a t e s were much lower (10 - 15 tonnes km"2 y r " 1 ) , because Lappland i s p r i m a r i l y u n d e r l a i n by more s t a b l e a m p h i b o l i t e s . Rapp's chemical measurement program was a n c i l l a r y to a more comprehensive a n a l y s i s of mechanical e r o s i o n processes so Rapp's chemical o b s e r v a t i o n s were not d e t a i l e d . Nonetheless, the study was exceedingly important because i t demonstrated that chemical denudation was the s i n g l e most important mass t r a n s f e r process i n an a r c t i c environment. T h i s c o n c l u s i o n c o n t r a d i c t e d the p r e v a i l i n g assumption that low temperatures i n h i b i t e d geochemical p r o c e s s e s . M i l l e r (1961) and Hembree and Rainwater (1961) measured denudation from two mountain ranges i n s e m i - a r i d U.S.A.. Both 6 s t u d i e s reached s i m i l a r c o n c l u s i o n s . S o l u t e c o n c e n t r a t i o n s i n stream baseflow were ne a r l y constant f o r watersheds of s i m i l a r l i t h o l o g y and catchment areas g r e a t e r than about 8 km2. T h i s was i n t e r p r e t e d to mean that " r a p i d e q u i l i b r i u m " o c c u r r e d between water and rock, independent of v e g e t a t i v e and p e d o l o g i c a l v a r i a b i l i t y . Thus, denudation r a t e s on uniform l i t h o l o g i e s were seen to be a simple f u n c t i o n of mean annual runoff ( c f . Carson and Kirkb y , 1972). V a r i a t i o n s between l i t h o l o g i e s were a t t r i b u t e d to the most s o l u b l e m i n e r a l o g i c sources. For example, C a r b o n i f e r o u s sandstones i n the Sangre de C r i s t o Range ( M i l l e r , 1961) produced high y i e l d s due to carbonate cements and t h i n limestone beds which were l e s s than 1% of the t o t a l rock u n i t . Gibbs (1967a, 1967b) s t u d i e d the geochemistry of Amazon Riv e r and deduced that 80% of the s o l u t e l o a d was d e r i v e d from the Andes Mountains which comprise only 12% of the bas i n a r e a . Gibbs c o u l d not i n f e r the c o n t r o l l i n g processes at t h i s s c a l e but the study was important because i t i n t r o d u c e d two concepts to the western l i t e r a t u r e . The f i r s t concept was that " r e l i e f " i s a surrogate f a c t o r i n chemical denudation. Drever (1982, p. 198) suggested that i n some s e t t i n g s t h i s f a c t o r may be r e l a t e d to the a b i l i t y of mechanical e r o s i o n to expose f r e s h rock s u r f a c e s f o r a t t a c k by chemical weathering. Carson and Kirkby (1972) suggested t h i s may simply r e l a t e to i n c r e a s i n g runoff r a t i o s at hi g h a l t i t u d e s . Kazarinov e t . a l . (1966) repor t e d e a r l i e r r e f e r e n c e s from the S o v i e t l i t e r a t u r e which r e l a t e d r e l i e f to i n t e n s i f i e d chemical denudation r a t e s . 7 Kazarinov e t . a l . (1966) proposed that mountains provide e l e v a t i o n head f o r high groundwater p o t e n t i a l s and la r g e volumes of j o i n t e d and f r a c t u r e d rock. T h i s combination was seen to prov i d e abundant d i s c h a r g e from long r e s i d e n c e time flowpaths and thus high s o l u t e l o a d s . T h e i r suggestion that denudation r a t e s be expressed as tonnes of s o l u t e removed per km3 of massif above the thalweg was l a r g e l y ignored i n the western l i t e r a t u r e . The second concept i n t r o d u c e d by Gibbs was that a small a r e a l source c o u l d dominate denudation from a much l a r g e r a r ea. T h i s f u r t h e r r e i n f o r c e d M i l l e r ' s (1961) o b s e r v a t i o n that s p a t i a l sampling was necessary i f proper i n t e r p r e t a t i o n s were to be drawn from geochemical budgets. Marchand (1971, 1974) e x p l a i n e d aspects of denudation i n the White Mountains, C a l i f o r n i a in terms of thermodynamic e q u i l i b r i u m with secondary products which he i d e n t i f i e d from p e t r o g r a p h i c and e l e c t r o n microprobe study of s o i l mineralogy. Marchand r e l a t e d the course of r e a c t i o n s to s t o i c h i o m e t r i c r e l a t i o n s h i p s among s o i l , stream, and s p r i n g waters and primary m i n e r a l s . From t h i s he suggested that chemical d i s e q u i l i b r i u m b e t t e r c h a r a c t e r i z e d the system. Steady s t a t e c o n c e n t r a t i o n s were only approached i n shallow groundwater routes and a c o n s i d e r a b l e "time-space i n t e r v a l " was necessary to achieve these steady s t a t e s . In sh o r t , Marchand i n d i r e c t l y suggested that the mean re s i d e n c e time of water i n the watershed can a f f e c t t o t a l denudation r a t e . Laney (1971) a l s o recognized t h i s f a c t and couched e x p l a n a t i o n s f o r t o t a l denudation from the Santa C a t a l i n a Range, 8 in terms of approximate rock-water contact times of s o i l water and s p r i n g water. Laney's h y d r o l o g i c data were inadequate to develop the concept q u a n t i t a t i v e l y . Throughout t h i s same p e r i o d , p u b l i c a t i o n s began appearing from e c o l o g i c a l s t u d i e s based on m u l t i - y e a r geochemical budgets of small f o r e s t e d watersheds ( V i t r o , 1953; Cole et a l . , 1967; Johnson et a l . , 1968; F r e d r i k s e n , 1972; Johnson and Swank, 1973). E c o l o g i s t s were concerned with long-term trends in biomass systems. They measured elements of b i o l o g i c a l importance that were near a n a l y t i c a l d e t e c t i o n l i m i t s and rec o g n i z e d more f u l l y the complexity of s o i l and h y d r o l o g i c systems. As a r e s u l t of t h e i r emphasis on mass budget formats, standards of chemical and h y d r o l o g i c e x p l a n a t i o n v i s - a - v i s denudation s t u d i e s improved s i g n i f i c a n t l y . The most widely p u b l i s h e d group of e c o l o g i s t s was connected with the Hubbard Brook Experimental F o r e s t , White Mountains, New Hampshire. Likens et a l . (1977) and Bormann and Likens (1979) summarized a decade of r e s e a r c h and c i t e d most of the r e l e v a n t i n t e r m e d i a t e p u b l i c a t i o n s . Two of t h e i r most important c o n t r i b u t i o n s to denudation s t u d i e s were the r e c o g n i t i o n that b i o l o g i c a l s t o r e s can s i g n i f i c a n t l y r e g u l a t e s o l u t e export r a t e s over p e r i o d s of decades and that i n t e r n a l b i o t i c and a b i o t i c c o r r o s i v e sources are v a r i a b l e and are as important as the atmospheric sources i n d r i v i n g r e a c t i o n s . Cleaves e t . a l . (1970) i n t e g r a t e d e v o l v i n g ecosystems models with the v a r i a b l e source area concept of hydrology (Betson and Marius, 1969; Dunne and Black, 1970a, 1970b) to 9 e x p l a i n the dynamics of denudation at Pond Branch Watershed i n Maryland. T h i s group combined s p a t i a l and temporal sampling with mass budget techniques, c a l c u l a t e d mass exchange between primary and secondary m i n e r a l s , and i n f e r r e d t h a t d i s c r e t e hydrochemical source areas e x i s t e d . They produced a conceptual biogeochemical model based on runoff mechanisms and the d i s t r i b u t i o n of secondary m i n e r a l s . T h e i r data suggested the zone of maximum weathering i n t e n s i t y was l o c a t e d at the base of s a p r o l i t e s on s i d e slopes but that s o l u t e exports were dominantly c o n t r o l l e d by a l a r g e f l u c t u a t i n g s t o r e of s o l u t e s i n p h r e a t i c zones of v a r i a b l e source areas. Denudation in the C o a s t a l C o r d i l l e r a The above f i n d i n g s on c o n t r o l s of chemical denudation r a t e s are extremely g e n e r a l and are t h e r e f o r e d i f f i c u l t to apply i n an o p e r a t i o n a l sense. The f o l l o w i n g s t u d i e s from the perhumid c o a s t a l c o r d i l l e r a i l l u s t r a t e t h i s p o i n t w e l l . Reynolds and Johnson (1972) conducted the f i r s t h i g h - a l t i t u d e denudation study i n oceanic North America around South Cascade G l a c i e r , Washington U.S.A. Reynolds (1971) had p r e v i o u s l y shown that pedogenic c l a y minerals were abundant above t r e e l i m i t and argued that deep r e s i d u a l s o i l s were absent only because of the r a p i d i t y of mechanical e r o s i o n , not because of thermodynamic l i m i t a t i o n s on weathering. Reynolds and Johnson (1972) expanded on t h i s theme by demonstrating that c l a y mineral assemblages and water chemical f a c i e s covary with bedrock l i t h o l o g y and that water becomes r a p i d l y m i n e r a l i z e d 10 d e s p i t e low ambient temperatures. They a l s o presented anion analyses that i m p l i c a t e d c a r b o n a t i o n as an important source of c o r r o s i v e p o t e n t i a l for weathering. Reynolds and Johnson's estimated c a t i o n i c denudation r a t e s at 14 tonnes km - 2 y r - 1 (28 tonnes km - 2 y r " 1 i f s i l i c o n i s i n c l u d e d ) . T h i s f i g u r e was hig h f o r a g r a n i t i c t e r r a i n ( f i g u r e 1.2) although i t should be noted that the l o c a l l i t h o l o g i e s were heterogeneous. The estimate was based n e i t h e r on a water budget nor on year round s o l u t e sampling but the approximation techniques appear reasonable. I o n i c c o n c e n t r a t i o n s at the bas i n o u t l e t were c o n s e r v a t i v e . Monthly discharge at the basin o u t l e t v a r i e d by a f a c t o r of ten while streamflow c o n c e n t r a t i o n s v a r i e d by a f a c t o r of only two. Futhermore, the authors p o i n t out that high denudation r a t e s are to be expected, given the magnitude of annual stream d i s c h a r g e . Reynolds and Johnson i n t e r p r e t e d these high c a t i o n i c denudation r a t e s to mean that temperate a l p i n e environments have intense r a t e s of surface weathering. They defended t h i s c o n c l u s i o n i n s e v e r a l ways. F i r s t , a r e p r e s e n t a t i v e sample from the a l p i n e catchment was c h e m i c a l l y s i m i l a r to two downstream r i v e r samples. T h i s was i n t e r p r e t e d to mean that the chemistry of waters d r a i n i n g Cascade mountains was f i x e d by weathering r e a c t i o n s before l e a v i n g a l p i n e environments. Second, g l a c i a l e r o s i o n p r o v i d e s many f r e s h m i n e r a l s u r f a c e s which, Reynolds and Johnson proposed, i n t e n s i f y r a t e s of subareal weathering. T h i r d , they hypothesize that the c o r r o s i v e p o t e n t i a l of water i s enhanced by t u r b u l e n t a e r a t i o n on steep mountain s l o p e s . ) 1 3 4 Annual Runoff (m) F i g u r e 1.2 Annual geochemical denudation r a t e s as a f u n c t i o n of annual run o f f f o r watersheds on g r a n i t i c l i t h o l o g i e s . See t a b l e 1.1 f o r suppo r t i n g i n f o r m a t i o n . A e r a t i o n i n c r e a s e s the q u a n t i t y of d i s s o l v e d gases in water, which i n turn i n c r e a s e s t h e i r a g g r e s s i v e n e s s as geochemical s o l v e n t s . The e f f e c t should be enhanced by c o l d , a l p i n e waters because carbon d i o x i d e s o l u b i l i t y i s i n v e r s e l y r e l a t e d t o temperature. In c o n t r a s t , F e l l e r (1974, 1977), Zeman (1975), and Zeman and Slaymaker (1978) measured r e l a t i v e l y modest geochemical budgets f o r s e v e r a l watersheds i n the southern Coast Mountains Table 1.1 Denudation ecosystems. ra t e s on s i l i c e o u s l i t h o l o g i e s with r e l a t i v e l y u n d isturbed Locat ion Area (ha) Sangre de C r i s t o 44 Range, New Mexico 3360 Santa C a t a l i n a Mtns., New Mexico 1800 Annual Prec Runoff (m) (m) 0.1 0.6 0.79 0.18 White Mtns. C a l i f o r n i a 274 0.43 0.14 4 Wind River Range,19632 Wyoming 5413 5 J u l i a s d a l e and 91 Rusapela, Zimbabwa 733 6 Tesque Watershed 163 #15, New Mexico 9 Coweeta #18, 12 North C a r o l i n a 8 Hubbard Brooke, White Mtns, N.H. 7 Pond Branch, Maryland 38 10 Rawson Lake, O n t a r i o 396 0.90 0.36 1 .22 0.92 0.74 1.80 0.95 1.32 0.83 0.2 0.70 0.22 0.97 0.35 L i t h o l o g y ; Envi ronment QM; LM to A. GD; LM to UM. A; s. G; LM to AG. G; s . G; UM to A. G, MG, MS; MF. QM, FS-; MF. FS; MF. GD; BF. Denudation Reference (tonnes/km 2/yr) S i C a t i o n s T o t a l 0.6 6.1 M i l l e r , 1961 1.29 0.81 2.1 Laney, 1971 1.13 3 .18 4.3 Marchand, 197 1 6.4 Hembree and 2.2 Rainwater, 1961 2.36 1 .56 3.7 Owens and 0.60 0.61 1.2 Watson, 1979 1.41 0.91 Gosz, 1980 Johnson and Swank, 1973 Likens et a l . , 1.81 3.75 5.6 1977 Cleaves et a l . , 1.10 0.73 1.83 1970 S c h i n d l e r 1.21 0.59 1 .81 et a l . , 1976 Table 1.1 continued L o c a t i o n Area Annual L i t h o l o g y ; Denudation Reference (ha) Prec Runoff Environment (tonnes/km 2/yr) (m) (m) Si Ca t i o n s T o t a l 11 Haney A, B.C. 23 2 .67 1 .70 QD;LM. 3. 6 3. 0 6. 6 F e l l e r , 1974 1 2 Jameison Cr., B.C. 300 3 .67 QD,QS;UM. 4. 3 5. 5 9. 8 Zeman, 1975 1 3 Williamson Creek, 4000 3 .33 3 .65 QD,QS; 6. 1 2 18. 3 24. 4 14 and 4 .86 5 .05 LM to UM. 9. 9 29. 7 38. 6 De t h i e r , 1977 1 5 Copper Lake, 500 4 .5? QD,QS; 3. 3 10. 2 13. 5 1 6 Washington 6 .2? AG to UM. 4. 5 12. 4 16. 9 1 7 South Cascade QD,MS; Reynolds and G l a c i e r , Wash. 6400 3 .84 4 . 1 AG. 7. 0 20. 7 27. 7 Johnson, 1972 18 Birkeness and 1 .35 1 .04 G,FS; 0. 8 Gj e s s i n g et a l ; 19 Fy r e s d a l / N i s s e d a l 25 1 .09 0 .92 BF, H. 0. 4 1976 (6), Norway to 256 key: QM=quartz monzonite or a d a m e l l i t e , G=granites, GD=granodiorite, QD=quartz d i o r i t e , MG=mica g n e i s s , MS=mica s c h i s t s , F S = f e l s i c s c h i s t s , QS=quartzose s c h i s t s . A=alpine, AG=alpine and g l a c e r i z e d , UM=upper montane f o r e s t LM=lower montane f o r e s t , MF=mixed, mostly hardwood, f o r e s t , BF=boreal f o r e s t , H=heathland, S=steppe or savana. 1 4 of B r i t i s h Columbia. F e l l e r ' s watersheds are l o c a t e d at the UBC Research F o r e s t near Haney B.C.. Zeman and Slaymaker monitored Jamieson Creek, about 25 km west of Haney. F e l l e r ' s purpose was to study the e f f e c t of c l e a r c u t t i n g on s o l u t e y i e l d s and Zeman and Slaymaker focused t h e i r r e s e a r c h on p r e c i p i t a t i o n chemistry so n e i t h e r study d i s c u s s e d weathering mechanisms d i r e c t l y . F e l l e r d i d examine s o l u t e exchanges at s e v e r a l l e v e l s of the h y d r o l o g i c cascade and determined that most mass t r a n s f e r o c c u r r e d w i t h i n humic epipedons of f o r e s t s o i l s . Denudation r a t e s from the Coast Mountain s i t e s were a l l very s i m i l a r and were roughly one t h i r d of those from South Cascade G l a c i e r . These r e s u l t s are troublesome because while the Coast Mountain s i t e s are a l s o g r a n i t i c (quartz d i o r i t e ) , they o v e r l a p one another i n a l t i t u d e , ranging from lower montane to a l p i n e ecosystems (Love, 1970) and vary g r e a t l y i n annual water budgets. Haney has one t h i r d the annual runoff of South Cascade G l a c i e r which may e x p l a i n i t s modest denudation r a t e . However, Jamieson Creek had water budgets of the same magnitude as South Cascade G l a c i e r . D e t h i e r (1977) conducted a d e t a i l e d geochemical and h y d r o l o g i c study of Williamson Creek and a g l a c e r i z e d subcatchment, Copper Lake, i n Washington S t a t e . D e t h i e r c o n t r i b u t e d to the f i e l d i n g e n e r a l , by i n t e g r a t i n g geochemical and h y d r o l o g i c concepts with then developing models of metal and anion f l u x e s i n s o i l systems (McC o l l , 1973; Johnson, 1975). The study was e x c e p t i o n a l i n i t s scope, given the l a r g e s c a l e (40 km2) of the study a r e a . 15 D e t h i e r a l s o demonstrated that montane catchments at Williamson Creek had higher denudation r a t e s , d e s p i t e lower r u n o f f , than t h e i r a l p i n e headwaters and that c o n s e r v a t i v e i o n i c f l u c t u a t i o n s i n s i m i l a r Cascade r i v e r s are due to compensatory seasonal mixing between a l p i n e and montane runoff sources. D e t h i e r e x p l a i n e d the d i s c r e p a n c y between montane and a l p i n e r a t e s i n terms of " s l i g h t l y h i g h e r " s o l u t e c o n c e n t r a t i o n s i n f o r e s t s o i l s o l u t i o n s which were c o r r e l a t i v e with i n c r e a s e d carbon d i o x i d e gas c o n c e n t r a t i o n s , and thus r e a c t i o n k i n e t i c s and l e a c h i n g r a t e s , i n s o i l s . In f a c t , by mass c o n s e r v a t i o n , f o r e s t e d catchments must have denuded at about 28 tonnes km"2 (compared to 13 tonnes km"2 i n a l p i n e catchments) dur i n g 1973. T h i s r e s u l t i s , however, problematic because Jamieson Creek has s i m i l a r l i t h o l o g y , f o r e s t cover, a l t i t u d i n a l range and n e a r l y i d e n t i c a l annual run o f f but only one t h i r d the denudation r a t e of Williamson Creek. Only minor l i t h o l o g i c a l d i f f e r e n c e s e x i s t between these watersheds. Jamieson Creek i s u n d e r l a i n by quartz d i o r i t e and a small (20%) area of metasedimentary roof pendant. Williamson Creek i s u n d e r l a i n by quartz d i o r i t e and an a r g i l l a c e o u s c h e r t - s l a t e - g r a y w a c k e . Dethier (1977, p. 161) a l s o noted no d i f f e r e n c e s i n s u r f a c e waters i n co n t a c t with e i t h e r l i t h o l o g y in Copper Lake catchment. L i t h o l o g y i s thus not a l i k e l y e x p l a n a t i o n f o r d i f f e r e n c e s t h i s l a r g e . B i o l o g i c a l r e g u l a t i o n i s a l s o u n l i k e l y to be a s i g n i f i c a n t f a c t o r . Jamieson Creek i s c h a r a c t e r i z e d by Zeman as mature and over-mature Mountain Hemlock f o r e s t which suggests the biomass 1 6 i s s t a b l e . D e t h i e r suggested that the d o u b l i n g in denudation r a t e s between South Cascade G l a c i e r and Copper Lake was due to d i f f e r e n c e s i n p l a g i o c l a s e f e l d s p a r s and mafic minerals between b a s i n s . T h i s may be t r u e , but i t i s not w e l l supported by the data i n F i g u r e 1.2 and Table 1.1. Only small r e l a t i v e d i f f e r e n c e s i n r a t e s can be seen between catchments of s i m i l a r runoff and having greater apparent d i f f e r e n c e s i n mineralogy than those between the two a l p i n e watersheds. D i s c u s s i o n G e n e r a l i z a t i o n s concerning the c o n t r o l s on chemical denudation are e s s e n t i a l l y black box models and do not appear to advance our understanding of cause and e f f e c t r e l a t i o n s h i p s i n these l a r g e s c a l e systems. I t appears that attempts to e x p l a i n s p a t i a l v a r i a b i l i t y in denudation r a t e s have been hampered by inadequate s p a t i a l sampling because the s t r a t a chosen have been too l a r g e and heterogeneous. For example, Reynolds and Johnson's (1972) three e x p l a n a t i o n s f o r i n t e n s i f i e d r a t e s of chemical denudation above t r e e l i m i t can be s p e c i f i c a l l y c r i t i c i s e d on the grounds of inadequate temporal and s p a t i a l sampling and inadequate a t t e n t i o n to p h y s i c a l h y d r o l o g i c mechanisms, to w i t : i . the s i m i l a r i t y between a l p i n e and lowland r i v e r water i n the Cascade Range probably occurs because the major source areas f o r r i v e r d ischarge d u r i n g mid-summer runoff are g l a c i a l (Dethier 1.977, p.235). Thus, the s i m i l a r i t y i s to be expected and does not c o r r o b o r a t e i n t e n s i f i e d r a t e s of weathering above t r e e 1 i m i t . i i . while g l a c i a l f l o u r may w e l l provide abundant f r e s h s u r f a c e s f o r m i n e r a l weathering, Reynolds and Johnson d i d not demonstrate what p r o p o r t i o n of runoff has o p p o r t u n i t y to react with g l a c i a l rock f l o u r , i i i . with regards to a e r a t i o n as a mechanism for i n t e n s i f i e d weathering, streams in humid environments are e f f l u e n t , not i n f l u e n t (Freeze and Cherry, 1979, p. 205). Thus, t u r b u l e n t a e r a t i o n should be u n r e l a t e d to r e a c t i o n s w i t h i n the s u r f i c i a l m a t e r i a l s which streams d r a i n . Unless s i g n i f i c a n t weathering r e a c t i o n s occur between streamwater and stream bed and banks, which i s most u n l i k e l y given the contact time and s u r f a c e area r e l a t i o n s h i p s , a c a u s a l l i n k between t u r b u l e n t a e r a t i o n and h i g h r a t e s of s u r f i c i a l weathering appears dubious. D e t h i e r (1977) showed g r e a t e r a t t e n t i o n to p h y s i c a l hydrology but he was hindered by the s c a l e of h i s i n v e s t i g a t i o n from making more i n s i g h t f u l comments on mechanisms. The most problematic of D e t h i e r ' s e x p l a n a t i o n s appears to r e l a t e to the h y d r o l o g i c flowpaths at Williamson Creek. D e t h i e r p r o v i d e s a coherent d i s c u s s i o n of seasonal v a r i a t i o n s i n s o i l s o l u t i o n s on s l o p e s based on b i o l o g i c a l p r o d u c t i v i t y of carbon d i o x i d e gas. S o i l s o l u t i o n c a t i o n c o n c e n t r a t i o n s on s l o p e s , however, are f a r below (Dethier 1977, Tables 60, 62, 65, 66) those i n p h r e a t i c 18 s o i l water zones adjacent to the stream channel network. De t h i e r was aware that groundwater was d i s c h a r g i n g to p h r e a t i c s o i l water zones but he i s vague when attempting to l i n k p h r e a t i c s o i l water c o n c e n t r a t i o n s p h y s i c a l l y to output from vadose zones of s o i l s ( D e t h i e r , 1977, p. 159-186). I t i s i n t e r e s t i n g to note t h a t F e l l e r (1977) was able to l i n k p h r e a t i c s o i l s o l u t i o n s e x p l i c i t l y to vadose zone processes and found an e n t i r e l y d i f f e r e n t c o n c e n t r a t i o n p a t t e r n . At Haney, p h r e a t i c s o i l water i s the l e a s t c o n c e n t r a t e d s o i l water i n the watershed and streamflow i s t h e r e f o r e h i g h l y d i l u t e . Statement of Problem There are l a r g e d i f f e r e n c e s i n denudation r a t e s r e p o r t e d from four s t u d i e s i n the c o a s t a l c o r d i l l e r a on s i m i l a r l i t h o l o g y . The d i f f e r e n c e s cannot be r e s o l v e d s o l e l y i n terms of annual r u n o f f . Nor can the d i s c r e p a n c y be e x p l a i n e d e a s i l y by d i f f e r e n c e s i n v e g e t a t i o n cover. T h i s conundrum may be r e l a t e d to the d i f f i c u l t y of a c h i e v i n g adequate experimental c o n t r o l of m u l t i v a r i a t e systems. The simple f a c t o r s l i t h o l o g y , r u n o f f , and ecosystem are r e l a t i v e l y e a s i l y i d e n t i f i e d s u r r o gates f o r a complex set of environmental f a c t o r s . At the very l e a s t t h i s set of f a c t o r s i n c l u d e s m i n e r a l s t a b i l i t y and s t o i c h i o m e t r y , net b i o l o g i c a l supply of s o l v e n t s , net biogeochemical demand f o r s o l u t e s , and the magnitude and frequency of h y d r o l o g i c events which d r i v e the e n t i r e system. Most biogeochemical s t u d i e s provide r e l i a b l e , s p a t i a l l y i n t e g r a t e d denudation estimates (although u n c o n t r o l l e d estimates 19 are s t i l l r e p o r t e d , i e . E y l e s et a l . , 1982). Fewer s t u d i e s have s y s t e m a t i c a l l y d e f i n e d the s p a t i a l v a r i a b i l i t y of mass t r a n s f e r r a t e s among homogeneous r o c k - s o i l - v e g e t a t i o n u n i t s . T h i s l i m i t s t h e i r power to i n f e r environmental cause and e f f e c t . Even fewer s t u d i e s have e x p l i c i t l y examined h y d r o l o g i c and s o l u t e flowpaths and thus d e f i n e d s o l u t e source a r e a s . T h i s l i m i t s t h e i r power to i n f e r the s i t e s of mass removal. The r e s e a r c h question f o r t h i s study i s : what environmental f a c t o r s c o n t r o l chemical denudation r a t e s i n the study area? The approach taken w i l l be to determine where mass i s removed from the landscape as a necessary p r e c o n d i t i o n f o r e x p l a i n i n g how mass i s removed. Thus the study w i l l pursue the same questions i m p l i c i t in e a r l i e r s t u d i e s by Reynolds and Johnson (1972) and D e t h i e r (1977) but w i l l address the problem from what i s p e r c e i v e d to be a more manageable s t a r t i n g p o i n t . In order to determine where mass i s removed, a mass budget format w i l l be a p p l i e d to a small (2.3 hectare) system. The p h y s i c a l hydrology of the watershed w i l l be i n v e s t i g a t e d to d e f i n e the source areas of runoff and the s p a t i a l v a r i a b i l i t y of runoff g e n e r a t i o n mechanisms. H y d r o l o g i c v a r i a b i l i t y should be a f u n c t i o n of topography, s u r f i c i a l m a t e r i a l s , s o i l development, and v e g e t a t i o n cover (Dunne et a l . , 1975). These same f a c t o r s were e a r l i e r i m p l i c a t e d as important i n f l u e n c e s on s o l u t e g e n e r a t i o n . Thus s p a t i a l and temporal s o l u t e sampling w i l l be i n t e n s i v e and w i l l be based on components of flow and on s o i l - v e g e t a t i o n complexes. R e c o g n i t i o n of p o t e n t i a l runoff and s o l u t e source areas may p r o v i d e s u f f i c i e n t understanding of the 20 l o c a t i o n s of mass t r a n s f e r s to allow unambiguous, mechanistic i n t e r p r e t a t i o n s of mass budgets. O r g a n i z a t i o n The study area w i l l f i r s t be d e s c r i b e d and methods of chemical and h y d r o l o g i c measurement w i l l be o u t l i n e d . Water budgets f o r two years w i l l be presented and runoff generation mechanisms w i l l be d e s c r i b e d . Geochemical budgets w i l l be summarized next. S p e c i f i c i o n i c sources w i l l be i n f e r e d from a n a l y s i s of s p a t i a l v a r i a b i l i t y of water chemistry. The geochemical budgets w i l l then be i n t e r p r e t e d with respect to runoff mechanisms and i o n i c sources to determine the most important c o n t r o l s on denudation here. F o l l o w i n g t h i s , r e s u l t s w i l l be summarized and the i m p l i c a t i o n s f o r past s t u d i e s w i l l be d i s c u s s e d . 21 Chapter 2. STUDY AREA Locat ion Goat Meadows i s a two km2 subalpine parkland l o c a t e d on the upper sl o p e s of a r i d g e between L i l l o o e t R i v e r and M i l l e r Creek, B r i t i s h Columbia ( f i g u r e s 2.1, 2.2). The meadows are about 14 km northwest of Pemberton i n the P a c i f i c Ranges of the Coast Mountains. The study watershed i s a n o r t h - f a c i n g catchment at the c r e s t of Goat Meadows between 1800 m and 1900 m a s l . T h i s catchment w i l l be r e f e r r e d to as Goat Meadows Watershed ( f i g u r e 2.3, 2.4) . Climate The meso-scale c l i m a t e i s c o l d , perhumid. Vigorous a l p i n e g l a c i e r s are common here because the P a c i f i c Ranges are oceanic. Goat Meadows i s very near the l o c a l g l a c i a l e q u i l i b r i u m l i n e a l t i t u d e but winter snowcover d i d not p e r s i s t beyond l a t e September dur i n g the two study years. Hydrometeorological data are l i m i t e d to the two years of study but L i l l o o e t R i v e r , to which the catchment d r a i n s , averages about 1840 mm runoff a n n u a l l y ( G i l b e r t , 1973). Most p r e c i p i t a t i o n (> 70%) f e l l as snow durin g the two study years. T e n q u i l l e Lake snowcourse (B.C. M i n i s t r y of Environment) i s at a s i m i l a r a l t i t u d e 15 km north of Goat Meadows and has a 22 F i g u r e 2 .1 L o c a t i o n of the study region i n southwestern B r i t i s h Columbia, Canada. 2 3 F i g u r e 2.2 L o c a t i o n of Goat Meadows Watershed i n the study r e g i o n . 24 F i g u r e 2.3 S o i l - v e g e t a t i o n a s s o c i a t i o n s i n Goat Meadows Watershed. See t a b l e 2.2 f o r a d e s c r i p t i o n of the map legend. F i g u r e 2.4 Topography and subcatchments w i t h i n Goat Watershed. Meadows 26 28 year mean Hay 1 snowpack of 1260 mm water eq-uili-va-nt ( f i g u r e 2.5). Summer p r e c i p i t a t i o n at Goat Meadows averaged 319 mm f o r 200H 0 J — 1 r 1 F e b r u a r y M a r c h A p r i l M a y F i g u r e 2.5 Mean and extreme snowpack storage (mm we) compared to 1979 and 1980 at T e n q u i l l e Lake snow course (B.C. M i n i s t r y of Envi ronment). the two study years so mean annual p r e c i p i t a t i o n at T e n q u i l l e Lake i s probably on the order of 1600 mm. Maximum May f i r s t accumulation at T e n q u i l l e Lake i s over 1800mm so i n wet years the annual t o t a l l i k e l y exceeds 2000 mm. Net winter accumulation and summer p r e c i p i t a t i o n at Goat 27 Meadows was 1232 mm and 1331 mm d u r i n g 1979 and 1980 r e s p e c t i v e l y . These were dry winters i n the southwestern Coast Mountains ( t a b l e 2.1). T e n q u i l l e Lake experienced a record low snowpack storage on June 1, 1979 due to low winter accumulation coupled with unusually high s p r i n g a b l a t i o n r a t e s . The 1980 accumulation season was wetter but n e i t h e r year appears r e p r e s e n t a t i v e of l a t e 20th century c l i m a t i c means. Table 2.1 Table 2.1. Comparison of average to 1979 and 1980 snowpack f o r 1 May at high a l t i t u d e snow courses i n the r e g i o n with records of 10 years or more. Snowcourse a l t itude years of May 1 1 979/ 1980/ Name (m) re c o r d mean(mm) mean mean W h i s t l e r Mtn. 1450 1 1 766 .57 .70 T e n q u i l l e Lake 1680 28 1 262 .57 .78 McGi11ivray 1800 29 658 .55 .78 M i s s i o n Ridge 1850 1 4 661 .58 .51 Green Mtn. 1710 20 737 .54 .69 suggests that high a l t i t u d e s i t e s i n the region had about 56% and 69% of t h e i r average May 1 snowpacks i n 1979 and 1980. Applying these f a c t o r s to the Goat Meadows data y i e l d s an estimated May 1 average snowpack of about 1500 mm and and average annual p r e c i p i t a t i o n near 1800 mm. Temperatures at Goat Meadows ranged from -40° C to +23° C dur i n g 1979 and -21°C to +21°C d u r i n g 1980. The extreme 1979 minimum oc c u r r e d d u r i n g an outbreak of c o n t i n e n t a l a r c t i c a i r that brought the c o l d e s t temperatures i n 11 years to s o u t h - c o a s t a l B.C. (Environment Canada, Canadian Weather Review). The mean annual a i r temperature f o r the study p e r i o d i s estimated to be 1° C. T h i s estimate i s crude because i t i s made 28 by combining a b l a t i o n season records at Goat "Meadows with accumulation season records at W h i s t l e r Roundhouse ( f i g u r e 2.6). 30 o o a> a. £ CO - 3 0 k; WhlstUr X Q o . l M . « d o w . X Missing > < Whls tUr X Qo.t Meadows XMUtlngXWhls l ler \ \ \ i 1 1 1 1 1 1 1 r D J F M A M J J A S 1979 ~ l 1 1 1 1 1 1 1 1 1 1 1 1 r— O N D J F M A M J J A S O N D 1980 F i g u r e 2.6. Mean monthly temperatures at Goat Meadows (1850 m) and W h i s t l e r Roundhouse (1902 m) f o r the study p e r i o d . Mean annual temperature was c a l c u l a t e d (1° C) a f t e r j o i n i n g these records with s t r a i g h t l i n e s . Bedrock L o c a l bedrock i s an a s s o c i a t i o n of metasediments and quartz d i o r i t e . The former were mapped by Woodsworth (1977) as l a t e Cretaceous Gambier Group and the l a t t e r belong to the Coast P l u t o n i c Complex (Roddick, 1976). The metasediments are part of a roof pendant surrounded by d i o r i t i c i n t r u s i v e s ( f i g u r e 2.7). Re p r e s e n t a t i v e samples are d e s c r i b e d from t h i n s e c t i o n i n Appendix A. The dominant l i t h o l o g y here (68%) i s a F i g u r e 2.7. Bedrock at Goat Meadows. 30 q u a r t z - a c t i n o l i t e - c h l o r i t e s c h i s t (#302) but the metamorphic group i s heterogeneous and metavolcanics (#300) are common. P l u t o n i c i n t r u s i o n produced a 5 m a u r eole of c a l c ium s i l i c a t e h o r n f e l s v i s i b l e along the south shore of the l a k e . The c o n t a c t i s bounded by a d i s l o c a t i o n zone of t i g h t i s o c l i n a l f o l d i n g to the south which i s h i g h l y f r a c t u r e d . The quartz d i o r i t e (#31) outcrops c o n t i n u o u s l y along the northwest boundary of the catchment. It i s f o l i a t e d and of middle to upper g r e e n s c h i s t f a c i e s metamorphism. Post i n t r u s i v e hydrothermal a l t e r a t i o n i s i n d i c a t e d by the presence of accessory p y r i t e , epidote, c h l o r i t e and s e r i c i t e . Dyke swarms of v e s i c u l a r b a s a l t (#301) and a f e l d s p a r porphyry (#19) a l s o c r o s s c u t t h i s u n i t . The i n t r u s i v e l i t h o l o g y i s massive but j o i n t blocks are d i s p l a c e d as much as one meter at the s u r f a c e . S u r f i c i a l M a t e r i a l s At l e a s t one l a t e P l e i s t o c e n e t i l l o v e r l i e s bedrock i n t h i s watershed. The t i l l i s d i s c o n t i n u o u s , t h i n , compact, and stoney. I t i s c h e m i c a l l y heterogeneous but i s composed mostly of quartz d i o r i t e and a b i o t i t e g r a n i t e (#303). S e v e r a l f i n e t e x t u r e d , Holocene d e p o s i t s o v e r l i e the t i l l . P y r o c l a s t i c e j e c t a from the Mt Mazama (6600 BP) and Bridge River (2400 BP) v o l c a n i c events (Clague, 1981) are c oncentrated in l o c a l sediment t r a p s . The ashes are i n t e r s p e r s e d with 0.1 to 0.3 m t h i c k , o r g a n i c - r i c h l o e s s a l d e p o s i t s (Jones, 1982) which cap a l l s t a b l e s i t e s . C olluvium o v e r l i e s the b a s a l t i l l i n a c t i v e s i t e s . Coarse 31 t a l u s occurs beneath g l a c i a l l y oversteepened c l i f f s . Stone-banked t e r r a c e s are a c t i v e below bedrock s l a b s , p a r t i c u l a r l y on n o r t h - f a c i n g s l o p e s . Well washed, sandy g r a v e l fans form on g e n t l e foot s l o p e s . S o i l s S o i l s i n t h i s watershed are d i f f i c u l t to c l a s s i f y , p r i m a r i l y because t h e i r g e n e t i c morphology i s obscured by repeated accumulations of the aforementioned Holocene s u r f i c i a l m a t e r i a l s and organic matter ( c f . V a l e n t i n e , 1976). With t h i s r e s e r v a t i o n i n mind, r e p r e s e n t a t i v e pedons are d e s c r i b e d and t e n t a t i v e l y c l a s s i f i e d i n Appendix C by the Canadian System of S o i l C l a s s i f i c a t i o n (Canada S o i l Survey Committee, 1978). P r o f i l e s range from O r t h i c Humo-Ferric Podzols (S79-3) i n w e l l - d r a i n e d t r e e i s l a n d s to Rego Humic G l e y s o l s on s a t u r a t e d f o o t s l o p e s (S79-11). The landscape, however, i s predominantly moderately developed O r t h i c D y s t r i c B r u n i s o l s , O r t h i c Sombric B r u n i s o l s , and Cumulic Regosols. V e g e t a t i o n V e g e t a t i o n at Goat Meadows i s t r a n s i t i o n a l between c o a s t a l Mountain Hemlock b i o g e o c l i m a t i c zones to the southwest and i n t e r i o r Englemann Spruce-Subalpine F i r zones to the northeast ( K r a j i n a , 1969; B i e l e t . a l . , 1976). The watershed i s near the upper a l t i t u d i n a l l i m i t of Parkland subzone at the a l p i n e - s u b a l p i n e ecotone (Brooke, 1965; Peterson, 1965) 32 D iscontinuous t r e e i s l a n d s at the s i t e grade i n t o krummholz l i f e - f o r m s 100 m f a r t h e r upslope. The l i m i t of a r b o r e a l s p e c i e s occurs about 2100 m amsl. The l o c a l v e g e t a t i v e mosaic i s heterogeneous due to steep m i c r o c l i m a t i c g r a d i e n t s and a v a r i e t y of geomorphic processes a c t i v e i n t h i s s t r e s s f u l environment. A d e s c r i p t i o n of l o c a l v e g e t a t i o n communities i s presented i n Appendix B. S o i l - V e g e t a t i o n Complexes S u r f i c i a l m a t e r i a l s , s o i l s , and v e g e t a t i o n covary s t r o n g l y in t h i s environment. The covariance i s s u f f i c i e n t l y d i s t i n c t and r e g i o n a l l y p e r s i s t e n t to r e c o g n i z e s i x d i s c r e t e environmental systems or s o i l - v e g e t a t i o n complexes with sharp geographic boundaries. These are mapped in f i g u r e . 2.2 and d e s c r i b e d b r i e f l y i n t a b l e 2.2. These s i x s o i l - v e g e t a t i o n complexes are sampling u n i t s f o r t h i s study because observable h y d r o l o g i c and geomorphic processes a l s o covary by s o i l - v e g e t a t i o n complex. They w i l l be c h a r a c t e r i z e d by i n f i l t r a b i l i t y and runoff generation mechanisms in Chapter 5 and by s o l u t e chemistry in Chapter 7. Holocene H i s t o r y .Aspects of Holocene c l i m a t e s at Goat Meadows are being r e c o n s t r u c t e d by G.E. Rouse, R.M. B u s t i n , and the author. The p r o j e c t w i l l be d e s c r i b e d i n a separate p u b l i c a t i o n . B r i e f l y , the r e c o n s t r u c t i o n i s based on s t r a t i g r a p h i c and p a l y n o l o g i c a l 33 Table 2.2. Summary of s o i l and v e g e t a t i o n groups that c h a r a c t e r i z e the s i x s o i l - v e g e t a t i o n complexes at Goat Meadows. See Appendix B and C f o r d e s c r i p t i o n s of these v e g e t a t i o n communities and s o i l groups. S o i l Vegetat ion Complex: A c t i v e Debris S i t e s Heath Communities Bedrock Dwarf Sedge Wetland Sedge Tree I s l a n d Pond Basin V e g e t a t i o n Area Communities: (%) Tolmia S a x i f r a g e ; 33 Cassiope-Moss. 30 Heath; Heath-Sedge-Forb. S o i l Groups: Regosols, Cumulic Regosols and weak D y s t r i c B r u n i s o l s O r t h i c D y s t r i c B r u n i s o l s and o c c a s i o n a l Sombric Bruni s o l s 16 e p i p e t r i c l i c h e n . none Dwarf Sedge; 12 Luetkea-Moss-L i c h e n . Sedge-Forb-Moss; 3 Sedge-Sphagnum. 2 Tree I s l a n d s . 4 Sedge-Sphagnum. O r t h i c Sombric and D y s t r i c B r u n i s o l s Humic Rego G l e y s o l s Humo-Ferric Podzols none a n a l y s i s of four cores e x t r a c t e d from Goat v Meadows pond. The cores c o n s i s t of interbedded peat, v o l c a n i c ash and l o e s s . P o l l e n , diatoms and m a c r o f o s s i l s are abundant. Temporal c o n t r o l i s based on f i v e radiocarbon dates and s t r a t i g r a p h i c c o r r e l a t i o n s of v o l c a n i c ash d e p o s i t s . A l l changes i n d e p o s i t i o n a l environments can be r e l a t e d d i r e c t l y to c l i m a t i c and v e g e t a t i o n changes because the s t r a t i g r a p h y of s u r f i c i a l m a t e r i a l s at the pond o u t l e t i s undisturbed, i n d i c a t i n g that the topography of the pond b a s i n has remained e s s e n t i a l l y constant throughout the p e r i o d of r e c o r d . Reconstructed c l i m a t i c events at Goat Meadows are s i m i l a r to a q u a n t i t a t i v e r e c o n s t r u c t i o n by Mathewes and Heusser (1981) f o r the F r a s e r lowland. D e g l a c i a t i o n occurred l o c a l l y before 34 10,500±500 BP and the e a r l y P o s t - g l a c i a l was wet and p o s s i b l y c o l d . Hypsithermal i n t e r v a l s l a s t e d from 10,500±500 to 6,000±150 BP. Throughout t h i s p e r i o d the pond ba s i n was a peat bog, the l o c a l ecosystem was s i g n i f i c a n t l y more a r b o r e a l than at present, and winter snowpacks may have been reduced by as much as 50% of those observed dur i n g 1979 and 1980. N e o g l a c i a t i o n appears to have begun s h o r t l y a f t e r 6000 BP. At t h i s time the pond basin became more l a c u s t r i n e , due to i n c r e a s e d winter snowpacks, and the ecosystem became more e r i c a c e o u s . 35 Chapter 3. METHODS Introduct ion Data c o l l e c t i o n and a n a l y s i s techniques are d e s c r i b e d in t h i s chapter. The r a t i o n a l e and methods of s o l u t e sampling are e x p l a i n e d f i r s t . T h i s i s followed by a d e s c r i p t i o n of hy d r o m e t e o r o l o g i c a l data and a technique f o r c o l l e c t i n g n e a r l y u n d i s t u r b e d s o i l monoliths that was developed d u r i n g t h i s study. Sampling S t r a t e g y The s o l u t e data set c o n s i s t s of 711 f i e l d samples (Table 3.1). F o r t y four percent of these samples, were c o l l e c t e d at three channel s t a t i o n s and at a subsurface i n t e r c e p t o r trench at the mouth of Mosquito Creek ( f i g u r e 3.1). These four s i t e s were sampled si m u l t a n e o u s l y , whenever a c t i v e , i n order to provide a comparative data set f o r the geochemical budgets (Chapter 6 ) . Sampling at other s i t e s (71 i n t o t a l , f i g u r e 3.1) was conducted to h e lp i d e n t i f y major s o l u t e sources and source areas i n the watershed (Chapter 7 ) . Solu t e c o n c e n t r a t i o n s were expected to vary by s o i l group because s o i l groups d i f f e r i n h y d r a u l i c and pedochemical p r o p e r t i e s . I t was reasoned that s o l u t e s r e l e a s e d to streamflow should covary as w e l l . D i f f e r e n c e s i n h y d r a u l i c p r o p e r t i e s were expected to lead to d i f f e r e n c e s i n s o i l - w a t e r contact time. 36 Table 3.1. D i s t r i b u t i o n of s o l u t e samples as components of the h y d r o l o g i c cascade. H y d r o l o g i c Component number of samples % of t o t a l P r e c i p i t a t i o n : 44 6 Snow and snowmelt 24 Bulk p r e c i p i t a t i o n 20 S o i l Water: 316 C a p i l l a r y (vadose) zone 131 18 Saturated ( p h r e a t i c ) zone 185 26 Surface water: 351 Overland flow and s u r f a c e d e t e n t i o n storage 23 3 Streamflow: 328 46 Basin o u t l e t 110 Mosquito weir 86 Hummingbird weir 47 Other s i t e s 85 T o t a l : 711 99 D i f f e r e n c e s i n c o r r o s i v e p o t e n t i a l were expected to l e a d to d i f f e r e n c e s in r e a c t i o n k i n e t i c s (Bussenberg and Clemancy, 1976; Berner, 1978) and thus i n f l u e n c e mechanisms and r a t e s of weathering (Huang and K e l l e r , 1970) and of l e a c h i n g (McColl, 1973; Johnson et a l . , 1977). For example, b r u n i s o l s have f i n e - t e x t u r e d , humic epipedons because they are developed on l o e s s , are s t a b l e , and are w e l l vegetated. Regosols have c o a r s e - t e x t u r e d mineral epipedons because r e g o s o l s are developed on t a l u s , are u n s t a b l e , and are p o o r l y vegetated. Weathering r e a c t i o n s and l e a c h i n g r a t e s should be enhanced by b i o s p h e r i c a c i d s and mobile anions while c o n t a c t times should be prolonged w i t h i n f i n e g r a i n e d m a t e r i a l s . T h e r e f o r e , b r u n i s o l s were expected to c o n t r i b u t e more s o l u t e s to streamflow than r e g o s o l s . As conceived, the sampling design was based on two s t r a t a , namely major s o i l groups and the major components of flow (overlandflow, s a t u r a t e d throughflow, and streamflow) w i t h i n each s o i l group. As executed, sampling was r e s t r i c t e d to s i t e s 37 • c h a n n e l s i t e s F i g u r e 3 . 1 . Sampling s i t e s at Goat Meadows watershed. See Appendix F f o r an index to these s i t e s and a complete l i s t i n g of the chemical data s e t . that were a c t i v e and a c c e s s i b l e . S e v e r a l l o g i s t i c a l f a c t o r s f o r c e d t h i s r e d u c t i o n i n the o r i g i n a l sampling s t r a t e g y . S p a t i a l sampling was g r e a t l y r e s t r i c t e d by deep snowcover. Furthermore, snowpits induced u n n a t u r a l i n f i l t r a t i o n by d i s t u r b i n g the ground thermal regime and snowpack s t r u c t u r e . Throughflow beneath r e g o s o l s was always d i f f i c u l t to sample because w e l l d e f i n e d p h r e a t i c zones were s p a t i a l l y l i m i t e d . 38 Throughflow i n b r u n i s o l s was t r a n s i e n t because i t d e c l i n e d r a p i d l y f o l l o w i n g storm events. T h i s was p a r t i c u l a r l y troublesome • because f a l l rainstorms were inf r e q u e n t and s h o r t - 1 i v e d . To circumvent these l o g i s t i c a l r e s t r i c t i o n s , pressure-vacuum s o i l water samplers ( l y s i m e t e r s ) were i n s t a l l e d f o l l o w i n g snowmelt, 1980. Vacuum sampler s i t e s were chosen a c c o r d i n g to s o i l group s t r a t a d e f i n e d i n Table 2.2. These samples w i l l be r e f e r r e d t o as c a p i l l a r y s o l u t i o n s because they are s o i l s o l u t i o n s withdrawn from the vadose or c a p i l l a r y zone of B h o r i z o n s at approximately 100 kPa t e n s i o n . A l l other stream and s o i l water samples w i l l be r e f e r r e d to as g r a v i t y s o l u t i o n s because they were sampled from s a t u r a t e d s i t e s ( t e n s i o n s < 0). The a d d i t i o n of c a p i l l a r y samples improved the a r e a l r e p r e s e n t a t i v e n e s s of the sampling set but the design i s s t i l l unbalanced with regard to components of flow (Table 3.1). However, s t a t i s t i c a l a n a l y s i s of the data set showed that both s o i l groups and components of flow were secondary f a c t o r s i n water chemistry v a r i a b i l i t y . The data f o l l o w a d e f i n i t e s t r u c t u r e but the s t r u c t u r e i s r e l a t e d to the s p a t i a l v a r i a b i l i t y of mineralogy and of groundwater flowpaths. T h i s major s t r u c t u r e w i l l be d e s c r i b e d and e x p l a i n e d i n Chapter 7. The i n f l u e n c e of major s o i l groups on water chemistry w i l l a l s o be e v a l u a t e d . 39 Chemical Techniques A l l f i e l d and l a b o r a t o r y glassware was cl e a n e d by soaking in c o n c e n t r a t e d n i t r i c a c i d , r i n s e d r e p e a t e d l y i n s i n g l e - d i s t i l l e d water, and r i n s e d at l e a s t twice i n the sample before c o l l e c t i o n . In cases where the sample r i n s e was not p o s s i b l e ( i e . bulk p r e c i p i t a t i o n c o l l e c t o r s ) , apparatus was given a second wash i n nuclear grade detergent and r i n s e d c o p i o u s l y with d i s t i l l e d water. Snow and snowmelt was c o l l e c t e d with p o l y e t h y l e n e beakers and funnels from small caves carved i n the wa l l of snowpits. Bulk p r e c i p i t a t i o n was c o l l e c t e d i n c o l l e c t o r s f o l l o w i n g the design of Likens et a l . (1967). C a p i l l a r y s o i l water s o l u t i o n s were sampled using vacuum l y s i m e t e r s (Wagner, 1962, Wood, 1973) e q u i v a l e n t to S o i l m o i s t u r e Equipment Co. Model 1920 pressure-vacuum s o i l water samplers. The samplers were i n s t a l l e d i n a s l u r r y of c l e a n , #90 g r i t alundum powder f o r good h y d r a u l i c communication with surrounding s o i l . P h r e a t i c s o i l water was sampled from uncased, PVC standpipes a f t e r pumping the w e l l dry and a l l o w i n g the pipe to r e f i l l . Open s o i l p i t s were used i n a s i m i l a r manner. In g e n e r a l , the s o i l p i t s were b e t t e r sampling s i t e s because the source of inflow to p i t s c o u l d be seen r e a d i l y . During c o l l e c t i o n , temperature and s p e c i f i c c o n d u c t i v i t y were determined u s i n g a Zeal mercury thermometer and a L a b l i n e Instruments Model MC-1 c o n d u c t i v i t y bridge and c e l l . Bulk samples were c o l l e c t e d i n reuseable p o l y e t h y l e n e b o t t l e s , each b o t t l e permanently assi g n e d to each c o l l e c t i o n s i t e . In most 40 cases, samples were pumped from the c o l l e c t i o n s i t e to the c o l l e c t i o n b o t t l e using a hand pump, S a r t o r i u s 47 mm f i l t e r stage and low pressure (30 kPa). Bulk samples were then t r a n s p o r t e d 200 m to a small c a b i n f o r a d d i t i o n a l p r o c e s s i n g . In the c a b i n , samples were brought to s t a b l e temperature along with pH b u f f e r s . pH was determined on a sample s p l i t , with g e n t l e mechanical s t i r r i n g , using an Orion model 407 s p e c i f i c ion meter, Orion 90-01 r e f e r e n c e and 91-01-00 pH probes. Meter range and slope s e t t i n g s were bracketed with at l e a s t two f r e s h l y made r e f e r e n c e b u f f e r s , one pH u n i t on e i t h e r s i d e of the unknown. Water samples to be ana l y z e d f o r c a t i o n s and s i l i c o n were f i l t e r e d immediately through S a r t o r i u s 0.45 micrometre c e l l u l o s e - n i t r a t e f i l t e r s which were p r e - r i n s e d twice with the sample. F i l t e r e d samples were a c i d i f i e d with c o n c e n t r a t e d n i t r i c a c i d t o pH 2 and s t o r e d i n 125 ml p o l y e t h y l e n e b o t t l e s . Samples were u s u a l l y analysed w i t h i n 30 days of c o l l e c t i o n and always w i t h i n 90 days of c o l l e c t i o n . S i l i c o n c o n c e n t r a t i o n s were determined by the molybdate blue c o l o r i m e t r i c method u s i n g procedures of Rainwater and Thatcher (1960) and a Pye Unicam SP6-500 UV/VIS spectrophotometer equipped with a through-flow c e l l . Major c a t i o n s were determined by atomic a b s o r p t i o n spectrophotometry using a Perkin-Elmer model 373 spectrophotometer at f a c i l i t i e s rented from P a c i f i c S o i l A n a l y s i s , Inc., Vancouver, B.C.. Four procedures were exp l o r e d ; a i r - a c e t y l e n e and n i t r o u s o x i d e - a c e t y l e n e flames, with and 41 without 0.5% lanthanum as a r a d i a t i o n b u f f e r . P r e c i s i o n with a l l four procedures was good but a i r - a c e t y l e n e without La underestimated C a + + and Mg + + c o n c e n t r a t i o n s by about 10% i n the c o n c e n t r a t i o n range of i n t e r e s t . N i t r o u s o x i d e - a c e t y l e n e was used consequently on u n t r e a t e d a l k a l i n e e a r t h samples and a i r - a c e t y l e n e was used on untreated a l k a l i n e metal samples. T h i s procedure e l i m i n a t e d random e r r o r s and p o s s i b i l i t y of p r o c e s s i n g blunders a s s o c i a t e d with d i l u t i n g samples with r a d i a t i o n b u f f e r s . T h i s a l s o minimized burner head c l o g g i n g and operator exposure to n i t r o u s oxide gas. Fresh working standards were prepared before each round of l a b o r a t o r y a n a l y s i s because of u n c e r t a i n t y concerning the s h e l f l i f e of d i l u t e standards. In a l l , e i g h t batches of standards were prepared between June, 1979 and November, 1980. In order to determine the magnitude of random e r r o r s i n the p r e p a r a t i o n of standards and i n d e t e r m i n a t i o n of unknowns, f i v e batches of standards were s t o r e d a f t e r use and l a t e r analyzed as "unknowns" a g a i n s t a f r e s h batch of standards d u r i n g the f i n a l round of p r o c e s s i n g . Each standard was read three times. The r e s u l t s shown i n t a b l e 3.2 are f o r standards which showed the g r e a t e s t v a r i a t i o n between batches. For example, the g r e a t e s t v a r i a t i o n in a l l c a l c i u m standards o c c u r r e d among the 2 mg/l standards. Table 3.2 shows that the standard d e v i a t i o n i n c a l c i u m c o n c e n t r a t i o n among these f i v e standards, when t r e a t e d as "unknowns", was 0.06 mg/l. Thus the v a r i a b i l i t y inherent i n p r e p a r i n g working standards, a n a l y z i n g unknowns and s t o r i n g standards f o r up to 19 months d i d not exceed 3% f o r major 42 c a t i o n s and 7% f o r s i l i c o n . T h i s serves as a c o n s e r v a t i v e estimate of the a n a l y t i c a l p r e c i s i o n of chemical methods i n t h i s study. Table 3.2. A n a l y t i c a l p r e c i s i o n as d e f i n e d by the maximum v a r i a t i o n among se t s of working standards when t r e a t e d as unknowns duri n g the l a s t round of l a b o r a t o r y a n a l y s i s . Note that s i l i c o n d e t erminations are repo r t e d in t h i s t a b l e as s i l i c a . standard standard r e l a t substance n cone. d e v i a t i o n e r r o r mg/1 mg/1 % Si02 24 2.0 0.13 6.2 Ca 1 5 2.0 0.06 3.0 Mg 1 5 1 .0 0.03 3.0 Na 1 5 0.5 0.01 1 .2 K 1 5 0.5 0.01 2.0 With regard to a n a l y t i c a l accuracy, e l e c t r o n e u t r a l i t y cannot be demonstrated because these samples are very d i l u t e and are beyond the p r e c i s i o n of a v a i l a b l e anion techniques. For example, mean sum-of-cation c o n c e n t r a t i o n at the bas i n o u t l e t stream d u r i n g 1980 was only 1.3 mg/1. P r e c i s i o n of anion analyses are approximately 0.2 mg/1 for bi c a r b o n a t e , 0.5 mg/1 fo r s u l f a t e s , and 0.1 mg/1 for c h l o r i d e (American S o c i e t y f o r T e s t i n g and M a t e r i a l s , 1975; and r e s u l t s of t h i s s t u d y ) . Thus u n c e r t a i n t i e s i n anion d e t e r m i n a t i o n s are about 60% of the expected sum of anions and eig h t times l a r g e r than u n c e r t a i n t i e s i n c a t i o n d e t e r m i n a t i o n s . One i n c i d e n t a l check f o r accuracy of r e s u l t s can be o f f e r e d . Each set of working standards was compared a g a i n s t the c u r r e n t working standards of P a c i f i c S o i l A n a l y s i s , Inc. T h i s check was made by G a l l i e as a f o r m a l i t y before each day's 43 p r o c e s s i n g i n order to check f o r blunders i n G a l l i e ' s standards. In every case the standard s e t s were f r e s h and t r u l y independent, having been made by two d i f f e r e n t chemists i n two d i f f e r e n t l a b o r a t o r i e s using d i f f e r e n t glassware, reagents and water. At no time were a p p r e c i a b l e d i f f e r e n c e s d e t e c t e d i n spectrophotometer response. T h i s suggests that the data from t h i s study are a c c u r a t e . Anion a n a l y s e s were attempted and, while not used i n t h i s r e p o r t , experience gained may be h e l p f u l to those working in s i m i l a r environments. F i e l d d e t e r m i n a t i o n s of a l k a l i n i t y (bicarbonate) were made on a r e g u l a r b a s i s , and a f t e r c o n s i d e r a b l e experimentation, a s a t i s f a c t o r y procedure was developed. Reproduceable r e s u l t s were achieved using 500 ml samples p o t e n t i o m e t r i c a l l y t i t r a t e d w e l l beyond endpoint using 0.02 N s u l f u r i c a c i d and c l o s e range b r a c k e t i n g of b u f f e r s . E q u i v a l e n c e p o i n t s should be c a l c u l a t e d by the Gran method (Dyrssen and S i l l e n , 1967; Stumm and Morgan, 1970) because c o l o r endpoints (American P u b l i c Health A s s o c i a t i o n , 1981) and even p o t e n t i o m e t r i c endpoints (Barnes, 1964) were found t o t a l l y inadequate. Even u s i n g very l a r g e sample s i z e s and Gran f u n c t i o n s , p r e c i s i o n was no b e t t e r than 0.2 mg/l because these waters are p o o r l y b u f f e r e d . C h l o r i d e d e t e r m i n a t i o n s using the c o l o r i m e t r i c t h iocyanate method (ASTM, 1975) worked very w e l l (±0.1 mg/l) when done manually (eg. not an A u t o A n a l i z e r ) and i n small batches. Reagents became unstable w i t h i n 30 minutes of f i n a l mixing. Although three techniques were explored f o r s u l f a t e s , none 44 was s a t i s f a c t o r y . Sample c o n c e n t r a t i o n by ion exchange i n the f i e l d and l a b o r a t o r y a n a l y s i s by barium c h l o r i d e t i t r a t i o n with t h o r i n i n d i c a t o r (ASTM, 1975; Environment Canada, 1979) worked best but p r e c i s i o n was never b e t t e r than 0.5 mg/1 and the procedure was too labor i n t e n s i v e f o r batch p r o c e s s i n g of f i e l d samples. Hydrometeorological Techniques Standard p r e c i p i t a t i o n was sampled at four l o c a t i o n s u sing storage p r e c i p i t a t i o n gauges. The gauge at the Stevenson screen was read d a i l y while the s i t e was occupied. The other gauges were read at the end of each p r e c i p i t a t i o n event. T h i s network was supported by a t i p p i n g bucket r a i n gauge (At=15 minutes) and a companion storage gauge. Mean event p r e c i p i t a t i o n was taken as the Thiessen-weighted average c a t c h of the four storage gauges. Snow a b l a t i o n was measured monthly as the change i n water e q u i v a l e n t snowpack storage between survey dates. The s p a t i a l v a r i a b i l i t y of snow depth was sampled along a compass and chain g r i d with a sampling d e n s i t y of 100 p o i n t s per h e c t a r e . Snow depth at each g r i d p o i n t was measured by averaging three to f i v e soundings made with a t h i n , r i g i d probe. The v a r i a b i l i t y of snow d e n s i t y was sampled along the same g r i d u s i n g a sampling d e n s i t y of 25 p o i n t s per he c t a r e . Density was measured at each g r i d p o i n t by averaging three determinations made with a F e d e r a l , or Mt. Rose snow sampler. T h i s instrument has a known b i a s (Work et al.,1965) so repeated 45 c a l i b r a t i o n s were made a g a i n s t p i t s t u d i e s using the more accurate CRREL snow k i t . The Mt. Rose sampler c o n s i s t e n t l y overestimated d e n s i t y by 10% i n the p r e v a i l i n g snow c o n d i t i o n s and a l l d e n s i t y estimates were c o r r e c t e d by t h i s amount. Both depth and d e n s i t y were h i g h l y v a r i a b l e across the watershed but both were normally d i s t r i b u t e d i n a l l surveys. Thus basin snowpack storage was taken as the product of mean basi n depth and d e n s i t y . Short term a b l a t i o n r a t e s were estimated d u r i n g i n t e n s i v e chemical sampling p e r i o d s using a b l a t i o n stakes as d e s c r i b e d by Jordan (1978) and snow l y s i m e t e r s d e s c r i b e d by Wankiewicz (1976), Jordan (1978), and Braun (1980). Snow l y s i m e t e r c a t c h was recorded with p l e x i g l a s s t i p p i n g buckets based on the design of Knapp (1973) and by event r e c o r d e r s designed and b u i l t by Mr. R. L e s l i e , Dept. of Geography, UBC. T i p p i n g bucket p r e c i s i o n was poor (±15%) and so d a i l y c a t c h was measured by t o t a l r e t e n t i o n gauging. Overcatch was a s e r i o u s problem with the pan l y s i m e t e r s and so few l y s i m e t r y data are used i n t h i s r e p o r t . Overcatch probably occured because i c e glands i n the snow pack c o n c e n t r a t e d meltwater along p r e f e r r e d pathways. T h i s e f f e c t may be reduced by p e r f o r a t i n g the snowpack with a snow probe. Atmospheric v a r i a b l e s were r e q u i r e d f o r evaporation modeling (Chapter 4). S o l a r r a d i a t i o n was measured with a K a h l s i c o a c t i n o g r a p h c a l i b r a t e d with a Kipp and Zonen pyranometer. A i r temperature and r e l a t i v e humidity changes were recorded by a Fuess thermohygrograph housed i n a Stevenson screen and c a l i b r a t e d by r e g u l a r checks a g a i n s t a v e n t i l a t e d 46 Assman psychrometer. The psychrometer was i n t u r n c a l i b r a t e d by Braun (1980) with a Hewlett Packard platinum r e s i s t a n c e probe. Vapor p r e s s u r e s were computed from r e l a t i v e humidity using t a b l e s of the Deutscher W e t t e r d i e n s t (1963). During snowfree p e r i o d s , p o t e n t i a l e v a p o r a t i o n was estimated c r u d e l y with a shallow, 0.3 m2 pan submerged in the pond. S o i l temperatures were measured with e i g h t , 5 kQ glass-bead t h e r m i s t o r s encased in epoxy and b u r i e d at 0.1 and 0.3 m depths at 4 s i t e s . R e sistance was read with a L a b l i n e Instruments MC-1 b r i d g e . Thermistors were c a l i b r a t e d i n water-ice s l u r r i e s a g a i n s t a Zeal mercury thermometer. P r e c i s i o n of t h i s t h e r m i s t o r - b r i d g e combination was ±0.2 °C over the range of temperatures observed i n the f i e l d . S o i l moisture was monitored at 3 s i t e s u s ing gypsum r e s i s t a n c e b l o c k s . These were c a l i b r a t e d a g a i n s t g r a v i m e t r i c s o i l moisture samples. The blocks d i s s o l v e d over the course of the study causing e r r a t i c s h i f t s i n c a l i b r a t i o n . The i n t e r m i t t e n t , g r a v i m e t r i c data are consequently used i n t h i s r e p o r t . Stream d i s c h a r g e was recorded with Stevens type-F water l e v e l r e c o r d e r s behind 90°, V-notch weirboards at the b a s i n o u t l e t , and on Mosquito and Hummingbird creeks . R e s e r v o i r s were made water t i g h t with p o l y e t h y l e n e sheet l i n i n g s . Basin o u t l e t weir was c a l i b r a t e d i n l a t e June of both study years by s l u g - i n j e c t i o n fluorometry using Rhodamine WT dye and a Turner 110 fluorometer f o l l o w i n g procedures of Church (1975). Mosquito and Hummingbird weirs were c a l i b r a t e d by t o t a l r e t e n t i o n 47 gauging. Marmot d i s t u r b a n c e and snow creep made Hummingbird weir u n r e l i a b l e throughout most of the study p e r i o d and i t was used f o r r e l a t i v e , r a ther than absolute d i s c h a r g e o b s e r v a t i o n s . Random e r r o r i n the stage-discharge r e l a t i o n s h i p s are summarized in t a b l e 3.3. The magnitude of r e l a t i v e e r r o r i s due to small sample s i z e s r a t h e r than lack of f i t with the model. Table 3.3. Discharge r a t i n g r e l a t i o n s h i p s for c a l i b r a t e d weirs using the model Q = a H exp b where H=stage. Confidence i n t e r v a l i s the l a r g e r v alue f o r the l i n e a r r e g r e s s i o n model lnQ=lna+blnH at the b i v a r i a t e mean. n r 2 a b CI(95%) 1/s Basin O u t l e t 13 0.998 0.01044 2.618 0.33 Mosquito 22 0.999 0.02065 2.411 0.15 Subsurface discharge was observed at two 4x5 m h i l l s l o p e p l o t s u s i n g i n t e r c e p t e r g u t t e r s and t i p p i n g buckets of the design of Knapp (1973). As d i s c u s s e d e a r l i e r , the t i p p i n g buckets were not p r e c i s e and d a i l y c a t c h was measured by t o t a l v o l u m e t r i c r e t e n t i o n r a t h e r than by t i p p i n g bucket response. At other l o c a t i o n s , PVC standpipes and s o i l p i t s were used f o r q u a l i t a t i v e o b s e r v a t i o n s . Other Techniques P h y s i c a l analyses of s o i l s were performed f o l l o w i n g procedures o u t l i n e d by L a v k u l i c h (1981). Mineralogy of rocks was determined from t h i n s e c t i o n s prepared at f a c i l i t i e s of the Department of G e o l o g i c a l Sciences, UBC. Mineralogy of 48 c l a y - s i z e d s o i l m a t e r i a l s was determined by x-ray d i f f r a c t i o n in the Pedology Laboratory, Department of S o i l Science, UBC by methods of L a v k u l i c h (1981). Water s o l u b l e s a l t s were e x t r a c t e d from <2 mm f r a c t i o n of a i r d r i e d s o i l s using 1:1 s o i l - w a t e r r a t i o s (by weight) r a t h e r than the more customary s o i l - w a t e r paste. T h i s m o d i f i c a t i o n was necessary because of l i m i t e d s o i l sample s i z e s , high organic matter contents, and a d e s i r e to determine s i l i c o n , pH, and major c a t i o n s by methods c o n s i s t e n t with water a n a l y s e s . Samples were g e n t l y a g i t a t e d f o r 10 seconds at the beginning and end of one hour c o n t a c t time. Supernatant was removed by vacuum f i l t r a t i o n . One hour contact times were used because p r i o r experimentation showed no s i g n i f i c a n t d i f f e r e n c e i n y i e l d s with c o n t a c t times between one and twenty four hours. S o i l monoliths were used f o r l a b o r a t o r y l e a c h i n g experiments. S o i l s at Goat Meadows are very stony. T h i s presented a l o g i s t i c a l problem because n e a r l y undisturbed monoliths were d e s i r e d . A very s a t i s f a c t o r y s o l u t i o n was developed based on COLDCURE brand epoxy r e s i n s manufactured by I n d u s t r i a l Formulators of Canada, W i l l i a m St., Burnaby, B.C.. These r e s i n s are completely hydrophobic when mixed and w i l l bond and cure under water. "Hot" for m u l a t i o n s are a v a i l a b l e (eg. COLDCURE CR) which cure below 0°C. Monoliths were c o n s t r u c t e d by t r e n c h i n g around the d e s i r e d s o i l and then c a r e f u l l y trimming excess s o i l from the remaining p i l l a r u n t i l the d e s i r e d s i z e and shape was obtained. Large stones i n the matrix were l e f t i n t a c t because the monolith was 49 wrapped in epoxy-saturated f i b e r g l a s s c l o t h which conforms to any contour. A d d i t i o n a l epoxy was p a i n t e d on the e x t e r i o r of the monoliths to make them water t i g h t . Wood or aluminum s p l i n t s were g l a s s e d on to the e x t e r i o r f o r a d d i t i o n a l s t r e n g t h . The epoxy s e t s w i t h i n 24 hours and appears to be f u l l y cured w i t h i n one week. Once s e t , the monolith can be separated from the s u b s o i l with a s i n g l e shovel cut and t r a n s p o r t e d to the l a b o r a t o r y . Once cured, the epoxy i s i n e r t in the s o i l s o l u t i o n s encountered i n t h i s study. Epoxy s t a b i l i t y i n strong a c i d s and bases i s not known. 50 Chapter 4. WATER BUDGETS I n t r o d u c t i o n Annual water budgets f o r the study p e r i o d w i l l be presented in t h i s c h a p t e r . Environmental and geometric c h a r a c t e r i s t i c s of the watershed that e f f e c t v a r i a t i o n s i n water budget components w i l l a l s o be o u t l i n e d . Budget Equations Water budgets are accounts of t o t a l water i n p u t s , throughputs, and outputs f o r a watershed over a s p e c i f i e d p e r i o d of time. Mass c o n s e r v a t i o n d i c t a t e s that d i f f e r e n c e s between inputs and outputs must be accompanied by e q u i v a l e n t changes in i n t e r n a l s t o r a g e . Thus, water budgets allow i n f e r e n c e of h y d r o l o g i c r e d i s t r i b u t i o n processes w i t h i n a watershed. The water budget f o r a watershed i s commonly represented as P - Q - ET - GW + AS = 0 (4.1) where P = p r e c i p i t a t i o n , Q = stream d i s c h a r g e , ET = e v a p o t r a n s p i r a t i o n , GW = groundwater discharge and AS symbolizes changes in r e l e v a n t i n t e r n a l s t o r e s . These s t o r e s i n c l u d e i n t e r c e p t i o n storage on p l a n t s , surface d e t e n t i o n storage i n ponds and streams, s o i l moisture, groundwater and snowpack storage. Gains to storage terms are p o s i t i v e i n s i g n while 51 l o s s e s to storage are negative. If the budget extends over a p e r i o d of one to s e v e r a l years, a few storage terms become t r i v i a l or redundant and need not be t r e a t e d e x p l i c i t l y . For example, at Goat Meadows watershed, v e g e t a t i o n i s rather l i m i t e d . I n t e r c e p t i o n storage i s ephemeral and very small r e l a t i v e to any f l u x term and/or measurement p r e c i s i o n . Thus, i n t e r c e p t i o n storage may be ignored. Surface d e t e n t i o n storage i s a more s i g n i f i c a n t term but very l a r g e storage changes are necessary i n order to have any meaningful e f f e c t on annual budgets. Another s i m p l i f i c a t i o n can be made with respect to snow storage. Regular snow surveys and a b l a t i o n stake measurements are made to p r o v i d e a check on snowmelt because Snowpack Storage - Melt = AS snow. For running budgets, however, one may t r e a t snowpack as a h y d r o l o g i c source e x t e r n a l to the watershed, take snowmelt (M) as an atmospheric input having p o s i t i v e s i g n , and the water budget i s modified to M + P = Q + ET + GW + AS (4.2) where AS equals changes to the two remaining major terms; s o i l moisture and groundwater. T h i s i s the form of the budget equation that w i l l be used here r e c o g n i z i n g that the omitted terms are s i g n i f i c a n t d u r i n g l i m i t e d p e r i o d s of each year. O p t i m a l l y , mass budgets are conducted on watersheds u n d e r l a i n by impermeable bedrock. In such cases, the groundwater f l u x can be ignored and a l l d i f f e r e n c e s i n annual input and output can be a t t r i b u t e d to changes in s o i l moisture storage and measurement i m p r e c i s i o n . U n f o r t u n a t e l y , Goat 52 Meadows watershed i s not u n d e r l a i n by impermeable bedrock and, because groundwater i s a d i f f i c u l t f l u x to assess, i n i t i a l development of the water budgets w i l l use an incomplete form of equation 4.2 : M + P = Q + E T + R (4.3) where R i s the r e s i d u a l composed of AS s o i l , AS groundwater, and groundwater (GW). Hydrometeorologic Data D a i l y hydrometeorologic data f o r the 1979 and 1980 a b l a t i o n seasons are presented i n f i g u r e s 4.1 and 4.2. Water budgets are s y n t h e s i s e d i n s e c t i o n 5 of t h i s chapter (Annual Water Budgets, t a b l e 4.2). A l l u n i t s are mm water e q u i v a l e n t (eg. volumes such as r u n o f f are d i v i d e d by b a s i n area to y i e l d depth per u n i t area f i g u r e s which are compatible with t r a d i t i o n a l l y non-volumetric terms such as p r e c i p i t a t i o n and e v a p o r a t i o n ) . A decimal calendar i s used f o r computational convenience; J u l i a n date January 1 being decimal day 1 and J u l i a n date December 31 being decimal day 365. The p e r i o d s of r e c o r d run roughly from May to October and are the longest p e r i o d s d u r i n g which f i e l d work was safe and l o g i s t i c a l l y f e a s i b l e . C o n veniently, these are the p e r i o d s d u r i n g which almost a l l runoff occurs. October to A p r i l i s normally an accumulation p e r i o d , the major h y d r o l o g i c change being an i n c r e a s e to snowpack storage. T h i s term can be obtained i n s p r i n g - b e f o r e the onset of melt and r u n o f f . Thus, I 1 I 1 i I r -April Miy _ Juno July August Soptombor October Figure 4.1. D a i l y h y d r o l o g i c f l u x e s , r e s e r v o i r l e v e l s and temperature curves f o r the a b l a t i o n season, 1979. cn co Figure 4.2. D a i l y h y d r o l o g i c f l u x e s , r e s e r v o i r l e v e l s and temperature curves f o r the a b l a t i o n season, 1980. 55 the budgets presented here are reasonably r e p r e s e n t a t i v e of the 1979 and 1980 annual water budgets. Table 4.2 i s s u b d i v i d e d i n t o three discharge seasons; snowmelt, summer drought, and f a l l r a i n s . The snowmelt season i s by f a r the dominant runoff event and i s f u r t h e r subdivided i n t o short term events d e f i n e d by the shape of the b a s i n ' s d i s c h a r g e hydrograph. T h i s can be seen c l e a r l y i n f i g u r e s 4.1 and 4.2. Before d i s c u s s i n g the most apparent f e a t u r e s of the water budgets a d e s c r i p t i o n of computational methods used in f i g u r e s 4.1, 4.2 and t a b l e 4.2 w i l l f o l l o w . D a i l y D i s t r i b u t i o n Methods Di scharge D a i l y d i s charge was computed by g r a p h i c a l s e p a r a t i o n (Garstka et a l , 1958) of the o r i g i n a l d i s c h a r g e hydrographs ( f i g . 4.4). Hydrographs were p l o t t e d with d i s c h a r g e transformed to n a t u r a l l o g a r i t h m s . Recession limbs were extended as s t r a i g h t l i n e s i n semi-log space to an a r b i t r a r y base l e v e l . Extending r e c e s s i o n limbs to a non-zero base l e v e l a v oids e x t r a p o l a t i n g r e c e s s i o n limbs to i n f i n i t y and l o c a l i z e s the i m p r e c i s i o n i n the slope of each limb. These graphs were e l e c t r o n i c a l l y d i g i t i z e d , detransformed and r e p l o t t e d on a l i n e a r s c a l e . The area beneath each event was then planimetered to y i e l d d a i l y d i s c h a r g e e s t i m a t e s . T h i s technique i s based on the o b s e r v a t i o n that discharge 56 r a t e s g e n e r a l l y decay e x p o n e n t i a l l y through time as basin storage d e c l i n e s . Extension of r e c e s s i o n limbs as s t r a i g h t l i n e s i n semi-log space mimics t h i s phenomenon and provi d e s a s i m p l i s t i c but o b j e c t i v e method of s e p a r a t i n g one event's c o n t r i b u t i o n to instantaneous discharge from the d e c l i n i n g d i s c h a r g e of p r e v i o u s events on which i t i s b u i l t . E x p o n e n t i a l discharge decay models watershed response as a l i n e a r r e s e r v o i r having the form: q2 = q1*k e x p - ( t 2 - t l ) (4.4) where q i s di s c h a r g e at times one and two and k i s slope of the r e c e s s i o n limb; the r e c e s s i o n c o n s t a n t . The v a l i d i t y of t h i s model f o r Goat meadows watershed w i l l be d i s c u s s e d i n more d e t a i l i n Chapter 5. Snowmelt Monthly snowmelt was estimated by p e r i o d i c , basin-wide snow surveys and short-term snowmelt was estimated at a b l a t i o n stakes (Chaper 3). The short-term a b l a t i o n estimates were made only d u r i n g p e r i o d s of i n t e n s i v e chemical sampling. While t h i s sampling schedule p r o v i d e s adequate c o n t r o l on annual budgets, i t does not allow convenient a n a l y s i s of the snowmelt season on the b a s i s of events as d e f i n e d i n f i g u r e s 4.1 and 4.2. For t h i s reason a simple melt model i s needed to r e d i s t r i b u t e snow survey r e s u l t s to a d a i l y b a s i s . S e v e r a l p h y s i c a l l y - b a s e d snowmelt models were a p p l i e d to the data with l i m i t e d success. The primary d i f f i c u l t y 57 encountered was in modeling short term changes i n albedo f o l l o w i n g snow and r a i n events. Thus, a simple l i n e a r r e g r e s s i o n r e l a t i o n s h i p was developed between mean d a i l y a i r temperature and mean d a i l y melt at a b l a t i o n s takes. The model was c a l i b r a t e d with data from days 172 to 188, 1979 and days 166 to 178, 1980. The sample was q u i t e small (n=l6) because the stakes were seldom read d a i l y and the e x p l a n a t i o n achieved gave a c o e f f i c i e n t of d e t e r m i n a t i o n of 0.69. Nonetheless, the model works w e l l d u r i n g the c a l i b r a t i o n p e r i o d s (modeled values are 0.98 and 1.00 of measured val u e s r e s p e c t i v e l y ) and i s adequate f o r simple r e d i s t r i b u t i o n purposes. Outside the c a l i b r a t i o n p e r i o d , i t overestimates melt d u r i n g the e a r l y season (April-May) and underestimates melt d u r i n g the l a t e season ( J u l y ) ( t a b l e 4.1). One obvious short-coming of t h i s simple model i s that mean d a i l y temperature i s the only surrogate used to represent the energy sources a v a i l a b l e f o r melt. In f a c t , sources of melt energy are numerous and t h e i r r e l a t i v e importance change throughout an i n d i v i d u a l melt season. For example, Jordan (1978) demonstrated that more than 90% of melt energy was r a d i a n t at M c G i l l i v r a y Pass, a subalpine s i t e 50 km to the north. I f r a d i a t i o n i s e q u a l l y important at Goat Meadows, one might suspect that e a r l y season melt i s overestimated at Goat Meadows because the s p r i n g snowpacks have hi g h e r albedo than the midseason snowpacks. The reverse i s a l s o l i k e l y a f a c t o r i n the l a t e season underestimates. Two other f a c t o r s , however, may be important i n causing l a t e season underestimates. 58 Table 4.1. Melt model performance. Cumulative modeled a b l a t i o n i s compared to measured a b l a t i o n at stakes (1980) and basin snow surveys (1979). decimal measured estimated r a t i o dates melt melt 1979 107-139 181.6 268.9 0.68 140-168 350.4 480.9 0.73 169-206 338.0 295.0 1.15 T o t a l 870.0 1044.8 0.83 1 980 151-165 205.4 223.0 0.92 166-178 285.7 286.2 1.00 179-196 252.6 291.8 0.87 197-225 104.9 76.0 1.38 T o t a l 848.6 877.0 0.97 F i r s t , Goat Meadows i s the l a s t s i t e on the ri d g e to l o s e i t s snow cover. S i g n i f i c a n t melt energy may be advected to the watershed dur i n g the l a t e melt season from dry, snowfree a r e a s . Meso-scale a d v e c t i o n of s e n s i b l e heat from the v a l l e y f l o o r to the r i d g e top was demonstrated by Braun (1980). The phenomenon may a l s o be s i g n i f i c a n t on a m i c r o - s c a l e . Second, l a t e melt season i s a p e r i o d of warm a i r temperatures and hi g h vapor pressure r e l a t i v e to the snowpack s u r f a c e which remains near 0° C with a f i x e d vapor pressure of only 611 Pa. Condensation dominates under these atmospheric c o n d i t i o n s , l i b e r a t i n g l a t e n t heat to the s u r f a c e , and can be an e f f e c t i v e source of energy f o r melt (see Eva p o r a t i o n Over Snow). 59 Evaporat ion Basin-wide evaporation was estimated with e m p i r i c a l rather than p h y s i c a l l y - b a s e d models. T h i s i s j u s t i f i e d because evaporation i s the s m a l l e s t s i g n i f i c a n t f l u x i n the water budget (see t a b l e 4.2) and because i n s t r u m e n t a t i o n and data requirements f o r p h y s i c a l l y - b a s e d models are high. The watershed i s a l s o q u i t e heterogeneous and i t s energy budget i s s u f f i c i e n t l y a d v e c t i v e to l i m i t both the g e n e r a l i t y and the v a l i d i t y of d e t a i l e d m i c r o - m e t e o r o l o g i c a l measurements taken at a s i n g l e s i t e . E v a poration Over Vegetated Surfaces E v a p o r a t i o n over vegetated s u r f a c e s was estimated with an e q u i l i b r i u m evaporation model ( S l a t y e r and M c l l r o y , 1961) using e m p i r i c a l c o e f f i c i e n t s developed f o r a r c t i c tundra by Stewart and Rouse (1976b), by Wright(1981), and t e s t e d f o r a l p i n e tundra by Jordan (1978). E q u i l i b r i u m evaporation i s the minimum l a t e n t heat f l u x expected from a s a t u r a t e d s u r f a c e QEeq = (s/(s+7>)(Q*-QG) (4.5) where s i s the slope of the s a t u r a t i o n vapor pressure curve at the mean ambient temperature (Lowe, 1976), 7 i s the psychrometric constant, Q* i s the net all-wave r a d i a t i o n balance at the s u r f a c e , and QG i s the ground heat f l u x . The expre s s i o n i s d e r i v e d from the Bowen r a t i o approach f o r the case where a i r above the su r f a c e remains unsaturated (Stewart and 60 Rouse, 1976a). Q*-QG d e f i n e s the maximum energy a v a i l a b l e to d r i v e l a t e n t heat f l u x (McNaughton and Black, 1973) and s / s + 7 i s a temperature dependent l i m i t i n g f u n c t i o n r e p r e s e n t i n g vapor pressure above the s u r f a c e . P r i e s t l y and T a y l o r (1972) showed e m p i r i c a l l y t h at the r a t i o of a c t u a l evaporation to e q u i l i b r i u m evaporation over s a t u r a t e d s u r f a c e s i s n e a r l y constant at 1.26. T h i s value a, the P r i e s t l y - T a y l o r f u n c t i o n , i s not p h y s i c a l l y - b a s e d but i s remarkably g e n e r a l and e f f e c t i v e (Monteith, 1981). Stewart and Rouse (1976b) extended t h i s work i n Hudson Bay lowlands. They confirmed the a p p l i c a b i l i t y of a 1.26 f o r sa t u r a t e d sedge meadows and shallow lakes and determined values of alpha near 1.0 f o r a v a r i e t y of dry, l i c h e n heath tundra. (Stewart and Rouse, 1976a, 1977). They f u r t h e r proposed a simple model f o r d a i l y e v aporation based on mean d a i l y screen temperatures and, assuming net ground heat f l u x of zero f o r long p e r i o d s , a l i n e a r approximation of the net sur f a c e r a d i a t i o n term from measurements of incoming s o l a r r a d i a t i o n . T h e i r models a r e : QEdry = 1.00(s/(s+7))(-0.108+0.634 K|) (4.6) QEwet = 1.26(s/(s+7))(-0.058+0.7365 K|) (4.7) fo r dry l i c h e n heath and wet sedge meadows r e s p e c t i v e l y where K| i s measured incoming s o l a r r a d i a t i o n . The f u l l r a d i a t i o n e xpression was determined by r e g r e s s i o n and i s composed e s s e n t i a l l y of a constant net longwave and a v a r i a b l e net shortwave term. A l l u n i t s are MJ n r 2 day" 1. Nearly i d e n t i c a l r a d i a t i o n r e l a t i o n s h i p s were determined independently by Jordan 61 (1978). Jordan i n t e r p r e t e d the r e s u l t to mean that net r a d i a t i o n i s c o n s e r v a t i v e over tundra s u r f a c e s of s i m i l a r albedo. Wright (1981) noted that the f u n c t i o n a l s o h e l d f o r bare, wet s u r f a c e s . In t h i s study, t o t a l energy a v a i l a b l e f o r evaporation was taken as: Q E t o t a l = (Fdry(QEdry) + Fwet(QEwet)) (4.8) where Fdry i s the percentage b a s i n area of bare rock, d e b r i s , heath, t r e e i s l a n d and dry sedge meadow. Fwet i s the percentage of basin area covered by lake and wetland sedge. Evaporation(E) i s expressed as the t o t a l l a t e n t heat f l u x d i v i d e d by the l a t e n t heat of v a p o r i z a t i o n : E = (QEtotal/Lv)(1-(%snowcover/l00)) (4.9) During p e r i o d s of snow cover, evaporation over v e g e t a t i o n was reduced by the f r a c t i o n of the watershed with snowpack(see snow cover curves, f i g s . 4.1, 4.2). Model Performance I t i s d i f f i c u l t to assess t h i s model's e f f e c t i v e n e s s . One c o n t r o l i s p o s s i b l e by comparing cumulative evaporation as estimated by equation 4.7 with cumulative evaporation measured with a non-standard evaporation pan. The pan was p l a c e d i n the pond d u r i n g 78 days of summer and f a l l , 1979. Weather for the p e r i o d was mostly sunny. The r a t i o of measured to estimated evaporation i s c o n s i s t e n t throughout the snowmelt p e r i o d and averages 1.08. T h i s appears q u i t e a c c e p t a b l e . However, i t bZ F i g u r e 4.3. Measured versus modeled pond e v a p o r a t i o n d u r i n g 78 days of 1979. should be noted that there are s i g n i f i c a n t d e v i a t i o n s from t h i s average d u r i n g summer ( f i g u r e 4.3). One reason f o r t h i s i s that the model assumes QG = 0. T h i s i s s u r e l y not the case d u r i n g l a t e melt p e r i o d s when s o i l s begin to thaw. Ln a d d i t i o n , the net r a d i a t i o n r e l a t i o n s h i p s i n equations 4.6 and 4.7 probably do not f i t f o r the l a t e melt season because meltwater i s near f r e e z i n g while a i r temperatures are w e l l above f r e e z i n g . Under such c o n d i t i o n s , s e n s i b l e and r a d i a n t energy i s absorbed by meltwater. T h i s energy may then be advected out of the system i n r u n o f f . The l i k e l y net e f f e c t of these two c o n d i t i o n s i s to overestimate e v a p o r a t i o n . A d d i t i o n a l l y , the model i s not c a l i b r a t e d f o r rock and bare s o i l . These s u r f a c e s cover almost h a l f the watershed and t h e i r e v a p o r a t i v e processes d i f f e r from those of w e l l vegetated 63 s u r f a c e s . Evaporation on bare rock i s l i m i t e d by the amount of water s t o r e d i n depressions on the rock s u r f a c e . T h i s amount i s normally s m a l l . Bare s o i l has c o n s i d e r a b l y more storage c a p a c i t y and evaporation r a t e s can be as h i g h as 0.9 times the r a t e of open water. However, evaporation r a t e s over bare s u r f a c e s w i l l d e c l i n e to near zero a f t e r about 5 to 10 mm are removed from storage. T h i s occurs because c a p i l l a r y and vapor f l u x t r a n s p o r t w i t h i n dry s o i l i s inadequate to s u s t a i n s i g n i f i c a n t e v a p o r a t i o n r a t e s (Hyde, 1954). P r e c i p i t a t i o n frequency was high throughout most of the study p e r i o d but, without l y s i m e t r i c measurements, the model's performance cannot be p r o p e r l y e v a l u a t e d . Again, t h i s should produce overestimate of a c t u a l e v a p o r a t i o n f l u x . D e s p i t e these u n c e r t a i n t i e s , the model i s d e f e n s i b l e on the grounds that an order of magnitude estimate i s a l l that i s r e q u i r e d given the s i z e of e v a p o r a t i v e f l u x here and the u n c e r t a i n t i e s of l a r g e r terms in the water budget, such as groundwater. Evaporation Over Snow Evapo r a t i o n over continuous snow cover i s l i m i t e d to p e r i o d s of c o l d , dry weather when ev a p o r a t i v e vapor g r a d i e n t s can form and to p e r i o d s of hot, dry, windy weather when l a r g e t u r b u l e n t , s e n s i b l e heat exchanges are p o s s i b l e . These l i m i t a t i o n s to evaporation over snow occur f o r two reasons. F i r s t , the s u r f a c e temperature of m e l t i n g snow does not exceed 0°C so s u r f a c e vapor pressure i s l i m i t e d to a maximum of 64 611 Pa, which i s low. A i r above the s u r f a c e must be e x c e p t i o n a l l y dry to induce an e v a p o r a t i v e gr a d i e n t ( s u r f a c e vapor pressure>atmospheric vapor p r e s s u r e ) , a c o n d i t i o n which i s favored by c o l d a i r temperatures. Second, the energy r e q u i r e d to convert i c e to vapor ( l a t e n t heat of s u b l i m a t i o n , Ls) i s h i g h , 2.83*1 0 6 J k g - 1 , being the sum of l a t e n t heat of f u s i o n ( L f ) and the l a t e n t heat of v a p o r i z a t i o n ( L v ) . As Lv i s 7.5 times g r e a t e r than L f , most net r a d i a t i o n at the s u r f a c e i s expended i n melt rather than evaporation (Oke, 1978). The l a t t e r becomes s i g n i f i c a n t only when l a r g e q u a n t i t i e s of s e n s i b l e energy are a v a i l a b l e to heat the s u r f a c e (eg. from hot, dry winds). Consequently, condensing c o n d i t i o n s should dominate over snow i n a temperate, humid environment such as high a l t i t u d e zones of the Coast Mountains. In a d d i t i o n , condensation i s a source of l a t e n t heat f o r the surface and can be an important source of melt (1 gm condensation y i e l d s 7.5 gm of melt energy e q u i v a l e n t ) . P h y s i c a l l y - b a s e d models f o r snow eva p o r a t i o n are d i f f u s i v e f l u x or "bulk aerodynamic" equations. Vapor f l u x between two r e f e r e n c e l e v e l s i n the atmosphere are computed as the product of a t r a n s p o r t c o e f f i c i e n t , based on temperature and wind p r o f i l e s , and the p o t e n t i a l g r a d i e n t or vapor pressure d i f f e r e n c e between the r e f e r e n c e l e v e l s . The equations impose s t r i n g e n t s i t e and data requirements. Consequently, e m p i r i c a l s i m p l i f i c a t i o n s have evolved, the most common being E = F(u)(es-ea) (4.10) 65 where E i s e v a p o r a t i o n ( L / T ) , F i s a d i f f u s i o n and p r o f i l e c o e f f i c i e n t , u i s windspeed(L/T), es-ea i s the atmospheric vapor pressure d e f i c i t . E s s e n t i a l l y , t h i s mass t r a n s f e r equation s u b s t i t u t e s the constant F f o r the wind p r o f i l e data i n the bulk aerodynamic equation. The most commonly c i t e d v a l u e s f o r F are due to Kuzmin (1961). Jordan (1978) determined a value of F which i s approximately 50% lower than Kuzmin's. Use of Jordan's c o e f f i c i e n t tends to overestimate snow evaporation r e l a t i v e to Kuzmin's because condensing c o n d i t i o n s are dominant. Thus, Jordan's value of F was accepted as a s a f e r upper-bound on snow ev a p o r a t i o n . Use of e i t h e r c o e f f i c i e n t produces almost t r i v i a l snow evaporation because p e r i o d s of evaporation are o f f s e t by p e r i o d s of condensation having s i m i l a r magnitude. Wind speed data at Goat Meadows are a v a i l a b l e only f o r the summmer and f a l l of 1981. The mean wind speed d u r i n g J u l y , August and September of that year was 1.26 m s e c " 1 (P. Jones, p e r s o n a l communication). Jordan (1978) measured mean wind speeds of 1.3 m s e c " 1 at M c G i l l i v a r y Pass dur i n g the a b l a t i o n season of 1976. No other h i g h a l t i t u d e data are known to be a v a i l a b l e . These two f i g u r e s are q u i t e low, are reasonably s i m i l a r , and conform to q u a l i t a t i v e o b s e r v a t i o n s made at Goat Meadows durin g the study p e r i o d . Thus 1.3 m sec " 1 i s taken as the mean wind speed f o r the snow e v a p o r a t i o n model. D a i l y snow evaporation was estimated as E(mm day" 1) = 0.23(6.11 -(emin+emax/2))(%snow cover/100) (4.11) 66 Annual Water Budgets Table 4.2 p r e s e n t s annual water budgets f o r 1979 and 1980. One f e a t u r e of the budgets i s the marked v a r i a n c e i n components from season to season and the r e l a t i v e l a c k of v a r i a n c e between y e a r s . T h i s p a t t e r n of v a r i a n c e i s due to s e v e r a l f a c t o r s , the most obvious being the p e r i o d i c i t y of annual c l i m a t e and the watershed's f i n i t e storage c a p a c i t y . The s e c t i o n to f o l l o w d i s c u s s e s the s i m i l a r i t i e s and d i f f e r e n c e s i n the 1979 and 1980 budgets w i t h i n the context of these two c o n t r o l s using runoff r a t i o s as i n d i c e s of i n t e r n a l p r o c e s s e s . R e s i d u a l s i n the budgets w i l l then be s c r u t i n i z e d i n order to d e f i n e the remaining v a r i a n c e i n the data s e t . Runoff R a t i o s Runoff r a t i o s (Q/M+P) are crude s u r r o g a t e s of storage changes w i t h i n a watershed because stream discharge i s the dominant h y d r o l o g i c output i n humid environments and melt and p r e c i p i t a t i o n n e a r l y d e f i n e t o t a l h y d r o l o g i c i n p u t s . There i s a r e c o g n i z a b l e p a t t e r n of annual runoff r a t i o s at Goat Meadows. Rat i o s are undefined d u r i n g the accumulation season because melt and r a i n are frozen and s t o r e d w i t h i n the snowpack at t h i s a l t i t u d e and groundwater t a b l e s are low. Melt i n c r e a s e s d u r i n g l a t e A p r i l and May, the snowpack becomes i s o t h e r m a l , and runoff commences. Runoff r a t i o s are i n i t i a l l y low d u r i n g e a r l y melt because s o i l and s u r f a c e d e t e n t i o n storage are recharged. Meltwater pathways w i t h i n and beneath the snowpack are i n i t i a l l y 67 Table 4.2. Water budgets f o r Goat Meadows watershed, 1979 and 1980. U n i t s are mm water e q u i v a l e n t . A s t e r i s k i n d i c a t e s estimated values d i s c u s s e d f u l l y i n Appendix E. 1 979 decimal # of dates days Melt Prec i p Q ET Q/M+P R Snowmelt 107-112 6 0.7 0.0 0.0 3.8 -3.1 113-124 1 2 159.9 17.6 120.0* 1 .7 0.68 55.8 125-136 1 2 9.6 16.4 6.0 2.6 0.23 17.4 137-149 1 3 1 22.7 14.7 160.7 2.3 1.17 -25.6 150-157 8 128.7 8.1 1 07.9 0.7 0.79 28.2 158-166 9 87.7 10.2 88.4 1 .8 0.90 7.7 167-173 7 97.4 3.8 83.3 0.8 0.82 17.1 174-183 10 1 98.4 19.9 1 54.7 7.2 0.71 56.4 184-205 22 70.3 46.3 1 76.7 34.7 1 .52 -94.8 s u b t o t a l 99 875.4 137.0 897.7 55.6 0.89 59. 1 Summer 206-251 46 11.0 162.4 0.0 59.5 114.7 F a l l 252-278 27 0.0 45.0 6.0 23.2 0.13 15.8 s u b t o t a l 73 11.0 208.2 6.0 82.7 0.03 130.5 Annual t o t a l 1 72 886.4 345.2 903.7 138.3 0.73 189.6 1980 dec imal # of dates days Melt Prec i Snowmelt 137-148 1 2 125.4* 40.3 149-158 10 97.6 35.6 159-163 5 85.6 5.9 164-178 1 5 346.9 38.9 179-186 8 1 22.2 7.2 187-198 1 1 1 45.6 3.8 199-225 27 104. 1 0.5 s u b t o t a l 88 1027.4 1 32.2 Summer 226-269 44 11.0 84.8 F a l l 270-288 19 0.0 75.7 s u b t o t a l 63 11.0 1 60.5 Annual t o t a l 151 1038.4 292.7 Q ET Q/M+P R 42. 4 1 .5 0.32 121.8 94. 2 0.3 0.71 38.7 75. 7 -0.4 0.83 16.2 260. 2 -3.2 0.67 1 28.8 118. 6 0.0 0.92 10.8 246. 0 3.9 1 .65 -100.5 182. 8 36.6 1 .75 -114.8 1019. 9 38.7 0.88 101.0 0. 0 33.6 62.2 7. 0 19.0 0.09 49.7 7. 0 52.6 0.04 111.9 1026. 9 91 .3 0.77 213.2 68 p o o r l y d e f i n e d and c o n s i d e r a b l e water can be ponded above i c e lenses and i n s u r f a c e d e p r e s s i o n s . In time, the h y d r a u l i c c o n d u c t i v i t y of the snowpack i n c r e a s e s , runoff w i l l melt a channel network i n the base of the pack and runoff w i l l become more d i r e c t (Wankiewicz, 1978). T h e r e a f t e r , runoff r a t i o s i n c r e a s e and become more s t a b l e . By J u l y and August the snowpack becomes d i s c o n t i n u o u s and melt inputs decrease d e s p i t e very high s p e c i f i c a b l a t i o n r a t e s . Runoff r a t i o s r i s e above u n i t y d u r i n g the l a s t event sequence of each year because inputs are reduced and b a s i n storage i s at a maximum, m a i n t a i n i n g stream d i s c h a r g e at only s l i g h t l y reduced r a t e s . General d i s c h a r g e commences from s o i l and s u r f a c e d e t e n t i o n s t o r a g e . By mid-August these s t o r e s are depleted- to l e v e l s that can no longer support f u r t h e r stream d i s c h a r g e and runoff r a t i o s again become undefined. Runoff i s i n f r e q u e n t throughout the remainder of the a b l a t i o n season. T h i s occurs because the o u t l e t stream i s fed by a pond where ev a p o r a t i v e and groundwater f l u x e s are h i g h . S e v e r a l s i g n i f i c a n t p r e c i p i t a t i o n events are necessary to induce runoff through the o u t l e t . The p a t t e r n i s common to a l l streams i n the area but i s most pronounced at pond o u t l e t s . Sometime i n f a l l , r a i n events become s u f f i c i e n t l y frequent to r e p l e n i s h s o i l and s u r f a c e d e t e n t i o n storage t o l e v e l s t h a t support streamflow. F a l l runoff events have been s h o r t - l i v e d i n the four years that Goat Meadows has been observed. In a l l but f a l l 1978, accumulation seasons were entered with s o i l s near f i e l d capac i t y . 69 The c h i e f d i f f e r e n c e i n ru n o f f r a t i o s between 1979 and 1980 i s that the r a t i o s are more s t a b l e d u r i n g 1980. I n s t a b i l i t y i n 1979 i s due to two f a c t o r s , both r e l a t e d to weather. The 1979 accumulation season began in l a t e October, 1978 with a major rainstorm, which turned to f r e e z i n g r a i n and then snow, fo l l o w e d by c l e a r , c o l d weather. S o i l moisture and s u r f a c e storage must have been near c a p a c i t y at t h i s time because the storm generated streamflow at the basin o u t l e t . E a r l y winter accumulation was w e l l below h i s t o r i c average ( f i g u r e 2.3) and snow storage at the end of the accumulation season was the lowest f o r the 28 years of r e c o r d at nearby T e n q u i l l e Lake snowcourse. A two week outbreak of c o n t i n e n t a l a r c t i c a i r covered southwestern B r i t i s h Columbia i n l a t e December dropping temperatures to -40°C at Goat Meadows. Lake i c e i n excess of 0.3 m t h i c k formed because the shallow snowpack provided poor thermal i n s u l a t i o n . As d i s c u s s e d i n Appendix E ( M i s s i n g Records), pond i c e caused e x t e n s i v e f l o o d i n g (gains to s u r f a c e d e t e n t i o n storage) w i t h i n the watershed u n t i l the i c e cracked on day 146. At l e a s t 1200 m3 water d r a i n e d w i t h i n hours and e x p l a i n s the high runoff r a t i o d u r i n g the event 137-149. The c o l d weather a l s o may have been the cause of e x t e n s i v e segregated i c e formation i n the upper 250 mm of the s o i l s . When insp e c t e d i n e a r l y A p r i l , 1979 s o i l s c o n t a i n e d numerous amorphous i c e nodules and d i s c o n t i n u o u s but e x t e n s i v e i c e l e n s e s up to 15 mm t h i c k . M u l t i c y c l e needle i c e in excess of 250 mm t h i c k remained i n t a c t beneath the snowpack in wetland 70 d e p r e s s i o n s p r o t e c t e d from snow creep. Surface d e t e n t i o n storage s i t e s were capped with s u r f a c e i c e approximately 20 mm to 50 mm t h i c k . Snowpacks co n t a i n e d s o f t , d i s c o n t i n u o u s b a s a l i c e l e n ses up to 10 mm t h i c k . Segregated i c e reduces the p e r m e a b i l i t y of some s o i l s s i g n i f i c a n t l y , which reduces the e f f e c t i v e s o i l moisture storage and encourages overland flow d u r i n g snowmelt (Dunne and Black, 1971; W i l l i a m s , 1976; Kane et a l . , 1978). I t i s l i k e l y that segregated i c e l i m i t e d s o i l i n f i l t r a b i l i t y , e f f e c t i v e s o i l moisture storage, and i n d i r e c t event ru n o f f d u r i n g 1979. L i m i t e d b a s i n storage c a p a c i t y i s i m p l i e d by the low instantaneous discharge r a t e s that are reached on r e c e s s i o n between snowmelt event c y c l e s , 1979 ( f i g u r e 4.4). Average minimum di s c h a r g e r a t e s i n 1979 are about h a l f of those i n 1980. In c o n t r a s t , i n d i r e c t event runoff was much higher d u r i n g snowmelt i n 1980. S o i l temperatures were at or below f r e e z i n g throughout t h i s p e r i o d , but segregated i c e was not observed and s o i l s were open to d a i l y melt i n p u t s . Whatever the cause, the e f f e c t of reduced i n d i r e c t runoff l e v e l s was to i n c r e a s e the v a r i a b i l i t y of runoff r a t i o s between i n d i v i d u a l events because d i r e c t r u n o f f , which i s h i g h l y v a r i a b l e , becomes a p r o p o r t i o n a l l y l a r g e r component of each event's budget. T h i s e f f e c t has important i m p l i c a t i o n s f o r many other phenomena observed d u r i n g the study p e r i o d and w i l l be e v a l u a t e d i n more d e t a i l i n chapters 5 and 8. 72 R e s i d u a l s R e s i d u a l s in the water budget were d e f i n e d i n equation 4.3. Assuming no b i a s i n the estimate of the other f l u x e s in equation 4.3, (a major assumption) and that measurement e r r o r s are t r u l y random and small, R = A S s o i l + GW. A negative r e s i d u a l i m p l i e s a l o s s to A S s o i l and/or a l a r g e net groundwater f l u x while a p o s i t i v e r e s i d u a l i m p l i e s a gain to A S s o i l and/or a small net groundwater f l u x . T h i s i s not true f o r short p e r i o d s . For example, the negative r e s i d u a l d u r i n g days 137-149, 1979 was caused by the r a p i d r e l e a s e of meltwater ponded above lake i c e on day 146. The r e s i d u a l r e p r e s e n t s the l o s s of f r e e water i n snowpack and s u r f a c e d e t e n t i o n storage,accumulated dur i n g the p e r i o d 113-136. However, the longer the p e r i o d of r e c o r d or the g r e a t e r the magnitude of each i n d i v i d u a l event, the g r e a t e r the r e l i a b i l i t y of the r e s i d u a l to r e f l e c t s o i l storage changes and groundwater f l u x r e l a t i v e to changes in other s t o r e s and to measurement e r r o r s . The most important d i f f e r e n c e i n r e s i d u a l s between 1979 and 1980 occurs during snowmelt season. The 1979 s p r i n g budget r e s i d u a l i s h a l f t h a t of 1980 (0.6 mm day" 1and 1.2 mm day" 1 r e s p e c t i v e l y ) . The summer-fall r e s i d u a l s i n both years average to about 1.8 mm day" 1 d e f i c i t i n outputs r e l a t i v e to i n p u t s . These r e s i d u a l s are s i g n i f i c a n t components of both the seasonal and annual budgets and demand r e s o l u t i o n . 7 3 Groundwater Losses Groundwater f l u x was measured i n d i r e c t l y by observing drawdown i n lake l e v e l s d u r i n g p e r i o d s of h y d r o l o g i c quiescence. Table 4.3 are water budgets f o r the pond duri n g one month of summer in both study years. A drop in stage, AH must equal the d i f f e r e n c e between t o t a l inputs and t o t a l outputs. Thus GW = Qin + P - E - AH. (4.12) E a r l y season i n f l u x r a t e s to the pond are s l i g h t underestimates because a c t i v e seeps c o u l d not be gauged and Hummingbird weir was i n o p e r a t i v e d u r i n g summer 1980. The data suggest an average r a t e of groundwater l o s s through the lake f l o o r of about 17 mm day" 1, which i s very high. One approach to e v a l u a t i n g t h i s term i s to assume that r a t e s of groundwater f l u x through the pond f l o o r are r e p r e s e n t a t i v e of groundwater f l u x r a t e s i n other areas in the watershed. T h i s assumption i s u n l i k e l y because the pond pr o v i d e s a h y d r o s t a t i c head of between 0.5 and 1.0 m to d r i v e moisture f l u x through the pond sediments. Flux r a t e s i n other areas of the watershed should be l e s s (assuming homogeniety of m a t e r i a l p e r m e a b i l i t y ) because h y d r o s t a t i c heads in s a t u r a t e d topographic d e p r e s s i o n s w i l l be s m a l l e r . Table 4.4 i l l u s t r a t e s two p o s s i b l e consequences of t h i s assumption. Column 3, pond c o n t r i b u t i o n to R, i s the case where a l l groundwater l o s s i s l o c a l i z e d to the lake f l o o r ( eg. 17 mm day" 1 * the number of days * (lake area / b a s i n a r e a ) ) . Column 4 i s t h i s same value d i v i d e d by the r e s i d u a l (R) f o r the p e r i o d and g i v e s the percentage of the r e s i d u a l that i s " e x p l a i n e d " .by 74 Table 4.3. Rates of groundwater l o s s through the pond f l o o r U n i t s are mm water e q u i v a l e n t . dec imal dates 1979 Qin P E dH dH GW stream a c t u a l c o r r e c t e d e s t . f l u x i n f l u x P r e c i p . Evap. stage l o s s through mm day" 1 pond f l o o r 206-220 221-230 231-240 T o t a l 1980 51.1 0.0 0.0 51.1 2.1 13.0 20.5 35.6 53. 9 25.7 28. 1 107.7 •233.5 •220.0 •220.0 •673.5 •234.2 •207.3 •212.4 •653.9 15.6 20.7 21.2 18.6 225-239 240-253 T o t a l 59.5 0.0 59.5 32.7 31.5 64.2 32.8 24.5 57.3 •1 55.4 •228.6 •383.6 •214.8 •235.6 •450.4 15.3 16.8 15.5 Table 4.4. Some i m p l i c a t i o n s of the assumption that r e s i d u a l i n the budget equation i s due to groundwater f l u x , t e x t f o r a complete d e s c r i p t i o n . a l l See Year and Season # of Days R (mm) Pond I nput to R(mm) 1979: Snowmelt 99 59.1 66.7 Summer-Fall 73 130.5 49.2 1980: Snowmelt 88 101.0 59.3 Summer-Fall 63 111.9 42.5 Pond Input /R * 100 1 1 3 38 59 38 Minimum GW C o n t r i b u t i n g Area (%) 3.5 10.5 6.8 10.5 lake l o s s e s alone. In both years, l e s s than 40% of the summer-fall r e s i d u a l can be e x p l a i n e d by t h i s case and durin g snowmelt 1980, l e s s than 60% i s e x p l a i n e d . Snowmelt 1979 i s most c u r i o u s because the computation i m p l i e s that a l l the r e s i d u a l can be e x p l a i n e d by lake groundwater l o s s e s and e i t h e r i . groundwater f l u x r a t e s f o r t h i s p e r i o d have been overest imated 75 i i . the pond was i n i t i a l l y empty at the s t a r t of snowmelt and t h e r e f o r e d i d not c o n t r i b u t e f o r almost two weeks or i i i . measurement i m p r e c i s i o n i s l a r g e r than expected. R e c a l l an e a r l i e r working h y p o t h e s i s that s o i l i n f i l t r a b i l i t y was l i m i t e d d u r i n g snowmelt 1979. If t r u e , groundwater l o s s e s from s o i l s should a l s o have been r e s t r i c t e d . Thus, the snowmelt 1979 value i s not t o t a l l y unexpected. Whatever the e x p l a n a t i o n , the data set as a whole suggest that known groundwater f l u x through the lake f l o o r i s i n s u f f i c i e n t to e x p l a i n the t o t a l r e s i d u a l except during snowmelt 1979. Column 5, c o n t r i b u t i n g area to e x p l a i n R, was d e r i v e d by d i v i d i n g R by the maximum groundwater f l u x p o s s i b l e (eg. 17 mm day" 1 * number of days in the p e r i o d ) . These f i g u r e s should p r o v i d e a minimum estimate of the b a s i n area c o n t r i b u t i n g to groundwater l o s s because, as mentioned above, groundwater flow r a t e s i n n o n - l a c u s t r i n e areas should be lower than those measured at the l a k e . At best, one may conclude t h a t , i f a l l the r e s i d u a l i s due to groundwater f l u x , then at l e a s t 7% to 11% of the watershed must be c o n t r i b u t i n g to t h i s f l u x . In a d d i t i o n , snowmelt 1979 was anomalous f o r i t appears that the pond was the major c o n t r i b u t i n g area during that p e r i o d . The r a t i o n a l next step i s to evaluate the assumption on which t h i s t e n t a t i v e c o n c l u s i o n i s b u i l t (eg. rates of groundwater l o s s through the pond f l o o r are r e p r e s e n t a t i v e of groundwater l o s s e s elsewhere). T h i s can best be done by 76 e s t i m a t i n g the c a p a c i t y and the temporal v a r i a b i l i t y of the remaining term i n the budget; s o i l moisture s t o r a g e . I f AS i s s i g n i f i c a n t , groundwater l o s s must be r e s t r i c t e d to the pond because the t o t a l r e s i d u a l i s s m a l l . S o i l Moisture C a p a c i t y A d e s c r i p t i o n of s o i l s at Goat Meadows was given i n Chapter 2 (see t a b l e 2.2) and Appendix C. The c l a s s i f i c a t i o n scheme can be s i m p l i f i e d f o r the purposes of a s s e s s i n g s o i l moisture storage c a p a c i t y because moisture c a p a c i t y i s p r i m a r i l y a f u n c t i o n of s o i l t e x t u r e , organic matter content, and h o r i z o n t h i c k n e s s . Many d i f f e r e n t pedons here are s i m i l a r i n t e x t u r e , h o r i z o n sequences and t h i c k n e s s . Table 4.5 l i s t s some p h y s i c a l p r o p e r t i e s of two t e x t u r a l a s s o c i a t i o n s that represent the spectrum of s o i l s i n the watershed. Most s t a b l e , w e l l - v e g e t a t e d s i t e s have s i m i l a r parent m a t e r i a l s and t e x t u r a l p r o p e r t i e s ; ash and o r g a n i c - r i c h , l o e s s a l epipedons o v e r l i e c o a r s e - t e x t u r e d a b l a t i o n and b a s a l t i l l . U nstable areas are predominantly c o a r s e - t e x t u r e d but are su b d i v i d e d i n t o two c l a s s e s ; r e g o s o l i c and g l e y s o l i c because the l a t t e r remain s a t u r a t e d d u r i n g much of the year. Exposed bedrock i s excluded from t h i s scheme because i t l a c k s s i g n i f i c a n t storage c a p a c i t y . C h a r a c t e r i s t i c h o r i z o n s and average h o r i z o n t h i c k n e s s e s are given f o r each t e x t u r a l group. T h i s g e n e r a l i z a t i o n i s j u s t i f i e d by experience gained through d e s c r i b i n g 10 pedons and examining many p i t s w i t h i n t h i s 2.3 hectare watershed. Each ho r i z o n has been reduced by the percentage of coarse fragments (>2 mm) to 77 Table 4.5. Some p h y s i c a l p r o p e r t i e s of s o i l s in the watershed that are r e l e v a n t to moisture c a p a c i t y . See text f o r complete d e s c r i p t i o n . P h y s i c a l P r o p e r t i e s (mm) Sta b l e S i t e s : Podzols and B r u n i s o l s . A c t i v e S i t e s : Regosols G l e y s o l s H orizons: Ah Bm Ae Omb Bhf Bmb Bf C BC Ahj C t a l u s II C t i l l Ah Cg T h i c k n e s s : 40 20 200 200 120 100 450 450 100 800 % F i n e s (< 2 mm): 69 65 50 40 30 38 48 30 30 40 E f f e c t i v e t h i c k n e s s : 28 1 3 1 00 80 36 38 216 1 35 30 320 Texture 'of f i n e s : f s l s i f s l s i Is s i s i Is s i Is Organic Matter (% of f i n e s ) 25 to 45 16 34 1 2 to 30 2 to 1 1 8 4 4 1 5 4 A v a i l a b l e moi sture .mm/mm s o i l 0.13 0.06 0.13 0.05 0.06 0.06 0.05 0 .05 0.06 0.05 T o t a l -a v a i l a b l e moi s t u r e : 3.6 0.8 13.0 4.0 1 .8 2.3 10.8 6.8 2.0 16.0 Bulk d e n s i t y (kg/m 3): 560-1100 2000 2050 1 700-1800 2000 1800 Po r o s i t y : 40-60 30 20-25 34 34 20 -25 32 32 Cap a c i t y at s a t u r a t i o n : 20 1 2 1 00 60 28 187 1 04 1 4 1 44 78 y i e l d an e f f e c t i v e h o r i z o n t h i c k n e s s . T h i s i s the t h i c k n e s s of the h o r i z o n were i t composed s o l e l y of the f i n e (< 2 mm) f r a c t i o n which i s r e s p o n s i b l e f o r v i r t u a l l y a l l s o i l moisture r e t e n t i o n . T e x t u r a l d e s c r i p t i o n s of the f i n e f r a c t i o n i s l i s t e d next along with r e p r e s e n t a t i v e organic matter content. A v a i l a b l e moisture i s d e f i n e d as the d i f f e r e n c e i n water content between a s o i l at 33 kPa and 1500 kPa s o i l matrix t e n s i o n (eg. f i e l d c a p a c i t y and w i l t i n g p o i n t r e s p e c t i v e l y ) . F i n e f r a c t i o n t e x t u r e can be a r e l i a b l e surrogate f o r a v a i l a b l e s o i l moisture ( N i e l s e n and Shaw, 1958; S l a t e r and W i l l i a m s , 1965). The f i g u r e s l i s t e d here are l i t e r a t u r e estimates of a v a i l a b l e moisture (mm water/mm dry s o i l ) . They are m u l t i p l i e d by the e f f e c t i v e h o r i z o n t h i c k n e s s to estimate the t o t a l moisture a v a i l a b l e . Table 4.5 a l s o l i s t s bulk d e n s i t y and p o r o s i t y of h o r i z o n s determined from s o i l c l o d s . The c a p a c i t y of these h o r i z o n s at s a t u r a t i o n i s estimated as the product of p o r o s i t y and e f f e c t i v e h o r i z o n t h i c k n e s s . Table 4.6 l i s t s a v a i l a b l e s o i l moisture f o r the watershed based on data from t a b l e 4.5. Table 4.6 pr o v i d e s estimates of t o t a l s o i l moisture storage under r e p r e s e n t a t i v e f i e l d c o n d i t i o n s . These f i g u r e s were computed by weighting the c a p a c i t y of each s o i l group, estimated from data i n t a b l e 4.5, by the r e l e v a n t basin area f o r each s t o r e . "Late r e c e s s i o n " i s r e p r e s e n t a t i v e of s o i l moisture storage d u r i n g most of the summer, f a l l , and presumably winter. In t h i s c o n d i t i o n , wetlands are s a t u r a t e d , a l l s o i l s are at or very near f i e l d Table 4.6. S o i l moisture storage estimates (mm) watershed under average and extreme c o n d i t i o n s . f o r 79 the T e x t u r a l Group: Podzols/Bruni s o l s Regosols G l e y s o l s Pond Other Surface Detention S t o r e s T o t a l (mm) T o t a l as a % of annual prec i p i t a t i o n A v a i l a b l e Moi s t u r e 23 20 1 NA NA 44 3-4 Water i n storage d u r i n g l a t e r e c e s s i o n 23 20 5 20 NA 68 5-6 Water i n storage d u r i n g peak snowmelt 95 30 5 25 5 1 60 12-13 c a p a c i t y , the pond i s f u l l but a l l other s u r f a c e d e t e n t i o n storage s i t e s are i n a c t i v e . "Peak Snowmelt" i s r e p r e s e n t a t i v e of most of the snowmelt season and at the peak of f a l l r a i n s t o r m events that are of s u f f i c i e n t d u r a t i o n t o generate d i s c h a r g e t e m p o r a r i l y at the ba s i n o u t l e t . In t h i s c o n d i t i o n , wetlands are s a t u r a t e d and a l l other s o i l s are at l e a s t at f i e l d c a p a c i t y . S t a b l e s i t e s are s a t u r a t e d to 200 mm above the t e x t u r a l c o n t a c t between the l o e s s and t i l l while unstable s i t e s are s a t u r a t e d to 10 mm above the t e x t u r a l c o n t a c t between c o l l u v i u m and t i l l . In a d d i t i o n , the pond and a l l other s u r f a c e d e t e n t i o n storage s i t e s are at maximum c a p a c i t y and are connected by an a c t i v e stream network. The most important f a c t that comes from these computations i s that s o i l moisture storage i n t h i s watershed i s r e l a t i v e l y s m a l l . Nominal c a p a c i t y i s only 5% of the t o t a l 1979 80 p r e c i p i t a t i o n and 6% of the 1980 i n p u t s . The c h i e f e x p l a n a t i o n for l i m i t e d s o i l c a p a c i t y i s that the s o i l s here are t h i n and, most imp o r t a n t l y , they are very coarse t e x t u r e d . Coarse fragments make up 40% to 50% of most h o r i z o n s . Half of t h i s i s g r a v e l . Sands are on average 70% of the m i n e r a l f i n e f r a c t i o n . The most e f f i c i e n t h o r i z o n s f o r moisture storage are s t a b l e , o r g a n i c - r i c h epipedons which have accumulated by a i r f a l l d u r i n g the Holocene above the t i l l and c o l l u v i u m . Given that the c a p a c i t y of these s o i l s i s smaller than the annual r e s i d u a l i t i s u n l i k e l y that changes i n s o i l moisture storage can be used to e x p l a i n the annual r e s i d u a l . T h i s f a c t becomes even more apparent i f one reviews the annual p a t t e r n of h y d r o l o g i c events in t h i s environment. Seasonal changes in s o i l moisture are l i m i t e d because: i . the watershed i s snowfree f o r only about four months of the year and, of the remaining e i g h t months with snow cover, only three to four are a c t i v e a b l a t i o n p e r i o d s with streamflow. i i . E v a p o t r a n s p i r a t i o n r a t e s are low because a i r temperatures are g e n e r a l l y c o o l , v e g e t a t i o n i s l i m i t e d , and slope drainage i s r a p i d . i i i . H y d r o l o g i c p e r i o d s which s u b d i v i d e each annual water budget are e s s e n t i a l l y independent of one another with respect to changes in s o i l moisture storage. For example, snowmelt season i s a p e r i o d i n which s o i l s are 81 f i r s t brought to peak storage but then are allowed to di s c h a r g e back to nominal c a p a c i t y d u r i n g t h i s season's l a s t event as the snowpack becomes d e p l e t e d . Summer can be a time of drought and s o i l storage can be drawn down ( f i g u r e 4.1, 4.2). Nonetheless these s t o r e s must be r e p l e n i s h e d i n order to generate discharge at the o u t l e t which i s the event that has been used here to mark the beginning of h y d r o l o g i c f a l l . C l e a r l y , summer p r e c i p i t a t i o n i s a l s o f a r in excess of summer evaporation f o r the ba s i n as a whole ( t a b l e 4.2) and both terms are l a r g e when compared to the l i m i t e d c a p a c i t y of these s o i l s . In s h o r t , s o i l moisture storage i s small i n comparison to f l u x r a t e s , events are of s u f f i c i e n t frequency, and seasons are of such short d u r a t i o n to exclude the hypothesis that s o i l moisture storage changes are a major component of annual water d e f i c i t s . One cannot r e j e c t the i n i t i a l h y p o t h e s i s that groundwater l o s s e s compose the m a j o r i t y of the annual budget d e f i c i t and that a s i g n i f i c a n t area of the watershed i s c o n t r i b u t i n g to t h i s l o s s . Summary Both study years were dry with runoff of about 1000 mm. V i r t u a l l y a l l runoff was generated by snowmelt d u r i n g 90 days between mid A p r i l and August. Evaporation i s a small term (90 mm to 140 mm) because the snow-free p e r i o d i s s h o r t , biomass i s l i m i t e d , and temperatures remain c o o l . A v a i l a b l e s o i l moisture i s s mall (at most 50 mm) because s o i l s are c o a r s e - t e x t u r e d and t h i n . The s o i l r e s e r v o i r i s thus l i m i t e d and e a s i l y r e p l e n i s h e d 82 during snowmelt and f a l l rains. The study s i t e is not ideal for measuring water budgets because net groundwater losses are s i g n i f i c a n t (at least 200 mm). However, the small study s i t e allowed detailed measurement of p r e c i p i t a t i o n and most mass leaves the catchment as runoff, rather than evaporation. Thus water budgets are tractable and provide an adequate basis for computing geochemical budgets. 83 CHAPTER 5. RUNOFF GENERATION I n t r o d u c t i o n Streamflow generation mechanisms at Goat Meadows are d e s c r i b e d i n t h i s chapter. The goal i s to i d e n t i f y the pathways and source areas of water w i t h i n the catchment because t h i s i n f o r m a t i o n w i l l be u s e f u l f o r understanding s o l u t e movements. This o b j e c t i v e i s pursued i n i t i a l l y by hydrograph a n a l y s i s . I t i s argued that Goat Meadows i s best viewed as a two component di s c h a r g e system of coupled r e s e r v o i r s . Runoff 'generation mechanisms are d e s c r i b e d next and a l i n k a g e between flow components, i d e n t i f i e d by hydrograph a n a l y s i s , and observed ru n o f f g e n e r a t i o n mechanisms i s suggested. F o l l o w i n g t h i s , the hypothesis that ground i c e induced the h y d r o l o g i c response of 1979 snowmelt, i s re e v a l u a t e d . Hydrograph A n a l y s i s Flow Regime The l o c a l flow regime i s s t r o n g l y s e a s o n a l . Almost a l l (99%) annual discharge occurs i n the snowmelt season, which l a s t s from May to e a r l y August. F i g u r e s 4.1 and 4.2 i l l u s t r a t e d t h a t snowmelt can be thought of as a s i n g l e , a l b e i t long l i v e d , event and i n three years of study, the only major event. Thus, 84 only snowmelt -hydrographs - w i l l -be •eva-l-ua-ted i n ••kh-i-s -st-udy. Flow d u r a t i o n curves ( f i g u r e 5.1) allow comparison of the snowmelt d i s c h a r g e regime d u r i n g both years. The curves are 2 0 | 1 1 1 1 1 20 40 60 80 100 P e r c e n t a g e of time d i s c h a r g e e x c e e d e d F i g u r e 5.1. Flow d u r a t i o n curves f o r the basin o u t l e t weir, very steep i n d i c a t i n g t h a t the b a s i n has a wide range of d i s c h a r g e r a t e s (eg. i t i s " f l a s h y " ) . The p e r i o d i c i t y and i n t e n s i t y of d a i l y snowmelt events and the magnitude of d a i l y meltwaves r e l a t i v e to the b a s i n ' s storage c a p a c i t y promote a l a r g e , d i r e c t d i s c h a r g e component r e s p o n s i b l e f o r t h i s " f l a s h i n e s s " . Snow melt hydrographs were p l o t t e d together i n f i g u r e 4 . 4 . There are apparent s i m i l a r i t i e s and d i f f e r e n c e s between the two. Both hydrographs show a p r o g r e s s i v e seasonal change in d a i l y 85 hydrograph shape. E a r l y snowmelt events have broad, low, and l a t e d a i l y discharge peaks r e l a t i v e to l a t e r i n the season when events c r e s t s h a r p l y i n e a r l y evening. T h i s e f f e c t occurs because of d e c r e a s i n g t r a v e l times and d e c r e a s i n g v a r i a b i l i t y of t r a v e l times of melt water as the snowpack t h i n s and r i p e n s (Woo and Slaymaker, 1975; Dunne, P r i c e , and Colbeck, 1976). O v e r a l l , however, 1979 and 1980 snowmelt hydrographs are very d i s s i m i l a r . The range of d i s c h a r g e r a t e s experienced in 1980 are more c o n s e r v a t i v e and the slopes of both r i s i n g and f a l l i n g limbs are consequently more g e n t l e . T h i s i m p l i e s that storage w i t h i n the watershed was much g r e a t e r during 1980 or e l s e the d a i l y d i s t r i b u t i o n of melt was very much attenuated r e l a t i v e to 1979. I t w i l l be argued i n subsequent a n a l y s i s that the former e x p l a n a t i o n i s the more p l a u s i b l e . Recession Limbs The simplest approach to q u a n t i f y i n g d i f f e r e n c e s i n h y d r o l o g i c response between the two years i s t o analyze d a i l y r e c e s s i o n limbs. A r e c e s s i o n limb i s the p o r t i o n of an event hydrograph between the i n f l e c t i o n p o i n t on the f a l l i n g limb and the next i n f l e c t i o n p o i n t which marks the beginning of the r i s i n g limb of a subsequent event. The r e c e s s i o n curve "represents withdrawal of water from storage a f t e r excess r a i n f a l l has ceased.... the n a t u r a l decrease i n r a t e of d i s c h a r g e r e s u l t i n g from the d r a i n i n g o f f process....and i s e s s e n t i a l l y dependent upon the p h y s i c a l f e a t u r e s of the channel alone" (Gray, 1970). Thus, i n c l a s s i c a l hydrology, the slope of the 86 T 1 1 1 1 1 r 0 2 4 4 8 7 2 9 6 1 2 0 1 4 4 1 6 8 Reces s i on time (hrs) F i g u r e 5 .2. Recession limbs from the b a s i n o u t l e t weir. r e c e s s i o n limb i s thought to have p h y s i c a l meaning. Recession limbs are negative e x p o n e n t i a l f u n c t i o n s so many watersheds can be modeled as simple l i n e a r r e s e r v o i r s . " L i n e a r " here i m p l i e s that the r a t e of water r e l e a s e from a r e s e r v i o r i s a f u n c t i o n of storage volume i n the r e s e r v o i r such t h a t : Q2 = Q1 K exp - C t 2 - t 1 ) 5.1 and S = Qt/lnK 5.2 where Q i s d i s c h a r g e at times t1 and t 2 , K i s the r e c e s s i o n c o n s t a n t , and S i s the volume of water s t o r e d i n the r e s e r v o i r . In f a c t , r e c e s s i o n curves are f r e q u e n t l y composed of more than one arc segment, each having a d i f f e r e n t r e c e s s i o n c o n s t a n t . The standard i n t e r p r e t a t i o n of these d i s c o n t i n u i t i e s 87 i s that they represent p o i n t s of r e c e s s i o n where a 'quick' r e s e r v o i r becomes exhausted while u n d e r l y i n g and l e s s d i r e c t r e s e r v o i r s continue to f u n c t i o n . F i g u r e 5.2 i s a p l o t of i n d i v i d u a l r e c e s s i o n curves from the b a s i n o u t l e t superimposed one on another. The p l o t i s r e s t r i c t e d to r e c e s s i o n curves from days without l a t e a fternoon or night time r a i n (eg. those having smooth, r e g u l a r c u r v e s ) . The 1979 limbs are very steep and e s s e n t i a l l y p a r a l l e l with l i t t l e v a r i a b i l i t y . The 1980 limbs are more ge n t l e with great v a r i a b i l i t y of slope at any given d i s c h a r g e r a t e . V a r i a b i l i t y i n the 1980 r e c e s s i o n limbs can be g r e a t l y reduced i f the limbs are superimposed on one another i r r e s p e c t i v e of discharge range, that i s , by o v e r l a p p i n g the a r c s of each curve f o r best f i t ( f i g u r e 5.3). T h i s process i s g r a p h i c a l l y e q u i v a l e n t to s y n t h e t i c r e c e s s i o n limbs produced i n the manner recommended by USACE (1956, page 191). In terms of l i n e a r r e s e r v o i r theory, r e c e s s i o n i n 1979 was discharge dependent but n o n - l i n e a r because K, the " r e c e s s i o n constant", v a r i e s from 1.02±0.05 to 1 .11±0.04 for d i f f e r e n t events. Recession d u r i n g 1980 i s a l s o n o n - l i n e a r because the limbs are d i s c h a r g e independent. However, d u r i n g 1980 K i s a constant (1 . 05±0.01). R e c a l l i n g Gray's d e f i n i t i o n , the d i s s i m i l a r i t y of r e c e s s i o n limbs between years and the marked r e g u l a r i t y w i t h i n years suggests that the p h y s i c a l c h a r a c t e r i s t i c s of the watershed were d i f f e r e n t between years. Furthermore, the r e g u l a r i t y of the 1980 r e c e s s i o n limbs, once overlapped, suggests that the 88 0 24 48 72 96 120 144 R e c e s s i o n time ( h r s ) F i g u r e 5.3. Recession limbs when overlapped (top) and s y n t h e t i c r e c e s s i o n limbs (bottom) f o r both y e a r s . 89 r e s e r v o i r ( s ) that c o n t r o l s the d a i l y event hydrograph i s coupled to an u n d e r l y i n g r e s e r v o i r ( s ) t h a t induces r e c e s s i o n limb d i s c h a r g e independence. In other words, as a f i r s t approximation Goat Meadows may be viewed as a two component dis c h a r g e system of coupled r e s e r v o i r s . Hydrograph Sepa r a t i o n Graphic i l l u s t r a t i o n of t h i s hypothesis i s provided i n f i g u r e 5.5 which shows the snowmelt hydrographs separated i n t o two components on the b a s i s of the s y n t h e t i c r e c e s s i o n limbs ( f i g u r e 5.4). The a p p r o p r i a t e s y n t h e t i c r e c e s s i o n curve was o v e r l a i n on each d a i l y r e c e s s i o n curve f o r best f i t of the a r c s . The base l e v e l of the s y n t h e t i c r e c e s s i o n limb was then marked on the hydrograph because i t p r o v i d e s an estimate of discharge r a t e from the u n d e r l y i n g r e s e r v o i r or flow component on which the d a i l y stormflow component i s superimposed. The d a i l y base l e v e l s were then connected by eye to r e v e a l the approximate p a t t e r n of seasonal d i s c h a r g e from the u n d e r l y i n g s t o r e . A second l i n e appears in f i g u r e 5.5 to g e n e r a l i z e the t o t a l d i s c h a r g e hydrograph. By comparing these two l i n e s one can see that the flow components so separated vary g r e a t l y between ye a r s . Both 1979 and 1980 have l a r g e t o t a l d i s c h a r g e events of about one week d u r a t i o n . 1980 a l s o has a l a r g e u n d e r l y i n g component throughout the e n t i r e snowmelt season. I t i s c o n s e r v a t i v e (well-damped), with a c l e a r downward trend, but responds to major d i r e c t d i s charge events with a l a g of no more 90 F i g u r e 5 . 4 . Method of hydrograph s e p a r a t i o n based on s y n t h e t i c r e c e s s i o n limbs. 160 170 180 190 200 Figure 5.5. Snowmelt hydrographs separated i n t o two flow components on the b a s i s of s y n t h e t i c r e c e s s i o n limbs. 92 than a couple of days. In c o n t r a s t , 1979 l a c k s t h i s component e n t i r e l y u n t i l the l a s t few weeks of the season when snowcover i s reduced to a few l a r g e v e s t i g i a l snowpatches. These phenomena are a l s o g e n e r a l . Mosquito weir e x h i b i t s a n e a r l y i d e n t i c a l p a t t e r n of r u n o f f components even though i t s topography and s o i l s are p h y s i c a l l y d i f f e r e n t and the area of Mosquito catchment i s l e s s than h a l f as l a r g e as that of the basin o u t l e t weir. Therefore the p a t t e r n i s not scale-dependent. Synopsis D i s c u s s i o n to t h i s p o i n t demonstrates that there are c l e a r d i f f e r e n c e s i n snowmelt hydrograph shape between years and that the p a t t e r n i s general to a l l areas of the watershed. Two discharge components were i d e n t i f i e d i n f o r m a l l y by non-standard hydrograph a n a l y s i s based on s y n t h e t i c r e c e s s i o n limbs. One component i s very responsive, or " d i r e c t " to d a i l y melt events while the other i s more c o n s e r v a t i v e , or " i n d i r e c t " . Snowmelt 1979 d i f f e r s from snowmelt 1980 because i t i s dominated by the d i r e c t component. T h i s suggests that there was a s i g n i f i c a n t change i n r u n o f f sources between 1979 and 1980. A l l hydrograph s e p a r a t i o n techniques are a r b i t r a r y and the one a p p l i e d here i s u n c o n v e n t i o n a l . If the flow components i d e n t i f i e d here have v a l i d i t y they should be a s s o c i a t e d e a s i l y with s p e c i f i c runoff g e n e r a t i o n mechanisms. Thus, subsequent s e c t i o n s w i l l d e s c r i b e mechanisms of runoff generation and runoff source areas at Goat Meadows. 93 Streamflow Processes The b a s i c models of stream and stormflow generation are now w e l l d e s c r i b e d (Freeze, 1974; Dunne, 1978; Dunne and Leopold, 1978). P r e c i p i t a t i o n f a l l i n g on slopes moves l a t e r a l l y i n t o stream channels by four major mechanisms: i . p r e c i p i t a t i o n - e x c e s s o v e r l a n d flow i i . s a t u r a t i o n overland flow i i i . subsurface throughflow i v . groundwater flow. Stormflow or d i r e c t event runoff (Weyman, 1975) can be generated by the f i r s t three processes. Groundwater response i s g e n e r a l l y thought to be too slow to generate s i g n i f i c a n t stormflow. A fundamental debate i n h i l l s l o p e hydrology i n previous decades centered on the r e l a t i v e importance of these d i r e c t runoff processes to stormflow g e n e r a t i o n . C o n s i d e r a b l e f i e l d and t h e o r e t i c a l evidence suggests that i n undisturbed, humid environments, stormflow i s generated p r i m a r i l y by p r e c i p i t a t i o n onto small s a t u r a t i o n o v e r l a n d flow zones adjacent to the su r f a c e water network (Dunne, 1978). Runoff gene r a t i o n at Goat Meadows c o n t r a d i c t s t h i s g eneral model only i n the f a c t that s a t u r a t i o n o v e r l a n d flow zones are ex t e n s i v e , c o v e r i n g up to 47% of the watershed. Some processes r e s p o n s i b l e f o r the unusual extent of these zones w i l l be d e s c r i b e d f o l l o w i n g d i s c u s s i o n of more c o n v e n t i o n a l runoff mechanisms and source areas. 94 P r e c i p i t a t i o n - e x c e s s overland flow Hortonian or p r e c i p i t a t i o n - e x c e s s overland flow occurs when r a i n f a l l r a t e s exceed i n f i l t r a b i l i t y . I n f i l t r a b i l i t y i s the ra t e that water w i l l i n f i l t r a t e s o i l i f j u s t ponding c o n d i t i o n s are imposed. I n f i l t r a b i l i t y depends on s o i l p r o p e r t i e s , some of which are time v a r i a n t . I n f i l t r a b i l i t y may decrease dur i n g events f o r s e v e r a l reasons, i n c l u d i n g r e d u c t i o n of h y d r a u l i c g r a d i e n t s as p r o f i l e s wet up, the s o i l s u r f a c e becomes compacted by r a i n s p l a s h , or s o i l v o i d s become blocked by c o l l o i d s . P r e c i p i t a t i o n in excess of i n f i l t r a b i l i t y c o l l e c t s i n su r f a c e d e p r e s s i o n s which may f i l l and overflow, a l l o w i n g water to move over the land s u r f a c e at high v e l o c i t i e s to adjacent stream channels. Humid environments are t y p i c a l l y w e l l vegetated and support abundant s o i l fauna and org a n i c matter that h e l p p r o t e c t the s o i l s u r f a c e from compaction and maintain open, f r i a b l e epipedons. Thus, p r e c i p i t a t i o n - e x c e s s o v e r l a n d flow i s normally r e s t r i c t e d to small " p a r t i a l source areas" where s o i l p r o p e r t i e s l i m i t i n f i l t r a b i l i t y (Betson, 1964). At Goat Meadows, p r e c i p i t a t i o n - e x c e s s o v e r l a n d flow i s r e s t r i c t e d to bedrock outcrops. These are f i x e d or " p a r t i a l source areas" because t h e i r i n f i l t r a b i l i t y and s u r f a c e d e t e n t i o n storage c a p a c i t y are always l i m i t e d . Bedrock s l a b s are ex t e n s i v e (16% of basin area) and e f f i c i e n t runoff c o n c e n t r a t i o n elements. Bedrock s l a b s do not, however, c o n t r i b u t e d i r e c t l y to stormflow because the outcrops are mantled downslope by c o a r s e - t e x t u r e d d e b r i s aprons. Debris aprons are t h i c k , h i g h l y 95 permeable, and t h e r e f o r e are not e a s i l y s a t u r a t e d . Thus outcrops are not w e l l connected to the channel network. Y a i r et a l . (1978) d e s c r i b e d a s i m i l a r phenomenon in a desert environment. O c c a s i o n a l l y d e b r i s lobes beneath bedrock s l a b s become s a t u r a t e d and generate s a t u r a t i o n o v e r l a n d flow. T h i s water u s u a l l y i n f i l t r a t e s the s o i l f a r t h e r downslope where the d e b r i s i s t h i c k e r and the water t a b l e l i e s at depth. Some ove r l a n d flow may reach a nearby channel and c o n t r i b u t e d i r e c t l y to stormflow. These c o n t r i b u t i n g areas are very small and should not be important d i r e c t r u n o f f sources. Betson and Marius (1969) d e s c r i b e d a s i m i l a r phenomenon in a humid environment. S a t u r a t i o n Overland Flow Dunne or s a t u r a t i o n overlandflow i s generated where the water t a b l e i n t e r s e c t s the e a r t h s u r f a c e . T h i s occurs p r i m a r i l y in d e p r e ssions and f o o t s l o p e s which are convergence zones f o r flowpaths from adjacent s l o p e s . As such, they r e c e i v e d i s p r o p o r t i o n a t e l y l a r g e volumes of l a t e r a l throughflow, they are the f i r s t areas to become f u l l y s a t u r a t e d , and they are the l a s t areas to f u l l y d r a i n . Thus, the extent of s a t u r a t i o n o v e r l a n d flow zones i s determined by antecedent c o n d i t i o n s . These " v a r i a b l e source areas" are most dynamic where s o i l s are t h i n and slopes are concave (Dunne, 1978). Where the water t a b l e i n t e r s e c t s the s o i l s u r f a c e , e x f i l t r a t i o n o c c u r s . E x f i l t r a t i n g water i s c a l l e d r e t u r n flow because subsurface s o i l water i s r e t u r n e d to the s u r f a c e . 96 A c t i v e r e t u r n flow zones are e f f e c t i v e l y impermeable and d i r e c t p r e c i p i t a t i o n must run o f f as o v e r l a n d flow. Of the two, d i r e c t p r e c i p i t a t i o n onto s a t u r a t e d areas i s f e l t to be a more important component of stormflow than r e t u r n flow. S a t u r a t i o n overland flow i s widespread at Goat Meadows. Conventional c o n t r i b u t i n g areas are the lake (900 m2) and g l e y s o l i c s o i l s (800 m2) adjacent to the s u r f a c e water network. Overland flow i s generated on these s u r f a c e s by d i r e c t p r e c i p i t a t i o n onto s a t u r a t e d a r e a s . The g l e y s o l s a l s o c o n t r i b u t e r e t u r n flow which s u s t a i n s streamflow between events. The importance of c o n v e n t i o n a l o v e r l a n d flow zones to stormflow can be evaluated by c a l c u l a t i o n of maximum runoff i n t e n s i t y . The maximum c o n t r i b u t i n g area of lake and g l e y s o l s i s 1700 m2. Maximum s u s t a i n e d snowmelt r a t e s are 5 mm h r " 1 . I f a l l snowmelt onto these s a t u r a t e d areas becomes r u n o f f , 1700 m2 x 5.0 x 10" 3 m h r " 1 or 8.5 m3 h r " 1 runoff w i l l r e s u l t . T h i s reduces to a b a s i n wide d i s c h a r g e i n t e n s i t y of 0.4 mm h r " 1 . Peak streamflow d i s c h a r g e i n t e n s i t i e s i n t h i s watershed o f t e n are f i v e times that value (2.0 mm h r " 1 ) . Hence, d i r e c t p r e c i p i t a t i o n onto c o n v e n t i o n a l c o n t r i b u t i n g areas must be only one of s e v e r a l d i r e c t runoff components a c t i v e i n t h i s watershed. Overland Flow On B r u n i s o l s Overland flow i s a l s o generated on a l l b r u n i s o l s with continuous v e g e t a t i o n cover. These s i t e s are w e l l vegetated so i t i s not obvious why o v e r l a n d flow should occur here. 97 B a r r e t t (1981) i n v e s t i g a t e d the causes of nea r - s u r f a c e s a t u r a t i o n i n one area of a two km2 basin to which Goat Meadows i s a f i n g e r t i p t r i b u t a r y . B a r r e t t demonstrated that s a t u r a t i o n was induced by a w a t e r - r e p e l l e n t l a y e r at or near the su r f a c e of b r u n i s o l s . The fundamental cause of wa t e r - r e p e l l e n c y was not i s o l a t e d . F i r e t y p i c a l l y i n t e n s i f i e s n a t u r a l w a t e r - r e p e l l e n c y and c h a r c o a l was noted i n s e v e r a l s o i l p i t s . However, i n few cases d i d the zone of maximum w a t e r - r e p e l l e n c y and c h a r c o a l c o i n c i d e . The w a t e r - r e p e l l e n c y may be due to am p h o p h i l l i c organic compounds c o a t i n g mineral g r a i n s . These organic compounds may accumulate as c o a t i n g s on s o i l p a r t i c l e s because the l o c a l c l i m a t e l i m i t s m i c r o b i a l decomposition of organic matter (eg. the environment i s probably b a c t e r i a - p o o r and f u n g i - r i c h ) . Given the impressive accumulations of s o i l o r g a n i c matter at Goat Meadows, most of which are 2400 to 10500 years o l d , and the f a c t t h a t the w a t e r - r e p e l l e n c y i s not s p e c i f i c to any s o i l - v e g e t a t i o n a s s o c i a t i o n , t h i s h y p othesis i s reasonable. S o i l p i t s excavated d u r i n g storms are t y p i c a l l y s a t u r a t e d at two l e v e l s ; the top 20 mm and the bottom 100 mm to 200 mm of the f i n e t e x t u r e d Holocene d e p o s i t s . S o i l between these s a t u r a t e d l a y e r s remains unsaturated. F i g u r e 5.6 i l l u s t r a t e s the zones of s a t u r a t i o n commonly observed at vegetated s i t e s . Near-surface s a t u r a t i o n i s r e s t r i c t e d to a 5 to 15 mm t h i c k l a y e r of moss-lichen groundcover above the f i n e - t e x t u r e d , o r g a n i c - r i c h mineral s o i l below. In sedge communities t h i s zone can be t h i c k e r (up to 25 mm) and extends to the base of a dense Figure 5.6. Flowpaths i n b r u n i s o l s at Goat Meadows. Shaded areas i n d i c a t e zones of s a t u r a t i o n . 99 mat of sedge r o o t s . Both the t h i c k n e s s and a r e a l extent of the n e a r - s u r f a c e s a t u r a t e d zone i s h i g h l y v a r i a b l e and not s u p r i s i n g l y , i t expands and c o n t r a c t s d i r e c t l y with the i n t e n s i t y and d u r a t i o n of input events. When f l u o r e s c e n t dyes are a p p l i e d to the s o i l s u r f a c e , most of the dye moves l a t e r a l l y downslope w i t h i n the moss-lichen and root mat. Overland flow i s generated where t h i s perched s a t u r a t e d zone i n t e r s e c t s the s o i l s u r f a c e . T h i s occurs on the treads of m i c r o - t e r r a c e s (a u b i q u i t o u s f e a t u r e of heath covered s l o p e s ) , and on the foot segments of h i l l s l o p e s which are dominated by sedge and leutkea-moss-lichen communities. In t h i s case, o v e r l a n d flow c o n s i s t s of r e t u r n flow from the moss-lichen mats and d i r e c t p r e c i p i t a t i o n onto the mats. T h i s i s a s a t u r a t e d flow system whose base i s w i t h i n a few centimetres of the s o i l s u r f a c e . The moisture c a p a c i t y of the perched s a t u r a t e d zone i s l i m i t e d by the t h i n n e s s of the zone. Response to input events i s thus r a p i d and a r e a l l y v a r i a b l e . B r u n i s o l i c s a t u r a t i o n overland flow c o n t r i b u t i n g areas may cover as much as 40% of the watershed. T h e i r extent d u r i n g s p e c i f i c events i s c o n t r o l l e d by antecedent s o i l moisture and the d u r a t i o n and i n t e n s i t y of the p r e c i p i t a t i o n event. F i g u r e 5.7 shows p a t t e r n s of o v e r l a n d flow that were mapped during f a l l r a i n s t o r m s . Note that the maximum extent of overland flow occurs d u r i n g snowmelt and i s much l a r g e r than the dark shaded area mapped in f i g u r e 5.7. However, even i f the smaller area (20%) of frequent s a t u r a t i o n o v e r l a n d in f i g u r e 5.7 i s s u b j e c t e d to peak snowmelt inputs of 5 mm h r " 1 the d i r e c t 1 0 0 F i g u r e 5 . 7 . Runoff source a r e a s a t Goat Meadows. 101 runoff produced can reach 1.0 mm h r " 1 . T h i s i s 2.5 times l a r g e r than the upperbound estimate f o r s a t u r a t i o n o verland flow on g l e y s o l s computed e a r l i e r . T h i s f i g u r e does not i n c l u d e r e t u r n flow c o n t r i b u t i o n s to o v e r l a n d flow nor p e r c o l a t i o n l o s s e s to deeper subsurface l a y e r s . Nonetheless, the estimate computed for b r u n i s o l i c c o n t r i b u t i n g areas suggests that s a t u r a t i o n overland flow i s the primary d i r e c t runoff mechanism i n t h i s watershed. An a d d i t i o n a l consequence of l a r g e s a t u r a t i o n o v e r l a n d zones i s that s u r f a c e d e t e n t i o n storage s i t e s are e x t e n s i v e and cover a l l c l o s e d depressions d u r i n g p r o t r a c t e d events ( f i g u r e 5.8). Surface d e t e n t i o n storage i s maintained f o r one to f i v e days f o l l o w i n g events by the w a t e r - r e p e l l e n t zone and by l a t e r a l throughflow. T h i s has important consequences f o r d i r e c t runoff because i t maintains the b a s i n i n a s t a t e of readiness f o r the next major event. Subsurface Throughflow Subsurface throughflow i s l a t e r a l movement of subsurface water e i t h e r as unsaturated flow or as shallow s a t u r a t e d flow perched above the main water t a b l e . Subsurface throughflow may d e l i v e r water d i r e c t l y to permanent channels or through i n t e r m i t t e n t channel networks i n a v a r i a b l e source area. Saturated throughflow i s important to stormflow i n humid environments, p a r t i c u l a r l y where s o i l s are deep and very permeable, s l o p e s are steep and r e c t i l i n e a r , and s a t u r a t i o n o v e r l a n d flow zones are a r e a l l y c o n f i n e d to narrow v a l l e y Figure 5.8. Schematic pattern of surface detention storage and subsurface saturation during snowmelt. Shaded areas indicate zones of saturation. 1 03 f l o o r s . Two zones of s a t u r a t e d subsurface throughflow are common at Goat Meadows. The f i r s t i s throughflow above the w a t e r - r e p e l l e n t zone. As p r e v i o u s l y d i s c u s s e d , l a t e r a l flow occurs through a high c o n d u c t i v i t y mat of sedge r o o t s , moss and l i c h e n on b r u n i s o l s . The root mat i s c o a r s e - t e x t u r e d and l a t e r a l v e l o c i t i e s can be high, as much as 2.5 10~ 3 m s" 1 (based on experiments using dyes as t r a c e r s ) . The second zone of s a t u r a t e d throughflow develops above the t i l l . T h i s d e p o s i t i s indur a t e d and the matrix i s n e a r l y impermeable. A stout p i c k i s r e q u i r e d to excavate the t i l l and t e s t p i t s f i l l e d with water took at l e a s t one week to d r a i n . Thus, where the t i l l i s continuous, unbroken, and unweathered i t p r o v i d e s c o n s i d e r a b l e r e s i s t a n c e to v e r t i c a l matrix flow. S a t u r a t e d throughflow above the t i l l occurs i n a l l s o i l - v e g e t a t i o n a s s o c i a t i o n s except t r e e i s l a n d s where s a t u r a t i o n was never d e t e c t e d . Throughflow drainage networks above the t i l l vary by s o i l type. B r u n i s o l s are s t a b l e , w e l l vegetated s o i l s which have e x t e n s i v e t r a n s i e n t s a t u r a t e d lenses perched above the t i l l . Regosols are un s t a b l e , p o o r l y vegetated s o i l s which lack such l e n s e s . Instead, most throughflow i n c o l l u v i u m i s concentrated i n t o a network of d i s c r e t e subsurface channels or i n f i l l e d p i pes j u s t above the t i l l . Throughflow Lenses Throughflow lenses were monitored c l o s e l y at a 20 m2 h i l l s l o p e throughflow p l o t i n heath v e g e t a t i o n . The s i t e was 1 04 chosen because l o c a l i n f i l t r a b i l i t y was high, o v e r l a n d flow was l i m i t e d , and most snowmelt was routed through the subsurface. F i g u r e 5.9 compares s p e c i f i c d i s c h a r g e from a snow l y s i m e t e r to s p e c i f i c discharge from a companion subsurface g u t t e r i n s t a l l e d at the l o e s s / t i l l c o n t a c t . I t i s i n f e r r e d that the Holocene u n i t s o f f e r l i t t l e r e s i s t a n c e to incoming meltwater because the wave i s t r a n s l a t e d without a p p r e c i a b l e a t t e n u a t i o n . Peak to peak la g s between i n f i l t r a t i o n and throughflow hydrographs are about 2 to 4 hours and trough to trough l a g s are only s l i g h t l y l o n g e r . T h i s responsiveness i s to be expected given that the s a t u r a t e d h y d r a u l i c c o n d u c t i v i t y of these m a t e r i a l s (computed from d i s c h a r g e r e l a t i o n s h i p s here and measured on s l i g h t l y d i s t u r b e d cores with a constant head permeameter by B a r r e t t ) i s on the order 10" 5 m s " 1 . Two to three hours are necessary f o r s a t u r a t e d flow to p e r c o l a t e 75 to 110 mm through the Holocene m a t e r i a l s to the subsurface zone of s a t u r a t i o n . S e v e r a l f e a t u r e s of f i g u r e 5.9 r e q u i r e d i s c u s s i o n . F i r s t , both the snowmelt and throughflow hydrographs have twin d i s c h a r g e peaks, one i n e a r l y morning and one i n l a t e evening. The morning peak i s due to e a r l y morning d i r e c t r a d i a t i o n on the snow pack s u r f a c e and to melt from the p i t w a l l which i s east f a c i n g . The l a t t e r i s an annoying d i s t u r b a n c e to the n a t u r a l response of the system but one that c o u l d not be avoided without c o n s i d e r a b l y more e l a b o r a t e i n s t r u m e n t a t i o n . In e f f e c t , the p i t w a l l c o n t r i b u t e s a l a r g e s l u g of meltwater to the system that i s c o n c e n t r a t e d along a l i n e p a r a l l e l to the g u t t e r and only 10 to 50 mm upslope. T h i s induces a bulge in the s a t u r a t e d zone j u s t 1 05 F i g u r e 5.9. S p e c i f i c d i s c h a r g e from a snow l y s i m e t e r (unshaded) and two subsurface i n t e r c e p t o r g u t t e r s mounted at the throughflow zones above, the w a t e r - r e p e l l e n t l a y e r (black) and above the t i l l (shaded). upslope of the g u t t e r and produces an u n n a t u r a l l y r a p i d e a r l y morning response. Second, the volume of d i s c h a r g e from the snow l y s i m e t e r and the throughflow g u t t e r do not balance d e s p i t e the f a c t t h at both have been a d j u s t e d to r e f l e c t proper c o n t r i b u t i n g a r e a s . T o t a l d a i l y d i s c h a r g e from the g u t t e r i s about 75 % of t o t a l d a i l y inputs to the zone. Furthermore, subsurface d i s c h a r g e d e c l i n e s to near zero on r e c e s s i o n which i m p l i e s that the subsurface s t o r e i s d e p l e t e d to low l e v e l s each day. 1 06 T h i s discrepancy i n d a i l y d i s c h a r g e amounts can only be e x p l a i n e d i f the water i s i n f i l t r a t i n g i n t o the t i l l because the t r a v e l time of a water molecule from the top of the p l o t to the g u t t e r i s estimated to be about s i x days. In other words, the s t o r e cannot be d e p l e t e d by g u t t e r discharge alone because the t r a n s m i s s i o n r a t e i s too slow to allow d a i l y d e p l e t i o n . Other flowpaths must be a v a i l a b l e . T h i s i s problematic because a l l s a t u r a t e d subsurface throughflow was seen to move along t h i s contact and the t i l l matrix i s known to be n e a r l y impermeable. The most probable e x p l a n a t i o n of these c o n f l i c t i n g f a c t s i s that the t i l l has a high bulk p e r m e a b i l i t y ; eg. the t i l l conducts n o n - c a p i l l a r y p e r c o l a t i o n to the groundwater network. N o n - c a p i l l a r y flow in s o i l s occurs i n l a r g e voids or "macropores" such as root channels and the margins of cobble faces (Bevan and Germann, 1982). Macropores conduct only g r a v i t y water i f they lack c a p i l l a r y - s i z e d spaces and so lack matrix p o t e n t i a l . Thus, to induce macropore flow i t i s necessary that the v o i d be fed by a s a t u r a t e d zone and that the surrounding matrix be e i t h e r s a t u r a t e d or impermeable. These c o n d i t i o n s are met at Goat Meadows. The matrix of the b a s a l t i l l undoubtedly has a s a t u r a t e d h y d r a u l i c c o n d u c t i v i t y many orders of magnitude lower than the o v e r l y i n g u n i t s . The strong t e x t u r a l d i s c o n t i n u i t y between the t i l l and i t s overburden c r e a t e s the s a t u r a t e d throughflow zone which i n turn feeds any e x i s t i n g s o i l v o i d s . Low matrix p e r m e a b i l i t y w i l l a l s o l i m i t the amount of water l o s t to the t i l l as i t flows 1 07 through the macropore network. M o r p h o l o g i c a l evidence f o r macropore flow i n the t i l l i s abundant beneath t r e e i s l a n d s and heath. Thick organic matter accumulations coat matrix f r a c t u r e s , root channels, and the undersides of cobbles i n Bf, Bm and BC h o r i z o n s . The organic matter i s c l e a r l y i l l u v i a t e d from above and accumulates near flow r e s t r i c t i o n s . Furthermore, these o b s e r v a t i o n s are c o n s i s t e n t with work by Chamberlain (1972), Cheng et a l . (1975), and Chow and DeVries (1972) f o r lower a l t i t u d e f o r e s t s o i l s i n B r i t i s h Columbia. F i n g e r i n g S a t u r a t e d throughflow above the t i l l i n b r u n i s o l s i s fed by s a t u r a t e d f i n g e r s which extend from the throughflow zone above the w a t e r - r e p e l l e n t l a y e r . F i n g e r s may develop due to s p a t i a l v a r i a b i l i t y i n s u r f a c e w a t e r - r e p e l l e n c y , dynamic i n s t a b i l i t y caused by c o n d u c t i v i t y d i f f e r e n c e s between organic and c o a r s e r ash d e p o s i t s , and by v a r i a t i o n s i n the depth of s u r f a c e water ponding. These mechanisms are d i s c u s s e d by B a r r e t t (1981). D i r e c t o b s e r v a t i o n u s i n g dyes d u r i n g a r t i f i c i a l i r r i g a t i o n suggests an a l t e r n a t i v e mechanism. Dye i s d i s t r i b u t e d along heath and sedge r o o t s . Dye d i f f u s e s slowly i n t o the surrounding matrix. T h i s i m p l i e s that s a t u r a t e d f i n g e r s are i n i t i a t e d by macropore flow. F i n g e r s were o c c a s i o n a l l y observed d i r e c t l y by d i g g i n g s o i l p i t s d u r i n g storms. I n d i r e c t evidence f o r f i n g e r i n g i s epipedon h o r i z o n a t i o n . Boundaries between h o r i z o n s are commonly 108 i r r e g u l a r and the h o r i z o n s o f t e n t h i n above troughs i n the boundary. T h i s i s i n d i c a t i v e of p r e f e r e n t i a l p e r c o l a t i o n and l e a c h i n g at these spots. A d d i t i o n a l evidence of f i n g e r i n g was noted i n the f a l l of 1980 when pressure-vacuum s o i l water samplers were i n s t a l l e d i n the unsaturated zone. Sampler U115 was embedded in a s u r f a c e d e t e n t i o n storage s i t e and was evacuated r e p e a t e d l y throughout the f a l l . Water y i e l d (100 kPa) to the sampler d i d not vary a p p r e c i a b l y even f o l l o w i n g storms when the hollow was f u l l and marked i n f i l t r a t i o n was o c c u r r i n g . In other words, h y d r a u l i c communication between the s u r f a c e and the subsurface was poor l o c a l l y . Much of the subsurface below the s u r f a c e d e t e n t i o n d e p r e s s i o n remained unsaturated and i n f i l t r a t i o n was s p a t i a l l y r e s t r i c t e d t o d i s c r e t e , v e r t i c a l l y s a t u r a t e d f i n g e r s . T h i s suggests that w a t e r - r e p e l l e n t s i t e s are l e s s leached than one might suspect based on c l i m a t i c data. Throughflow Channels Subsurface s a t u r a t e d throughflow above the t i l l i n a c t i v e c o l l u v i u m i s very d i s s i m i l a r to that d e s c r i b e d i n vegetated areas. T a l u s and d e b r i s lobes are coarse t e x t u r e d and not w a t e r - r e p e l l e n t so t h e i r s a t u r a t e d h y d r a u l i c c o n d u c t i v i t i e s and i n f i l t r a b i l i t y are h i g h . T a l u s d e p o s i t s are a l s o t y p i c a l l y t h i c k and steep. Consequently overland flow and s a t u r a t e d throughflow lenses are r a r e , the l a t t e r never being g r e a t e r than a few m i l l i m e t r e s t h i c k . S a t u r a t i o n i s common but i t i s r e s t r i c t e d to a network of g r a v e l l y subsurface channels j u s t 109 above the t i l l . S e v e r a l throughflow channels are v i s i b l e where they e x i t to the s u r f a c e along the lower l e f t bank of Hummingbird Creek. These were never gauged nor exhumed but they remain a c t i v e f o r s e v e r a l days a f t e r major events and are suspected to extend headward n e a r l y to the bedrock i n t e r f l u v e s . Where v i s i b l e , the channels c o i n c i d e with the l a t e r a l margins of s t a b l e , o v e r l a p p i n g d e b r i s l o b e s . They are of c o a r s e r t e x t u r e than the surrounding matrix, ranging from very coarse sand to g r a v e l and small c o b b l e s . I t i s the author's impression that these are l a g d e p o s i t s which have been overgrown by moss and subsequently b u r i e d slowly by Holocene a i r f a l l d e p o s i t s and/or by r e a c t i v a t e d d e b r i s lobes ( c f . Jones, 1971; Gilman and Newson, 1980). Another a c t i v e throughflow channel was a c c i d e n t l y exhumed du r i n g c o n s t r u c t i o n of an i n t e r c e p t o r t r e n c h at a r e g o s o l i c s i t e . T h i s channel was the only s a t u r a t e d pathway f o r water d r a i n i n g through c o l l u v i u m 1.5 m deep in a 15 m wide bedrock s l o t . The channel was not i d e n t i f i e d as the source of s a t u r a t e d flows u n t i l l a t e i n the snowmelt season, 1980 but l i m i t e d manual gauging was p o s s i b l e f o r a few weeks before the major 1980 flows ceased. Maximum di s c h a r g e through 100 cm 2 of the channel was 2.5 l i t e r s / m i n u t e so i t s h y d r a u l i c c o n d u c t i v i t y i s about 10~ 2 m s " 1 . T h i s f i g u r e i s reasonable s i n c e the channel i s a sandy g r a v e l . T h i s c o n d u c t i v i t y i s three orders of magnitude g r e a t e r than that of b r u n i s o l i c l o e s s a l caps and, given the presumed c o n n e c t i v i t y 1 1 0 of the throughflow channels to the stream channel system, may provide a very e f f i c i e n t network f o r d r a i n i n g subsurface flow. Two f e a t u r e s were common to a l l observed throughflow channels. F i r s t , the channels are very coarse, l i n e a r zones d i r e c t l y above t i l l and are surrounded by a f i n e r - t e x t u r e d c o l l u v i a l matrix. Throughflow channels t h e r e f o r e have lower matrix p o t e n t i a l s than the surrounding c o l l u v i u m and a s a t u r a t e d zone probably develops above low p e r m e a b i l i t y t i l l to feed the channel. If c o r r e c t , these o b s e r v a t i o n s imply that s i g n i f i c a n t throughflow channel a c t i v i t y should be expected only d u r i n g s u s t a i n e d p r e c i p i t a t i o n events. Second, subsurface channel d i s c h a r g e continues f o r s e v e r a l days f o l l o w i n g p r e c i p i t a t i o n events and was observed to be s u s t a i n e d s o l e l y by unsaturated flow from the o v e r l y i n g c o l l u v i u m . Since unsaturated flow i s a much l e s s e f f i c i e n t mass t r a n s f e r process than s a t u r a t e d flow, the subsurface channel network must be e x t e n s i v e . These o b s e r v a t i o n s suggest that the e f f e c t i v e drainage d e n s i t y of the watershed i s much higher than i s apparent s u p e r f i c i a l l y . A s i g n i f i c a n t f r a c t i o n of the water that i n f i l t r a t e s the s u r f a c e w i l l have a r e l a t i v e l y l i m i t e d residence time because flowpaths to an a c t i v e , s a t u r a t e d , subsurface zone w i l l be r e l a t i v e l y s h o r t . Furthermore, the p r e f e r r e d , s a t u r a t e d pathways that e x i s t appear to be h y d r a u l i c a l l y e f f i c i e n t and we l l connected to the channel network. 111 Groundwater flow Groundwater as used in t h i s study r e f e r s to water moving along s a t u r a t e d flowpaths i n bedrock, not overburden. Groundwater flownets through bedrock cannot be r e c o n s t r u c t e d because at the time of f i e l d work i t was not deemed economically f e a s i b l e t o t r a n s p o r t d r i l l i n g apparatus to the s i t e . Groundwater s i m u l a t i o n s were attempted as an a l t e r n a t i v e . The l a c k of p i e z o m e t r i c data, the known he t e r o g e n e i t y of the bedrock, suspected a n i s o t r o p i c flow along shear zones and the topographic complexity of watershed p r e c l u d e d the use of e l a b o r a t e models. NUM5, a two dimensional, steady s t a t e , f i n i t e d i f f e r e n c e model (provided by R.A. Freeze, Department of G e o l o g i c a l S c i e n c e s , UBC) was run on topographic c r o s s s e c t i o n s with a v a r i e t y of water t a b l e c o n f i g u r a t i o n s . The model r e a f f i r m e d the obvious. L o c a l topography i s steep and i r r e g u l a r . E q u i p o t e n t i a l l i n e s are very s e n s i t i v e t o v a r i a t i o n s i n groundwater t a b l e h e i g h t . When water t a b l e s are low, the e n t i r e basin f u n c t i o n s as a groundwater sink or recharge zone and groundwater flowpaths are not expected to emerge w i t h i n the watershed. However, i f water t a b l e s are high (eg. during snowmelt) groundwater d i s c h a r g e i s expected on the south shore areas of the l a k e . I t must be understood c l e a r l y that the s i m u l a t i o n s assume that i s o t r o p i c flow i s o c c u r r i n g through homogenous formations. T h i s i s s u r e l y not the case at Goat Meadows. Nonetheless, the topography here suggests that discharge as w e l l as recharge can occur and that the a c t u a l flowpath p a t t e r n i s complex. 1 1 2 Synopsis P r e c i p i t a t i o n o v erland flow i s generated p r i m a r i l y on bedrock s l a b s and was not observed to c o n t r i b u t e s i g n i f i c a n t l y to stormflow. S a t u r a t i o n o v e r l a n d flow i s generated on g l e y s o l s and b r u n i s o l s . S a t u r a t i o n o v e r l a n d flow zones are t h e r e f o r e l a r g e and they are h i g h l y r e s p o n s i v e . T h i s unusual responsiveness develops because a t h i n s a t u r a t e d throughflow zone forms above a strong w a t e r - r e p e l l e n t l a y e r i n b r u n i s o l s . Throughflow above the w a t e r - r e p e l l e n t zone i s mostly l a t e r a l and r a p i d because the zone i s composed of a coarse t e x t u r e d mat of sedge r o o t s , moss and l i c h e n . Return flow from t h i s zone i s ext e n s i v e because small topographic slope i r r e g u l a r i t i e s are common. Surface d e t e n t i o n storage areas occur i n a l l vegetated, topographic hollows. Surface d e t e n t i o n storage i s maintained f o r days f o l l o w i n g events by l a t e r a l throughflow above the w a t e r - r e p e l l e n t zone and probably by throughflow above the t i l l . V e r t i c a l p e r c o l a t i o n i n b r u n i s o l s appears to be r e s t r i c t e d to s a t u r a t e d f i n g e r s . S e v e r a l processes may i n i t i a t e f i n g e r i n g but the most common mode of flow observed i n c o n t r o l l e d c o n d i t i o n s was macropore flow along root h o l e s . The root holes are fed by throughflow above the w a t e r - r e p e l l e n t zone. Macropore flow i s s u s t a i n e d below the w e l l d e f i n e d w a t e r - r e p e l l e n t l a y e r and water d i f f u s e s l a t e r a l l y only s l o w l y . Saturated throughflow a l s o develops d i r e c t l y above the t i l l . Throughflow drainage pathways vary by s o i l group. Regosols concentrate throughflow i n t o a network of 1 13 c o a r s e - t e x t u r e d subsurface channels which are w e l l connected with the stream channel network. B r u n i s o l s have e x t e n s i v e throughflow lenses above the t i l l . These feed a system of f r a c t u r e s i n the b a s a l t i l l which p r o v i d e s at l e a s t one mechanism f o r water to reach the groundwater network. The groundwater network appears to be complex and d i s c h a r g e areas are v a r i a b l e i n extent due to steep, i r r e g u l a r topography. Discharge i s to be expected on the south shore of the pond only d u r i n g p e r i o d s of high groundwater t a b l e s . Flow Components and Runoff Mechanisms The o v e r a l l h y d r o l o g i c c o n f i g u r a t i o n at Goat Meadows suggests that the a c t u a l drainage d e n s i t y of the watershed i s much higher than suspected because most subsurface water moves along p r e f e r r e d , s a t u r a t e d pathways. T h i s should reduce the expected t r a v e l times of water w i t h i n the ba s i n and produce r a p i d streamflow response to events. T h i s i s i n f a c t c o n s i s t a n t with the r e s u l t s of hydrograph a n a l y s i s which showed that the catchment i s very responsive to melt events. Observations of runo f f g e n e r a t i o n and c o n t r i b u t i n g areas a l s o suggest that the d a i l y event hydrograph i s generated p r i m a r i l y by d i r e c t p r e c i p i t a t i o n onto s a t u r a t e d areas and r e t u r n flow because these are the major "quick" stormflow g e n e r a t i o n mechanisms here and t h e i r c o n t r i b u t i n g areas are very l a r g e . S i m i l a r l y , the i n d i r e c t hydrograph component should be generated by s a t u r a t e d subsurface throughflow above the t i l l and 1 14 above the w a t e r - r e p e l l e n t zone. The i n d i r e c t hydrograph component i s too c o n s e r v a t i v e to be generated by overland flow. The u n d e r l y i n g hydrograph component a l s o appears to be too responsive to be composed simply of unsaturated flow because unsaturated flow i s a r e l a t i v e l y i n e f f i c i e n t mass t r a n s f e r p r o c e s s . These assignments are i n t u i t i v e but they are w e l l supported by the f a c t s . Consider an a l t e r n a t i v e h y p o t h e s i s . Assume that these hydrograph components are a r t i f i c i a l and that d i f f e r e n c e s i n hydrograph shape between snowmelt 1979 and 1980' are a r t i f a c t s of d i f f e r e n c e s i n the d a i l y d i s t r i b u t i o n of melt. Melt energy d u r i n g 1979 snowmelt was more r a d i a t i v e than d u r i n g 1980 (217 W nr 2 d a y 1 vs 193 W m~2 d a y - 1 ) , which was warmer and wetter. As a consequence, average d a i l y snowmelt events d u r i n g 1979 were somewhat s h o r t e r l i v e d and more intense than d u r i n g 1980 because melt waves were more co n c e n t r a t e d temporally d u r i n g r a d i a t i v e melt days. T h i s may e x p l a i n some of the d i f f e r e n c e in hydrograph shape between years (1979 has steeper r i s i n g and f a l l i n g limbs, s h o r t e r , higher peaks, and lower t r o u g h s ) . Nonetheless, the l a t e snowmelt season, 1980 had many hot sunny days with peak di s c h a r g e i n t e n s i t i e s as high as d u r i n g 1979 and yet both the r e c e s s i o n limbs and the behavior of the u n d e r l y i n g component do not change a p p r e c i a b l y . Thus a change i n input regime does not provide a c o n s i s t e n t e x p l a n a t i o n of the f a c t s . R e c a l l the hypothesis i n t r o d u c e d e a r l i e r that d i f f e r e n c e s in runoff between years were induced by ground i c e which l i m i t e d i n f i l t r a b i l i t y and encouraged overland flow. The i n d i r e c t 1 1 5 hydrograph component developed i n 1979 only when the snowcover became d i s c o n t i n u o u s . Snowpack breakup allowed the s o i l s to thaw, and a p p a r e n t l y improved t h e i r i n f i l t r a b i l i t y because there was a marked i n c r e a s e i n subsurface throughflow (observed i n standpipes) at that time. Hence, the appearance of the i n d i r e c t component d u r i n g l a t e snowmelt 1979, i t s presence throughout the 1980 season, and i t s a s s o c i a t i o n with subsurface throughflow suggest that the i n d i r e c t hydrograph component i s r e a l and i s generated by discharge from p r e f e r r e d , s a t u r a t e d , subsurface pathways. In s h o r t , the hydrograph s e p a r a t i o n technique appears to be v a l i d because the components so separated can be i d e n t i f i e d with two d i f f e r e n t runoff g e n e r a t i n g mechanisms with d i f f e r e n t response times. T h i s idea w i l l be explored f u r t h e r with respect to s o l u t e v a r i a b i l i t y i n Chapter 8. Summary Hydrograph a n a l y s i s i d e n t i f i e d two run o f f or flow components. These runoff components were l a b e l e d d i r e c t and i n d i r e c t on the b a s i s of t h e i r response to d a i l y melt c y c l e s . The most d i r e c t component i s generated by d i r e c t p r e c i p i t a t i o n onto s a t u r a t e d areas and by r e t u r n flow from b r u n i s o l s . T h i s component i s the most important f o r stormflow g e n e r a t i o n . Peak discharge i n t e n s i t i e s o f t e n reach 0.44 m3 s" 1 km"2 from c o n t r i b u t i n g areas of 30% (to as l a r g e as 45%) of the b a s i n . The second or i n d i r e c t component i s a l s o very responsive to event i n p u t s , but i t i s more c o n s e r v a t i v e than the f i r s t . Peak 1 1 6 dis c h a r g e i n t e n s i t i e s reach 0.09 m3 s" 1 km"2 and l a g d i r e c t event peaks by one h a l f to s e v e r a l days. T h i s component i s generated by s a t u r a t e d throughflow above the w a t e r - r e p e l l e n t zone and s a t u r a t e d throughflow above the t i l l . Of the two, throughflow above the w a t e r - r e p e l l e n t zone should respond the f a s t e s t to events because that zone i s very near the s o i l s u r f a c e and has a higher s a t u r a t e d h y d r a u l i c c o n d u c t i v i t y . In r e g o s o l s , s a t u r a t e d throughflow i s concentrated i n t o a network of c o a r s e - t e x t u r e d channels or i n f i l l e d p ipes i n c o l l u v i u m d i r e c t l y above the t i l l . T h i s network appears to be ex t e n s i v e and i s w e l l connected to stream channels. D i f f e r e n c e s i n hydrograph shape between years i s a f u n c t i o n of l i m i t e d s o i l i n f i l t r a b i l i t y and thus subsurface throughflow caused by ground i c e duri n g snowmelt i n 1979. Taken together these o b s e r v a t i o n s suggest that the a c t u a l drainage d e n s i t y of the h y d r o l o g i c system i s much g r e a t e r than expected because most p r e c i p i t a t i o n e i t h e r bypasses the s o i l as ov e r l a n d flow or e l s e moves along a high c o n d u c t i v i t y network of s a t u r a t e d subsurface pathways. T h i s i s w e l l supported by the temporal v a r i a b i l i t y of s o l u t e s and w i l l be documented i n Chapter 8. 1 1 7 Chapter 6. GEOCHEMICAL BUDGETS I n t r o d u c t i o n Net mass removed from the watershed per annum i s the d i f f e r e n c e between atmospheric d e p o s i t i o n and h y d r o l o g i c export. U n c e r t a i n t i e s a r i s e i n e s t i m a t i n g these f l u x e s c h i e f l y because the v a r i a b i l i t y of s o l u t e s i n p r e c i p i t a t i o n and streamflow i s hig h . These t o p i c s w i l l be d i s c u s s e d i n the s e c t i o n s which f o l l o w . D e p o s i t i o n Rates Atmospheric d e p o s i t i o n occurs as dry a e r o s o l s and as s a l t s d i s s o l v e d i n p r e c i p i t a t i o n . D e p o s i t i o n r a t e s at Goat Meadows Table 6.1. Goat Meadows p r e c i p i t a t i o n chemistry (mmoles m~ 3). Data are means and 95% co n f i d e n c e i n t e r v a l s . n Si(OH)„ Ca Mg Na K H Snow 17 1.8±1.1 0.3±0.1 0.2±0.1 1.4±0.8 0.2±0.2 5.0±1.3 Rain 27 7.3±4.2 4.3±3.3 0.7±0.3 11.6±5.8 2.3±1.3 19.0±6.2 T o t a l 44 5.2±2.7 2.8±1.7 0.5±0.2 7.7±3.9 1.5±0.9 10.0±2.0 were estimated using 44 bulk p r e c i p i t a t i o n , snowmelt, and snow grab samples. These samples i n t e g r a t e both wet and dry f a l l o u t and are assumed to be r e p r e s e n t a t i v e of t o t a l atmospheric d e p o s i t i o n . The sample set i s d i l u t e , a c i d i c and h i g h l y v a r i a b l e (Table 6.1). Mean c o n c e n t r a t i o n s of a l l ions are very low by g l o b a l 1 18 Table 6.2. Examples of p r e c i p i t a t i o n chemistry from mountainous areas of North America and a g l o b a l average estimate (mmoles r r r 3 ) . 1 D e t h i e r (1 979) ; 2 Zeman (1 973 ) , Zeman and Slaymaker (1 978 ) ; 3 T e t i ( l 9 7 9 ) ; "Feth et a l . , (1964); 5 L i k e n s et a l . , (1977); 6 G a r r e l s and Mackenzie (1971). Locat ion n Si(OH), , Ca Mg Na K H Goat Meadows 44 5.2 2.8 0.5 7.7 1 .5 10.0 Williamson Creek 1 40 <2.7 1 .9 1 . 1 9.6 1.8 15.9 Jameison Creek 2 many 0.8 5.2 2.5 13.9 0.5 1 .2 M i l l e r Creek 3 1 2 4.1 2.2 0.8 3.8 1 .5 S i e r r a Nevada" 42-71 4.3 10.0 7.0 20.0 8.2 Hubbard Brook 5 many 4.2 2.1 5.2 1 .8 74.0 World Average 6 ? 2.2 11.1 86. 1 7.7 2.0 standards but are s i m i l a r to those reported from other high a l t i t u d e s i t e s i n the c o a s t a l c o r d i l l e r a (Table 6.2). I o n i c r a t i o s i n the sample set are a l s o c h a r a c t e r i s t i c of the region (Zeman 1975; D e t h i e r , 1979). The c h i e f a i r mass source areas are marine, p r e c i p i t a t i o n events are frequent, so wet f a l l o u t predominates and marine (Na) rather than c o n t i n e n t a l (Ca, K) s a l t s are most abundant. Snowmelt i s almost always more d i l u t e and a l k a l i n e than bulk p r e c i p i t a t i o n . During e a r l y melt season, c o n c e n t r a t i o n s of a l l ions are not f a r above a n a l y t i c a l d e t e c t i o n l i m i t s . However, c a t i o n c o n c e n t r a t i o n s i n c r e a s e s i g n i f i c a n t l y by l a t e melt season as the snowpack a c q u i r e s a cover of dust, p o l l e n and a l g a e . T h i s i n t r o d u c e s c o n s i d e r a b l e u n c e r t a i n t y concerning a proper method of computing snowmelt l o a d s . For t h i s study, snowmelt loads were estimated using the mean c o n c e n t r a t i o n of c l e a n snowpacks. I t i s reasoned that the r i s e i n c o n c e n t r a t i o n i n meltwaters at the end of the melt season i s a l s o r e f l e c t e d i n bulk p r e c i p i t a t i o n samples and should not be i n c l u d e d again i n snowmelt. As w i l l be seen, any reasonable method w i l l y i e l d e s s e n t i a l l y the same r e s u l t , 1 . 1 9 v i s - a - v i s denudation e s t i m a t e s , because of the great d i s p a r i t y between a b s o l u t e d e p o s i t i o n and export r a t e s and the small u n c e r t a i n t y in d e p o s i t i o n r a t e s r e l a t i v e to those of export r a t e s . S o l u t e s i n bulk p r e c i p i t a t i o n were more v a r i a b l e than i n any study c i t e d i n Table 6.2. T h i s v a r i a b i l i t y may r e f l e c t l a r g e p a r t i c u l a t e d e p o s i t i o n at Goat Meadows. L o c a l e o l i a n d e p o s i t i o n i s on the order of 10 tonnes km - 2 y r - 1 (Jones, 1982). The mineralogy and d i s t r i b u t i o n of the l o e s s suggest i t i s winnowed from l o c a l t a l u s cones and i s r e d e p o s i t e d nearby by g r a v i t a t i o n a l sedimentation. Bulk p r e c i p i t a t i o n was c o l l e c t e d at weekly i n t e r v a l s . I t i s very l i k e l y that some f i n e - g r a i n e d l o e s s was trapped and reacted with p r e c i p i t a t i o n in the c o l l e c t o r . Thus, i t can be argued that wet f a l l o u t i s overestimated and that some d e p o s i t i o n i s from i n t e r n a l basin r e d i s t r i b u t i o n , r a ther than r e g i o n a l i n p u t . C e r t a i n l y the l a t t e r was not the case f o r the most a c i d i c and concentrated bulk p r e c i p i t a t i o n samples. They were h e a v i l y contaminated by c o n i f e r o u s p o l l e n from f o r e s t e d slopes to the south. In r e t r o s p e c t , separate, even i n t e r m i t t e n t , wet and dry f a l l o u t sampling programs would have been e n l i g h t e n i n g . D e p o s i t i o n r a t e s were computed as: D e p o s i t i o n = Cmelt*Melt+Crain*Precip ± (2*SEmelt*Melt + 2*SErain*Precip) where C i s the mean c o n c e n t r a t i o n of an ion i n melt and in r a i n , Melt i s the volume of snowmelt, P r e c i p i s the volume of bulk 1 20 p r e c i p i t a t i o n , and SE i s the standard e r r o r of the mean i o n i c c o n c e n t r a t i o n s . The u n c e r t a i n t y term t h e r e f o r e represents approximate 95% confidence i n t e r v a l s on the d e p o s i t i o n estimate. Annual d e p o s i t i o n r a t e s are presented i n t a b l e 6.4. Note that the estimates i n t a b l e 6.4 have been reduced by 17% because in both years 17% of t o t a l p r e c i p i t a t i o n and snowmelt, l e s s evaporation l o s s e s , was l o s t to the r e g i o n a l groundwater system. Thus, 17% of annual d e p o s i t i o n cannot be i n c l u d e d in computations of net export v i a the sur f a c e water system. Concentration-Discharge R e l a t i o n s h i p s Parametric s o l u t e r a t i n g curves were r e q u i r e d to estimate c o n c e n t r a t i o n s at s p e c i f i c d i s c harge l e v e l s i n export c a l c u l a t i o n s . L i n e a r , l o g - l i n e a r and l o g - l o g r e g r e s s i o n models were ex p l o r e d f o r both the bas i n o u t l e t and Mosquito weirs. The best model f o r each s o l u t e was then chosen by c r i t e r i a e x p l a i n e d by T e t i (1979, p. 1 19-120). In a l l cases v a r i a n c e was reduced by s t r a t i f y i n g 1979 snowmelt samples from a l l other 1979 and 1980 samples. T h i s i s p h y s i c a l l y as w e l l as s t a t i s t i c a l l y j u s t i f i a b l e because the hydrochemical system was perturbed by ground i c e durin g the snowmelt season of 1979. The best models are summarized i n t a b l e 6.3. The most s u c c e s s f u l models are l o g a r i t h m i c . Strong r e l a t i o n s h i p s are common i n the 1979 snowmelt data. In c o n t r a s t , c o n c e n t r a t i o n s are dis c h a r g e i n s e n s i t i v e during the remainder of the study p e r i o d and model f i t i s poor. In these 121 cases the mean sample c o n c e n t r a t i o n ±2s was taken as the best estimate of i o n i c v a r i a n c e in streamflow. Table 6.3. C o n c e n t r a t i o n - d i s c h a r g e r e l a t i o n s h i p s f o r the basin o u t l e t weir. U n i t s are mmoles m~3. Mean annual discharge r a t e s f o r 1979 and 1980 were 2.54 and 3.04 l i t e r s / s e c r e s p e c t i v e l y . p r e d i c t e d mean cone, cone. of the sample set Substance Model r r 2 SEy at Q n=1 4 1979 (snowmelt) Si(OH)4 50 .80-21.11*logQ -0.87 0 .76 8 .08 42 .3 Ca 43 .65*Qexp(-0.26) -0.79 0 .62 1 .4 1 1 .5 Mg 1 .95*Qexp(-0.18) -0.66 0 .39 1 .4 1 .6 Na 1 7 .78*1 OexpOO. 1 1Q) -0.93 0 .86 1 .65 9 .2 K none H none n = 96 1980 (and f a l l , 1979) Si(OH)4 none Ca 21 .61-1.1161ogQ -0.23 0 .05 2 .50 21 . 1 Mg none Na none K 2 . 0 -1 -0 .461ogQ -0.61 0 .37 0 .27 1 .8 H none 2.0 ±2.2 1.7 ±1.5 79.5±17.0 2.8 ±0.6 14.3 ±3.3 0.7 ±1.0 Export Rates Two computational methods were compared before e s t i m a t i n g s o l u t e s exported v i a streamflow. The simplest method was Y i e l d = Cq*Runoff + 2*SEc*Runoff where C i s the c o n c e n t r a t i o n of the s o l u t e at q, the mean annual d i s c h a r g e r a t e estimated from 6 hour i n t e r v a l flow frequency a n a l y s i s , Runoff i s the t o t a l annual runoff volume, and SEc i s the standard e r r o r of the c o n c e n t r a t i o n d i s c h a r g e r e l a t i o n s h i p . 1 22 2SEc approximates the 95% confidence i n t e r v a l f o r the estimate. SEc r e p r e s e n t s by f a r the g r e a t e s t u n c e r t a i n t y among a l l the techniques used i n t h i s study to estimate i n d i v i d u a l c o n c e n t r a t i o n and discharge d e t e r m i n a t i o n s as w e l l as t o t a l r u n o f f . Thus i t prov i d e s a c o n s e r v a t i v e estimate of the t o t a l e r r o r s of the y i e l d e stimate. Solute y i e l d s were a l s o estimated using flow frequency i n t e r v a l s : n n Y i e l d = Z Q *C*At ± Z Q*2SEc*At i=0 i=0 where n i s the number of flow frequency i n t e r v a l s over the annual d i s c h a r g e range, Q i s the mean dis c h a r g e f o r the i n t e r v a l i , C i s the estimated c o n c e n t r a t i o n at discharge Q, At i s the time that flows of frequency i were observed and SEc i s the standard e r r o r of the c o n c e n t r a t i o n d i s c h a r g e r e l a t i o n s h i p at Q. Twice the standard e r r o r thus p r o v i d e s approximate 95% confidence i n t e r v a l s on the t o t a l e stimate. The two computational methods were w i t h i n e i g h t percent agreement i n a l l cases. The agreement i s somewhat s u p r i s i n g given the l o g a r i t h m i c d i s c h a r g e frequency d i s t r i b u t i o n s but i s probably to be expected given the i n s e n s i t i v i t y of these c o n c e n t r a t i o n d i s c h a r g e r e l a t i o n s h i p s . The estimates based on flow frequency are more accurate and are used here. However, the e x e r c i s e suggests that a reasonably good estimate of export can be made i f mean d i s c h a r g e , c o n c e n t r a t i o n at t h i s d i s c harge and t o t a l r u n o f f are known. 1 23 Geochemical Budgets Net c a t i o n and s i l i c o n y i e l d s at Goat Meadows were at l e a s t 1.6 and 3.4 tonnes km"2 y r " 1 d u r i n g 1979 and 1980 ( t a b l e 6.4, 6.5). These t o t a l s were c a l c u l a t e d as : Denudation=Deposition-Export±(deposition error+export e r r o r ) There are s i g n i f i c a n t d i f f e r e n c e s i n net y i e l d between years d e s p i t e the f a c t that annual runoff was r e l a t i v e l y s i m i l a r . T h i s problem w i l l be addressed f u l l y i n Chapter 8. However, some more s u b t l e aspects of t a b l e 6.5 can be addressed at t h i s time. F i r s t , these t o t a l s do not i n c l u d e 15% to 16% of the annual p r e c i p i t a t i o n (17% of annual p r e c i p i t a t i o n l e s s evaporation) l o s t to the r e g i o n a l groundwater t a b l e . I f the watershed were u n d e r l a i n by water t i g h t bedrock the t o t a l s would be d i f f e r e n t . Second, 70% to 85% of the d i s s o l v e d l o a d i n streamflow i s r e l e a s e d by e a r t h sources and t h e r e f o r e u l t i m a t e l y by rock weathering. Most of t h i s mass i s removed as s i l i c o n and ca l c i u m . Magnesium and potassium l o s s e s are very s m a l l . A s i g n i f i c a n t p r o p o r t i o n of sodium and potassium i n streamflow comes from the atmosphere. Hydrogen ion i s accumulating i n the watershed but not i n s u f f i c i e n t q u a n t i t i e s to account f o r the c a t i o n s denuded i f h y d r o l y s i s r e a c t i o n s are r e s p o n s i b l e f o r a l l s i l i c a t e weathering. Other sources of c o r r o s i v e p o t e n t i a l must come from w i t h i n the watershed. T h i r d , these estimates n e g l e c t two p o t e n t i a l l y l a r g e sources of e r r o r ; net b i o l o g i c a l s o l u t e uptake and unmeasured 1 24 Table 6.4. Geochemical budgets f o r Goat Meadows Watershed, b a s i n o u t l e t weir. U n i t s are moles. % of % of ion from net Ion D e p o s i t i o n - Export = Net Y i e l d e a r t h y i e l d sources 1979 Si 77 ±43 916 ±334 -839 ±377 92 69 Ca 33 ±22 260 ± 56 -227 ± 78 87 19 Mg 8 ± 3 36 ± 58 - 28 ± 61 78 2 Na 99 ±48 203 ± 68 -104 ±116 51 9 K 18 ±1 1 41 ± 45 - 23 ± 56 56 2 H 208 ±59 35 ± 31 + 173 ± 90 0 0 T o t a l 443 1 425 -1 048 ±778 70 101 1 980 S i 76 ±43 1853 ±396 -1 777 ±439 96 70 Ca 30 ±19 495 ±117 - 446 ±136 94 18 Mg 8 ± 3 65 ± 14 - 57 ± 17 88 2 Na 91 ±46 333 ± 77 - 242 ±1 23 73 10 K 1 7 ±1 1 42 ± 13 - 25 ± 24 60 1 H 203 ±57 1 6 ± 23 + 184 ± 80 0 0 T o t a l 425 2801 -2360 ±819 85 101 1979 as % of 1980 104% 51% 44% 6.5. Denudation r a t e s at Goat Meadows, basin o u t l e t I on Denudation Rate % of Denudat (tonnes /km 2/yr) 1979 1 980 1979 1980 Si 1.04 ±0.47 2.20 ±0.54 64 65 Ca 0.40 ±0.14 0.82 ±0.24 25 24 Mg 0.03 ±0.07 0.06 ±0.02 2 2 Na 0.11 ±0.12 0.25 ±0.12 7 7 K 0.04 ±0.10 0.04 ±0.04 2 1 T o t a l 1.62 ±0.90 3.37 ±0.96 100 99 1 25 export of ions adsorbed on suspended sediment. Ne i t h e r i s c o n s i d e r e d to be a l a r g e source of e r r o r i n t h i s p r o j e c t . The l o c a l ecosystem appears to be s t a b l e and standing biomass i s s m a l l . A n a l y s i s of lake sediments provide no evidence to support s i g n i f i c a n t v e g e t a t i o n changes w i t h i n the l a s t millennium. There i s evidence of minor t r e e i s l a n d expansion d u r i n g the p e r i o d 1920 to 1945. T h i s trend i s r e g i o n a l and i s r e p o r t e d to be r e l a t e d to decreased winter snowpacks d u r i n g that p e r i o d (Brink, 1959; F r a n k l i n et a l . , 1971). Pioneer t r e e s at Goat Meadows are stunted dwarfs and probably r e p r e s e n t an i n s i g n i f i c a n t change i n t o t a l standing biomass. Biomass s t a b i l i t y as organic matter in s o i l s i s more d i f f i c u l t to a s s e s s . G r i e r (1973) measured organic matter d i s t r i b u t i o n s i n heath communities in Washington S t a t e that are s i m i l a r to heaths at Goat Meadows. If G r i e r ' s data are a p p l i c a b l e , l e s s than 5% of t o t a l organic matter i s l i v i n g or a t t a c h e d dead matter. L i t t e r i s f u l l y twice t h i s mass. In other words, l o c a l decomposition r a t e s are slow and almost a l l biomass i s s t o r e d as organic matter in s o i l s . Furthermore, most primary p r o d u c t i v i t y i n mesic sedge communities occurs below ground and i s d i f f i c u l t to measure a c c u r a t e l y (Scott and B i l l i n g s , 1964; T h i l e n i u s , 1975). Hence, standing biomass i s an u n r e l i a b l e measure of e c o l o g i c a l s t a b i l i t y i n t h i s environment. Despite d i f f i c u l t i e s i n a s s e s s i n g the biomass system s t a t e , tundra and shrub tundra have primary p r o d u c t i v i t i e s on the order of only 1.3 to 4.1 tonnes km"2 y r - 1 (major c a t i o n s and s i l i c o n : 1 26 Rodin and B a z i l e v i c h , 1967). Only 47% of Goat Meadows i s vegetated. T h e r e f o r e , annual b i o l o g i c a l demand f o r s i l i c o n and major c a t i o n s may be as l i t t l e as 0.6 to 2.0 tonnes km"2. T h i s i s 20% to 60% of the 1980 denudation rate and, even i f the system were i n a s t a t e of f l u x , much of t h i s would have been returned to the s o i l s u r f a c e as l i t t e r f a l l . In s h o r t , b i o c y c l i n g i s a r e l a t i v e l y small term i n t h i s watershed's o v e r a l l geochemical f l u x and probably d i d not r e g u l a t e f l u x r a t e s d u r i n g the p e r i o d of study. Losses of ions absorbed on suspended sediment should a l s o be small because suspended sediment l o s s e s appear to be s m a l l . The pond i s an e f f i c i e n t sediment t r a p . Holocene sediment accumulations i n the pond b a s i n have been steady at about 0.03 m3 y r " 1 . The t e x t u r e of l a c u s t r i n e sediments i s very s i m i l a r to l o e s s which caps a l l s t a b l e s o i l p r o f i l e s here. If the lake sediment i s l o e s s , the present accumulation i m p l i e s a sedimentation r a t e of 32 ton km"2 y r " 1 or only two to three times g r e a t e r than the value f o r surrounding s o i l s (Jones, 1982). Open water should be a more e f f i c i e n t l o e s s t r a p than s o i l s . The a n t i t h e s i s , that a l l sediment i s a l l u v i a l , i m p l i e s sedimentation r a t e s are on the order of 1 ton km"2 y r " 1 which i s a small f r a c t i o n of accumulation r a t e s on s o i l s . T h i s i s h i g h l y u n l i k e l y . T h i s r e s u l t i s i n t e r e s t i n g because i t i m p l i e s that very l i t t l e f i n e sediment i s t r a n s p o r t e d i n the l o c a l f l u v i a l system. B i r k e l a n d and Andrews (1982) r e p o r t a s i m i l a r r e s u l t from the 1 27 San Juan Mountains, Colorado. At Goat Meadows the c o n c l u s i o n i s a l s o supported by the morphology of l o c a l streams which e i t h e r flow over d r y l a n d sedge without e r o d i n g a channel, or flow below the s u r f a c e among cobble pavements. In other words, there are no f i n e - t e x t u r e d a l l u v i a l channels w i t h i n the watershed. Geochemical Budgets For Subcatchments Mosquito and Hummingbird subcatchments had l a r g e and c o n s i s t e n t d i f f e r e n c e s i n s o l u t e c o n c e n t r a t i o n s ( t a b l e 6.6). Table 6.6. Comparison of mean s o l u t e c o n c e n t r a t i o n s (mmoles m 3) at the three weirs based on simaltaneous sampling. F i g u r e s i n brackets are standard d e v i a t i o n s . I on Basin O u t l e t Mosquito Hummingbi rd n=1 5 1 979 Si(OH)„ 45. 1 (15.1) 68.7 (28.8) 30.6 (28.5) Ca 14.1 (7.5) 23.0 (12.9) 7. 1 (8.2) Mg 1 .9 (1.1) 2.8 (1.9) 1 . 1 (1.2) Na 10.5 (7.9) 14.0 (9.2) 9.2 (7.2) K 2.0 (1.1) •1.6 (1.1) 2.5 (2.0) H 2.2 (1.1) 1 .2 (0.8) 5.9 (2.2) n = 26 1 980 S i (OH) „ 75.8 (8.0) 97.4 (8.9) 61 .0 (24.9) Ca 19.6 (3.3) 28.9 (3.7) 9.0 (4.5) Mg 2.7 (0.5) 3.7 (0.4) 1 .3 (0.7) Na 14.3 (2.4) 17.4 (1.4) 11.6 (7.2) K 1 .7 (0.4) 2.1 (0.3) 1 . 1 (0.8) H 1 .2 (0.8) 0.6 (0.1 ) 3.1 (1.9) Mosquito streamflow was always the more concentrated s u r f a c e water. Hummingbird streamflow was the more d i l u t e . The basin o u t l e t was a mixture of these two sources and the r e s i d u a l area surrounding the pond. Subcatchment geochemical budgets were 1 28 d e s i r e d to q u a n t i f y these d i f f e r e n c e s i n a b s o l u t e s o l u t e y i e l d . Complete water budgets f o r the subcatchments were not p o s s i b l e because of missing d i s c h a r g e records at Mosquito and Hummingbird weirs. Mosquito weir was f l o o d e d f o r s e v e r a l weeks dur i n g e a r l y snowmelt season, 1979 and the water l e v e l r e corder f a i l e d r e p e a t e d l y d u r i n g l a t e snowmelt season, 1980. Hummingbird weir c o u l d not be c a l i b r a t e d by r e t e n t i o n nor f l u o r o m e t r i c techniques due to i t s topographic p o s i t i o n . Only t h e o r e t i c a l d i s c h a r g e amounts, based on the f i x e d geometry of the 90°, V-notch weir, are a v a i l a b l e . F o r t u n a t e l y , snowpack accumulation ac r o s s the watershed i s w e l l known and d i f f e r e n c e s i n r a i n f a l l do not show c o n s i s t e n t s p a t i a l t r e n d s . A d d i t i o n a l l y , r u n o f f r a t i o s between the subcatchments must a l s o be very s i m i l a r because double-mass d a i l y d i s charge graphs between the c a l i b r a t e d weirs show only s m a l l , random d e v i a t i o n s from one to one correspondence throughout both snowmelt seasons. In s h o r t , i t appears reasonable to apply the b a s i n o u t l e t r u n o f f r a t i o to the subcatchment p r e c i p i t a t i o n t o t a l s to estimate annual subcatchment di s c h a r g e t o t a l s . T h i s may i n t r o d u c e b i a s i n t o the r e s u l t s because the s p a t i a l d i s t r i b u t i o n of groundwater l o s s e s i s not w e l l known. Groundwater i s , however, a minor term i n the water budget and temporal v a r i a b i l i t y of s o l u t e c o n c e n t r a t i o n s introduces much gre a t e r u n c e r t a i n t y in geochemical budgets. Thus, t h i s h y d r o l o g i c approximation should i n t r o d u c e l i t t l e b i a s i n t o the o v e r a l l r e s u l t . Furthermore, b i a s so i n t r o d u c e d w i l l tend to 129 underestimate d i f f e r e n c e s between subcatchments because Mosquito Creek w i l l be shown to have the l a r g e r groundwater component in i t s geochemical budget. Subcatchment budgets can be computed with confidence only for 1980. During t h i s p e r i o d , c o n c e n t r a t i o n discharge r e l a t i o n s h i p s were f l a t and so the mean sample c o n c e n t r a t i o n provides a good estimate of streamflow c o n c e n t r a t i o n over the f u l l range of d i s c h a r g e . However, duri n g 1979, c o n c e n t r a t i o n discharge r e l a t i o n s h i p s were steep and c u r v i - l i n e a r . Since the simultaneous samples were not taken at the mean d i s c h a r g e , they do not provide a good estimate of average streamflow c o n c e n t r a t i o n s d u r i n g 1979. Table 6.7 compares estimated r a t e s of denudation between catchments d u r i n g 1980 based on the aforementioned procedures. The budget computed f o r the r e s i d u a l area (by mass co n s e r v a t i o n ) i s very reasonable, with the exception of potassium which appears to be overestimated. C l e a r l y there are s i g n i f i c a n t d i f f e r e n c e s between catchments. Mosquito d e l i v e r s much of the mass to the basin o u t l e t because i t s denudation r a t e i s twice that of Hummingbird catchment and i t i s about h a l f the area of Goat Meadows. T h i s i s an important c l u e to understanding the major processes o p e r a t i v e here. Before e x p l a i n i n g these d i f f e r e n c e s , the sources of the i n d i v i d u a l ions must be i d e n t i f i e d . T h i s i s the subject of Chapter 7. 1 30 Table 6.7. Denudation r a t e s (tonnes/km 2/yr) and t o t a l mass denuded (kg) f o r Goat Meadows and subcatchments based on the mean of simultaneous samples c o l l e c t e d at the three weirs, 1980. I on O u t l e t Mosquito Hummingbird R e s i d u a l Wei r Wei r Wei r Area S i 2.20 2.78 1 .60 1.91 Ca 0.82 1.16 0.30 0.89 Mg 0.06 0.09 0.02 0.07 Na 0.25 0.31 0.16 0.26 K 0.04 0.05 0.01 0.08 T o t a l 3.37 4.39 2.09 3.21 (tonnes/k m2) Catchment Area(m 2) 22700 1 0275 7425 5000 Mass Removed (kg) 76.5 45. 1 15.5 16.1 Summary Deundation r a t e s are h i g h l y v a r i a b l e at Goat Meadows i n both time and space. Almost a l l mass i s removed during 90 days of snowmelt. Most of t h i s mass i s s i l i c o n and c a l c i u m (89% by weight). Much of the mass i s removed from Mosquito catchment (59% by weight) which i s being denuded at twice the r a t e of Hummingbird catchment. Mass removed d u r i n g 1979 was l e s s than h a l f the mass removed d u r i n g 1980. S t a t i s t i c a l u n c e r t a i n t i e s i n these budgets are l a r g e r d u r i n g 1979 (56% r e l a t i v e e r r o r ) than d u r i n g 1980 (28% r e l a t i v e e r r o r ) p r i m a r i l y because streamflow c o n c e n t r a t i o n s were c o n s e r v a t i v e during 1980. Unmeasured i o n i c l o s s e s due to s o r p t i o n on suspended sediments are thought to be small because suspended sediment l o s s e s are s m a l l . B i o l o g i c a l r e g u l a t i o n of s o l u t e export r a t e s i s a l s o c o n s i d e r e d to have been minor d u r i n g the study p e r i o d because the biomass appears to be s t a b l e and primary 131 p r o d u c t i v i t y i s probably s m a l l e r than annual geochemical denudat i o n . 1 32 Chapter 7. SOLUTE SOURCES I n t r o d u c t i o n The purpose of t h i s chapter i s to i d e n t i f y the major sources and flow paths of s o l u t e s a t Goat Meadows. T h i s i n f o r m a t i o n i s necessary f o r proper i n t e r p r e t a t i o n of denudation r a t e s and pr o c e s s e s . I n i t i a l a n a l y s i s w i l l show t h a t s o l u t e v a r i a b i l i t y i s p r i m a r i l y c o n t r o l l e d by the d i s t r i b u t i o n of v o l c a n i c ash i n s o i l s and by the l o c a t i o n of groundwater r e t u r n flow zones w i t h i n the watershed. Secondary c o n t r o l s of s o l u t e v a r i a b i l i t y i n c l u d e the a v a i l a b i l i t y of p l a n t l i t t e r as a potassium source and the d i s t r i b u t i o n of bedrock mineralogy with respect to groundwater • flow paths. These t o p i c s w i l l be d i s c u s s e d i n the s e c t i o n s that f o l l o w . N a t u r a l S o l u t e P o p u l a t i o n s The s o l u t e data set c o n s i s t s of 711 f i e l d samples d e s c r i b e d in Chapter 3. Frequency d i s t r i b u t i o n s of i o n i c c o n c e n t r a t i o n i n the data set are p o s i t i v e l y skewed, l e p t o k u r t i c , and i n the case of potassium and magnesium, are polymodal. E x p l o r a t o r y R-mode f a c t o r a n a l y s i s i n d i c a t e d that the data set contained two orthogonal f a c t o r s . The f i r s t f a c t o r was loaded h e a v i l y by cal c i u m and magnesium c o n c e n t r a t i o n s . The second f a c t o r was 1 33 loaded h e a v i l y by sodium and potassium c o n c e n t r a t i o n s . T h i s f a c t , and the pol y m o d a l i t y of potassium and magnesium, suggested that two major subpopulations were present i n the data s e t . Numerical taxonomy (UBC C l u s t e r , UBC Computing Centre) was a p p l i e d to group the normalised samples a c c o r d i n g to s i m i l a r i t y i n a l l - i o n taxonomic space. The l a r g e s t break i n the c l u s t e r i n g procedure oc c u r r e d at 28 groups. T h i s l e v e l of s u b d i v i s i o n o c c u r r e d a f t e r v i r t u a l l y a l l (93%) of the g r a v i t y s o l u t i o n samples had j o i n e d i n t o seven l a r g e c l u s t e r s . C a p i l l a r y s o l u t i o n s only began to group during l a t e r i t e r a t i o n s and g e n e r a l l y j o i n e d one another, rather than j o i n i n g g r a v i t y s o l u t i o n c l u s t e r s . Thus, c a p i l l a r y s o l u t i o n s are g e n e r a l l y d i s s i m i l a r from g r a v i t y s o l u t i o n s . Segregation of the data i n t o p o s i t i v e and negative t e n s i o n groups removed the p o l y m o d a l i t y of potassium and magnesium and induced lognormally d i s t r i b u t e d p o p u l a t i o n s f o r a l l i o n s . Furthermore, s i n c e the c a p i l l a r y s o l u t i o n samples are a r e a l l y unbiased, t h i s s u b d i v i s i o n produced a s t a t i s t i c a l l y sound design f o r l a t e r a n a l y s i s of water chemistry v a r i a t i o n s among and between s o i l groups. Subpopulation C h a r a c t e r i s t i c s Both the absolute and r e l a t i v e abundance of i o n i c c o n c e n t r a t i o n d i f f e r s between c a p i l l a r y and g r a v i t y s o l u t i o n samples. Numerical taxonomy by ab s o l u t e or by r e l a t i v e c o n c e n t r a t i o n (molar percentages) produced e s s e n t i a l l y the same r e s u l t . Thus, the two p o p u l a t i o n s are s t o i c h i o m e t r i c a l l y 134 d i s t i n c t and t h e i r s t o i c h i o m e t r y i s r e l a t e d to t o t a l c a t i o n i c c o n c e n t r a t i o n . D i s c r i m i n a n t a n a l y s i s of the c l u s t e r s produced by numerical taxonomy i n d i c a t e d t h a t the subpopulations covered a broad continuum of i o n i c r a t i o s with c a t i o n s being ranked on d i s c r i m i n a n t v a l u e : Na >> Ca >> K >> Mg >> S i . R-mode f a c t o r a n a l y s i s of the i n d i v i d u a l subgroups suggested that c a p i l l a r y s o l u t i o n s are n e a r l y c h e m i c a l l y homogeneous. A l l c a t i o n s loaded on a s i n g l e f a c t o r . G r a v i t y s o l u t i o n s were s t i l l heterogeneous because they c o n t a i n e d two orthogonal f a c t o r s loaded r e s p e c t i v e l y by calcium-magnesium and by sodium. Subsequent p e r u s a l r e v e a l e d that the sodium f a c t o r was shared only by p r e c i p i t a t i o n samples and the most d i l u t e g r a v i t y s o l u t i o n s . The calcium-magnesium f a c t o r was shared by the few r e g i o n a l groundwater samples c o l l e c t e d downstream from Goat Meadows. Hydrochemical F a c i e s These s t a t i s t i c a l trends are g r a p h i c a l l y summarized i n F i g u r e 7.1 which i s a hydrochemical f a c i e s or t r i l i n e a r diagram (Back and Hanshaw, 1970). The f a c i e s diagram shows the r e l a t i v e abundance of sodium, c a l c i u m and potassium i n a l l samples. These ions are i l l u s t r a t e d because they were shown s t a t i s t i c a l l y to be. the best d i s c r i m i n a t o r s . P o i n t s p l o t t e d i n f i g u r e 7.1 are the c e n t r o i d s of c l u s t e r s 135 F i g u r e 7.1. R e l a t i v e and a b s o l u t e abundance of Na, Ca, and K i n a l l f i e l d water samples (n=71l). P o i n t s represent the c e n t r o i d s of c l u s t e r s d e f i n e d by numerical taxonomy. Open symbols denote c l u s t e r s formed by only one or two samples. U n i t s are mmole nr 3 . 1 36 d e f i n e d by numerical taxonomy. The c e n t r o i d s are a l s o p r o j e c t e d onto a l o g - c o n c e n t r a t i o n graph to show how ab s o l u t e c o n c e n t r a t i o n i s r e l a t e d to r e l a t i v e c o n c e n t r a t i o n . It i s apparent from f i g u r e 7.1 that c a p i l l a r y s o l u t i o n s tend towards sodium f a c i e s and g r a v i t y s o l u t i o n s tend toward ca l c i u m f a c i e s . Less apparent i s the systematic v a r i a t i o n i n abs o l u t e and r e l a t i v e i o n i c abundance a l l u d e d to in the pre v i o u s d i s c u s s i o n . T h i s p a t t e r n i s c l e a r i n F i g u r e 7.2 and w i l l now be d e s c r i b e d and e x p l a i n e d i n terms of r e a c t i o n s with s p e c i f i c m i n e r a l s . E v o l u t i o n Sequences F i g u r e 7.2 i n c l u d e s 89% of the samples from f i g u r e 7.1. Thus f i g u r e 7.2 shows that almost a l l water samples are members of 13 c l u s t e r s which p l o t c l o s e l y along two l i n e s . A p r o p e r t y of t r i l i n e a r diagrams i s that samples formed by the mixing of two c h e m i c a l l y d i s t i n c t sources p l o t along a s t r a i g h t l i n e which j o i n s the sources (Freeze and Cherry, 1979, p. 249). The systematic p a t t e r n i n F i g u r e 7.2 suggests that s o l u t e c o n c e n t r a t i o n s at Goat Meadows are c o n t r o l l e d by the mixing of three major sources. One source i s p r e c i p i t a t i o n ( p l o t t e d as a c l o s e d c i r c l e in f i g u r e 7.2). T h i s i s a r a t i o n a l i n f e r e n c e because a l l water en t e r s the h y d r o l o g i c cascade as d i l u t e , a c i d i c , sodium f a c i e s r a i n or snow. P r e c i p i t a t i o n then a c q u i r e s an i o n i c load by r e a c t i n g with s o l u b l e e a r t h and b i o l o g i c a l m a t e r i a l s along i t s flowpath. Through r e a c t i o n s , p r e c i p i t a t i o n evolves c h e m i c a l l y . 1 3 7 F i g u r e 7.2. R e l a t i v e and a b s o l u t e abundance of Na, Ca, and K i n water samples along the main chemical sequences. P o i n t s represent the c e n t r o i d s of major c l u s t e r s d e f i n e d by numerical taxonomony and c o n t a i n 89% of a l l f i e l d samples. U n i t s are mmole nr 3 . 1 38 The two l i n e s i n Fig u r e 7.2 s i g n i f y two chemical e v o l u t i o n sequences. These sequences show compos i t i o n a l changes in p r e c i p i t a t i o n with contact time among s o l u b l e m a t e r i a l s . One e v o l u t i o n sequence i s toward a sodium source. T h i s source i s a s s o c i a t e d with r e a c t i o n s unique to the s o i l s because c a p i l l a r y s o l u t i o n s c l u s t e r along the sodium sequence. The second e v o l u t i o n sequence i s toward a c a l c i u m source. T h i s source i s not unique to the s o i l s because i t i n f l u e n c e s a l l g r a v i t y s o l u t i o n s as w e l l as the r e g i o n a l groundwater system. The c a l c i u m source i s u b i q u i t o u s . Furthermore, the a s s o c i a t i o n of groundwater samples and g r a v i t y s o l u t i o n s suggests t h a t some ca l c i u m i s d e r i v e d from the l o c a l bedrock l i t h o l o g i e s . The s e c t i o n s that f o l l o w suggest how water s u p p l i e d by p r e c i p i t a t i o n evolves along these two chemical sequences by e v a l u a t i n g the a v a i l a b l e t e r r e s t r i a l r e a c t a n t s and h y d r o l o g i c flowpaths w i t h i n Goat Meadows. D i s c u s s i o n w i l l then focus on the remaining 11% of the data set which do not conform to these e v o l u t i o n sequences. I t w i l l be shown that t h e i r v a r i a n c e i s due to the i n f l u e n c e of a f o u r t h , but minor chemical source and the mixing of s o l u t i o n s from the main chemical sequences. Sodium E v o l u t i o n Sequences Samples on the sodium e v o l u t i o n sequence are c a p i l l a r y s o l u t i o n s . The sodium source i s t h e r e f o r e present i n the s o i l s . T h i s source appears to be the g l a s s f r a c t i o n of v o l c a n i c ash. The steps that allow t h i s deduction w i l l now be t r a c e d . F i r s t , s o i l s o l u t i o n s are sodium f a c i e s due to d i s s o l u t i o n 1 39 or exchange r e a c t i o n s , r a t h e r than simple e v a p o r a t i v e c o n c e n t r a t i o n of sodium f a c i e s p r e c i p i t a t i o n . Sodium c o n c e n t r a t i o n s i n s o i l s o l u t i o n s are one order of magnitude g r e a t e r than i n p r e c i p i t a t i o n , evaporation i s a minor term i n the water budget of t h i s watershed and s o i l s o l u t i o n s are g r e a t l y e n r i c e d i n s i l i c o n , magnesium and potassium r e l a t i v e to p r e c i p i t a t i o n . Second, r e a c t i o n s w i t h i n B, C and perhaps even Omb h o r i z o n s are dominantly i n o r g a n i c , r a t h e r than o r g a n i c , exchange or d i s s o l u t i o n phenomena. Sodium i s the dominant c a t i o n in water s o l u b l e s a l t e x t r a c t s from subsurface h o r i z o n s (Figure 7.3, Appendix F ) . As sodium i s not an e s s e n t i a l p l a n t n u t r i e n t , and B and C h o r i z o n s are the most d e f i c i e n t h o r i z o n s i n organic carbon, organic matter i s not a primary sodium source. T h i r d , s o i l s o l u t i o n s are probably sodium f a c i e s because of primary mineral weathering r a t h e r than secondary i n t e r f e r e n c e s with calcium, magnesium and potassium m o b i l i t y . Undisturbed, 40 kg s o i l monoliths were removed to the l a b o r a t o r y and leached with f i v e meters water e q u i v a l e n t (more than three years e q u i v a l e n t p r e c i p i t a t i o n ) of d i s t i l l e d water at a v a r i e t y of r a t e s over a p e r i o d of 6 weeks. Leachates were sodium f a c i e s throughout the experiment. I t i s u n l i k e l y that calcium or magnesium p r e c i p i t a t e s would have remained i n s o l u b l e under these l e a c h i n g r a t e s . The t e s t i s not i r r e f u t a b l e but i t suggests t h a t l e a c h a t e s are sodium f a c i e s because of d i s s o l u t i o n r e a c t i o n s with sodium-rich, primary m i n e r a l s . Fourth, most n a t u r a l s o i l s o l u t i o n s are n e a r l y balanced 1 40 F i g u r e 7.3. R e l a t i v e and a b s o l u t e abundance of water s o l u b l e Na, Ca, and K from m i n e r a l s o i l h o r i z o n s . U n i t s are micromoles per 100 g s o i l . 141 s t o i c h i o m e t r i c a l l y i n a l l four major c a t i o n s with v o l c a n i c g l a s s ( f i g u r e 7.4). V o l c a n i c g l a s s i s a l s o the only i n o r g a n i c s o i l substance that i s of t h i s composition. The mineralogy of s o i l parent m a t e r i a l s i s reasonably w e l l known. L o c a l l y d e r i v e d s u r f i c i a l m a t e r i a l s ( t i l l , c o l l u v i u m , and l o e s s ) are v a r y i n g mixtures of the two bedrock l i t h o l o g i e s . Quartz d i o r i t e i s overwhelmingly the most ext e n s i v e bedrock here. Modal mineralogy of the bedrock i s approximately known from o p t i c a l a n a l y s i s (Appendix A ) . Ionic abundances of these minerals i s l e s s w e l l known because the amphiboles are a broad s o l i d s o l u t i o n s e r i e s (Table 7.2). V o l c a n i c g l a s s composition i s w e l l known. The ashes were i d e n t i f i e d as Mazama and Bridge River p y r o c l a s t i c s by radiocarbon d a t i n g of o r g a n i c - r i c h , l a c u s t r i n e sediments and by e l e c t r o n microprobe a n a l y s i s . The bulk chemistry of t h e i r g l a s s f r a c t i o n s i s n e a r l y i d e n t i c a l and has been analyzed by s e v e r a l techniques at other l o c a l i t i e s by Smith and Westgate (1969), Westgate et a l . (1970), Borchardt et a l . (1971), Randle et a l . (1971), Sneddon (1973). R e f e r r i n g to F i g u r e 7.4, v o l c a n i c g l a s s and p l a g i o c l a s e are the only abundant i n o r g a n i c s o i l substances which c o n t a i n s i g n i f i c a n t q u a n t i t i e s of sodium. N e i t h e r n a t u r a l s o i l s o l u t i o n s (Figure 7.4) nor water s o l u b l e s a l t e x t r a c t s ( F i g u r e 7.3) p l o t toward p l a g i o c l a s e i n t r i l i n e a r space. Furthermore, i f p l a g i o c l a s e or the calcium-magnesium s i l i c a t e s were the dominant weathering sources i n s o i l s , then s o i l s o l u t i o n s would be sodium f a c i e s due to c a l c i u m and magnesium r e t e n t i o n i n s o i l exchange complexes. Exchangeable s a l t s would a l s o be r i c h i n 142 » 1 dlor lt ic Hornblende F i g u r e 7.4. R e l a t i v e abundance of major c a t i o n s i n m i n e r a l s , g l a s s and water samples at Goat Meadows. D i o r i t i c hornblende composition taken from Deer et a l . , 1966 p. 173. Shaded area i s complete range of hornblende compositions. 1 43 Table 7 . 1 . R e l a t i v e abundance of minerals i n <63 micrometre f r a c t i o n of modern l o e s s near Goat Meadows (Jones, 1 9 8 1 ) . Both the m i n e r a l assemblage and the d i s t r i b u t i o n of the l o e s s suggests d i o r i t i c t a l u s cones are the source of l o e s s l o c a l l y . P l a g i o c l a s e most abundant Mica K a o l i n i t e V e r m i c u l i t e C h l o r i t e O r t h o c l a s e Quartz l e a s t abundant Table 7 . 2 . Approximate molar r a t i o s of elements i n bedrock l i t h o l o g i e s (quartz removed) and L i l l o o e t - t y p e Bridge River g l a s s ( a n a l y s i s from Westgate et a l . , 1970, n=7) . Element Quartz D i o r i t e Quartz-A c t i n o l i t e -C h l o r i t e V o l c a n i c Glass S c h i s t S i 69 64 82 Ca 14 16 2 Mg 6 20 1 Na 5 0 10 K 7 0 4 T o t a l 101 100 100 I o n i c R a t i o s Assumed: C h l o r i t e = Mg2 Fe3 Si3 A12 O10 (OH)8 A c t i n o l i t e = Ca2 Mg2 Fe3 Si8 022 (OH)2 Hornblende = Ca2 Mg2 Fe2 Si7 A12 022 (OH)2 B i o t i t e = K2 Mg2 Fe4 Si6 A12 022 (OH)4 P l a g i o c l a s e i s andesine Quart c o n s i d e r e d i n s o l u a b l e d i v a l e n t c a t i o n s . In f a c t , water s o l u b l e s a l t e x t r a c t s from mineral h o r i z o n s are sodium f a c i e s ( f i g u r e 7.3). Again, water s o l u b l e s a l t e x t r a c t i o n s , l i k e the monolith l e a c h i n g experiment, are e q u i v o c a l because water may p r e f e r e n t i a l l y e x t r a c t sodium, which i s u s u a l l y more mobile than d i v a l e n t c a t i o n s , from s o i l exchange s i t e s . I t seems u n l i k e l y , however,;, that a l l four c a t i o n s , each with d i f f e r e n t i o n i c m o b i l i t i e s , would be so c l o s e l y r e l a t e d s t o i c h i o m e t r i c a l l y to a known s o i l substance i f 1 44 i o n i c exchange r e a c t i o n s , r a t h e r than simple h y d r o l y s i s , were c o n t r o l l i n g the composition of s o i l s o l u t i o n s . On balance, i t i s not completely s a t i s f y i n g to assume that primary d i s s o l u t i o n of a s i n g l e s o i l substance should so completely dominate s o i l s o l u t i o n s . A d d i t i o n a l l y , i f g l a s s i s the primary weathering source then most of the g l a s s must d i s s o l v e congruently and calc i u m , magnesium and potassium must be f u l l y mobile in these s o i l s ( f i g u r e 7.4). On the other hand, the c o n c l u s i o n that s o i l waters are sodium f a c i e s because of r e a c t i o n s with v o l c a n i c g l a s s i s r a t i o n a l . V o l c a n i c g l a s s i s p h y s i c a l l y and c h e m i c a l l y s u s c e p t i b l e to r a p i d h y d r o l y s i s because g l a s s i s amorphous, f i n e - t e x t u r e d , v e s i c u l a r , and occurs here as porous l a y e r s i n the w e l l a e r a t e d zone of s o i l s . A n d e s i t i c ash i s repor t e d to be l e s s s t a b l e than ferromagnesian m i n e r a l s and even a n o r t h i t e (Hay, 1959). Mazama and Bridge River ashes are d a c i t i c (Stevenson, 1947). However, f i e l d s t u d i e s of these u n i t s i n western North America r e p e a t e d l y s t r e s s t h e i e importance t o apparent pedogenesis because of hig h d i s s o l u t i o n r a t e s r e l a t i v e to other s o i l m i n e r a l s (Beke and Pawluk, 1971; King and Brewster, 1976; Van Ryswyk and Okazaki, 1979). For example, Sneddon (1973) demonstrated that the chemical c h a r a c t e r i s t i c s of two mountain s o i l s developed on Bridge River ash i n B r i t i s h Columbia are much l e s s developed than expected, based on t h e i r morphology, because the g l a s s weathers q u i c k l y but r e s u l t s i n few c r y s t a l l i n e secondary p r o d u c t s . Smectite c l a y m i n e r als are a s s o c i a t e d with h o r i z o n s r i c h i n 1 45 v o l c a n i c g l a s s ( t a b l e 7.3). While smectites a l s o occur below Table 7.3. R e l a t i v e abundance of c r y s t a l l i n e c l a y m i n e r als (< 2 micrometer in h o r i z o n s of pedons d e s c r i b e d in Appendix C. P r o f l l e : Horizon Depth Parent Secondary M i n e r a l s : M a t e r i a l Rao Smc Ver M/V M/S Humo-Ferr i c Podzol (S79-3) -Ae 0-5 A Bfh 5-11 L Bf 11-27 T BC 27-38 T Sombric Brunisol(S79-8) Ah 0-10 L Bm 10-14 A Omb 14-25 L Bmb 25-37 A Bmb 37-40 C,L Regosol(S79-9a) Ahj 0-7 C,L,A Bm 7-20 C,L,A Gleysol(S79-11) Cg 10-90 C,F 1 4 0 0 1 2 1 4 0 0 4 2 4 0 0 3 1 2 2 0 3 0 3 0 0 3 3 2 0 0 4 3 3 0 0 0 0 0 0 0 3 3 1 0 0 3 3 2 1 0 3 3 2 0 0 Primary M i n e r a l s : Chi Mi Plag Amph Qtz 0 0 0 0 1 0 0 0 0 1 2 0 0 1 0 3 2 2 2 1 2 1 0 1 1 2 1 3 0 1 3 1 0 1 1 0 0 1 0 0 3 1 0 1 1 2 2 2 0 1 2 2 0 0 0 Key: 4=dominant 3=abundant 2=present l=trace 0=not present A=volcanic ash C=colluvium F = f l u v i a l L=loess T = t i l l K a o=kaolinite Smc=Smectite V e r = v e r m i c u l i t e M/V,M/S= m i c a - v e r m i c u l i t e and mica-smectite i n t e r g r a d e s C h l = c h l o r i t e Mi=mica P l a g = P l a g i o c l a s e Amph=amphiboles Qtz=quartz ash r i c h h o r i z o n s , they are not abundant above the younger Bridge River ash l a y e r (see Ah h o r i z o n , S79-8, t a b l e 7.3). T h i s d i s t r i b u t i o n suggests that s m e c t i t e s are c r y s t a l l i n e secondary products of v o l c a n i c g l a s s and have been t r a n s l o c a t e d from younger to o l d e r parent m a t e r i a l s . Smectites are commonly repo r t e d as secondary c r y s t a l l i n e 1 46 products of v o l c a n i c ash weathering. Exceptions have been noted (Sneddon, 1973), authogenesis has not been documented (Borchardt, 1977), and n o n - c r y s t a l l i n e products (allophane) are normally dominant. Nonetheless, many workers have r e p o r t e d the a s s o c i a t i o n . King & Brewster (1976) suggested that smectites form i n v e s i c l e s of g l a s s where i o n i c a c t i v i t i e s remain high ( c f . Tardy et a l . , 1973). That n o t i o n i s not c o n t r a d i c t e d by t h i s study because sme c t i t e s are c l e a r l y forming and yet a l l s o i l s o l u t i o n s p l o t in k a o l i n i t e s t a b i l i t y f i e l d s of chemical p o t e n t i a l diagrams. T r a n s l o c a t i o n s of smectites from younger to o l d e r s u r f i c i a l m a t e r i a l s i s c o n s i s t e n t with the o b s e r v a t i o n that macropore flow i s common i n these s o i l s . T r a n s l o c a t i o n s may e x p l a i n why BC ho r i z o n s , developed on t i l l , a l s o y i e l d sodium f a c i e s e x t r a c t s . The t i l l c o n t a i n s a system of di a g o n a l f r a c t u r e s which are coated with organic matter and sesq u i o x i d e accumulations. The organic matter i s c l e a r l y t r a n s l o c a t e d from above. Smectites, and presumably v o l c a n i c ash, are a l s o p r e s e n t . Thus, the ash and i t s a l t e r a t i o n products are w e l l d i s t r i b u t e d i n these s o i l s . In c o n t r a s t , only one s o l u b l e s a l t e x t r a c t from a mineral s o i l h o r i z o n (Figure 7.3) was of ca l c i u m f a c i e s . That sample was taken from a C hor i z o n of a cumulic r e g o s o l which was composed of f r e s h d i o r i t i c t a l u s . The sample o v e r l a y o l d e r t a l u s c o n t a i n i n g v o l c a n i c ash. T h i s r e s u l t suggests that s o l u t e s d e r i v e d from the l o c a l l i t h o l o g i e s should be ca l c i u m f a c i e s because the l o c a l l i t h o l o g i e s are calcium-magnesium s i l i c a t e s . I f v o l c a n i c g l a s s were absent or more s t a b l e , a l l 147 waters in the s o i l system would be c a l c i u m f a c i e s . Synopsis V o l c a n i c ash i s w e l l d i s t r i b u t e d i n s o i l s at Goat Medows. The g l a s s f r a c t i o n of v o l c a n i c ash i s h i g h l y unstable i n s i m i l a r weathering environments. Most n a t u r a l s o i l s o l u t i o n s are balanced s t o i c h i o m e t r i c a l l y i n a l l c a t i o n s with v o l c a n i c g l a s s . Thus, congruent d i s s o l u t i o n of v o l c a n i c g l a s s appears to be r e s p o n s i b l e f o r a s u b s t a n t i a l p r o p o r t i o n of s o l u t e s i n s o i l s o l u t i o n s . However, an a l t e r n a t i v e h y p o t h e s i s that s o i l s o l u t i o n s are sodium f a c i e s due to negative sodium enrichment by ion exchange cannot be d i s c o u n t e d c o n c l u s i v e l y with the c u r r e n t d a t a . The problem w i l l be pursued in f u t u r e r e s e a r c h . In e i t h e r case, s o i l s o l u t i o n s can be c h a r a c t e r i z e d c o n f i d e n t l y as predominantly sodium f a c i e s and most p l o t along a very narrow s t o i c h i o m e t r i c range between p r e c i p i t a t i o n and v o l c a n i c g l a s s . Calcium E v o l u t i o n Sequence A l l waters that evolve along the c a l c i u m e v o l u t i o n sequence are g r a v i t y s o l u t i o n s ( F i g u r e 7.2). V i r t u a l l y a l l g r a v i t y s o l u t i o n s (93%) p l o t along t h i s path. They range from n e a r l y u n a l t e r e d , d i l u t e , sodium f a c i e s p r e c i p i t a t i o n to h i g h l y c o n c e n t r a t e d c a l c i u m f a c i e s groundwater. I t w i l l be argued that the c a l c i u m sources i n t h i s system are the l o c a l calcium-magnesium s i l i c a t e s and that streamflow i s c a l c i u m f a c i e s because of small a d d i t i o n s of c o n c e n t r a t e d groundwater 1 48 flow through bedrock. E x p l a i n i n g the sources of c a l c i u m i n g r a v i t y s o l u t i o n s i s more awkward than e x p l a i n i n g the sources of sodium in c a p i l l a r y samples. Water can reach the s a t u r a t e d zone of s o i l s and the stream channel network by a v a r i e t y of routes (downward, l a t e r a l and upward). Nor can t h i s three dimensional h y d r o l o g i c system be i s o l a t e d and s t u d i e d i n c o n t r o l l e d c o n d i t i o n s , as can be done with the s o i l system. Furthermore, i t i s f r u s t r a t i n g to d i s c u s s a phenomenon (groundwater) which c o u l d n e i t h e r be measured nor sampled s e p a r a t e l y . However, an i n f e r e n t i a l approach based on s p a t i a l sampling w i l l be tendered. The approach i s p e d e s t r i a n but, by v i r t u e of a t e s t a b l e h y p o t h e s i s , i s p e r s u a s i v e . Calcium F a c i e s Sources Areas The only s p a t i a l l y contiguous source area of concentrated c a l c i u m f a c i e s waters i s the narrow r e t u r n flow (discharge) zone adjacent to Mosquito Creek ( F i g u r e 7.5). V i r t u a l l y a l l samples which form the calcium f a c i e s c l u s t e r s in F i g u r e 7.2 were taken from t h i s a r ea. Streamflow i n Mosquito Creek can be fed by four p o s s i b l e ru n o f f mechanisms (Chapter 5) depending on p r e v a i l i n g discharge i n t e n s i t y . i . o v e r land flow l a r g e l y from bedrock s l a b s and s u r f a c e d e t e n t i o n storage s i t e s on the r i g h t bank headwaters. i i . s a t u r a t e d subsurface throughflow above the t i l l from r e g o s o l s which border the creek. 1 49 Figure 7.5. Meadows. Possible recharge and discharge zones at Goat 1 50 i i i . upward r e t u r n flow from the g r a v e l fan at the mouth of the creek. i v . upward groundwater flow to the creek bed and to the g l e y s o l s i n the g r a v e l fan. Wherever sampled, n e i t h e r o v e r l a n d flow nor subsurface throughflow are s u f f i c i e n t l y c o n c e n t r a t e d or c a l c i u m - r i c h to e x p l a i n the high c a l c i u m load from Mosquito Creek. Indeed, these are the d i l u t i o n components of the system which prevent c l e a r i d e n t i f i c a t i o n of the d i f f u s e c a l c i u m source. Unless the r e g o s o l s near Mosquito Creek are c h e m i c a l l y more r e a c t i v e than a l l other r e g o s o l s sampled, they are not the source of these high c a l c i u m c o n c e n t r a t i o n s . Return flow from the g r a v e l fan i s c a l c i u m f a c i e s , c o n c e n t r a t e d and s u s t a i n s streamflow d u r i n g the summer and f a l l r e c e s s i o n p e r i o d s . However, i o n i c c o n c e n t r a t i o n s i n Mosquito Creek are commonly hi g h e s t i n the channel reach upstream from the fan and must t h e r e f o r e be fed by a c o n c e n t r a t e d source w i t h i n the g u l l y . Furthermore, s o l u b l e s a l t e x t r a c t s from the g l e y s o l s of the fan are sodium f a c i e s ( F i g u r e 7.3) and s m e c t i t e s are abundant ( t a b l e 7 . 3 ) . Thus co n c e n t r a t e d , c a l c i u m - r i c h s o l u t i o n s w i t h i n the fan are not l i k e l y due to r e a c t i o n s w i t h i n the g l e y s o l s . These f a c t s imply that the dominant source of c a l c i u m i s upward groundwater r e t u r n flow from the bedrock. 151 Regional Groundwater The notion that groundwater r e t u r n flow i s the dominant source of calcium deserves c o n s i d e r a t i o n because r e g i o n a l groundwaters are c a l c i u m f a c i e s . S e v e r a l groundwater samples were c o l l e c t e d by G a l l i e i n f a l l , 1980 from seeps at bedrock outcrops downvalley from Goat Meadows. T e t i (1979) c o l l e c t e d groundwater samples over the summer, 1976 from s p r i n g s on the south s i d e of Goat Meadows r i d g e (Figure 7.6). T e t i ' s s p r i n g s v a r i e d widely in di s c h a r g e but t h e i r s o l u t e c o n c e n t r a t i o n s v a r i e d by no more than 10% over the e n t i r e summer. Therefore they are c l e a r l y from the r e g i o n a l groundwater system. These sets of samples p l o t along the ca l c i u m f a c i e s sequence and c l o s e to the c a l c i u m apex (Figure 7.2). T h i s suggests that g r a v i t y water at Goat Meadows i s r e a c t i n g with the same set of mi n e r a l s as the r e g i o n a l groundwater system. Furthermore, the mineral s u i t e c o n t r o l l i n g r e a c t i o n s i n the groundwater system i s d i s t i n c t from the s u i t e c o n t r o l l i n g r e a c t i o n s i n the s o i l s . L o c a l Groundwater Within Goat Meadows the most con c e n t r a t e d g r a v i t y s o l u t i o n s were sampled at the b e d r o c k - t i l l i n t e r f a c e d u r i n g the i n i t i a l days of snowmelt (May) 1979. These samples were c o l l e c t e d from standpipes along Mosquito Creek. At t h a t time, subsurface stormflow was n e g l i g i b l e because segregated i c e r e s t r i c t e d s o i l i n f i l t r a b i l i t y . 152 F i g u r e 7.6. Groundwater sampling s i t e s on Goat Meadows rid g e by T e t i (1979) and t h i s study. 1 53 At no other time were s i m i l a r c o n c e n t r a t i o n s observed. Standpipes were i n s t a l l e d by s h o v e l i n g a p i t through the t i l l and repacking sediment around the p i p e . The holes were never cased i n concrete f o r fear of chemical contamination by c a l c i u m carbonate. Since the standpipes never entered bedrock, nor excluded downward p e r c o l a t i n g s o i l water, i t i s not s u r p r i s i n g that high a b s o l u t e calcium c o n c e n t r a t i o n s were r a r e l y d e t e c t e d . Nonetheless, standpipe samples were c o n s i s t e n t l y more c a l c i u m - r i c h and more conc e n t r a t e d than water from throughflow zones. Calcium D i f f e r e n c e s Between Watersheds More compelling evidence f o r c o n c e n t r a t e d groundwater r e t u r n flow l i e s i n the d i f f e r e n c e s i n denudation r a t e s between watersheds. Geochemical budgets (Chapter 6) c l e a r l y i n d i c a t e that most c a t i o n i c denudation (70% by weight) i s due to c a l c i u m l o s s e s . Hummingbird catchment i s being denuded at one h a l f the r a t e of Mosquito catchment (one quarter the r a t e of Mosquito catchment in c a l c i u m ) . T h i s d i f f e r e n c e i s most e a s i l y e x p l a i n e d as a l a c k of groundwater r e t u r n flow i n Hummingbird catchment. S o i l s i n Mosquito Catchment do not appear to be weathering a p p r e c i a b l y f a s t e r than those i n Hummingbird catchment. Mosquito catchment i s predominantly r e g o s o l i c ; p o o r l y weathered, w e l l d r a i n e d , a c t i v e d e b r i s . Furthermore i t w i l l l a t e r be shown that there are no s i g n i f i c a n t d i f f e r e n c e s i n c a p i l l a r y c a l c i u m c o n c e n t r a t i o n s between r e g o s o l s and b r u n i s o l s . There are s i g n i f i c a n t d i f f e r e n c e s i n the mean throughflow 1 54 p a t h l e n g t h between the two catchments but the source area of high c a l c i u m c o n c e n t r a t i o n s in Mosquito Creek i s the r e t u r n flow zone and not the ( s o i l ) throughflow zones. High weathering r a t e s i n deep, unobserved l e v e l s of the t i l l i n Mosquito catchment i s u n l i k e l y . Everywhere they were observed, weathering zones were r e s t r i c t e d to the c o n t a c t zone with the o v e r l y i n g Holocene f i n e s (Bf h orizons) and to the system of f r a c t u r e s throughout the t i l l (BC h o r i z o n s ) . Most flow w i t h i n the t i l l i s along these f r a c t u r e zones because the unweathered matrix i s extremely compact (see Chapter 5 ) . No morphological evidence was found i n any s o i l p i t that suggested a deep zone of weathering at the base of the t i l l . Furthermore the t i l l appears u n i f o r m l y heterogeneous and any a r e a l v a r i a b i l i t y in m i n e r a l o g i c composition should have l i t t l e e f f e c t , given the magnitude of denudation r a t e s between watersheds. M o r p h o l o g i c a l D i f f e r e n c e s Between Watersheds Two f a c t o r s d i f f e r s i g n i f i c a n t l y between watersheds; topography and the d i s t r i b u t i o n of t i l l cover. Mosquito has more than twice the r e l i e f of Hummingbird and i n c l u d e s steep rocky c l i f f s , a deep g u l l y cut to bedrock, and a l a r g e , g entle r e t u r n flow zone. Hummingbird has r e l a t i v e l y g e n t l e s l o p e s , i s u n d e r l a i n by a continuous cover of t i l l (except f o r the i n t e r f l u v e s ) , and l a c k s a conspicuous r e t u r n flow zone upstream from the weir. Steep topography p r o v i d e s h y d r a u l i c p o t e n t i a l ( e l e v a t i o n 1 55 head) to d r i v e a c t i v e groundwater flow. Stepped topography encourages groundwater d i s c h a r g e along f o o t s l o p e s . T i l l a c t s as an a q u i t a r d i n discharge regions where t o t a l head i s i n s u f f i c i e n t to d r i v e groundwater r e t u r n flow i n t o the o v e r l y i n g s o i l s . Thus, groundwater flow i s a minor component of Hummingbird Creek's l o a d , most s o l u t e s are d e r i v e d from r e a c t i o n s w i t h i n s o i l s , Hummingbird Creek i s sodium f a c i e s and i s denuding a t a very low r a t e . V e r i f i c a t i o n The h y p o t h e s i s that t i l l a c t s as a a q u i t a r d f o r groundwater re t u r n flow i n Hummingbird catchment was t e s t e d at' the end of the study p e r i o d by excavating a p i t through the t i l l at s i t e #5 (Figure 3.1) i n lower Hummingbird channel. F o l l o w i n g excavation, stormflow of 30 September, 1980 at Hummingbird weir was near the h i g h e s t c o n c e n t r a t i o n l e v e l s of the e n t i r e study p e r i o d . S i m i l a r c o n c e n t r a t i o n l e v e l s were reached only during the waning few days of snowmelt in both y e a r s . These are p e r i o d s when groundwater r e t u r n flow can n a t u r a l l y form an i n f l u e n t i a l component of Hummingbird Creek's d i s c h a r g e . Furthermore, a j e t of water was observed i n the base of the p i t . The j e t had s u f f i c i e n t f o r c e to e n t r a i n coarse, sand-sized p a r t i c l e s . A pressure head i n excess of 0.05 m was measured c r u d e l y a f t e r d r i v i n g a c o n f i n i n g pipe i n t o the sediments. Water from the j e t c o u l d n e i t h e r be sampled nor gauged s e p a r a t e l y because the p i t was l o c a t e d i n an a c t i v e channel but the composite sample obtained (#80674) had a t o t a l c o n c e n t r a t i o n 1 56 of 620 mmoles rrr 3 (Ca ,Mg>Na, K ) . Groundwater Flowpaths and Mineralogy One major problem remains. Since groundwater flow i s important here and 70% of the watershed i s u n d e r l a i n by a s c h i s t high i n c h l o r i t e and a c t i n o l i t e , why are magnesium c o n c e n t r a t i o n s so low i n g r a v i t y s o l u t i o n s ( t a b l e 7 . 4 ) ? T h i s problem can be r e s o l v e d , but not c o n c l u s i v e l y . Table 7 . 4 . R e l a t i v e molar r a t i o s of elements denuded from Mosquito catchment ( 1 980 ) and i n bedrock l i t h o l o g i e s (quartz removed) and v o l c a n i c g l a s s . Element Net Y i e l d Quartz Quartz- Br idg< From Mosq. D i o r i t e Act i n o l i t e - R iver Creek C h l o r i t e Ash S c h i s t S i . 68 69 64 82 Ca 20 14 1 6 2 Mg 2 6 20 1 Na 9 5 0 10 K 1 7 0 4 T o t a l 100 101 1 00 100 The major discharge zone f o r groundwater i s Mosquito Creek. Assuming i s o t r o p i c flow, the most l i k e l y c o n t r i b u t i n g area f o r r e t u r n flow to the creek i s the high e l e v a t i o n area i n the southwest corner of Mosquito catchment ( f i g u r e 7.5). Of a l l p o t e n t i a l groundwater flowpaths i n the watershed, these are the longest and s t e e p e s t . The topographic t r a n s i t i o n at the r e t u r n flow zone i s a l s o the most abrupt. These flowpaths a l s o head i n a c l o s e d b a s i n which i s an e x c e l l e n t i n f i l t r a t i o n source because water can pond to 0.5 m deep d u r i n g snowmelt. 1 57 The l i t h o l o g y through which these groundwaters must flow i s quartz d i o r i t e and not the s c h i s t . Quartz d i o r i t e i s massive and flowpaths must be r e s t r i c t e d to j o i n t p l a n e s . J o i n t s v i s i b l e at the s u r f a c e are wide (0.1 m to 0.01m) because the r i d g e i s c o l l a p s i n g to the west. The j o i n t s are l i n e d with e p i d o t e . Epidote t y p i c a l l y forms along j o i n t s and f i s s u r e s as a hydrothermal a l t e r a t i o n product of p l a g i o c l a s e or as an a l t e r a t i o n product of c h l o r i t e under low temperature shear s t r e s s e s (Deer et a l . , 1966, p. 67). In terms of c a t i o n i c composition, epidote i s the only pure calcium s i l i c a t e i n the l o c a l m i neral system ( f i g u r e 7.4). Since v i r t u a l l y a l l g r a v i t y s o l u t i o n s p l o t d i r e c t l y toward the c a l c i u m apex (even i n calcium-magnesium-sodium space), epidote i s the only mineral of t h i s composition, and epidote l i n e s the f r a c t u r e s through which groundwater must flow, i t i s presumed that epidote i s the c h i e f weathering source i n groundwater routes which r e t u r n w i t h i n Goat Meadows. C l e a r l y , a l t e r n a t i v e e x p l a n a t i o n s are p o s s i b l e . For example, ferromagnesian m i n e r a l s i n the d i o r i t e c o u l d be important c a l c i u m sources i f magnesium were being conserved i n t h e i r a l t e r a t i o n products ( i e . d i o c t a h e d r a l s m e c t i t e s ) . A n o r t h i t e i n the i n t e r i o r of zoned andesine c r y s t a l s c o u l d a l s o be a c a l c i u m source ( c f . Mankiewicz and Sweeney, 1977) i f p l a g i o c l a s e was preserved at depth but absent where v i s i b l e i n the j o i n t system. However, these are complicated e x p l a n a t i o n s and n e i t h e r appears to f i t the f a c t s as c u r r e n t l y known. 1 58 Furthermore, epidote i s in the proper s i t e s f o r weathering and i s of the proper chemical composition. Synopsis I t i s t e n t a t i v e l y concluded that the c a l c i u m sequence i s c o n t r o l l e d by r e a c t i o n s between water and epidote along groundwater flowpaths i n quartz d i o r i t e . N a t u r a l l y , c a l c i u m and magnesium are a l s o d e r i v e d from aqueous r e a c t i o n s with a l l l o c a l s u r f i c i a l m a t e r i a l s and bedrock. However, v o l c a n i c g l a s s appears to be l e s s s t a b l e than calcium-magnesium s i l i c a t e s i n vadose s o i l water zones and c a l c i u m f a c i e s groundwater i s a more con c e n t r a t e d source in p h r e a t i c s o i l water zones. D i f f e r e n c e s in denudation r a t e between Mosquito and Hummingbird catchments are caused by t o p o g r a p h i c a l l y induced groundwater c o n t r i b u t i o n s to streamflow. A t t e n t i o n w i l l now be d i r e c t e d to the small set of water samples which do not conform to s e q u e n t i a l changes i n i o n i c composition. Mixed F a c i e s S o l u t i o n s A m i n o r i t y (11%) of samples do not conform to the sodium and c a l c i u m sequences p r e v i o u s l y d i s c u s s e d ( f i g u r e 7.7). These i n c l u d e 7% of the g r a v i t y s o l u t i o n s and 30% of the c a p i l l a r y s o l u t i o n s . These samples tend toward mixed f a c i e s because of i n t e r v e n i n g f a c t o r s . The most important n a t u r a l f a c t o r i s a d d i t i o n of potassium leached from f r e s h p l a n t t i s s u e . A second f a c t o r may be the d i l u t i o n of mineral s o i l s o l u t i o n s d u r i n g 1 59 i n f i l t r a t i o n events by water from o v e r l y i n g h o r i z o n s that are poor in v o l c a n i c g l a s s . Potassium Sources The few g r a v i t y s o l u t i o n s that do not p l o t along the c a l c i u m sequence are c h e m i c a l l y unique only because they are r e l a t i v e l y e n r i c h e d i n potassium ( f i g u r e 7 . 7 ) . In other words, t h e i r c a l c i u m , magnesium, and sodium c o n c e n t r a t i o n s are s i m i l a r to a l l other g r a v i t y s o l u t i o n s . The source of potassium i n these samples i s f r e s h p l a n t l i t t e r . T h i s i s deduced from the r e l a t i v e abundance of potassium among s o l u b l e s a l t e x t r a c t s and the temporal and s p a t i a l i d i o s y n c r a s i e s of the deviant samples. Humic epipedons are the only s o i l h o r i z o n s high i n water s o l u b l e potassium ( f i g u r e 7.8) and of these, LFH and LH e x t r a c t s are much higher i n potassium than Ah e x t r a c t s . M i n e r a l h o r i z o n e x t r a c t s ( f i g u r e 7.3) c o n t a i n l i t t l e potassium. Inorganic sources of potassium i n c l u d e v o l c a n i c g l a s s , o r t h o c l a s e , muscovite, b i o t i t e , and p o s s i b l y hornblende. These m i n e r a l s are more or l e s s u b i q u i t o u s i n s o i l s . Since the d i s t r i b u t i o n of anomalously h i g h potassium c o n c e n t r a t i o n s i n s o l u b l e s a l t e x t r a c t s i s l i m i t e d to humic epipedons and i s most apparent i n LFH h o r i z o n s , mineral-water r e a c t i o n s cannot e x p l a i n potassium v a r i a b i l i t y . G r a v i t y s o l u t i o n s e n r i c h e d in potassium are predominantly o v e r l a n d flow and s u r f a c e d e t e n t i o n storage samples. These samples were c o l l e c t e d i n i n t i m a t e c o n t a c t with f r e s h organic 160 F i g u r e 7.7. R e l a t i v e and a b s o l u t e abundance of Na, Ca, and K i n mixed f a c i e s water samples. P o i n t s represent the c e n t r o i d s of c l u s t e r s d e f i n e d by numerical taxonomony and c o n t a i n 11% of a l l f i e l d samples. Open symbols are s i n g l e samples. U n i t s are mmole m~3. 161 F i g u r e 7.8. R e l a t i v e and a b s o l u t e abundance of water s o l u b l e Na, Ca, and K from humic s o i l , h o r i z o n s . U n i t s are micromoles per 100 g s o i l . 1 62 matter. These samples are a l s o temporally r e s t r i c t e d to the f i r s t month of snowmelt and the f i r s t major f a l l storms. These are p e r i o d s when f r e s h l e a f l i t t e r i s most abundant. T r a n s i e n t i n c r e a s e s i n i o n i c c o n c e n t r a t i o n d u r i n g events i s c o n v e n t i o n a l l y r e f e r r e d to as " f l u s h i n g " ( S t e e l e , 1968). Potassium i s commonly f l u s h e d (Cleaves et a l . , 1970; Johnson and Swank, 1973). Potassium f l u s h i n g at Goat Meadows i s short l i v e d because potassium i s e a s i l y leached from p l a n t t i s s u e (Gosz et a l . 1973), biomass i s l i m i t e d so potassium supply i s s m a l l , and su r f a c e r u n o f f i s abundant so the source i s q u i c k l y d e p l e t e d . However, organic matter can be a rather l a r g e i o n i c sink i n t r e e i s l a n d s because these s i t e s are r e l a t i v e l y dry and the biomass i s l a r g e . The sink of ions i n LFH h o r i z o n s i s a l s o not l i m i t e d to potassium. F i v e of the most co n c e n t r a t e d and s t a t i s t i c a l l y deviant ( f i g u r e 7.7) samples from Goat Meadows are c a p i l l a r y s o l u t i o n s from a s i n g l e t r e e i s l a n d s i t e (#122, f i g u r e 3.1). These s o l u t i o n s are thought to be LFH lea c h a t e s because a l l samples were h i g h l y c o l o r e d , potassium i s a dominant ion and, durin g one i n f i l t r a t i o n event, i o n i c c o n c e n t r a t i o n s i n c r e a s e d , rather than decreased. T h i s i s c o n s i s t e n t with o b s e r v a t i o n s of i o n i c c o n c e n t r a t i o n in f o r e s t s o i l s of the c o a s t a l c o r d i l l e r a (Cole, 1963; Cole et a l . 1967; Bourgeois and L a v k u l i c h , 1972; F e l l e r , 1977; Moon 1981). Leachates from f o r e s t l i t t e r are g e n e r a l l y the most conce n t r a t e d s o l u t i o n s w i t h i n the vadose zone of s o i l s . C a t i o n i c c o n c e n t r a t i o n s i n s o i l s o l u t i o n s decrease with 1 63 i n c r e a s i n g depth in mineral h o r i z o n s due to exchange r e a c t i o n s such as hydrogen ion f o r c a t i o n s by roots and by organic matter. The rat e of exchange i s a f u n c t i o n of many f a c t o r s i n c l u d i n g seasonal b i o l o g i c a l demand, mobile anion supply (bicarbonate i n the c o a s t a l f o r e s t s ) , and l e a c h i n g r a t e s ( M c C o l l , 1973; F e l l e r 1977; Johnson et a l . , 1977). T h i s i s r e l e v a n t because i t suggests that b i o c y c l i n g can be an important t r a n s l o c a t i o n process where biomass i s h i g h and l e a c h i n g r a t e s are low. The general environment, however, i s dominated by low biomass and high l e a c h i n g r a t e s . Thus b i o c y c l i n g i s probably not an overwhelming process i n r e g u l a t i n g i o n i c f l u x e s f o r the watershed as a whole and should have a minor e f f e c t on short-term stream chemistry v a r i a t i o n s . T h i s does not mean that v e g e t a t i o n p l a y s an unimportant r o l e i n weathering r e a c t i o n s here. Indeed, a l l a v a i l a b l e s t u d i e s suggest that the chemical p r o p e r t i e s of high a l t i t u d e s o i l s developed on v o l c a n i c ash are c o n t r o l l e d i n l a r g e part by organic c o l l o i d s . For example, Bockheim (1972) s t u d i e d s o i l s on Mt Baker, Washington and noted that f u l v i c a c i d s were the dominant or g a n i c compounds in both subalpine and a l p i n e s o i l groups and t h a t " c h e l u v i a t i o n " was the dominant s o i l forming process. The pH-dependent c a t i o n exchange c a p a c i t y of a l p i n e meadow s o i l s was highest i n t u r f y Ah h o r i z o n s as were a l l other measures of organic substances except f u l v i c a c i d carbon. T h i s c o n t r a s t e d s h a r p l y with s o i l s i n t r e e i s l a n d s where organic and f e r r u g i n o u s substances were accumulated in B2 h o r i z o n s . A s i m i l a r p a t t e r n i s suggested by water s o l u b l e s a l t 1 64 e x t r a c t s at Goat Meadows. A n a l y s i s of v a r i a n c e of water s o l u b l e s a l t e x t r a c t s i n d i c a t e s that s o l u t e y i e l d s covary s y s t e m a t i c a l l y with h o r i z o n and that o r g a n i c - r i c h h o r i z o n s are the most r e a c t i v e by t h i s t e s t ( t a b l e 7.5). Ah h o r i z o n s are probably Table 7.5. Mean c o n c e n t r a t i o n of water s o l u b l e s a l t s from s o i l h o r i z o n s and v a r i a n c e i n water s o l u b l e s a l t e x t r a c t s e x p l a i n e d by the independent v a r i a b l e " h o r i z o n " (p<0.0l). A l l u n i t s are micromoles per 100 g s o i l . Note that b r u n i s o l s and r e g o s o l s account f o r 94% of the t o t a l area of s o i l s i n t h i s watershed and that most of t h e i r mass i s i n Bm and C h o r i z o n s . S o i l - V e g : Hor izon n S i ( O H ) a Ca Mg Na K pH Regosols: Ahj 3 17.1 7.8 3.7 9.8 5.6 4.80 C 5 24.6 6.0 1 .5 7.7 1.8 5.06 B r u n i s o l s : Ah 6 32.9 24.7 13.7 40.6 47.7 4.43 Omb 5 34.7 9.9 8.1 46.6 21.3 4.46 Bm 1 4 24.3 4. 1 3.8 19.2 7.8 4.69 G l e y s o l s : Cg 1 47. 1 16.5 51.8 47.4 33.0 5.90 Podzols: L f h 6 1 26.2 91 .7 28. 1 90.6 508.7 4.95 Ae 3 44.6 12.3 15.7 51.6 99.4 4.40 Bhf 4 35.3 9.7 11.1 39.7 18.5 4.48 Bf 5 26.7 7.5 8.1 28.9 8.3 4.32 BC 5 23.6 2.6 6.6 10.0 1 .6 4.76 % v a r i a n c e e x p l a i n e d by h o r i z o n 74 46 49 69 75 43 among the most r e a c t i v e m i n e r a l horizons because they are b i o l o g i c a l l y p r o d u c t i v e , r e c e i v e frequent a d d i t i o n s of f r e s h m i n e r a l matter as l o e s s , h o l d moisture w e l l because they o v e r l i e the w a t e r - r e p e l l e n t zone, and are f r e q u e n t l y shunted by throughflow. O r g a n i c - r i c h h o r i z o n s beneath t r e e i s l a n d s do not 1 65 r e c e i v e as much l o e s s nor have as ex t e n s i v e a ne a r - s u r f a c e root system as sedge but t r e e s are h i g h l y p r o d u c t i v e and have deep root systems. Variance Induced By I n f i l t r a t i o n The remaining unexplained v a r i a n c e i n the data set occurs at nine c a p i l l a r y water sampling s i t e s (#105,119,122,123,124,125,126,128). S i t e 122 i s the aforementioned t r e e i s l a n d s i t e and i t s B h o r i z o n s o l u t i o n s appear to be i n f l u e n c e d by LFH l e a c h a t e s . I t i s l e s s c l e a r why the other s i t e s d e v i a t e from the the main sodium sequence but the v a r i a n c e among these samples i s not great (Figure 7.7) and i s probably a l s o r e l a t e d to p e r c o l a t i o n of l e a c h a t e s from o v e r l y i n g h o r i z o n s . A l l m i n e r a l h o r i z o n s o l u t i o n s (except the aforementioned t r e e i s l a n d s i t e , #122) become d i l u t e d d u r i n g i n f i l t r a t i o n events ( f i g u r e 7.9). At many s i t e s , sodium i s d i l u t e d more s t r o n g l y than other i o n s . Thus, they t e m p o r a r i l y d e v i a t e from the main sodium sequence. Most of these s i t e s have t u r f y Ah ho r i z o n s . S o l u b l e s a l t e x t r a c t s from Ah hor i z o n s are en r i c h e d in c a l c i u m and potassium r e l a t i v e to deeper ho r i z o n s (Figure 7.8, 7.3). T h i s may be due to the f a c t that Ah hor i z o n s are developed i n humus and l o e s s d e p o s i t e d s i n c e 2400 BP, the time of the e a r l i e s t Bridge R i v e r e r u p t i v e event, and do not c o n t a i n sodium-rich v o l c a n i c ash. What ever the cause, the p a t t e r n of t r a n s i e n t d i l u t i o n d u r i n g i n f i l t r a t i o n events suggests that the d i l u t i n g s o l u t i o n s are unsaturated flows from o v e r l y i n g Ah 166 September 1980 October F i g u r e 7.9. Temporal v a r i a b i l i t y of c a p i l l a r y zone s o l u t e s , 1980. U n i t s are mmoles m"3. 1 67 h o r i z o n s . Since Ah h o r i z o n s are e n r i c h e d i n potassium and c a l c i u m r e l a t i v e to sodium, the u n d e r l y i n g m i n e r a l horizons are d i l u t e d more s t r o n g l y i n sodium than other i o n s . The use of vacuum samplers may have enhanced unsaturated flow from humic to mineral h o r i z o n s . T u r f y Ah h o r i z o n s are a l l s t r o n g l y w a t e r - r e p e l l e n t . B a r r e t t (1981) argued that i n f i l t r a t i o n r a t e s i n w a t e r - r e p e l l e n t s i t e s are c o n t r o l l e d by the wetted pore volume w i t h i n the w a t e r - r e p e l l e n t zone and the t e n s i o n g r a d i e n t s between the l o e s s above and below the zone. Vacuum samplers may have helped overcome t h i s n a t u r a l r e s i s t a n c e to downward unsaturated flow by i n c r e a s i n g the t e n s i o n g r a d i e n t s between h o r i z o n s . Thus, the v a r i a n c e observed in c a p i l l a r y s o l u t i o n s may not be as common under n a t u r a l c o n d i t i o n s . Vacuum samplers u n e q u i v o c a l l y s p o i l e d c a p i l l a r y samples at the g l e y s o l i c s i t e 1 2 3 by drawing g r a v i t y s o l u t i o n s upward i n t o the , vadose zone (see f i g u r e 7.9). T h i s e f f e c t probably c o u l d not have been avoided without using very low vacuum p r e s s u r e s . Synopsis Variance i n g r a v i t y s o l u t i o n s i s due t o a d d i t i o n s of potassium, leached from LH and LFH h o r i z o n s , p r i m a r i a l l y i n o v e r l a n d flow. Given the small potassium budgets at Goat Meadows and the l i m i t e d s t anding biomass, b i o c y c l i n g i s thought to e x e r c i s e a minor c o n t r o l on s o i l s o l u t i o n s here. B i o c y c l i n g i s an important t r a n s l o c a t i o n process i n s o i l development of t r e e i s l a n d s i t e s . V a r i a nce i n c a p i l l a r y samples may be due to t r a n s i e n t 1 68 d i l u t i o n of mineral h o r i z o n s o l u t i o n s by Ah h o r i z o n s o l u t i o n s d u r i n g i n f i l t r a t i o n . Ah hor i z o n s are developed in o r g a n i c - r i c h l o e s s , r a t h e r than v o l c a n i c ash, so Ah s o l u t i o n s are r e l a t i v e l y d e p l e t e d i n sodium. I t i s not c l e a r how much of t h i s v a r i a n c e was operator induced by the use of vacuum samplers. S o i l S o l u t i o n D i f f e r e n c e s Between S o i l Groups The i n i t i a l sampling design f o r t h i s study was fashioned a f t e r the no t i o n that s o l u t e c o n c e n t r a t i o n s should vary as a f u n c t i o n of e f f e c t i v e weathering r a t e s between s o i l groups (see Sampling Design, Chapter 3). From the preceding d i s c u s s i o n i t i s c l e a r t h a t d i f f e r e n c e s i n s o l u t e c o n c e n t r a t i o n s between s o i l groups are small r e l a t i v e to d i f f e r e n c e s i n s o l u t e c o n c e n t r a t i o n s between s o i l water and groundwater from bedrock. The q u e s t i o n i s now r e s t a t e d . How minor are the d i f f e r e n c e s between s o i l groups? The answer i s , simply, very small indeed. One-way a n a l y s i s of v a r i a n c e using vadose zone s o l u t e c o n c e n t r a t i o n s as a dependent v a r i a b l e of s o i l groups i n d i c a t e s that only 15% to 28% of a l l s o l u t e v a r i a b i l i t y i s e x p l a i n e d by s o i l group (p<0.0l). With few exce p t i o n s ( C a + 2 i n the g l e y s o l s ) , a weak p a t t e r n emerges between the mean c o n c e n t r a t i o n of s o i l groups: Podzols>>Brunisols>Gleysols>Regosols. The g r e a t e s t d i f f e r e n c e i n mean c o n c e n t r a t i o n between the major s o i l groups ( b r u n i s o l s and reg o s o l s ) are i n s i l i c o n , sodium, and potassium ( t a b l e 7.6). These elements are r e s p e c t i v e l y the 169 Table 7.6. Mean concentration of c a p i l l a r y s o i l solutions and variance in c a p i l l a r y s o i l solutions as a function of major s o i l group (p<0.0l). Units are mmole irr 3 (± figures are 95% CI on the means). Basin Si(OH) a Ca Mg Na K Group Area n Regosols:33 49 91.6±12.3 13.6± 2.4 6.0±0.7 31.4± 4.8 9.6± 1.6 Brunisols: Dystric: 30 37 140.0±14.2 14.3± 3.1 7.6±1.2 53.6± 9.9 15.2± 3.1 Sombric: 12 31 116.3±16.2 15.6± 5.2 8.3±1.6 42.0± 9.9 14.6± 4.3 Gleysols: 3 6 99.8±28.8 65.8±30.4 6.3±3.2 40.0±24.5 9.8± 6.2 Podzols: 2 8 247.2±58.7 46.8±24.7 18.5±8.9 74.4±31.6 46.0±27.9 A l l : 80 131 116.5 16.6 7.4 41.7 13.3 variance explaned(%): 28 22 22 15 20 major constituents of volcanic glass. Smaller differences in means occur in calcium and magnesium concentrations. These elements are the most abundant cations in the l o c a l l y derived s u r f i c i a l materials (table 7.4). This weak pattern among a l l f i e l d samples i s much more strongly expressed in the water soluble s a l t extracts from individual horizons. In the laboratory data set, 96% to 75% of the variance in s i l i c o n , sodium, and potassium i s explained by s o i l horizon where as only 46% and 49% of the variance in calcium and magnesium is explained by s o i l horizon (table 7.5). As glass i s the major weathering source in s o i l s , these analyses suggest that much of the variance i s related to the s p a t i a l d i s t r i b u t i o n of the glass. Since c a l c i c s i l i c a t e s are well distributed throughout the s o i l s , calcium and magnesium concentrations in the f i e l d samples offer the only unbiased index of differences in e f f e c t i v e weathering intensity between s o i l groups. 1 70 D i v a l e n t c a t i o n c o n c e n t r a t i o n s i n vadose zone s o i l s o l u t i o n s are s i g n i f i c a n t l y higher i n podzols and g l e y s o l s than in b r u n i s o l s and r e g o s o l s ( t a b l e 7.6). However, high c a p i l l a r y s o l u t i o n s at the aforementioned s i t e s were i n f e r r e d to be due, i n p a r t , to LFH l e a c h a t e s beneath t r e e i s l a n d s , to e v a p o r a t i v e c o n c e n t r a t i o n of c a l c i u m f a c i e s s o l u t i o n s from the c a p i l l a r y f r i n g e of g l e y s o l s , and to operator-induced contamination by f r e e water i n g l e y s o l s (see F i g u r e 7.9). In a d d i t i o n , podzols and g l e y s o l s are minor elements of the s o i l landscape at Goat Meadows. Amoung b r u n i s o l s and r e g o s o l s , which dominate the landscape, there are no s i g n i f i c a n t d i f f e r e n c e s i n mean c a l c i u m and magnesium c o n c e n t r a t i o n s (p<0.0l). A comparative study of b r u n i s o l i c and r e g o s o l i c mass budgets was attempted in 1980 using 4 x 5 m h i l l s l o p e p l o t s . No u s e f u l mass budget data r e s u l t e d because of l o g i s t i c a l problems at the r e g o s o l i c s i t e . Throughflow there occurred v i a a c o a r s e - t e x t u r e d p i p e . The pipe was not d i s c o v e r e d u n t i l l a t e in the snowmelt season a f t e r snowcover was n e a r l y d e p l e t e d at the b r u n i s o l i c p l o t . Furthermore, d e s p i t e much hard work, i t was never c o n f i d e n t l y concluded that the subsurface throughflow zone in the r e g o s o l i c p l o t had been p h y s i c a l l y i s o l a t e d from the pipe network upslope. Thus, without a sound water budget, v e r i f i c a t i o n was i m p o s s i b l e . The s i m i l a r i t y of s o l u t e s between s o i l groups i s troublesome because t h e r e are c l e a r m orphological d i f f e r e n c e s between s o i l groups. Indeed, morphology i s the c r i t e r i o n of s o i l c l a s s i f i c a t i o n and c l a s s i f i c a t i o n schemes are designed to 171 embody theory of pedogenic process (Simonson, 1959). Bockheim (1972) s t u d i e d the morphology and genesis of s o i l s formed i n s i t u on shale bedrock near t r e e l i m i t at S k y l i n e D i v i d e , Mount Baker, Washighton. At l e a s t three a d d i t i o n s of v o l c a n i c ash were noted. Bockheim's s i t e s were a l l i n c l o s e p r o x i m i t y . Parent m a t e r i a l s , topography ( s i c ) , c l i m a t e and time were thus h e l d r e l a t i v e l y constant so that m orphological response to v e g e t a t i o n c o u l d be compared d i r e c t l y . S o i l s beneath t r e e i s l a n d s were s i g n i f i c a n t l y b e t t e r developed than those i n sedge-forb meadows. Both chemical and p h y s i c a l evidence c l e a r l y i n d i c a t e d that t r e e i s l a n d s o i l s had g r e a t e r weathering r a t e s than d i d subalpine meadow s o i l s . T h i s same p a t t e r n appears true at Goat Meadows s u p e r f i c i a l l y . Furthermore, m o r p h o l o g i c a l d i f f e r e n c e s between o r t h i c b r u n i s o l s , cumulic b r u n i s o l s , and r e g o s o l s are e q u a l l y d i s t i n c t . N a t u r a l l y , cumulic and r e g o s o l i c pedons have not formed i n s i t u so morphological d i s p a r i t y need not i n d i c a t e any r e a l d i f f e r e n c e in weathering r a t e s ( c f . King and Brewster, 1978). Nonetheless, the presence or absence of a v e g e t a t i v e cover should have some e f f e c t on weathering r a t e s and s o i l s o l u t i o n chemistry. One e x p l a n a t i o n f o r the r e s u l t s i s that the method of comparison i s inadequate although i t i s not at a l l c l e a r why t h i s should be the case. Another p o s s i b i l i t y i s that c u r r e n t s o i l morphology i s more a product of Hypsithermal than contemporary pedogenesis. Goat Meadows was much more c o n t i n e n t a l from 10,500 to 6000 1 72 BP than at p r e s e n t . The pond was t e r r e s t r i a l , r a t h e r than a q u a t i c , and much of the b r u n i s o l s were f o r e s t e d (see Chapter 2). Howell and H a r r i s (1978) contend that post-Hypsithermal c l i m a t e change s i g n i f i c a n t l y reduced " p o d z o l i z a t i o n " i n mountain s o i l s of western A l b e r t a ( c f . van Ryswyk and Okazaki, 1979). The assumptions on which t h e i r c o n c l u s i o n s are based do not f i t the c l i m a t i c r e c o n s t r u c t i o n at Goat Meadows nor i s t h e i r data base c o n c l u s i v e . However, i f Howell and H a r r i s are c o r r e c t , v e g e t a t i o n changes can provide a p o s s i b l e e x p l a n a t i o n f o r the d i s c r e p a n c y between apparent (morphological) and a c t u a l ( s o l u t e c o n c e n t r a t i o n s ) s o i l l e a c h i n g r a t e s between s o i l groups. Whatever the cause, no unambiguous evidence can be o f f e r e d to support the hypothesis that d i s t i n c t d i f f e r e n c e s c u r r e n t l y e x i s t i n weathering r a t e s a c r o s s the watershed. T h i s t e n t a t i v e c o n c l u s i o n i s not i n t u i t i v e l y s a t i s f y i n g because i t c o n t r a d i c t s the n o t i o n that form and process are i n some way r e l a t e d . Thus i t deserves a more r i g o r o u s t e s t . The most e f f i c i e n t approach to t e s t i n g t h i s h y p o thesis would be a comparative elemental and m i n e r a l o g i c a l d e p l e t i o n study between s o i l groups. A d e p l e t i o n study i s now f e a s i b l e because c u r r e n t denudation r a t e s and processes f o r the watershed are documented. V o l c a n i c ash l a y e r s p r o v i d e s t r a t i g r a p h i c c o n t r o l . S e d i m e n t o l o g i c a l evidence from lake cores shows that l o e s s a l a d d i t i o n s have o c c u r r e d at a steady r a t e through time. P a l y n o l o g i c a l evidence shows that the Holocene has been punctuated by s i g n i f i c a n t and r a p i d s h i f t s i n v e g e t a t i o n and p r e c i p i t a t i o n . C o nveniently, the Mazama ash bed d e l i n e a t e s the 173 most s i g n i f i c a n t t i m e - s t r a t i g r a p h i c - c l i m a t i c boundary of the Holocene. T h i s problem w i l l be pursued in subsequent r e s e a r c h . Summary S o i l s o l u t i o n l o s s e s to streamflow are sodium f a c i e s . T h i s occurs because sodium r i c h v o l c a n i c g l a s s i s l e s s s t a b l e than c a l c i u m - r i c h , l o c a l l y d e r i v e d s u r f i c i a l m a t e r i a l s and/or because c a l c i u m i s r e t a i n e d on s o i l exchange complexes. S o i l s o l u t i o n s from humic hor i z o n s can be r e l a t i v e l y e n r i c h e d with potassium and d e f i c i e n t i n sodium because humic h o r i z o n s are developed on l o e s s and organic matter r a t h e r than v o l c a n i c g l a s s . The chemical i n f l u e n c e of v o l c a n i c g l a s s i s e x t e n s i v e because of c o l l o i d a l t r a n s l o c a t i o n s . B i o c y c l i n g t r a n s l o c a t i o n s are s i g n i f i c a n t i n podzols beneath c o n i f e r o u s v e g e t a t i o n . The importance of b i o c y c l i n g to t r a n s l o c a t i o n s i n b r u n i s o l s cannot be e v a l u a t e d a c c u r a t e l y with the c u r r e n t data but r e s u l t s suggest that b i o c y c l i n g i s r e l a t i v e l y l e s s important i n these s o i l s and the r e a c t i v e f r a c t i o n i s l o c a t e d p r i m a r i l y i n humic epipedons. D i f f e r e n c e s i n s o l u t e c o n c e n t r a t i o n s between b r u n i s o l s and r e g o s o l s are minor. The p a t t e r n of v a r i a n c e i n f i e l d and l a b o r a t o r y s o i l s o l u t i o n s suggests that s p a t i a l v a r i a b i l i t y of v o l c a n i c g l a s s i s a more important c o n t r o l on s o i l l o s s e s than environmental c o n t r o l on r e a c t i o n r a t e s . The data are not c o n c l u s i v e and an elemental d e p l e t i o n study i s recommended. Calcium i s the l a r g e s t component of c a t i o n i c denudation but c a l c i u m i s only a minor component of s o i l l o s s e s . Thus, most 1 7 4 c a l c i u m i s d e r i v e d from bedrock weathering along groundwater flowpaths. The most probable groundwater flowpaths that c o n t r i b u t e s i g n i f i c a n t d i s c h a r g e w i t h i n the study s i t e flow along j o i n t planes i n quartz d i o r i t e . These j o i n t planes are l i n e d with epidote where v i s i b l e . E p idote i s the only m i n e r a l in the watershed that s a t i s f i e s the chemical composition sequence of stream and groundwater. Thus epidote l i n i n g s of j o i n t planes are assumed to be the most important c a l c i u m source. P r e c i p i t a t i o n enters the groundwater system v i a exposed bedrock s l a b s and through p h r e a t i c s o i l water zones i n c l o s e d d e p r e s s i o n s . Thus, groundwater may be d i l u t e and sodium f a c i e s i n i t i a l l y . Flowpaths w i t h i n the bedrock are short and the system must be f a i r l y dynamic. However, the s u r f a c e h y d r o l o g i c system has l i t t l e c a p a c i t y and snowmelt runo f f i s intense so groundwater resid e n c e times are probably much g r e a t e r than residence time of s o i l water. Thus, groundwater i s h i g h l y c o n c e n t r a t e d r e l a t i v e to s o i l water, even when the groundwater system i s most a c t i v e . Groundwater r e t u r n flow can occur i n l o w l y i n g areas. Where h y d r a u l i c p o t e n t i a l i s s u f f i c i e n t , groundwater d i s c h a r g e s i n t o the o v e r l y i n g s o i l s , making s o i l and stream water c a l c i u m f a c i e s . The s a t u r a t e d s o i l water system i s d i l u t e and only small a d d i t i o n s of c o n c e n t r a t e d groundwater appear necessary to convert sodium f a c i e s water to c a l c i u m f a c i e s . 1 75 Chapter 8. DENUDATION I n t r o d u c t i o n The purpose of t h i s chapter i s to i n t e r p r e t the geochemical budgets presented i n Chapter 6. One goal i s to e x p l a i n the near d o u b l i n g in denudation r a t e s between study y e a r s . T h i s i s necessary i n order to i d e n t i f y the major c o n t r o l s on denudation at Goat Meadows. M a t e r i a l from p r e v i o u s chapters w i l l be b r i e f l y reviewed and i n t e g r a t e d to e x p l a i n temporal v a r i a b i l i t y of s o l u t e loads i n streamflow. I t w i l l be argued that d i f f e r e n c e s i n denudation r a t e s between study years i s s u f f i c i e n t l y e x p l a i n e d by the e f f e c t s of segregated ground i c e on s o i l i n f i l t r a b i l i t y . The second goal of t h i s chapter i s to assess the r e p r e s e n t a t i v e n e s s of denudation r a t e s at Goat Meadows r e l a t i v e to r e g i o n a l denudation r a t e s . D i f f e r e n c e s in denudation between Goat Meadows and surrounding catchments w i l l be shown to be due to d i f f e r e n c e s i n the p r o p o r t i o n of groundwater r e t u r n flow i n t o t a l streamflow. A Conceptual Runoff Model Evidence was given i n Chapter 5 to support a two component runof f model. The two components were l a b e l e d " d i r e c t " and " i n d i r e c t " on the b a s i s of t h e i r temporal response to input 176 events. D i r e c t runoff i s generated by r e t u r n flow from s a t u r a t e d throughflow above the w a t e r - r e p e l l e n t zone and by d i r e c t p r e c i p i t a t i o n onto these s a t u r a t e d areas. D i r e c t runoff i s generated on b r u n i s o l s and g l e y s o l s . I n d i r e c t runoff i s generated by s a t u r a t e d throughflow above the t i l l and above the w a t e r - r e p e l l e n t zone. I n d i r e c t runoff i s generated by a l l s o i l groups i n the watershed. D i r e c t and i n d i r e c t runoff converge along the stream channel network. The lowest reaches of the stream network are g l e y s o l i c s i t e s . These s o i l s are almost always s a t u r a t e d and support streamflow between events. T h i s i s a l s o the major zone of groundwater discharge i n the watershed. Groundwater i s not thought to c o n t r i b u t e s i g n i f i c a n t l y to stormflow. T h i s runoff model p r o v i d e d a conceptual b a s i s to support g r a p h i c a l decomposition of seasonal snowmelt hydrographs (Figure 5.5). There are c l e a r d i f f e r e n c e s in runoff between ye a r s . S o i l i n f i l t r a b i l i t y was low d u r i n g 1979. As a r e s u l t , the i n d i r e c t r u n o f f component was l i m i t e d and a l a r g e p r o p o r t i o n of r u n o f f reached the stream network as o v e r l a n d flow generated by d i r e c t p r e c i p i t a t i o n onto s a t u r a t e d areas. S o i l i n f i l t r a b i l i t y was high d u r i n g 1980. The i n d i r e c t runoff component was l a r g e and more a v a i l a b l e runoff flowpaths were e x p l o i t e d . The d i r e c t runoff component was consequently reduced and may have contained a l a r g e r p r o p o r t i o n of r e t u r n flow from s a t u r a t e d s o i l above the w a t e r - r e p e l l e n t zone. 1 77 Solute Dynamics The runoff model prov i d e s the framework f o r a coherent hydrochemical model. Streamflow c o n c e n t r a t i o n s d i f f e r e d between years because of v a r i a t i o n s i n the r e l a t i v e c o n t r i b u t i o n of runoff components to streamflow and because runoff components d i f f e r s i g n i f i c a n t l y i n mean i o n i c c o n c e n t r a t i o n . Table 8.1 l i s t s average compositions of h y d r o l o g i c flow components sampled du r i n g the study p e r i o d . These samples have a v a r i e t y of o r i g i n s and, as d i s c u s s e d i n chapter 7, have systematic v a r i a t i o n s i n i o n i c composition which are not adequately r e f l e c t e d when summarized as mean c o n c e n t r a t i o n data. Nonetheless, t a b l e 8.1 adequately i l l u s t r a t e s the r e l a t i v e d i f f e r e n c e i n t o t a l i o n i c c o n c e n t r a t i o n i n major h y d r o l o g i c flow components. Table 8.1. Mean c o n c e n t r a t i o n (mmoles i r r 3 ) of h y d r o l o g i c flow components. R e l a t i v e e r r o r s (2s/sum of cations*100) l i s t e d f o r the sum of c a t i o n s are r e p r e s e n t a t i v e of the v a r i a n c e of each s o l u t e . Groundwater samples are from s p r i n g s 400 m from Goat Meadows and were c o l l e c t e d by T e t i (1979). Flow n Si(OH)„ Ca Mg Na K sum of 2s/sum Component: cat ions * 100 Snowmelt 1 7 1 .8 0.3 0.2 1 .4 0.2 2.1 57% Overland flow 23 37.6 4.8 1 .6 2.8 3.4 12.6 73% Vadose zone 131 116.5 16.6 7.4 41.7 13.3 79.0 1 4% Throughflow 183 64.0 17.4 3.2 14.2 1.9 36.7 18% Groundwater 8 263.0 686.3 60.6 78.4 67.3 892.6 9% Mosquito 86 91 .8 29. 1 3.5 17.0 1 .9 51.5 23% Hummingbi rd 47 48.9 8.1 1 .2 10.9 1 .6 21 .8 73% Basin O u t l e t 1 10 75.2 19.5 2.6 12.5 1.7 36.3 32% 178 During snowmelt 1979, streamflow c o n c e n t r a t i o n d i s c h a r g e r e l a t i o n s h i p s were steep and c u r v i l i n e a r ( F i g u r e 8.1). Peak d a i l y d i s c h a r g e l e v e l s were e x c e p t i o n a l l y high because d i r e c t runoff was e x c e s s i v e . Since i n f i l t r a b i 1 i t y was l i m i t e d , d i r e c t p r e c i p i t a t i o n onto s a t u r a t e d areas dominated r u n o f f . Consequently, stormflow was e x c e s s i v e l y d i l u t e . S a i d another way, water that cannot enter the s o i l w i l l leave the watershed as n e a r l y u n a l t e r e d p r e c i p i t a t i o n . Minimum d a i l y d i s c h a r g e l e v e l s were low because i n d i r e c t runoff was suppressed. Streamflow c o n c e n t r a t i o n s at low dis c h a r g e were n e v e r t h e l e s s high because i n d i r e c t runoff i s co n c e n t r a t e d . I n d i r e c t runoff was supported predominantly by throughflow w i t h i n the g l e y s o l s because throughflow i n b r u n i s o l s and r e g o s o l s was l i m i t e d by ground i c e e f f e c t s on i n f i I t r a b i 1 i t y . T h i s p a t t e r n of r u n o f f sources had a profound e f f e c t on denudation r a t e s . Since c o n c e n t r a t i o n s decrease s i g n i f i c a n t l y with d i s c h a r g e , loads decay at hi g h discharge values and denudation r a t e s peak at in t e r m e d i a t e values (Figure 8.2). However, once snowpack became d i s c o n t i n u o u s , ground i c e melted, s o i l s opened, throughflow i n c r e a s e d , and the hydrochemical system moved toward another s t a t e . In t h i s l a t e r s t a t e , streamflow c o n c e n t r a t i o n s were much l e s s s e n s i t i v e to changes i n d i s c h a r g e ( f i g u r e s 8.1, 8.3) because d i r e c t and i n d i r e c t runoff components were w e l l coupled. I n d i r e c t r u n o f f moderated streamflow c o n c e n t r a t i o n s because s a t u r a t e d throughflow was a s i g n i f i c a n t f r a c t i o n of streamflow 179 ( C U J / t « | O U J U I ) U 0 H » J t U 8 3 U 0 0 F i g u r e 8.1. C o n c e n t r a t i o n - d i s c h a r g e r e l a t i o n s h i p s at Mosquito weir, 1979 and 1980. 180 Q ( l / s ) Figure 8.2. Load-discharge relationships at Mosquito weir, 1979 and 1980. 181 J 1 1 1 i i • • j i i _ 162 164 16C 168 170 172 F i g u r e 8.3. Temporal v a r i a b i l i t y of c a l c i u m , sodium, and d i s c h a r g e components at the b a s i n o u t l e t weir June 1 to J u l y 1, 1980. The top frame shows the t o t a l d i s c h a r g e hydrograph. The shaded area i s the i n d i r e c t component. The cent e r frame shows the r e s i d u a l or d i r e c t component (shaded) set to d i s c h a r g e base zero, along with the i n d i r e c t component. 1 82 at a l l times and throughflow i s more concentrated than o v e r l a n d flow by a f a c t o r of t h r e e . C o n c e n t r a t i o n changes duri n g d a i l y snowmelt events were small and s y s t e m a t i c . Counterclockwise h y s t e r e s i s ( f i g u r e 8.4) was c h a r a c t e r i s t i c , probably because of changes in d i r e c t runoff sources. D i r e c t p r e c i p i t a t i o n onto s a t u r a t e d areas dominates d i r e c t runoff on the hydrograph r i s i n g limb. Return flow from s a t u r a t e d s o i l above the w a t e r - r e p e l l e n t zone dominates d i r e c t r u n o f f on the hydrograph f a l l i n g limb. Streamflow c o n c e n t r a t i o n s were subsequently higher on the f a l l i n g limb than on the r i s i n g limb. Quick d i l u t i o n and c o n c e n t r a t i o n " s p i k e s " were never observed, probably because s a t u r a t i o n o v e r l a n d flow i s generated over l a r g e areas and i s w e l l mixed. S i m i l a r l y , p r e c i p i t a t i o n excess o v e r l a n d flow g e n e r a t i n g areas are small and are p o o r l y connected to the stream channel network. Co n c e n t r a t i o n changes between weekly event sequences were a l s o s m a l l . The c o n s e r v a t i v e and p r o g r e s s i v e r i s e i n streamflow c o n c e n t r a t i o n between weekly events was l i k e l y due to d e p l e t i o n of the s h o r t e s t s a t u r a t e d throughflow paths. As r e c e s s i o n c o n t i n u e s , longer flowpaths, c o n t a i n i n g longer residence-time water, c o n t r i b u t e p r o p o r t i o n a t e l y more to streamflow. The most important consequence of the c o n s e r v a t i v e nature of s o l u t e s i n t h i s system s t a t e i s that load i s d i r e c t l y p r o p o r t i o n a l to discharge ( f i g u r e 8.2). Thus, in the absence of ground i c e , denudation i s a simple f u n c t i o n of t o t a l annual d i s c h a r g e . 183 15 l " 1 2 3 4 Q (l/s) F i g u r e 8.4. R e p r e s e n t a t i v e h y s t e r e s i s at Mosquito weir, 1980. 1 84 Source Areas The s p a t i a l d i s t r i b u t i o n of s o l u t e c o n c e n t r a t i o n s i s complex. While most (70%) s o l u t e v a r i a n c e i n the e n t i r e data set i s e x p l a i n e d by sampling l o c a t i o n ( a n a l y s i s of v a r i a n c e , P<0.01), only one i o n i c source area can be mapped unambiguously. That area i s Mosquito Creek and the g l e y s o l s surrounding Mosquito Creek and the south shore of the pond. As d i s c u s s e d i n chapter 7, s o l u t e samples from t h i s area are unique because they are c o n c e n t r a t e d and are ca l c i u m f a c i e s , due l a r g e l y to groundwater i n p u t s . Hence, i o n i c source areas appear to be as much a r e f l e c t i o n of groundwater d i s c h a r g e zones as they are a r e f l e c t i o n of s o l u t e dynamics i n s u r f i c i a l environments. Denudation Components Table 8.2 l i s t s denudation r a t e s at Goat Meadows and other s i t e s i n the c o a s t a l c o r d i l l e r a . Rates vary by a f a c t o r of 24. If the 1980 data at Goat Meadows can be taken as r e p r e s e n t a t i v e of long term r a t e s , the study s i t e has 1/6 the denudation r a t e of the r e g i o n a l mean. These l a r g e d i s c r e p a n c i e s may occur because groundwater c o n t r i b u t i o n s to r e g i o n a l denudation have not been f u l l y accounted f o r . R e c a l l from Chapter 7 that d i f f e r e n c e s i n denudation r a t e s between Mosquito and Hummingbird basin were a t t r i b u t e d to the presence and absence of groundwater r e t u r n flow zones. Hummingbird watershed i s being denuded at one h a l f the r a t e of Mosquito catchment f o r t h i s reason (Table 8.3). S o i l system 185 Table 8.2. Regional denudation study, T e t i (1979), Zeman and and Reynolds and Johnson (1972) Basin Area (km 2) Goat Meadows 1 979 0.2 1980 0.2 M i l l e r Creek 1 976 22.5 C e n t r a l Creek 1 976 3.1 F i r Creek 1 976 3.5 MacLean Creek 1 976 3.6 Jamison Creek 1 971 3.0 Copper Lake 1 973 5.0 1 974 5.0 Wi 11iamson 1 973 40.0 Creek 1 974 40.0 South Cascade G l a c i e r 1 970 6.4 es t i m a t e s . Data are from t h i s Slaymaker(1978), De t h i e r (1977), Runoff Denudation Rate (m) Si+Ca+Mg+Na+K tonnes/km/yr 0.90 1.6 1.03 3.4 2.4 11.3 1.2 18.7 2.5 7.5 3.0 12.7 3.67 9.8 4.5 13.3 6.2 16.9 3.65 24.4 5.05 38.6 4.1 27.7 Table 8.3. L o c a l denudation estimates (tonnes/km/yr). Watershed 1976 1979 1980 Basin O u t l e t 1.6 3.4 Mosquito 2.7 4.5 Hummingbird 0.8 2.0 Ash Lake 11.0 Middle Lake 10.3 M i l l e r Creek 11.3 C e n t r a l Creek 18.7 F i r Creek 7.5 MacLean Creek 12.7 Goat Meadows with "Groundwater" term added 9.4 11.9 outputs are minor r e l a t i v e to groundwater y i e l d s . Table 8.3 l i s t s data f o r adjacent North Fork, M i l l e r Creek and i t s subcatchments. These r a t e s were produced from d e t a i l e d seasonal s o l u t e data from T e t i (1979). The M i l l e r Creek f i g u r e was c a l c u l a t e d from flow frequency records provided by T e t i . C e n t r a l Creek i s the highest value i n the t a b l e and heads on 186 Goat Meadows Ridge. T e t i (1979) concluded that i t s high s o l u t e load was due to springwater inputs from an assumed shear zone mapped by Woodsworth (1977). T e t i a l s o concluded that the provenance of water from a l l subcatchments was d i s t i n g u i s h a b l e by s t o c h i o m e t r i c r e l a t i o n s h i p s to bedrock. Denudation r a t e s from Ash Lake and Middle Lake (see F i g u r e 7.6) were computed from s i n g l e s u r f a c e water samples c o l l e c t e d 17 September 1980. These catchments l i e downstream from Goat Meadows. Con c e n t r a t i o n s i n grab samples were ad j u s t e d downward by a f a c t o r determined by comparing Goat Meadows streamflow c o n c e n t r a t i o n s on 17 September 1980 to the mean annual streamflow c o n c e n t r a t i o n . These estimated mean annual c o n c e n t r a t i o n f i g u r e s are t h e r e f o r e crude but, when i n s e r t e d i n t o the Goat Meadows water budget, produce denudation f i g u r e s comparable to those f o r M i l l e r Creek. As an a d d i t i o n a l t e s t , the Goat Meadows denudation f i g u r e s were combined with a groundwater term computed as the product of mean groundwater c o n c e n t r a t i o n from T e t i ' s s p r i n g s ( f i g u r e 7.6) and 15% of the Goat Meadows water budget l o s t to the r e g i o n a l groundwater t a b l e . The r e s u l t i n g f i g u r e s are very comparable to denudation r a t e s f o r the l a r g e r watersheds (Table 8.3). It i s concluded that r e g i o n a l denudation measurements from high-order catchments i n the M i l l e r Creek-Goat Meadows area i n c l u d e s u b s t a n t i a l c o n t r i b u t i o n s from groundwater. Chemical denudation r a t e s from s t r i c t l y s o i l water systems i n a l p i n e environments on g r a n i t i c l i t h o l o g i e s i n the Coast Mountains are l i k e l y to be much smal l e r and, i f Goat Meadows i s any 187 i n d i c a t i o n , they are smaller by a f a c t o r 5 to 10. P r e c i s e estimates of s u r f i c i a l denudation are not p o s s i b l e because groundwater c o n t r i b u t e d to a l l watersheds s t u d i e d but approximate p a r t i t i o n i n g of t o t a l s o l u t e export i s p o s s i b l e ( t a b l e 8.4) by combining volumes of r u n o f f , estimated by hydrograph s e p a r a t i o n ( f i g u r e 5.5), with mean s o l u t e c o n c e n t r a t i o n s of runoff components ( t a b l e 8.1). During 1980, roughly 66% of•streamflow at the b a s i n o u t l e t was generated by d i r e c t r u n o f f , or s a t u r a t i o n o v e r l a n d flow. Assuming that the hydrograph s e p a r a t i o n s are of the proper order of magnitude, 772 moles (23 kg) or 28% of export at the basin o u t l e t was c o n t r i b u t e d by s a t u r a t i o n o v e r l a n d flow. S o l u t e s c o n t r i b u t e d by s a t u r a t e d throughflow are more d i f f i c u l t to estimate a c c u r a t e l y because subsurface water samples had a v a r i e t y of sources and the i n d i r e c t hydrograph component a l s o i n c l u d e s groundwater d i s c h a r g e . However, based on the mean c o n c e n t r a t i o n of 185 subsurface samples, s a t u r a t e d throughflow c o n t r i b u t e d 797 moles (23.5 kg) or 29% of export d u r i n g 1980. Combining these f i g u r e s , export r a t e s from s u r f i c i a l m a t e r i a l s were s i m i l a r to denudation r a t e s observed f o r Hummingbird catchment (2 tonnes km"2 y r - 1 ) . The r e s i d u a l export of over 1.4 tonnes km"2 y r " 1 was presumably c o n t r i b u t e d by groundwater and, by mass c o n s e r v a t i o n , had a calcium-sodium molar r a t i o of 5 to 1. These order of magnitude f i g u r e s are crude but they are in agreement with i n t e r p r e t a t i o n s presented throughout t h i s t h e s i s . Furthermore, these f i g u r e s are important fo r what they suggest about the processes of mass removal from s u r f i c i a l m a t e r i a l s . 188 Table 8.4 l i s t s the load of s o l u t e s s t o r e d i n s o i l s , based on data presented p r e v i o u s l y i n t h i s r e p o r t . Water s o l u b l e s a l t s were estimated as the product of the mean water s o l u b l e s a l t e x t r a c t i o n s by h o r i z o n ( t a b l e 7.4) and the mass of <2 mm f r a c t i o n of each s o i l h o r i z o n . The d i s s o l v e d l o a d of s o l u t e s i n s o i l s o l u t i o n s was computed as the product of the mean c o n c e n t r a t i o n of c a p i l l a r y s o i l water samples f o r each s o i l group ( t a b l e 7.5) and the estimated moisture content of each s o i l group at f i e l d c a p a c i t y . Moisture at f i e l d c a p a c i t y was assumed to be 15% of <2 mm s o i l f r a c t i o n , by volume, because most s o i l s are sandy loams. The data in t a b l e 8.4 and 8.5 r e i t e r a t e the f a c t that s o i l moisture i s l i m i t e d because s o i l s are extremely c o a r s e - t e x t u r e d , t h i n and w e l l d r a i n e d . S o i l s o l u t i o n s w i t h i n the range of t e n s i o n s s t u d i e d (0 to 100 kPa) are a l s o d i l u t e . The load of d i s s o l v e d c a t i o n s i n s o i l storage i s consequently small (< 200 moles). When compared to the l o a d removed a n n u a l l y from s o i l s by throughflow (> 800 moles y r " 1 ) , and to the number of d a i l y snowmelt events (>90), the s t o r e of d i s s o l v e d ions i n s o i l s o l u t i o n s must not be turned over e f f i c i e n t l y . In other words, s o i l s o l u t i o n s are not f u l l y shunted. Shunting i s c l e a r l y l i m i t e d by the l a r g e q u a n t i t y of d i r e c t p r e c i p i t a t i o n onto s a t u r a t e d a r e a s . If water cannot enter the s o i l i t w i l l not d i s p l a c e s o i l s o l u t i o n s . Shunting may a l s o be reduced because a l a r g e p r o p o r t i o n of throughflow i s c o n c e n t r a t e d along p r e f e r r e d pathways. S o i l pores w i t h i n a given matrix are n e i t h e r uniform i n 189 Table 8.4. Q u a n t i t i e s of s o l u t e s s t o r e d i n s o i l s as water s o l u b l e s a l t s on exchange complexes and as d i s s o l v e d loads i n s o i l s o l u t i o n s . S o i l group: volume of s o i l (m 3) t o t a l s o i l mass >2 mm s o i l mass moisture at f i e l d capac i ty (tonnes)(tonnes) (m 3) water s o l u b l e s a l t s (moles) s o l u t e load i n s o l u t ion (moles) Regosol 1 2 258 23 045 8 868 707 3 708 108 B r u n i s o l 5 085 8 208 3 381 314 2 776 67 G l e y s o l 817 1 462 569 48 1 270 1 1 Podzol 254 401 1 67 1 6 186 7 T o t a l 18 414 33 1 16 1 2 985 1 085 7 940 193 Table 8.5. Water s o l u b l e s a l t s , d i s s o l v e d load i n s o i l s o l u t i o n s , and 1980 export r a t e s f o r Goat Meadows catchment, 1980. Note that the r e s i d u a l was computed as the d i f f e r e n c e between export l o a d at the b a s i n o u t l e t and the loads c o n t r i b u t e d by overland flow and s a t u r a t e d throughflow. Thus throughflow d i s c h a r g e a l s o i n c l u d e s the r e s i d u a l d i s c h a r g e . I f the r e s i d u a l i s computed using a mixing of loads equation and groundwater c o n c e n t r a t i o n s from t a b l e 8.1, the r e s i d u a l term had a discharge component of 4% of t o t a l streamflow discharge at the basi n o u t l e t . Discharge Load (m 3) (moles) F l u x e s : Input from p r e c i p i t a t i o n 30 216 222 S a t u r a t i o n o v e r l a n d flow 15 386 772 Saturated throughflow 7 925 797 Re s i d u a l (groundwater) - 1 216 Export at O u t l e t 23 311 2 785 Storage: Water s o l u b l e s a l t s on exchange complexes - 7 940 D i s s o l v e d l o a d i n s o i l s o l u t i o n s 1 085 193 190 s i z e , i n shape, nor i n c o n n e c t i v i t y . When s o i l i s unsaturated, small pores are f i l l e d with water and conduct most of the flow because the l a r g e s t pores are f i l l e d mostly with a i r . When s o i l i s s a t u r a t e d , l a r g e pores become f i l l e d with water and c o n t r o l water flow. Thus, flow volumes i n s a t u r a t e d zones can be s e v e r a l o r d e r s of magnitude g r e a t e r than i n unsaturated zones. In both c o n d i t i o n s there e x i s t a number of "dead end" pores which have poor communication with regions of flow. T h i s leads to v a r i a b l e c o n t r i b u t i n g volumes w i t h i n a s i n g l e monolith. DeSmedt and Wierrenga (1979) r e f e r to c o n t r i b u t i n g and n o n - c o n t r i b u t i n g f r a c t i o n s as " a c t i v e " and " i n a c t i v e " zones. The a c t i v e zone i s c h a r a c t e r i z e d by mobile pore water, r e l a t i v e l y short water resid e n c e times and d i s p e r s i v e mixing of s o l u t e s . The i n a c t i v e zone i s c h a r a c t e r i z e d by r e l a t i v e l y immobile pore water, longer residence times and d i f f u s i o n t r a n s p o r t of ions toward the a c t i v e zone along c o n c e n t r a t i o n g r a d i e n t s . S i m i l a r processes may a l s o be o p e r a t i v e at l a r g e r s c a l e s i n p r e f e r r e d pathways. Water residence times i n f i n g e r s , subsurface channels and s a t u r a t e d throughflow lenses are short because s a t u r a t e d s o i l s are h y d r a u l i c a l l y e f f i c i e n t . Once a p r e f e r r e d pathway becomes a c t i v e , shunting w i l l d i m i n i s h because s o l u t e s have been f l u s h e d from the region of flow. A d d i t i o n a l s o l u t e c o n t r i b u t i o n s from nearby unsaturated zones should be l i m i t e d because ions must migrate toward the s a t u r a t e d zone by d i f f u s i o n or unsaturated flow, which are r e l a t i v e l y i n e f f i c i e n t mass t r a n s f e r p r o c e s s e s . 191 I n e f f i c i e n t shunting i s a l s o i m p l i e d by the magnitude of e a s i l y d i s s o l v e d c a t i o n s and s i l i c o n s t o r e d on s o i l exchange s i t e s . Laboratory e x t r a c t s of water s o l u b l e s a l t s provide a s i m p l i s t i c measure of s o i l c o l l o i d s u r f a c e r e a c t i v i t y . C a t i o n s and s i l i c o n so e x t r a c t e d must be p r i m a r i l y exchangeable ions from the s u r f a c e of c o l l o i d s , r a t h e r than from weathering r e a c t i o n s , because these ions are r e l e a s e d almost immediately on c o n t a c t with water and the l o a d r e l e a s e d i s d i r e c t l y p r o p o r t i o n a l to the w a t e r - s o i l r a t i o employed. In the c u r r e n t study 1:1 w a t e r - s o i l r a t i o s , by weight, were used. When t h i s a r t i f i c i a l measure of s o i l r e a c t i v i t y i s e x t r a p o l a t e d to the mass of s o i l at Goat Meadows ( t a b l e 8.4, 8.5), there are roughly 8 000 moles of r e a d i l y s o l u b l e c a t i o n s and s i l i c a a v a i l a b l e to r a p i d l y m i n e r a l i z e i n f i l t r a t i n g p r e c i p i t a t i o n . T h i s i s two orders of magnitude gre a t e r than the observed l o a d i n s o i l s o l u t i o n s , one order of magnitude g r e a t e r than the export r a t e from s o i l s and s e v e r a l times gr e a t e r than the basin export r a t e during 1980 when s o i l s were open to i n f i l t r a t i o n . An apparent d i s c r e p a n c y t h i s l a r g e between p o t e n t i a l and a c t u a l s o i l r e a c t i v i t y may be due to many f a c t o r s . However, given the h e t e r o g e n e i t y of flowpaths i n t h i s system, i t i s tempting to suggest that the d i s c r e p a n c y i s due to l i m i t e d s o i l moisture in which to d i s s o l v e these e a s i l y exchangeable ions and to l i m i t e d s o i l s o l u t i o n shunting to r e p l e n i s h s o i l s with f r e s h , d i l u t e s o l u t i o n . S o i l moisture and shunting may t h e r e f o r e be more important l i m i t i n g f a c t o r s f o r short term denudation r a t e s than s o i l 1 92 r e a c t i v i t y , i n t h i s environment. Weathering r e a c t i o n s occur throughout the year but almost a l l s o l u t e s are r e l e a s e d to streamflow dur i n g only 90 days of snowmelt. The water s o l u b l e exchange c a p a c i t y of these s o i l s appears to be s u f f i c i e n t to " b u f f e r " s o i l s o l u t i o n s d u r i n g p e r i o d s of h y d r o l o g i c a c t i v i t y . However, the c a p a c i t y to m i n e r a l i z e s o i l s o l u t i o n s r a p i d l y can not be e x p l o i t e d e f f i c i e n t l y unless s o i l s o l u t i o n s move unifo r m l y through the s o i l m atrix. Hence, low r a t e s of s u r f i c i a l denudation measured at Goat Meadows do not n e c e s s a r i l y imply environmental l i m i t a t i o n s on chemical e n e r g e t i c s . Summary D i f f e r e n c e s i n denudation r a t e s between years i s adequately e x p l a i n e d by a change i n runoff components induced by ground i c e . During snowmelt 1979, s a t u r a t i o n overlandflow so dominated stormflow that c o n c e n t r a t i o n - d i s c h a r g e r e l a t i o n s h i p s were steep and instantaneous denudation r a t e s peaked at intermediate d i s c h a r g e v a l u e s . Throughout the remainder of the study p e r i o d , throughflow was an important ru n o f f source and streamflow c o n c e n t r a t i o n s were n e a r l y i n s e n s i t i v e to v a r i a t i o n s i n di s c h a r g e . In t h i s s t a t e the system i s s u f f i c i e n t l y d i s t r i b u t e d , responsive and heterogeneous that d i s c r e t e runoff sources become extremely d i f f i c u l t to i d e n t i f y and instantaneous denudation r a t e s vary d i r e c t l y with d i s c h a r g e . T h i s c l e a r change i n s t a t e i l l u s t r a t e s the d i f f i c u l t i e s one faces i n e s t i m a t i n g long term denudation r a t e s from short term r e c o r d s . V a r i a t i o n s i n estimated denudation r a t e s among watersheds 1 93 in the Goat Meadows-Miller Creek area are l a r g e because watersheds d i f f e r i n r e l a t i v e groundwater c o n t r i b u t i o n s . Groundwater i s much more co n c e n t r a t e d than s o i l e f f l u e n t so very small a d d i t i o n s to streamflow can produce l a r g e changes i n geochemical budgets. In f a c t , chemical denudation r a t e s from s u r f i c i a l m a t e r i a l s at Goat Meadows are an order of magnitude lower than suggested by e a r l i e r r e g i o n a l s t u d i e s , p o s s i b l y because groundwater c o n t r i b u t i o n s were not f u l l y accounted f o r in p r evious s t u d i e s . Despite t h i s d i s c r e p a n c y , the data from Goat Meadows do not c o n t r a d i c t p r e v i o u s r e s e a r c h c o n c l u s i o n s that a l p i n e environments are c h e m i c a l l y e n e r g e t i c . Mass removal r a t e s from s u r f i c i a l m a t e r i a l s are low, i n p a r t , because most water bypasses the s o i l as o v e r l a n d flow or moves as s a t u r a t e d throughflow along p r e f e r r e d pathways thereby l i m i t i n g s o i l s o l u t i o n shunting. 1 94 Chapter 9. CONCLUSIONS The purpose of t h i s study was to examine some of the environmental f a c t o r s r e s p o n s i b l e f o r c o n t r o l l i n g chemical denudation at Goat Meadows. The simplest way to ev a l u a t e processes w i t h i n the geochemical cascade at Goat Meadows i s to view the watershed as a s e r i e s of h y d r o l o g i c r e s e r v o i r s . Chemical denudation must be a f u n c t i o n o f : i . the number and type of h y d r o l o g i c r e s e r v o i r s i n the landscape i i . the net chemical r e a c t i v i t y of each h y d r o l o g i c r e s e r v o i r and i i i . the volume and f l u x r a t e of water w i t h i n each h y d r o l o g i c r e s e r v o i r S o l u t e export l o a d i s the product of s o l u t e c o n c e n t r a t i o n and disc h a r g e volume. Sol u t e c o n c e n t r a t i o n i s a f u n c t i o n of the mean residence time of water i n each r e s e r v o i r and the abs o l u t e chemical k i n e t i c s of the r e s e r v o i r . Residence time i s the r a t i o of r e s e r v o i r volume and h y d r o l o g i c f l u x r a t e . In e f f e c t , each r e s e r v o i r can be c h a r a c t e r i z e d by d i f f e r i n g v o l u m e t r i c c a p a c i t y , net chemical r e a c t i v i t y , and h y d r o l o g i c pathways. The pathways r e g u l a t e the t o t a l volume and the f l u x r a t e of water that can rea c t c h e m i c a l l y w i t h i n each r e s e r v o i r . The major h y d r o l o g i c r e s e r v o i r s at Goat Meadows d i f f e r s i g n i f i c a n t l y i n hydrochemical response. During the p e r i o d of t h i s study, most water moved through the s u r f a c e water r e s e r v o i r 195 and at high r a t e s (see t a b l e 9.1). Less water moved through s o i l s and at r e l a t i v e l y slower r a t e s . The l e a s t water moved at the slowest r a t e s through the groundwater r e s e r v o i r . The net geochemical r e s u l t was that most mass was removed from bedrock in the groundwater : r e s e r v o i r and much l e s s mass was removed from s u r f i c i a l m a t e r i a l s by s o i l and s u r f a c e water. If one c o n s i d e r s the chemical and h y d r o l o g i c c h a r a c t e r i s t i c s of each r e s e r v o i r i t can be seen that h y d r o l o g i c pathways are f a r more i n f l u e n t i a l to chemical denudation r a t e s at Goat Meadows than i s the chemical r e a c t i v i t y of s o i l s and bedrock. Table 9.1. Major r e s e r v o i r s i n the biogeochemical cascade at Goat Meadows and some f a c t o r s that r e l a t e to t h e i r r e l a t i v e c o n t r i b u t i o n to chemical denudation. C o n c e n t r a t i o n u n i t s mmoles m~3. are Reservoi r : Mean c a t i o n concentrat ion Discharge Volume: Denudat ion C o n t r i b u t i o n : R e l a t i v e React i v i t y : H y d r o l o g i c Pathways: Bedrock 400-800 4% to 10% 43% low long, l i n e a r j o i n t networks S o i l s 37-79 24% to 30% 27% to 29% high Surface 1 2 66% 28% high, perhaps v a r i a b l e s a t u r a t e d f i n g e r s s a t u r a t i o n channels and lenses overland flow Residence Time i n Pathways: weeks to months C o n t r o l l i n g f a c t o r : very long mean reside n c e t ime hours to days short mean residence time and incomplete shunting of long r e s i d e n c e time water hours very short mean residence time 1 96 Groundwater discharge from bedrock c o n t r i b u t e s the g r e a t e s t l o a d t o streamflow because i t i s conc e n t r a t e d r e l a t i v e to s o i l e f f l u e n t . There i s l i t t l e reason to b e l i e v e that t h i s occurs because the groundwater system i s unusually r e a c t i v e c h e m i c a l l y . J o i n t systems i n quartz d i o r i t e should have l e s s s u r f a c e area than s o i l s and should not c o n t a i n any unique sources of c o r r o s i v e p o t e n t i a l . J o i n t systems do not c o n t a i n f r e s h , f i n e - g r a i n e d v o l c a n i c ash, l o e s s , and humus. Hence, groundwater i s c o n c e n t r a t e d because i t r e s i d e s i n long, l i n e a r flow networks of low p e r m e a b i l i t y f o r extended p e r i o d s of time. Long re s i d e n c e times allow r e a c t i o n s to approach thermodynamic e q u i l i b r i u m with bedrock. The s p a t i a l v a r i a b i l i t y of denudation r a t e s due to groundwater i s consequently c o n t r o l l e d by geometric or h y d r o l o g i c f a c t o r s , more than by chemical k i n e t i c f a c t o r s . S u r f i c i a l denudation r a t e s are low at Goat Meadows, i n p a r t , because the residence time of water i n con t a c t with s o i l s i s l i m i t e d . Goat Meadows d r a i n s a c o n s i d e r a b l e q u a n t i t y of p r e c i p i t a t i o n w i t h i n a short p e r i o d of each year through l a y e r e d and w a t e r - r e p e l l e n t s o i l s . Overland flow and s a t u r a t e d throughflow along p r e f e r r e d subsurface pathways are common. Overland flow i s d i l u t e and c o n t r i b u t e s l e s s than 30% to t o t a l denudation. The l i m i t e d chemical c o n t r i b u t i o n of ove r l a n d flow i s not l i k e l y due to l i m i t a t i o n s on chemical r e a c t i v i t y at the s o i l s u r f a c e . Overland flow i s the most a c i d i c water i n the catchment and the s o i l s u r f a c e should be a h i g h l y r e a c t i v e environment because i t i s both w e l l watered and w e l l a e r a t e d and c o n t a i n s f r e s h p l a n t l i t t e r and f i n e - g r a i n e d l o e s s . T h i s p o i n t 1 97 i s d i f f i c u l t to s u b s t a n t i a t e and needs t e s t i n g because overland flow may be capable of f l u s h i n g the s o i l s u r f a c e of e a s i l y s o l u b l e m a t e r i a l d u r i n g snowmelt. I t i s more l i k e l y , however, that o verland flow i s d i l u t e p r i m a r i a l l y because overland flow runs o f f in a matter of hours, having had l i t t l e p h y s i c a l contact with s u r f i c i a l m a t e r i a l s . The s o i l water system c o n t r i b u t e s a much smaller load to streamflow than expected, probably because concentrated, long residence time s o i l s o l u t i o n s are not f u l l y d i s p l a c e d d u r i n g snowmelt. Most s o i l throughflow bypasses the s o i l matrix as sa t u r a t e d throughflow i n f i n g e r s , subsurface channels and s a t u r a t e d l e n s e s . T h i s g r e a t l y reduces the e f f e c t i v e s o i l - w a t e r c o n t a c t time and contact area and reduces the degree of d i s p e r s i v e mixing between long and short r e s i d e n c e time s o i l waters. There i s l i t t l e reason to b e l i e v e that the chemical output from the s o i l system i s low because s o i l s are c h e m i c a l l y u n r e a c t i v e . While r e g o s o l s and b r u n i s o l s had s i g n i f i c a n t l y lower vadose s o i l s o l u t i o n c o n c e n t r a t i o n s than podzols, the water s o l u b l e exchange c a p a c i t y of a l l s o i l s at Goat Meadows appears to be s u f f i c i e n t to r a p i d l y m i n e r a l i z e s e v e r a l orders of magnitude more s o i l water than at present i f enough s o i l moisture was a v a i l a b l e to d i s s o l v e these s a l t s and i f that moisture was d i s p l a c e d r e g u l a r l y by p r e c i p i t a t i o n . Furthermore, vadose zone s o i l s o l u t i o n c o n c e n t r a t i o n s can be an order of magnitude more conc e n t r a t e d than throughflow. Thus, given s u f f i c i e n t c o n t a c t time, s o i l waters can become q u i t e c oncentrated. 198 A d d i t i o n a l l y , there i s s u p r i s i n g l y l i t t l e s p a t i a l v a r i a b i l i t y i n s o l u t e c o n c e n t r a t i o n s among a l p i n e s o i l - v e g e t a t i o n complexes, at the s c a l e of t h i s study. G l e y s o l s form the only unambiguous i o n i c source area at Goat Meadows. E f f l u e n t from g l e y s o l s appears to be c h e m i c a l l y more con c e n t r a t e d than e f f l u e n t from b r u n i s o l s and r e g o s o l s p r i m a r i l y because g l e y s o l s are l o c a t e d i n groundwater discharge s i t e s , although t h i s p o i n t r e q u i r e s t e s t i n g i n c o n t r o l l e d circumstances because g l e y s o l s form a s a t u r a t e d , moderate residence time system and may c o n t r i b u t e more load per u n i t volume than other s o i l s . Among rego s o l s and b r u n i s o l s , the small s o l u t e v a r i a b i l i t y d e t e c t e d under comparable h y d r o l o g i c c o n d i t i o n s (eg. vadose zone c o n c e n t r a t i o n s ) seems to be r e l a t e d simply to l i t h o l o g i c a l v a r i a t i o n s (eg. the d i s t r i b u t i o n of v o l c a n i c a s h ) . Whatever the cause, t h i s a l p i n e s o i l landscape appears to be c h e m i c a l l y homogeneous at the s c a l e of t h i s study. Consequently the s p a t i a l d i s t r i b u t i o n of a l p i n e s o i l s should a f f e c t denudation r a t e s p r i m a r i l y i n the way that s o i l groups a f f e c t flowpaths, runoff components and shunting, which are a l l h y d r o l o g i c f a c t o r s . In summary, most of the observed temporal and s p a t i a l v a r i a b i l i t y i n denudation r a t e s can be a t t r i b u t e d d i r e c t l y to v a r i a t i o n s i n runoff g e n e r a t i o n mechanisms or runoff sources. During the two years of study, denudation r a t e s v a r i e d by a f a c t o r of more than two d e s p i t e s i m i l a r annual r u n o f f . T h i s s h o r t term temporal v a r i a b i l i t y was caused by changes i n h y d r o l o g i c p a r t i t i o n i n g amoung s u r f a c e water, s o i l water and 199 groundwater. The lower denudation r a t e s of 1979 were caused by segregated ground i c e which l i m i t e d s o i l i n f i l t r a b i 1 i t y , subsurface throughflow and groundwater flow. The higher denudation r a t e s of 1980 o c c u r r e d because more subsurface flowpaths were a v a i l a b l e i n s u r f i c i a l m a t e r i a l s a l l o w i n g more s o i l - w a t e r c o n t a c t , s o i l s o l u t i o n shunting and groundwater flow. V a r i a t i o n s i n denudation r a t e s between subcatchments were a l s o l a r g e i n both study y e a r s . This short-term s p a t i a l v a r i a b i l i t y was r e l a t e d to topography, which induced v a r i a b l e groundwater c o n t r i b u t i o n s to streamflow. Mosquito catchment was denuded at more than twice the r a t e of Hummingbird catchment because Mosquito catchment had steep, stepped topography which induced more groundwater flow to r e t u r n to p h r e a t i c s o i l water zones. S i m i l a r l y , Goat Meadows watershed was denuded at approximately one t h i r d the r a t e of l a r g e r adjacent catchments because Goat Meadows i s a r i d g e - t o p watershed where most groundwater does not r e t u r n to the s u r f a c e w i t h i n the catchment (eg. recharge, rather than d i s c h a r g e , predominates). H y d r o l o g i c pathways are t h e r e f o r e more important than the inherent chemical r e a c t i v i t y of s o i l s and bedrock i n c o n t r o l l i n g chemical denudation at Goat Meadows. Runoff g e n e r a t i n g mechanisms c o n t r o l denudation r a t e s i n at l e a s t two ways. The f i r s t i s by p a r t i t i o n i n g water between s u r f a c e , s o i l and groundwater r e s e r v o i r s . The second i s by c o n t r o l l i n g flowpaths, c o n t a c t - t i m e s and shunting of water w i t h i n s u r f a c e , s o i l and bedrock r e s e r v o i r s . 200 D i s c u s s i o n The p r o j e c t documented in t h i s r e p ort was based on a conceptual model, i m p l i c i t i n the l i t e r a t u r e on denudation, which assumed that s o i l s are the source of most s o l u t e s i n streamflow because s o i l s are c o n s p i c u o u s l y a c t i v e weathering zones and because s o i l s are normally the source of most r u n o f f . S o l u t e s i n s o i l s o l u t i o n s are u l t i m a t e l y generated by aqueous d i s s o l u t i o n of primary minerals (weathering r e a c t i o n s ) . Short term s o i l s o l u t i o n m i n e r a l i z a t i o n r a t e s were consequently assumed to be c o n t r o l l e d by the k i n e t i c s of primary mineral d i s s o l u t i o n , and not by the k i n e t i c s of exchange r e a c t i o n s i n s o i l s . I t f o l l o w s that a c t u a l r e a c t i o n r a t e s i n d i f f e r e n t s o i l groups are most s t r o n g l y i n f l u e n c e d by the supply of d i s s o l v e d a c i d s from the biosphere and atmosphere and by mobile anions i n s o i l s o l u t i o n s because these substances are important i n sup p o r t i n g d i s s o l u t i o n r e a c t i o n s . The i n i t i a l working model was a l s o based on the assumption that s o i l water movement i s r e l a t i v e l y uniform. Hence streamflow i s generated from a r e a l l y s m a l l , t o p o g r a p h i c a l l y c o n t r o l l e d , s a t u r a t e d s o i l water zones adjacent to stream channels. Unsaturated s o i l s which surround s a t u r a t e d s o i l water zones were assumed to be open to i n f i l t r a t i o n of p r e c i p i t a t i o n . V e r t i c a l p e r c o l a t i o n was assumed to be more or l e s s uniform. Free p e r c o l a t i o n should e f f i c i e n t l y d i s p l a c e c o n c e n t r a t e d s o i l s o l u t i o n s to streamflow, r e p l e n i s h s o i l s with f r e s h , d i l u t e s o l u t i o n s , and r e g u l a t e e f f e c t i v e chemical r e a c t i o n r a t e s by c o n t r o l l i n g c ontact times and c o n c e n t r a t i o n g r a d i e n t s between 201 mineral l a t t i c e s and water. The i m p l i c a t i o n s of t h i s model f o r i o n i c v a r i a b i l i t y i n streamflow are that low flow stream s o l u t i o n s are r e p r e s e n t a t i v e of s o i l s o l u t i o n s and that the co n n e c t i o n between i n i t i a l m i n e ral d i s s o l u t i o n and the appearance of the s o l u b l e weathering products i n the stream i s r a p i d and d i r e c t . A n a l y s i s of two annual geochemical budgets from Goat Meadows i n d i c a t e d that the expected set of c o n t r o l s d i d not dominate t h i s s o l u t e system. In other words, the i n i t i a l model was i n a p p r o p r i a t e f o r t h i s environment. Furthermore, key elememts of t h i s system were not observed i n d e t a i l , namely groundwater flow i n bedrock, s o i l water flow in subsurface channels, m i c r o - s c a l e s o i l water flow and s o l u t e exchange r e a c t i o n s w i t h i n i n d i v i d u a l s o i l h o r i z o n s . As a r e s u l t , an i n f e r e n t i a l approach was necessary to i n t e r p r e t the data s e t . Three, r e l a t i v e l y unambiguous, c o n c l u s i o n s r e s u l t : i . i n t h i s r e g i o n , s o i l water movement i s heterogeneous, i i . in t h i s r e g i o n , groundwater flow through bedrock i s the source of most s o l u t e s i n streamflow and i i i . i n t h i s r e g i o n , h y d r o l o g i c pathways are more important than the inherent chemical r e a c t i v i t y of s o i l s and bedrock i n r e g u l a t i n g chemical denudation r a t e s . The g e n e r a l i t y of these c o n c l u s i o n s i s not known. The study environment i s i n many r e s p e c t s unique and there are few 202 comparable s m a l l - s c a l e watershed s t u d i e s i n the l i t e r a t u r e . The i m p l i c a t i o n s of these c o n c l u s i o n s are s i g n i f i c a n t nonetheless. They imply that where groundwater c o n t r i b u t i o n s are not d e f i n e d , watershed experiments can produce h i g h l y b i a s e d r e s u l t s of s u r f i c i a l denudation r a t e s which confound i n t e r p r e t a t i o n s of environmental process-response. They a l s o imply that streamflow generation mechanisms and the s p a t i a l d i s t r i b u t i o n of streamflow source areas are fundamental, i f not dominant, c o n t r o l s on chemical processes of landscape e v o l u t i o n . T h i s i s the f i r s t study known to the author that e x p l i c i t l y documents and d e s c r i b e s how some of these process may operate p h y s i c a l l y to i n f l u e n c e denudation r a t e s . 203 REFERENCES American P u b l i c H e a l t h A s s o c i a t i o n , 1981, Standard Methods for the examination of water and wastewater: 15th. ed., Washington, D.C., 1134 p. 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PETROGRAPHIC DESCRIPTION OF LITHOLOGIES D e s c r i p t i o n s i n t h i s appendix were i n t e r p r e t e d by Mr. Robert R a i n b i r d ( C a r l e t o n U n i v e r s i t y ) who has experience with s i m i l a r rocks in northern O n t a r i o . GAMBIER GROUP: Sample #302: Q u a r t z - A c t i n o l i t e - C h l o r i t e S c h i s t . Mineralogy: quartz 60% a c t i n o l i t e 21% c h l o r i t e 13% e p i d o t e 3% d i o p s i t e 1% sphene 1% b i o t i t e 1% D e s c r i p t i o n : T h i s sample i s very f i n e g r a i n e d and the quartz i s m i c r o c r y s t a l l i n e . Well developed s e g r e g a t i o n l a y e r i n g occurs between quartzose and micaceos bands, which e x i b i t w e l l d e f i n e d c r e n u l a t i o n and at l e a s t two phases of deformation. C h l o r i t e i s f i n e r g r a i n e d than a c t i n o l i t e but otherwise the two m i n e r a l o g i e s appear very s i m i l a r . C h l o r i t e i s a a l t e r a t i o n product of the amphiboles. Sample #300: S i l i c i c T u f f . Mineralogy: quartz s e r i c i t e e p i d ote hornblend p y r i t e 90% 5% 2% 2% 1% D e s c r i p t i o n : T h i s sample i s composed of t h i n l y laminated quartz and s e r i c i t e - r i c h i n t e r b e d s which are h i g h l y f r a c t u r e d and sheared at 60° to the a x i s of f o l i a t i o n . Metamorphism has obscured the o r i g i n a l rock t e x t u r e so c l a s s i f i c a t i o n as a t u f f i s s p e c u l a t i v e . Quartz g r a i n s are h i g h l y s t r a i n e d , m i c r o c r y s t a l i n e and elongate with s e r i a t e boundaries. S e r i c i t e occurs as d i s c r e e t l a y e r s of f i n e , n e e d l e - l i k e g r a i n s i n t e r s t i t i a l to the q u a r t z . Epidote v e i n l e t s (0.2-0.5 mm) cut the a x i s of f o l i a t i o n but the other a c c e s s o r y minerals are f i n e l y disseminated throughout the s e c t i o n . 218 COAST PLUTONIC COMPLEX: Sample #31: Quartz D i o r i t e . Mineralogy: quartz p l a g i o c l a s e K - f e l d s p a r hornblende e p i d o t e s e r i c i t e c h l o r i t e muscovite c l i n o p y r o x e n e opaques 30% 20% 1 5% 1 5% 1 0% 3% 2% 5% D e s c r i p t i o n : G e n e r a l l y t h i s sample has a medium g r a i n e d , g r a n i t i c t e x t u r e but the o r i e n t a t i o n of hornblende c r y s t a l s i n d i c a t e d e f i n i t e f o l i a t i o n and approaches a g n e i s s i c t e x t u r e i n p l a c e s . Quartz c r y s t a l s are f i n e to medium g r a i n e d (0.5-5.0 mm), s t r o n g l y r e c r y s t a l i z e d with s e r i a t e boundaries, and moderately s t r a i n e d e x h i b i t i n g cloudy to undulose e x t i n c t i o n which i s predominantly u n i - d i r e c t i o n a l . P l a g i o c l a s e g r a i n s are coarse and granular (0.2-1.0 mm) with i n d e f i n i t e boundaries. These are normally zoned with an approximate o v e r a l l composition of An40 (andesine). S e r i c i t e and minor epidote-hornblend a l t e r a t i o n i s apparent. Hornblende g r a i n s are f i n e to medium t e x t u r e d , elongate, lathe-shaped c r y s t a l s which form f i b r o u s masses i n t e r s t i t i a l to quartz and f e l d s p a r . Most c r y s t a l s are r e c r y s t a l l i z e d primary g r a i n s but some are secondary a l t e r a t i o n products of p l a g i o c l a s e . E pidote i s g e n e r a l l y f i n e g r a i n e d , a l t e r s p l a g i o c l a s e , K - f e l d s p a r and hornblend or i s developed along f r a c t u r e s forming m i c r o - v e i n l e t s . Sample #301: V e s i c u l a r B a s a l t . Mineralogy: D e s c r i p t i o n : T h i s sample c o n s i s t s of 1 mm to 2 mm g r a i n s of p l a g i o c l a s e i n a very f i n e - g r a i n e d aggregate of hornblend, q u a r t z , and p l a g i o c l a s e . Hornblende and p l a g i o c l a s e g r a i n s are bladed and i n t e r l o c k i n g with quartz which i s i n t e r s t i t i a l . Thin f r a c t u r e s have provided channelways f o r p o i k i l i t i c p y r i t e , coarse epidote and f i n e s e r i c i t e a l t e r a t i o n . Otherwise the rock appears to be u n a l t e r e d and postdates the event which caused f o l i a t i o n i n the other u n i t s . hornblende p l a g i o c l a s e 35% 20% 15% 15% 1 0% 5% quartz p y r i t e e p i dote s e r i c i t e 219 Sample #19: Feldspar Porphry. Mineralogy: p l a g i o c l a s e K - f e l d s p a r quartz epidote c l i n o p y r o x e n e hornblende s e r i c i t e b i o t i t e 30% 30% 1 0% 1 0% 10% 3% 2% 5% D e s c r i p t i o n : T h i s sample has a p o r p h y r i t i c t e x t u r e with phenocrysts of f e l d s p a r s i n a matrix of f i n e g r a i n e d q u a r t z , f e l d s p a r , hornblende and epi d o t e . The rock has been only weakly a l t e r e d ; epidote r e p l a c e s p l a g i o c l a s e , s e r i c i t e r e p l a c e s K - f e l d s p a r , and b i o t i t e surrounds and i n t r u d e s the l a r g e s t hornblende g r a i n s . C l i n o p y r o x i n e may a l s o be r e p l a c i n g hornblende. F o l i a t i o n i s absent but some f i n e f r a c t u r e s are i n f i l l e d by e p i d o t e . T h i s rock may be a l a t e stage, hypabyssal e q u i v a l e n t of the quartz d i o r i t e . D e s c r i p t i o n : T h i s sample has a medium to c o a r s e - g r a i n e d g r a n i t i c t e x t u r e with i n t e r l o c k i n g ( r e c r y s t a l i z e d ) quartz g r a i n s that are s e v e r e l y f r a c t u r e d from expansion of the micas. The micas have expaned i n the course of subar e a l chemical weathering ( c f . B u s t i n and Mathews, 1978). Some p l a g i o c l a s e g r a i n s are a l s o f r a c t u r e d . The micas are w e l l o r i e n t e d i n one d i r e c t i o n d e f i n i n g f o l i a t i o n . P l a g i o c l a s e and K - f e l d s p a r g r a i n s are v a r i a b l y a l t e r e d to s e r i c i t e . B i o t i t e i s v a r i a b l y a l t e r e d to muscovite and minor hornblend. ACCESSORY LITHOLOGY IN THE PLEISTOCENE TILL: Sample #303: B i o t i t e G r a n i t e . Mineralogy: p l a g i o c l a s e quartz K - f e l d s p a r b i o t i t e muscovite hornblend s e r i c i t e 40% 30% 1 5% 8% 3% 2% 2% 220 Appendix B. MAJOR VEGETATION ASSOCIATIONS, GOAT MEADOWS WATERSHED A l l taxonomic i d e n t i f i c a t i o n s i n t h i s appendix were made by Ms. Sarah Chaney ( U n i v e r s i t y of C a l i f o r n i a , B e r k e l e y ) . A complete s p e c i e s c o l l e c t i o n i s on f i l e at the Herbarium, U n i v e r s i t y of B r i t i s h Columbia. Please see t a b l e 2.2 f o r the r e l a t i o n s h i p of these v e g e t a t i o n a s s o c i a t i o n s to s o i l groups. References c i t e d i n t h i s appendix p o i n t to formal d e s c r i p t i o n s of s i m i l a r p l a n t communities by e c o l o g i s t s . TOLMIE SAXIFRAGE: C h a r a c t e r i s t i c : S a x i f r a g e t o l m i e i  M a r s u p e l l a b r e v i s s i m a  Luzula p i p e r i  Juncus drummondii I n c i d e n t a l : Carex p y r e n a i c a P o l y t r i c h u m sexangulare T h i s a s s o c i a t i o n i s found on a c t i v e d e b r i s lobes and t a l u s . Cover r a r e l y exceeds f i v e percent of the s u r f a c e . Juncus and Luzula are u s u a l l y f o l l o w e d by Cassiope. See Brooke, 1965. CASSIOPE, MOSS: C h a r a c t e r i s t i c : Cassiope mertensiana  P o l y t r i c h u m sexangulaie I n c i d e n t a l : Juncus drummondii  Luzula p i p e r i i  Carex n i g r i c a n s  Rhancomitrium sudeticum  Stereocaulon sp. Phyllodoce sp. Cassiope and Poly t r i h u m form moss and cobble meadows on s t a b i l i z e d d e b r i s l o b e s . V o l c a n i c ash s t r a t i g r a p h y suggests that the lobes are pre-Hypsithermal. 221 HEATH WITH DWARF TREES: C h a r a c t e r i s t i c : O v erstory: Cassiope mertensiana  Phyllodoce empetriformis, intermedia, g l a n u l i f o r a  Abies l a s i o c a r p a  Pinus a l b i c a u l i s  Luetkea p e c t i n a t a Understory: Lycopodium s i t c h e n s e  G a u l t h e r i a humifusa  Clado n i a sp. Inc i d e n t a l : A r n i c a r y d b e r g i i  E r i g e r o n p e r e g r i n u s  Hieracium g r a c i l e  Deschampsia atropurpurea  P e d i c u l a r i s arnithorhyncha Cassiope i s predominant. Phyllodoce i s common on d r i e s t s i t e s . T h i s a s s o c i a t i o n i n t e r g r a d e s with LML i n topographic d e p r e s s i o n s . See Brink, 1965, Brook, 1965, Kuramoto and B l i s s , 1970, and Douglas and B l i s s , 1977. LUETKEA, MOSS, LICHEN: C h a r a c t e r i s t i c : Luetkea p e e t i n a t a  Rhasomitrium sudeticum  Sterocaulon sp. S o l o r i n a crocea Inc i d e n t a l : Juncus p a r r y i , drummondi i  Carex s p e c t a b i l i s , n i g r i c a n s  Lycopodium s i t c h e n s e  H i e i a c i u m g r a c i l e  Cassiope mertensiana  Cladonia sp. Luzula p i p e r i T h i s a s s o c i a t i o n i s common i n areas of s u r f a c e d e t e n t i o n storage and i s normally adjacent t o Heath and Heath-Sedge-Forb a s s o c i a t i o n s . Cassiope i s d e c r e a s i n g l y important i n s a t u r a t e d s i t e s . 222 DWARF SEDGE: Carex n i g r i c a n s  Juncus drummondi i  Deschampsia atropurpurea  Carex s p e c t a b i l i s  P o l y t r i c h u m sexanqulaie T h i s a s s o c i a t i o n i s i n d i c a t i v e of s u r f a c e d e t e n t i o n storage and the most a c t i v e s a t u r a t i o n o v e r l a n d flow zones. Carex rhizomes form dense, t u r f y root mats. See Brink, 1965, Kuramoto and B l i s s , 1970, and Douglas and * b l i s s , 1977. HEATH, SEDGE, FORB: C h a r a c t e r i s t i c : P hyllodoce empetriformis  Cassiope mertensiana  Luetkea p e c t i n a t a  Juncus p a r r y i  Pinus a l b i c a u l i s  Abies l a s i o c a r p a  Lupinus l a t i f o l i u s  Anemone o c c i d e n t a l i s  Deschampsia atropurpurea  Carex s p e c t a b i 1 i s Inc i d e n t a l : Carex p y r e n a i c a  S a x i f r a g a f e r r u g i n e a  E r i q e r o n p e r e g r i n u s  A r n i c a rydberqi i P e d i c u l a r i s racemosa  Cl a d o n i a sp. Hreracium q r a c i l e  Rhizocarpum qeoqraphica  Antennaria a l p i n a  P o t e n t i l l a f l a b e l l i f o l i a Pinus i s mature, with f u l l - g r o w n to dwarf i n d i v i d u a l s . 223 TREE ISLANDS: C h a r a c t e r i s t i c : Abies l a s i c a r p a  Tsuqa mertensiana  Pinus a l b i c a u l i s  Vaccinium membranaccum  Rhododendron a l b i f o r u m  Phyllodoce sp. Cassiope mertensiana  Leutkea p e c t i n a t a Inc i d e n t a l : R i b i e s l a z i f l o r u m  L e t h a r i a columbiana  C l a d o n i a sp. T h i s a s s o c i a t i o n i s found only on the h i g h e s t , w e l l d r a i n e d s i t e s with l i g h t winter snowpacks. See Brink, 1965, Brooke, 1 965. SEDGE, FORB, MOSS: C h a r a c t e r i s t i c : Carex n i g r i c a n s , s p e c t a b i l i s  Juncus drummondi i , mertensianus  Epil o b i u m alpinum, l a t i f o l i u m  P h i l o n t i s fontana  deschampsia atropurpurea Inc i d e n t a l : Leptarrhena p y r o l i f o l i a  S a x i f r a q a f e r r u q i n e a  V a l e r i a n a s i t c h e n s i s  Veratrum v i r i d e E p ilobium d i s t i n g u i s h e s t h i s a s s o c i a t i o n from Sedge. These s i t e s appear to be c r y o t u r b a t e d , and are i n v a r i a b l y g l e y s o l i c . SEDGE, SPHAGNUM: Carex n i g r i c a n s , s p e c t a b i l i s Sphagnum other mosses T h i s a s s o c i a t i o n i s l i m i t e d to overhanging banks of ponds and seeps where water i s always abundant. 224 Appendix C. SELECTED SOIL PROFILE DESCRIPTIONS #S79-3 : TREE ISLAND 15 m WNW of Base S t a t i o n 2 Pedon : O r t h i c Humo-Ferric Podzol. T h i s p r o f i l e appears to meet morp h o l o g i c a l c r i t e r i a f o r Ferro-Humic Podzol except f o r the t h i c k n e s s of the Bhf h o r i z o n . S i t e : Crest of small h i l l 5 m a l t i t u d e above the l a k e . Surface i s g e n t l y u n d u l a t i n g , s l o p i n g a t 5° to the southwest. Drainage i s r a p i d to w e l l d r a i n e d . The s i t e i s exceedingly stoney and very rocky. Boulders and stones from the t i l l c o n s t i t u t e 30% of a l l p r o f i l e s . V e g e t a t i o n : 150 m2 t r e e i s l a n d surrounded by heath and dwarf t r e e a s s o c i a t i o n . Overstory c o n s i s t s of Abies l a s i o c a r p a ( f u l l form, 8 m height, 500 stems/hectar, 250 mm DBH") and a few Tsuga  mertensiana (stunted form, 4 m h e i g h t , 120 mm DBH). F i r stems are regenerated growth from two parent t r u n k s . Hemlock stems are sexual i n d i v i d u a l s . Understory c o n s i s t s of Phyllodoce sp., Cassiope mertensiana, Luetkea p e e t i n a t a , Vaccinium membranaceum and o c c a s i o n a l Rhododendron a l b i f l o r u m . Parent M a t e r i a l s : Compacted t i l l o v e r l i e s bedrock of quartz d i o r i t e . The t i l l i s capped by l o c a l l o e s s , organic h o r i z o n s and at l e a s t one v o l c a n i c ash. Horizon Depth(cm) D e s c r i p t i o n LFH 3.0-0.0 Dark r e d d i s h brown (5YR2.5/2m) compressed organic mat composed of f i r needles i n a matrix of u n i d e n t i f i a b l e organic m a t e r i a l ; abrupt, wavy boundary; 1 to 5 cm t h i c k . Ae 0.0 5.0 Brown(7.5YR5/2m), P i n k i s h gray(7.5YR7/2d) loam; l o o s e , f r i a b l e , s l i g h t l y s t i c k y , not p l a s t i c ; s t r u c t u r e l e s s ; abrupt, i r r e g u l a r boundary; 1 to 6 cm t h i c k . V o l c a n i c g l a s s <10% i n very f i n e sand and coarse s i l t f r a c t i o n . II Bhf or OmM?) 5.0-11.0 Dark r e d d i s h brown(5YR3/2m) loam; s o f t , f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s ; abrupt i r r e g u l a r boundary; 3-7 cm t h i c k . III Bf 11-27 Y e l l o w i s h red(5YR5/6m) g r a v e l l y , sandy loam with many coarse (20 to 30 mm) d i s t i n c t dark r e d d i s h brown(5YR3/2m) and dark r e d d i s h brown(2.5YR2.5/4) mottles o c c u r i n g mostly along t r e e r o o t s and cobbles i n the matrix; s l i g h t l y s t i c k e y , s l i g h t l y p l a s t i c ; weak, subangular, coarse blocky s t r u c t u r e ; smooth, 225 c l e a r boundary; 14 -17 cm t h i c k . L i g h t o l i v e gray(5Y6/2m) g r a v e l l y loamy sand with many (20% i n matrix, 50% to c o n t i n i o u s c o a t i n g s 2 mm t h i c k on the bottom of g r a v e l ) medium, d i s t i n c t , dark r e d d i s h brown (2.5YR3/4m) mo t t l e s ; stones >30% of h o r i z o n ; compacted; l i g h t l y hard, f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; few coarse r o o t s ; s t r u c t u r e l e s s ; i r r e g u l a r , abrupt boundary; 10-12 cm t h i c k . Quartz d i o r i t e 226 #S79-5 LML (HEATH-SEDGE) groove near 0E1 Pedon: O r t h i c D y s t r i c B r u n i s o l S i t e : S l i g h t l y s l o p i n g (2°-3°), u n d u l a t i n g foot slope l o c a t e d i n a g l a c i a l l y eroded bedrock trough that i s mantled t h i n l y by compacted t i l l . Minor P o s t - g l a c i a l i n f i l l i n g has o c c u r r e d i n p l a c e s due to slope f a i l u r e s on the s i d e s of the trough. T h i s i n f i l l i n g i s s i g n i f i c a n t i n that i t has reduced p o t e n t i a l drainage i n t h i s low angle s i t e . T h i s i s a major s u r f a c e d e t e n t i o n storage s i t e f o r s e v e r a l weeks d u r i n g peak s p r i n g snowmelt when temporary ponds downstream become f u l l and backup. I n f i l t r a t i o n i s l i m i t e d because the epipedon i s s t r o n g l y w a t e r - r e p e l l a n t . V e g e t a t i o n : 100% cover of Luetkea, Moss and Lichen a s s o c i a t i o n . O c c a s i o n a l heather and sedge i n c l u s t e r s . Parent M a t e r i a l s : At l e a s t one v o l c a n i c ash o v e r l i e s an o r g a n i c - r i c h h o r i z o n which i s presumed to be a b u r i e d , former heath or sedge v e g e t a t i o n and l o e s s . The v o l c a n i c ash i s l i k e l y two e r u p t i v e events from the Bridge River vent (Sneddon, 1970). The Mazama ash i s l i k e l y missing from t h i s c o n t r o l s e c t i o n because Mazama ash appears to have been d e p o s i t e d on a t h i c k snowpack which made subsequent d e p o s i t i o n on the s o i l s u r f a c e h i g h l y v a r i a b l e . These p o s t - G l a c i a l d e p o s i t s o v e r l i e compacted P l e i s t o c e n e t i l l . H orizon Depth(cm) D e s c r i p t i o n LFH 0.7-0.0 Moss and l i c h e n mat o v e r l i e decomposing heath needles and u n i d e n t i f i e d organic m a t e r i a l ; t h i c k ; abrupt, smooth boundary; 0.2 -1.0 cm t h i c k . I Ah 0.0-3.0 Very dark g r a y i s h brown(10YR3/2m), dark g r a y i s h brown(10YR4/2d) f i n e sandy loam; s o f t , f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s to very weak p l a t y s t r u c t u r e ; t u r f y with abundant very f i n e and f i n e r o o t s , few medium and coarse heather r o o t s ; abrupt, i r r e g u l a r boundary; 1-3 cm t h i c k . I Bm 3.0-3.5 Dark g r a y i s h brown(10YR4/2m), y e l l o w i s h brown(10YR5/4d) very f i n e sandy loam; l o o s e , very f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s ; abundant very f i n e and f i n e r o o t s , few medium r o o t s ; very few coarse r o o t s ; abrupt broken boundary; 0-0.5 cm t h i c k . I Bmb1 3.5-6.0 Dark y e l l o w i s h brown(10YR4/6m), pa l e brown(10YR6/3d) to l i g h t y e l l o w i s h brown(10YR6/4d) very f i n e sandy loam; l o o s e , very f r i a b l e , s l i g h t l y s t i c k e y , s l i g h t l y 227 II Omb 6.0-10.0 III Bmb2 10.0-18.0 III BC 20.0-60.0 p l a s t i c ; s t r u c t u r e l e s s ; abundant f i n e and very f i n e r o o t s ; few medium : r o o t s ; very abrupt, i r r e g u l a r boundary; 1-3 cm t h i c k . Dark brown(10YR3/2m), brown(10YR4/3d) f i n e sandy loam; s o f t , f r i a b l e ; s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s ; abundant f i n e and medium r o o t s ; abrupt, wavy boundary, 4-5 cm t h i c k . Dark y e l l o w i s h brown(10YR3/6m), y e l l o w i s h brown(10YR5/4d) g r a v e l l y loamy sand; 30% to 50% stones and g r a v e l ; s o f t , f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s ; r a r e f i n e and medium r o o t s ; c l e a r i r r e g u l a r boundary; 5-8 cm t h i c k . Pale olive(5Y6/3m) g r a v e l l y loamy sand with many f i n e , prominant' Red ( 2 . 5YR'4/8m) mottles on g r a i n s ; 30% to 50% stones; very compact; s l i g h t l y hard, f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s ; no r o o t s ; abrupt i r r e g u l a r boundary; 35-40 cm t h i c k . IV R Gambier Group s c h i s t . 228 S79-7 HEATH: Heather and f o r b h i l l s l o p e . Pedon : O r t h i c D y s t r i c B r u n i s o l S i t e : S t r o n g l y sloping(20°) southeast f a c i n g h i l l s l o p e 15m long. Slope i s w e l l d r a i n e d but r e c e i v e s o v e r l a n d flow from a s u r f a c e d e t e n t i o n storage s i t e to the north d u r i n g prolonged storms and snowmelt. The s i t e becomes snow-free r e l a t i v e l y e a r l y each s p r i n g . Surface cover i s patchy and the s i t e s u f f e r s numerous needle i c e events each f a l l . Where a v e g e t a t i v e mat e x i s t s , c h a r c o a l can be found j u s t below the mat. V e g e t a t i o n : 20% to 60% cover of Heather, Sedge, Forb a s s o c i a t i o n . C o n s i d e r a b l e s u r f a c e d i s t u r b a n c e l i m i t s v e g e t a t i o n here. Parent m a t e r i a l s : At l e a s t one v o l c a n i c ash o v e r l i e s c o l l u v i u m and compacted basal t i l l . Epipedons are e n r i c h e d with l o e s s winnowed from a c t i v e s i t e s to the west. Horizon Depth(cm) D e s c r i p t i o n Ahj 0.0-0.5 Very dark g r a y i s h brown(10YR3/2m), gray(10YR5/1d) f i n e sandy loam; lo o s e , very f r i a b l e , not s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s to weak p l a t e y s t r u c t u r e ; p l e n t i f u l to abundant very f i n e and f i n e r o o t s , few medium r o o t s ; smooth, abrupt but d i s c o n t i n u o u s boundary; 3-5 cm t h i c k . Bm 5.0-6.0 Dark gray(10YR3/1m), gray(10YR5/1d) sandy loam; lo o s e , very f r i a b l e , not s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s ; p l e n t i f u l very f i n e and f i n e r o o t s ; abrupt, smooth but d i s c o n t i n u o u s boundary; 0-1 cm t h i c k . II Bmb 6.0-40.0 Dark y e l l o w i s h brown(10YR4/4m) g r a v e l l y loamy sand; stones are 20%to 30% of h o r i z o n ; s o f t f r i a b l e , not s t i c k y , not p l a s t i c ; s t r u c t u r e l e s s ; p l e n t i f u l very f i n e , f i n e and medium r o o t s ; c l e a r , smooth boundary; 25-34 cm t h i c k . Rooting zone ends at 40 cm. III BC 40.0-48.0 Pale yellow(5Y7/3m) g r a v e l l y loamy sand with many f i n e , y e l l o w i s h brown(10YR5/8m) mott l e s ; s l i g h t l y hard, f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s ; no r o o t s ; i r r e g u l a r , abrupt boundary; 4 to 10 cm t h i c k . IV R Gambier Group s c h i s t . 229 S79-8: SEDGE: Whaleback s u r f a c e d e t e n t i o n storage s i t e . Pedon : O r t h i c Sombric B r u n i s o l S i t e : T h i s p i t i s l o c a t e d i n a shallow trough 2 m wide, 8 m long, and 1.5 m deep cut i n bedrock between a g l a c i a l l y abraded rock knob to the southwest and a b r u n i s o l i c - m a n t l e d slope to the n o r t h e a s t . The trough has been encroached from both s i d e s by a s e r i e s of d e b r i s lobes and f u n c t i o n s as a t r a p f o r water-borne f i n e s . C u r r e n t l y t h i s i s a s u r f a c e d e t e n t i o n storage s i t e f o l l o w i n g any s i g n i f i c a n t p r e c i p i t a t i o n event. Drainage i s impeded by two n e a r l y i n t e r s e c t i n g , t u r f e d banked t e r r a c e s downstream and standing water remains f o r s e v e r a l days to one week a f t e r each event, depending on the event's magnitude. Boulders c o n s t i t u t e at l e a s t 30% of a l l p r o f i l e s . V e g e t a t i o n : Sedge a s s o c i a t i o n . 100% cover tending toward Luetkea, Moss and Lichen a s s o c i a t i o n i n a few s c a t t e r e d patches. Carex rhizomes form dense, t u r f y mat i n the Ah h o r i z o n . Parent m a t e r i a l s : C olluvium from bedrock and t i l l i n t e r t o u n g e s with both v o l c a n i c ashes, l o e s s , and organic d e p o s i t s . Horizon Depth(cm) D e s c r i p t i o n LH 0.3-0.0 Polytri c h u m and Carex rhyzome mat; 3 mm t h i c k . Ah 0.0-10.0 Very dark brown(10YR2/2m) very f i n e sandy loam or s i l t loam; t u r f y with extremely abundant very f i n e to f i n e sedge r o o t s ; s o f t , f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s ; abrupt, smooth boundary; 10 cm t h i c k . Contains c h a r c o a l washed i n from slopes above. Bm 10.0-14.0 L i g h t o l i v e brown(2.5YR5/4m), pa l e yellow(2.5Y7/4d) s i l t loam with y e l l o w i s h red(5YR5/6m) h o r i z o n t a l l a y e r , 2 mm t h i c k at base; s o f t , f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s ; abundant very f i n e and f i n e r o o t s ; very abrupt, smooth boundary; 0 to 4 cm t h i c k . Bridge River v o l c a n i c ash. II Omb 14.0-25.0 Very dark brown(10YR2/2m), o l i v e brown(2.5Y4/4d) s i l t c l a y loam(?), h i g h l y c o l l o i d i a l ; s o f t , f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s ; abundant very f i n e and f i n e r o o t s ; abrupt, wavy boundary; 11 to 15 cm t h i c k . III Bmb1 25.0-37.0 Y e l l o w i s h brown(10YR5/6m) f i n e sandy loam with many f i n e , d i s t i n c t , dark red(2.5YR3/6m) mottles o c c u r i n g around 230 IV Bmb2 37.0-40.0 V Bmb3-Omb(?) 40.0-49.0 VI R 49.0 r o o t l e t s i n the matrix; s o f t , f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; abundant very f i n e and f i n e r o o t s ; s t r u c t u r e l e s s ; very abrupt, wavy boundary; 0 to 12 cm t h i c k . Mazama ash. Glas s i s at l e a s t 70% of the h o r i z o n . Y e l l o w i s h brown(10YR5/4m) l i g h t y e l l o w i s h brown(2.5Y6/4d) sandy loam with many, f i n e dark red(2.5YR3/6m) m o t t l e s ; few f i n e r o o t s ; s o f t , f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s ; abrupt smooth boundary; 3 to 17 cm t h i c k . A b u r i e d d e b r i s lobe. Very dark brown(10YR2/2m) sandy loam(?), h i g h l y c o l l o i d i a l ; s o f t f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s ; abundant very f i n e r o o t s ; 0 to 10 cm t h i c k . B a s a l t i c d i k e c u t s country rock of Gambier Group s c h i s t . 231 S79-9A ACTIVE: Weak B r u n i s o l on Whaleback. Pedon: O r t h i c D y s t r i c B r u n i s o l S i t e : F l a t , smooth, c r y o t u r b a t e d cobble pavement e n r i c h e d i n s i l t s winnowed from nearby t a l u s . T h i s s i t e forms a small broad c r e s t at the head of Mosquito G u l l e y and r e c e i v e s d i r e c t r a i n and snowmelt only. T h i s i s the d r i e s t , most exposed and c r y o t u r b a t e d s i t e i n the watershed. Depth to bedrock nowhere exceeds 25 cm. V e g e t a t i o n : 5% cover of S a x i f r a g e a s s o c i a t i o n . Parent m a t e r i a l s : Lag d e p o s i t e of t i l l e n r i c h e d with s i l t s , v o l c a n i c ash and u n d e r l y i n g bedrock. Horizon Depth(cm) D e s c r i p t i o n Ahj 0.0-7.0 Pale brown(10YR6/3d) g r a v e l l y loamy sand; very f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c , weak p l a t e y s t r u c t u r e ; few medium r o o t s ; abrupt smooth boundary; 7 cm t h i c k . Bm 7.0-20.0 Y e l l o w i s h brown(10YR5/4d) g r a v e l l y loamy sand; very f r i a b l e , not s t i c k y , not p l a s t i c , s t r u c t u r e l e s s , i r r e g u l a r abrupt boundary; 13 to 18 cm t h i c k . II R Gambier Group s c h i s t . S79-9B: ACTIVE: Talus slope near 3W3. Pedon: O r t h i c Regosol S i t e : S t e e p l y s l o p i n g (18°) t a l u s s l o p e . Very a c t i v e . V e g e t a t i o n : None. Parent M a t e r i a l s : C o l l u v i u m . Horizon Depth(cm) D e s c r i p t i o n C 0.0-30.0 Olive(5Y5/3m) g r a v e l l y coarse sand. Coarse fragments exceed 60% of h o r i z o n ; very f r i a b l e ; s t r u c t u r e l e s s ; 10 to 55 cm t h i c k . II R Gambier Group s c h i s t . 232 S79-11 WETLAND: G r a v e l fan above Mosquito weir. Pedon : Rego Humic G l e y s o l S i t e : C olluvium and water borne m a t e r i a l s washed from surrounding s l o p e s have formed a low angle fan of d e b r i s at the mouth of Mosquito Creek. The s i t e remains f u l l y s a t u r a t e d throughout most of the a b l a t i o n season. S i t e slopes uniformly at 2° to the n o r t h e a s t and i s armored with subangular cobbles and g r a v e l . T h i s pedon grades i n t o f e r r u g i n o u s b r u n i s o l s on the s l o p e s to the west and grades i n t o n o n d e s c r i p t cumulic r e g o s o l s to the e a s t . V e g e t a t i o n : Surface cover of moss and other s p e c i e s i n the Sedge Forb a s s o c i a t i o n i s 80% to 100%. Parent M a t e r i a l s : Compacted t i l l and lake s i l t s are o v e r l a i n by a complex s e r i e s of d e b r i s lobes and a t h i c k cover of g r a v e l which i s d e f i n i t e l y bedded in p l a c e s . Horizon Depth(cm) D e s c r i p t i o n LH 0.5-0.0 Moss mat, 0.5 cm t h i c k . Not sampled. Ah 0.0-10.0 Dark g r a y i s h brown(2.5Y4/2m) g r a v e l l y sandy loam; s l i g h t l y hard, f r i a b l e , s l i g h t l y s t i c k y , s l i g h t l y p l a s t i c ; s t r u c t u r e l e s s ; abundant very f i n e and f i n e r o o t s , few medium r o o t s ; c l e a r to gradual boundary; 5 to 10 cm t h i c k . Cg 10.0-90.0 01ive(5Y5/3) g r a v e l l y sandy loam; s l i g h t l y hard, f r i a b l e , not s t i c k y , very s l i g h t l y p l a s t i c ; few f i n e to medium roo t s above 18 depth; very compacted below 50 cm depth; s t r u c t u r e l e s s ; 60 to 100 cm t h i c k . 233 Appendix D. HYBROMETEROLOGICAL DATA 1 979 Julian Air Temperature Melt Prec ip Q ET date min max mean (W m2 ) (mm) (mm) (mm) (mm) 106 -5.5 -2.9 -4.2 frozen 107 -4.9 -2.4 -3.6 0 0 .45 108 -7.6 -2.9 -5.2 0 0 .55 1 09 -8.6 -1 .4 -5.0 0 0 .75 1 10 -8.6 0.6 -4.0 f rozen 0 .60 1 1 1 -5.5 2.7 -1 .4 0 .71 1 1 2 -2.4 2.7 0.2 0.7 0 .71 1 1 3 -2.4 4.8 1 .2 3.3 0 .75 1 1 4 0.1 6.8 3.4 9.0 0 .75 1 1 5 -0.4 7.8 3.7 9.7 0 .37 1 1 6 2.7 9.9 6.3 16.4 0 .33 1 1 7 5.8 11.9 8.8 22.9 0 .10 1 18 6.8 14.0 10.4 27.0 0 .23 1 19 2.7 10.9 6.8 17.8 -0.14 1 20 3.7 11.9 7.8 20.3 -0 .41 121 3.7 8.9 6.3 16.4 0. 17 1 22 1 .7 5.8 3.7 9.7 -0.12 1 2 3 0.6 3.7 2.1 5.6 16.3 -0.24 1 24 0.6 0.6 0.6 1 .8 1 .3 -0.06 1 25 -0.9 1 .7 0.4 1 .2 6.3 -0.10 126 -1.4 0.6 -0.4 0.8 0 .04 1 27 -1.4 -1 .4 -1 .4 0 . 1 3 1 28 -3.5 0.6 -1 .4 0 .31 129 -2.4 130 131 0.1 1 32 1 .3 2 23 133 1 34 2.8 1.3 1 35 2.8 6.6 1 36 2.8 0.3 1 .7 137 -1 .4 3.2 0.9 2.5 0.3 2.4 0 10 138 -1.4 3.7 1 . 1 320. 43 3.0 5.2 0 46 1 39 -1 .9 6.3 2.2 297. 73 • 5.9 9. 1 0. 52 1 40 1 .2 2.7 1 .9 1 03. 63 5.5 0.4 0.7 0. 48 141 -0.4 7.8 3.7 313. 04 10.5 11.7 0. 29 142 5.3 13.0 9.1 263. 42 25.5 18.2 0. 15 143 3.7 7.8 5.7 186. 30 16.1 17.2 -0.20 1 44 1 .7 7.8 4.7 288. 77 13.2 20.7 -0.03 1 45 1 .7 9.4 5.5 1 74. 30 15.4 14.6 -0.37 146 1 .7 3.7 2.7 238. 30 7.7 8.6 55.4 -0.08 147 -4.5 0.1 -2.2 193. 87 0.0 5.1 I 0.39 J u l i a n A i r Temperature Melt Prec i p Q ET date min max mean (W m2) (mm) (mm) (mm) (mm) 1 48 -5.5 3.2 -1.1 247.75 0.0 4.0 0.44 1 49 -1.4 9.9 4.3 185.27 1 1 .9 | 0.15 1 50 0.6 10.4 5.5 312.42 15.2 6.6 0.26 151 -0.4 13.0 6.3 297.46 17.3 1,3.3 0.44 1 52 7.3 14.0 10.6 236.82 29. 1 13.4 -0.17 1 53 7.8 13.0 10.4 301.40 28.4 25. 1 -0.13 154 5.3 9.4 7.3 230.82 20.0 25.4 -0.23 1 55 3.2 3.7 3.4 128.67 9.4 3.2 11.0 -0.21 1 56 0.6 4.2 2.4 306.73 6.7 4.9 12.4 0.27 1 57 -2.4 4.2 0.9 281.96 2.6 0.9 0.48 1 58 -0.4 6.8 3.2 289.98 8.9 5.9 0.40 159 1 .7 7.8 4.7 238.61 12.7 12.2 0.10 1 60 3.7 8.9 6.3 73.49 16.8 13.1 -0.12 161 4.8 10.9 7.8 20.7 24.4 0.04 1 62 5.8 7.8 6.8 18.0 8.8 19.4. 0.17 1 63 0.6 4.2 2.4 227.73 6.4 6.2 0.35 1 64 -2.4 3.2 0.4 256.35 1 .2 1 . 1 5.1 0.41 1 65 -1.9 1 .7 -0.1 144.74 0.0 0.3 1 .0 0.36 1 66 -1.4 3.7 1 . 1 144.61 3.0 1 .0 0.07 1 67 -0.4 3.7 1 .6 115.50 4.2 4.5 0.05 1 68 ' 5.8 13.0 9.4 317.61 23.8 27.2 0.38 1 69 3.2 7.8 5.5 179.05 21.4 10.7 -0.10 1 70 2.7 6.8 4.7 191.32 18.0 13.1 0.00 171 0.6 5.8 3.2 171.26 12.0 0.5 9.8 0.03 1 72 0.6 6.3 3.4 180.89 12.5 12.2 0.22 1 73 1 .2 1 .8 1 .5 148.24 5.5 0.2 5.7 0.22 174 1 .2 6.3 3.7 201 . 17 12.7 11.7 0.19 1 75 1 .2 11.9 6.5 335.89 21.5 17.1 0.87 1 76 7.8 14.0 10.9 334.99 34.6 21.1 1.13 1 77 7.3 15.0 11.1 303.46 33.2 27.3 0.96 1 78 7.3 15.0 11.1 318.87 31.3 25. 1 1.14 1 79 8.9 17.1 13.0 316.90 33.7 21.5 1 .22 180 7.8 14.0 10.9 177.35 25.9 9.9 20.0 0.30 181 0.6 4.2 2.4 209.82 5.5 7.5 11.0 0.76 182 -2.4 0.2 -1.1 176.63 0.0 2.5 0.0 0.58 1 83 -1.4 0.6 -0.4 99.51 0.0 0.0 0.08 1 84 -0.4 8.3 3.9 234.54 6.1 6.3 1 .02 185 5.8 7.8 6.8 121.32 9.6 5.7 13.3 0.17 186 4.8 11.9 8.3 236.64 9.9 0.6 16.2 1.18 187 5.8 14.0 9.9 238.66 10.1 16.4 1 .33 188 5.3 7.8 6.5 139.41 5.7 15.4 17.6 0.36 1 89 3.7 7.8 5.7 104.48 4.0 4.0 28.5 0.04 1 90 5.8 15.0 10.4 188.77 6.4 6.8 19.9 1 .04 191 3.7 5.8 4.7 104.12 2.3 9.3 17.1 0.09 1 92 3.2 5.8 4.5 121.28 1 .8 3.4 6.9 0.28 193 1 .7 7.3 4.5 179.41 1 .4 0.6 5. 1 0.93 1 94 2.7 8.9 5.8 155.72 1 .5 3.9 0.72 1 95 4.8 13.5 9. 1 1 .6 5.1 2.00 196 9.9 17.1 13.5 293.25 1 .8 5.3 2.71 1 97 13.0 20. 1 16.5 284.34 1 .5 4.8 2.79 J u l i a n A i r Temperature K l M e l t P rec i p Q ET da te min max mean (W m 2 ) (mm) (mm) (mm) (mm) 198 14.5 21.2 17.8 299.70 1 .6 3 4 3.08 1 99 15.0 22.2 18.6 296.47 1 .3 3 1 3.08 200 15.5 23.2 19.3 237.27 0.8 1 5 2.24 201 14.0 20.7 17.3 270.05 0.8 1 3 2.65 202 9.9 15.0 12.4 323.79 0.6 3.12 203 6.8 15.0 10.9 258.45 0.5 2.17 204 6.8 15.5 11.1 269.16 0.5 1 . 1 2.32 205 7.8 14.5 11.1 195.26 0.5 1 .0 1 .37 206 7.3 17.1 12.2 253.53 2.20 207 10.9 18.6 14.7 286.26 2.78 208 10.9 16.0 13.4 258.72 2.33 209 8.3 14.0 11.1 235.75 1 .92 210 5.8 11.9 8.8 186.89 1.21 21 1 6.8 17.1 11.9 260.56 2.28 212 9.4 15.0 12.2 258.63 2.27 213 7.8 16.0 11.9 244.48 2.06 214 6.8 14.0 10.4 218.28 1 .66 215 5.8 9.9 7.8 169.60 2.2 0.98 216 5.3 13.0 9.1 212.37 1 .54 217 4.8 10.4 7.6 218.86 1 .57 218 2.7 13.0 7.8 218.46 1 .57 219 5.8 14.0 9.9 272.43 2.33 220 6.8 17.1 11.9 264.77 2.34 221 10.9 19.1 15.0 255.41 2.35 222 10.9 19.6 15.2 228.76 1 .98 223 8.9 17.1 13.0 231 .36 1 .93 224 11.9 20. 1 16.0 250.75 2.33 225 14.0 21.2 17.6 213.58 1 .85 226 9.9 15.0 12.4 121.28 3.7 0.43 227 7.8 9.9 8.8 79. 18 1 .2 0.04 228 7.8 13.5 10.6 158.05 0.89 229 7.8 9.9 8.8 75.24 10.3 0.04 230 4.8 8.9 6.8 127.86 0.5 0.46 231 4.2 10.9 7.5 217.12 1 .6 1 .55 232 7.8 16.0 11.9 225.00 0.2 1 .80 233 13.0 19.1 16.0 226.52 3.7 1 .98 234 7.8 13.5 10.6 160.46 7.7 0.92 235 6.8 11.9 9.3 222.18 0.2 1 .67 236 6.8 12.4 9.6 1 05.83 0.7 0.21 237 8.3 16.0 12.1 246.85 3.1 2.11 238 9.4 16.0 12.7 179.59 1 .22 239 8.9 15.5 12.2 167.05 1 .04 240 7.8 14.0 10.9 183.62 1 .23 241 8.3 17.1 12.7 242.46 2.07 242 7.3 13.5 10.4 187.24 1 .26 243 5.8 11.4 8.6 122.98 1 .2 0.41 244 4.8 7.8 6.3 55.76 9.3 0.01 245 4.8 5.8 5.3 55.89 15.4 0.01 246 2.2 5.8 4.0 64.94 4.6 0.02 247 1 .7 3.2 2.4 92.79 13.0 0.05 236 J u l i a n A i r Temperature K l Melt Prec i p Q ET date min max mean (W m2 ) (mm) (mm) (mm) (mm) 248 1 .7 4.8 3.2 99.74 23. 1 0.11 249 1 .7 5.3 3.5 66.46 4.3 0.03 250 3.2 8.3 5.7 59.25 36.3 0.02 251 1 .7 3.2 2.4 126.96 20.2 0.40 252 1 .7 6.8 4.2 6.8 0.40 253 1 .2 7.8 4.5 183.62 | 1 .06 254 3.7 9.4 6.5 200.46 5 9 1.31 255 6.8 11.9 9.3 201 .31 1 .41 256 9.9 16.0 12.9 196.16 1 .45 257 12.4 18.6 15.5 197.55 1 .55 258 11.4 14.5 12.9 184.47 1 .29 259 4.8 11.4 8.1 173.32 1 .03 260 5.8 16.0 10.9 189.04 1 .30 261 11.9 19.1 15.5 176.85 1 .25 262 10.9 16.0 13.4 173.32 1.15 263 10.9 15.5 13.2 7.2 1 .20 264 2.7 6.8 4.7 0.4 1 .20 265 4.8 9.9 7.3 186.75 1.17 266 6.3 11.9 9.1 172.20 1 .04 267 8.9 15.5 12.2 182.32 1 .24 268 10.4 17.1 13.7 94.94 0.07 269 3.7 5.8 4.7 38.51 4.2 0.00 270 1 .7 3.7 2.7 160.24 25.6 0.76 271 -2.4 5.8 1 .7 47.79 1 .8 0.00 272 -0.9 1 .7 0.4 129.88 6. 1 0.41 273 1 .7 5.8 3.7 128.40 1 .0 0.43 274 2.7 8.3 5.5 275 1 .7 9.9 5.8 276 6.8 16.5 11.6 277 6.8 11.4 9.1 278 6.8 14.0 10.4 279 8.9 15.5 12.2 280 7.3 11.4 9.3 281 5.8 10.9 8.3 282 8.3 17.1 12.7 283 12.4 17.1 14.7 1980 131 4.2 11.9 8.0 264.45 30.8 20.8 fl o o d e d 0.08 1 32 5.3 13.0 9.1 234.27 35.0 -0.16 1 33 2.7 5.8 4.2 94.45 16.3 0.8 -0.37 1 34 -0.4 2.7 1 . 1 137.58 4.5 -0.03 1 35 -0.9 0.6 -0.1 98.30 0.0 0.11 136 -1.9 3.7 0.9 121.99 3.7 | -0.12 1 37 -0.9 8.9 4.0 240.49 15.6 8.3 1 1 -0.56 138 0.6 9.4 5.0 175.87 19.4 -0.04 139 1 .7 6.8 4.2 253.44 16.3 6 2 0.10 J u l i a n A i r Tempe r a t u r e K l d a t e m i n max mean (W m 2 ) 1 40 - 0 . 9 - 0 . 4 - 0 . 6 9 7 . 5 9 141 - 0 . 4 2 .7 1 . 1 3 .99 1 42 - 0 . 4 2 .7 1 . 1 2 9 8 . 4 0 1 43 - 3 . 5 - 0 . 4 - 1 . 9 182 . 09 1 44 - 4 . 5 3.7 - 0 . 4 2 0 9 . 5 9 1 45 - 0 . 4 2 .7 1 . 1 1 03 . 09 1 46 - 0 . 4 6.8 3.2 285 .41 1 47 1 .7 3.7 2 .7 107 .80 1 48 - 0 . 4 3.7 1 .6 138 . 88 1 49 0 .6 6 .3 3 .4 182 .27 1 50 0 .6 8 .9 4 . 7 228 .31 151 0 . 6 8 . 9 4 . 7 3 0 2 . 0 7 1 52 3.2 4 .8 4 . 0 115 . 10 1 53 - 0 . 9 1 .7 0 .4 9 5 . 48 1 54 - 3 . 5 4 . 8 0 . 6 2 0 2 . 8 7 155 - 0 . 9 3.7 1 .4 1 23 . 83 1 56 - 0 . 4 2 .2 0 . 9 136 . 15 1 57 0.1 6 .8 3.4 2 8 2 . 4 6 1 58 0 . 6 6 .3 3.4 214 .21 1 59 1 .7 7 .3 4 . 5 2 7 9 . 7 3 1 60 4 . 8 6 .8 5.8 108 .38 161 1 .7 7.8 4 . 7 2 4 4 . 3 9 1 62 1 .7 6.8 4 . 2 175.51 1 63 0 .6 8 . 9 4 . 7 2 1 8 . 1 9 1 64 3 .7 12 .4 8 .0 2 8 3 . 3 5 1 65 4 . 8 15 .0 9 .9 3 0 3 . 2 8 1 66 6 .3 15 .0 10 .6 2 4 1 . 5 2 1 67 5.3 8 .3 6 .8 144 . 92 1 68 3 .7 8 . 9 6 .3 1 28 . 53 1 69 1 .7 4 . 8 3 .2 9 9 . 4 7 1 70 1 .7 8 .3 5.0 215 .41 171 2 .7 11 .9 7 .3 3 1 3 . 4 9 1 72 6 .8 10 .9 8 .8 2 3 6 . 1 5 1 73 3 .7 8 . 9 6 .3 2 0 8 . 5 2 1 74 3.2 4 . 8 4 . 0 1 36 . 06 1 75 0 .6 5.8 3.2 2 0 0 . 3 2 176 1 .2 9 .9 5 .5 3 2 3 . 6 6 1 77 6 .8 8 . 9 7 .8 9 4 . 9 4 178 0 . 6 0 .6 0 . 6 179 1 .4 5.3 3 .3 2 1 3 . 9 4 180 6 .3 5.3 5.8 2 0 2 . 8 3 181 - 0 . 9 4 . 8 1 .9 1 23 . 16 182 1 .2 9 .9 5 .5 191 . 10 183 5.8 12 .4 9.1 2 6 4 . 2 3 184 5.8 9 .9 7 .8 2 2 3 . 9 2 185 2 . 7 6 .8 4 . 7 1 4 8 . 5 5 186 - 1 . 4 2 .7 0 . 7 171 . 30 187 - 0 . 4 5.3 2 .4 1 7 6 . 0 5 188 1 .2 9 .4 5.3 189 5.8 13 .5 9 .6 1 90 5.8 13 .5 9 . 6 237 M e l t P r e c i p Q ET (mm) (mm) (mm) (mm) 0 . 0 10 . 1 0 . 10 4 . 5 4 .2 0 .12 4 . 5 0 .9 0 .44 0 . 0 1 .9 35 0 0 . 52 0 . 0 0 . 44 4 . 5 1 .9 0 . 23 12 . 5 0 . 16 10 .6 9 .4 0 . 13 6 .4 3 .6 - 0 . 1 1 12 .3 4 7 - 0 . 3 3 16.8 21 7 0 . 07 16 .8 16 2 0 . 1 9 14 .4 0 .9 8 0 0 . 15 1 .7 1 1 . 1 0 . 10 2 .4 2 .8 0 . 24 5.2 8 . 1 9 0 - 0 . 1 7 3.4 7 .8 - 0 . 1 0 12 .3 13 9 0 . 13 12 .3 5 .0 20 7 0.01 16 .2 27 0 0 . 03 2 0 . 7 5 .9 13 9 - 0 . 1 1 16 .8 19 7 - 0 . 1 7 15.1 7 6 - 0 . 1 5 16 .8 7. 6 - 0 . 0 4 3 0 . 8 24. 5 - 0 . 0 4 3 8 . 1 28. 6 - 0 . 4 4 4 0 . 4 1 .0 45 . 9 - 0 . 9 0 2 6 . 0 0 .7 17. 6 - 0 . 8 5 2 4 . 1 4 .3 16. 3 - 0 . 2 5 12 .4 1 0 .8 26 . 0 - 0 . 2 6 19 .2 4. 6 - 0 . 0 9 2 7 . 9 23 . 2 - 0 . 1 2 3 3 . 6 20 . 5 - 0 . 0 5 2 4 . 1 26 . 3 - 0 . 2 0 15.1 1 .8 15. 9 - 0 . 2 4 12.1 9. 9 - 0 . 0 2 2 0 . 2 16 .6 0 . 15 2 8 . 6 8 .8 13 .7 - 0 . 0 3 2 . 5 1 1 .5 13.8 0 . 10 11.1 15 .2 0 . 19 19. 1 0 .7 14 .3 - 0 . 2 6 6 .2 2 .7 5 .9 - 0 . 0 8 17 .6 15. 6 - 0 . 0 6 2 8 . 3 22 . 5 0 . 17 2 3 . 8 17. 5 0 . 06 13 .9 3 .8 2 5 . 3 - 0 . 3 7 2 . 2 2. 2 0 . 34 6 .6 3 .8 7. 7 0 . 24 13.8 14 .2 | 2 3 . 4 3 3 . 3 I 2 2 . 0 28 . 6 1 .50 J u l i a n A i r T e m p e r a t u r e d a t e m i n max mean 191 7 .8 14 .0 10 .9 1 92 5.8 5.8 5.8 1 93 1 .7 7 .8 4 . 7 1 94 4 .8 13 .0 8 . 9 195 6 .3 9 .9 8.1 196 4 . 8 10 .9 7 .8 1 97 4 . 8 6 .8 5.8 198 2 .7 9 .4 6 .0 199 3.2 11 .9 7 . 5 200 5.3 13 .0 9.1 201 5.3 8 . 9 7.1 202 5.8 15 .0 10.4 203 9 .9 2 0 . 7 15 .3 204 15 .0 18 .6 16.8 205 7 .8 13 .0 10.4 206 6 .8 16 .0 11.4 207 7 .8 14 .0 10 .9 208 8 .3 17.1 12 .7 209 7 .8 16 . 5 12.1 210 8 . 9 15 .0 11 .9 21 1 6 .8 14 . 5 10 .6 212 6 .8 15 .0 10 .9 213 6 .8 14 .5 10 .6 214 6 .8 9 .9 8 .3 215 3.2 6 .8 5.0 216 2 .7 6 .9 4 . 8 217 2 .7 8 . 9 5.8 218 1 .7 7 .8 4 . 7 219 3 .7 7 .3 5 .5 220 3 .7 10.4 7 .0 221 5.8 14 .0 9 .9 222 8 . 9 16 .0 12 .4 223 9 .9 17 .6 13 .7 224 9 . 9 17.1 13 . 5 225 8 .3 17.1 12 .7 226 10.4 17.1 13 .7 227 6 .8 13 .0 9 . 9 228 5.8 9 .4 7 .6 229 5.3 9 .9 7 .6 230 5.8 7 .3 6 .5 231 2 . 7 14 .0 8 . 3 232 5.3 10 .4 7 .8 233 4 . 8 10 .9 7 .8 234 5.8 13 .0 9 .4 235 6 .8 11 .9 9 .3 236 3 .7 9 .9 6 .8 237 2 .2 10 .9 6 .5 238 4 . 2 12 .4 8 .3 K l M e l t P r e c i p Q ET (W m z ) (mm) (mm) (mm) (mm) 2 3 . 0 3 4 . 9 11 .3 2 1 . 3 1 60 . 15 8 . 5 2 0 . 5 0 .20 2 0 6 . 2 8 14 .8 2 5 . 0 0 .52 126 .07 12 .3 1 3 .5 - 0 04 193 .02 9 . 9 2 4 . 2 0 .62 9 7 . 7 7 10 .2 12.1 - 0 . 1 5 2 1 2 . 9 5 8 . 9 1 0 .7 0 .96 2 0 3 . 5 5 9 . 5 12 .0 0 97 2 0 7 . 9 4 9 .6 1 5 .3 1 09 126 .47 6 . 5 13 .6 0 23 2 4 3 . 2 7 8 .3 17 .5 1 55 2 9 1 . 8 6 10 .5 24 .0 2 43 2 0 5 . 0 2 9 .8 0 . 5 23.1 1 38 - 5.0 1 3 .3 4 . 8 3.4 3 .3 2 .6 13 5 2 . 5 1 .7 1 . 1 1 . 1 57 4 1 32 . 38 0 .8 0 51 8 4 . 2 0 0 .3 0. 05 192.71 0 .3 1 . 1 6 1 75 . 69 0 .3 0. 99 1 73 . 59 0 .3 0. 94 150 .88 0 .3 0. 70 2 1 9 . 8 0 0 .4 1. 54 2 0 0 . 7 7 0 .6 1 .40 2 3 8 . 3 9 0 . 5 1 . 99 2 5 1 . 4 2 0 . 5 6 6 2. 22 2 3 2 . 4 3 0 . 5 1 . 95 2 4 1 . 3 0 0 . 5 2. 02 6 .52 5.9 2 . 04 0 . 06 1 .59 0 .78 .80 0 . 90 1 .80 1 .51 2 5 4 . 7 4 9 0 . 6 4 141 . 65 2 1 5 . 1 5 1 5 1 . 4 6 . 7 1 56 . 75 241 .34 2 1 2 . 3 7 239 J u l i a n A i r Temperature Kl date min max mean (W m2) 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 1 255 256 257 258 259 260 261 262 263 264 -265 -266 267 268 -269 -270 271 272 273 -274 275 276 O u t l e t 5, 7, 5. 5, 7, 8, 3, 6, 3, 1 2 6 2 7 2 2 2 7 7 8 3 7 8 4 9 8 2 7 7 8 8 3 7 6 4 4 7 6 4 4 3 8 7 4 1 1 9 18.1 c l o s e s on 6.8 9.9 6.8 9.9 14.0 18.1 17.1 1 1 3 6 1 2 1 1 1 1 8 4 2 9 7 8 4 4 4 9 2 7 1 .7 3 3, 2 8 1 1 13, 8, 4, 3, 6, 9, 4, 4, 2, 3, 4, 5, 2, 3, 2, 4 , 7, 6, 6, 9, 13, 14, 9, 2, 4, 2 7 9 5 7 5 7 7 7 2 3 0 8 4 7 5 8 9 7 8.0 9.1 8 7. 3. 1 0 1 , 3 1 4, 5 10 6, 3, 1 , 3, 5, 71 , 1 42, 83, 1 42, 1 29, 1 54, 48, 1 27, 39 01 93 86 43 96 05 41 1 76, 1 96, 1 94, 197, 77, 43, 176, 161 , 1 54, 1 70, 98, 38, 61 , 82, 112, 56, 1 46, 1 48 , 1 59, 1 39, 87, 37, 68 92 46 41 1 2 53 94 67 10 63 53 29 36 36 28 70 54 24 93 68 02 71 Melt P r e c i p Q (mm) (mm) (mm) 11.5 3.6 2.4 3.6 1 .2 0.3 13.6 6.8 23. 1 11.1 0.6 50.0 21.2 2.2 ET (mm) 0.03 0.59 0.04 0.59 0.45 0.76 0.00 0.42 4.0 04 36 45 51 04 00 0.99 0.88 0 1 81 01 0.11 0.00 0, 0, 02 04 0.24 0.01 0.06 0.66 0.81 0.64 0.05 0.00 7.0 14.0 #282, No p r e c i p u n t i l s n o w f a l l s on #284-286. 240 Appendix E. MISSING RECORDS Di scharge The 1979 a b l a t i o n season began sometime a f t e r day 111. The s i t e was unoccupied fo r three weeks and a frozen s t i l l i n g - w e l l prevented a c q u i s i t i o n of a u s e f u l discharge t r a c e f o r t h i s event. A s u b j e c t i v e estimate of maximum runoff f o r t h i s event i s 120 mm. T h i s estimate was made by simply sketching a t r i a n g u l a r discharge event f o l l o w i n g the mean a i r temperature curve (see f i g . 4.1). Peak discharge was p l a c e d at a l e v e l s i m i l a r to subsequent events and c o i n c i d e s with the peak a i r temperature. T h i s i s thought to produce an a b s o l u t e upper-bound on r u n o f f for the p e r i o d based on the f o l l o w i n g two assumptions: F i r s t , some meltwater w i l l normally be s t o r e d w i t h i n any watershed as s o i l moisture, s u r f a c e d e t e n t i o n storage, and as fr e e water in the snowpack before s i g n i f i c a n t runoff begins. The A p r i l 1979 snowpack was c o l d and presumably dry ( f i g E.1). In order f o r a p p r e c i a b l e runoff to occur, the pack must become isothermal at 0° C so t h a t i n f i l t r a t i n g meltwater does not r e f r e e z e . T h i s process of " r i p e n i n g " i s accompanied by an increase i n f r e e water content w i t h i n the pack of up to 8% by volume. E i g h t percent of the A p r i l 1979 snowpack i s 70.5 mm. Melt f o r t h i s p e r i o d was about 126 mm so as much as h a l f of t h i s c o u l d be s t o r e d as f r e e water, warming the pack ( t h i s phenomenon i s w ell i l l u s t r a t e d d u r i n g e a r l y 1980 where runo f f r a t i o s remained low d e s p i t e strong m e l t ) . On the other hand, t h i c k i c e lenses were common i n the A p r i l snowpack, 1979. Ice lenses i n h i b i t f r e e , v e r t i c a l p e r c o l a t i o n of meltwater and c o n c e n t r a t e i t along p r e f e r r e d pathways (Wankiewicz, 1978). T h i s may r i p e n the pack h o r i z o n t a l l y above major i c e lenses or v e r t i c a l l y along drainage l i n e s so that runoff c o u l d occur even i n a predominantly c o l d pack. Second, another impediment to runoff i n 1979 was lake i c e which exceeded 0.3 m and g r e a t l y r e s t r i c t e d d i s c h a r g e through the o u t l e t . At l e a s t 500 m3 (22 mm) of meltwater remained ponded above the lak e i c e causing f l o o d i n g upstream s u f f i c i e n t to inundate and make i n o p e r a t i v e the t r i b u t a r y weirs u n t i l the lake i c e was broken by a rain-on-snow event on day 146. T h i s runoff b a r r i e r was c l e a r l y i n f l u e n t i a l d u r i n g the p e r i o d 125-149 and should have s i g n i f i c a n t l y r e t a r d e d runoff d u r i n g event 113-124. The 1980 a b l a t i o n season began the f i r s t week in May at Goat Meadows. D i f f i c u l t i e s i n l o c a t i n g and excavating the weir, i n i t i a l r e c o r d e r f a i l u r e s and f l o o d i n g below the weir r e s e r v o i r caused a l o s s of the f i r s t 10 days of discharge data. On day 137 the o u t l e t channel melted s u f f i c i e n t l y f o r proper weir o p e r a t i o n and a continuous r e c o r d was obtained from that p o i n t onward. Unrecorded d i s c h a r g e f o r t h i s p e r i o d was l i k e l y small and should 241 not s e r i o u s l y e f f e c t the o v e r a l l magnitude of the annual budget. E Denslty(kg/m3) Temperature(C) F i g u r e E . I . D e n s i t y and temperature p r o f i l e at Hummmingbird weir, A p r i l 1979. Mean d e n s i t y i s 410 kg n r 3 . A b l a t i o n A b l a t i o n measurements were u n r e l i a b l e f o r a 12 day p e r i o d (137-148) d u r i n g 1980. Melt f o r these days was approximated by comparing measured a b l a t i o n r a t e s at high a l t i t u d e , Coast Mountain snow surveys (B. C. M i n i s t r y of Environment, 1980) with e s t i m a t e d a b l a t i o n from the melt model ( t a b l e E.1). A c o n s i s t e n t p a t t e r n r e s u l t s and melt f o r the p e r i o d of m i s s i n g measurements i s estimated at 125 mm. 242 snow survey s t a t i o n a l t i tude (m) decimal r a t i o of melt dates measured/estimated W h i s t l e r Mtn. M c G i l l i v r a y Pass O r c h i d Lake 1 450 1800 1 37-1 54 1 35-1 49 1 .36 1 .35 Snow P i l l o w Green Mtn. 1 170 1710 1 36-1 52 1 36-1 49 1 .36 1 .20 Mean 1 .32 Table E.1. Comparison of Coast Mountain snow survey records and estimated melt at Goat Meadows watershed f o r l a t e May, 1980. The data suggest the model underestimates a c t u a l melt by a f a c t o r near 1.32. T h i s f a c t o r i s used to weight the Goat Meadows modeled values f o r days 137-148, 1980. 243 Appendix F. CHEMICAL ANALYSES OF WATER Solute data are organized by sample type and by c o l l e c t i o n s i t e . G r a v i t y water samples are l i s t e d f i r s t , f o l l o w ed by p r e c i p i t a t i o n samples, c a p i l l a r y water samples, and s o l u b l e s a l t e x t r a c t i o n s . See f i g u r e 3.1 f o r the l o c a t i o n of each sampling s i t e . C o n c e n t r a t i o n data are i n mmoles m~3. Solu b l e s a l t e x t r a c t s are expressed as y i e l d of s o l u t e , i n micromoles per 100 g a i r dry s o i l . INDEX OF SITES 0 Basin o u t l e t weir 1 Mosquito weir 2 Mosquito fan subsurface s i t e 3 Bulk p r e c i p i t a t i o n 4 Snowmelt 5 Hummingbird channel a r t e s i a n t e s t s i t e 6 Hummingbird weir 7 Hummingbird s u r f a c e d e t e n t i o n storage s i t e 8 Mosquito channel s i t e #2 9 Mosquito channel s i t e #1 10 Hummingbird channel s i t e #1 11 Hummingbird channel s i t e #2 13 Hummingbird standpipe p2 14 Hummingbird standpipe p3 22 Hummingbird standpipe p11 27 Pond, west shore 28 Pond, north shore 30 Mosquito standpipe s1 31 Mosquito standpipe s2 33 R e s i d u a l standpipe s4 34 Hummingbird standpipe s5 37 Mosquito standpipe s8 38 Mosquito standpipe s9 39 Mosquito standpipe S10 40 Mosquito standpipe s11 41 Mosquito standpipe s i 2 45 Mosquito s11 o v e r l a n d flow s i t e 46 Mosquito S12 o v e r l a n d flow s i t e 47 Mosquito s2 o v e r l a n d flow s i t e 48 R e s i d u a l s4 o v e r l a n d flow s i t e 50 R e s i d u a l seep 51 R e s i d u a l "mosquito weir" seep 52 Mosquito "marmot" seep 53 Hummingbird weir subsurface channel 63 Mosquito t a l u s p i t 64 Mosquito fan p i t 66 R e s i d u a l o u t l e t beach p i t 67 R e s i d u a l monolith p i t 68 Mosquito whale back p i t 244 71 Mosquito standpipe s52 91 Regosol p l o t snow l y s i m e t e r 94 B r u n i s o l p l o t snow l y s i m e t e r 96 B r u n i s o l p l o t lower g u t t e r 97 Regosol p l o t subsurface channel 101 to 128 see c a p i l l a r y s o i l water samples 130 upper Hummingbird s u r f a c e d e t e n t i o n storage s i t e 131 Mosquito U5 s u r f a c e d e t e n t i o n storage s i t e 133 Mosquito channel s i t e #3 (standpipe i n t a l u s ) 400 Regional 401 Regional 402 Regional 403 Regional 404 Regional 405 Regional C a p i l l a r y water or pressure-vacuume sampler s i t e s : Sedge s i t e s : 101,103,105,114,118,125,126 Heath s i t e s : 102,104,106,108,109,110,116,123, A c t i v e d e b r i s s i t e s : 107,111,112,117,119,120,121,124,128 Tree I s l a n d s i t e s : 113,115,122, Wetland s i t e s : 127 GRAVITY WATER SAMPLES S i t e ID# Si(OH), Ca Mg Na K pH Date Time Q 1/s BASIN OUTLET WEIR: 0 79004 52. 4 34. 6 5 .3 21 . 7 3 .0 5. 51 180579 954 0. 85 0 79005 35. 6 7. 4 1 .6 3. 0 2 .0 5. 51 260579 840 6. 67 0 79018 66. 2 17. 4 2 .4 18. 2 0 .7 150679 921 0. 29 0 79048 56. 4 . 13. 9 1 .6 15. 2 1 .2 220679 837 1 . 58 0 79054 58. 0 1 1 . 4 1 .2 15. 2 1 .5 230679 1 1 54 1 . 24 0 79058 32. 7 12. 9 1 .6 17. 3 1 .2 6. 10 220679 2001 2. 36 0 79067 28. 4 9. 7 1 .6 17. 3 2 .5 250679 946 1 . 64 0 79073 32. 7 5. 7 1 .2 0. 0 0 .7 250679 1815 13. 30 0 79087 46. 8 15. 4 2 . 4 5. 2 5 . 1 20779 1 1 00 0. 55 0 79080 29. 8 7. 2 1 .2 0. 8 2 .0 5. 72 290679 1746 8. 98 0 79099 32. 7 9. 9 1 .2 1 . 3 2 .3 5. 98 50779 1642 9. 1 7 0 79105 28. 4 10. 9 1 .2 1 . 3 1 .5 80779 1300 9. 73 0 791 10 65. 2 20. 7 2 .0 14. 3 2 .0 200779 1607 0. 38 0 79126 72. 1 20. 7 2 .4 15. 2 2 .0 220779 1 935 0. 1 0 0 79135 66. 5 22. 2 2 .0 17. 3 3 .0 230779 1655 0. 05 0 79140 66. 5 17. 9 2 .0 19. 1 3 .0 6. 20 240779 1040 0. 01 0 79195 65. 7 20. 9 2 .4 15. 6 2 .8 5. 50 100979 1630 0. 46 0 80003 63. 8 25. 9 3 .2 12. 1 1 .7 170580 1900 0. 90 0 80010 77. 2 22. 7 2 .8 13. 0 1 .7 5. 92 10680 1308 2. 69 0 8001 6 77. 2 22. 9 2 .8 12. 6 1 .7 310580 1030 3. 25 0 80014 61 . 2 21 . 2 2 .8 12. 1 1 .7 290580 1630 1 . 65 0 80015 66. 5 21 . 2 2 .8 12. 6 1 .7 300580 1630 2. 29 0 80018 85. 1 26. 9 3 .2 17. 3 2 .3 40680 2026 0. 73 245 S i t e ID# S i ( O H ) , Ca 0 8001 7 74. 5 22. 7 0 80019 85. 1 27. 1 0 80020 82. 5 24. 2 0 80021 77. 2 21 . 9 0 80037 77. 2 24. 2 0 80038 71 . 8 22. 2 0 80031 69. 2 20. 2 0 80039 71 . 8 21 . 9 0 80036 79. 8 24. 7 0 80041 69. 2 22. 2 0 80044 74. 5 22. 9 0 80045 74. 5 22. 4 0 80047 79. 8 23. 2 0 80048 77. 2 23. 9 0 80042 69. 2 21 . 7 0 80040 74. 5 22. 7 0 80043' rr. 8 23". 2 0 80046 77. 2 23. 9 0 80050 69. 2 18. 7 0 80055 82. 5 22. 2 0 80059 74. 5 19. 2 0 80070 82. 5 20. 4 0 80083 85. 1 20. 9 0 80104 74. 5 19. 4 0 801 14 69. 2 18. 2 0 801 25 82. 5 21 . 2 0 801 35 77. 2 18. 7 0 80144 55. 9 15. 4 0 80154 61 . 2 14. 2 0 801 63 77. 2 20. 4 0 801 75 82. 5 19. 2 0 80171 82. 5 20. 2 0 801 74 85. 1 20. 2 0 80172 79. 8 18. 9 0 801 78 87. 8 20. 4 0 801 79 87. 8 21 . 2 0 801 73 82. 5 19. 2 0 80176 79. 8 19. 2 0 80177 85. 1 19. 9 0 80186 93. 1 21 . 7 0 80183 79. 8 19. 7 0 80188 74. 5 18. 2 0 801 84 82. 5 19. 7 0 80182 71 . 8 18. 4 0 80187 87. 8 20. 7 0 80185 85. 1 20. 4 0 80189 82. 5 19. 9 0 80181 82. 5 20. 4 0 80180 85. 1 20. 4 0 80191 85. 1 19. 9 Mg Na K PH Date Time Q 1/s 2.8 13. 0 2.3 1 0680 1630 2.53 3.2 15. 6 2.0 50680 826 0". 77 3.2 14. 3 1 .7 70680 826 3.33 3.2 16. 5 2.8 90680 226 5.80 3.2 15. 2 1 .7 90680 1 430 4.70 2.8 13. 9 1 .7 90680 1 630 4.94 2.8 13. 0 1 .7 5. 75 90680 1 200 4.76 3.2 13. 4 1 .7 90680 1830 5.20 3.2 14. 7 2.0 90680 1 240 4.64 2.8 14. 3 1 .7 90680 2230 5.87 2.8 14. 3 1 .7 100680 430 5.60 2.8 13. 9 1 .7 100680 630 5.20 3.2 14. 3 1 .7 100680 1030 4.64 3.2 15. 2 1 .7 100680 1230 4.40 2.8 13. 4 1 .5 100680 30 5.94 2.8 13. 4 1 .7 90680 2030 5.60 3.2 14. 7 1 .7 100680 230 5.83 3.2 14. 7 1 .7 100680 830 4.88 2.8 13. 0 1 .5 100680 1 700 4.12 2.8 15. 2 2.3 100680 2030 3.95 2.4 13. 0 1 .7 6. 10 110680 825 3.14 2.8 15. 6 2.3 5. 82 110680 2047 2.86 2.8 14. 3 2.0 6. 13 120680 935 2.69 2.4 12. 6 1 .5 5. 78 120680 2042 4.23 2.4 1 1 . 3 1 .5 5. 80 130680 244 5.39 2.8 13. 9 1 .7 5. 94 130680 913 4.29 2.4 15. 2 2.3 5. 90 130680 1515 4.52 2.0 1 1 . 3 1 .7 5. 79 1 30680 2045 7.13 2.0 10. 4 1 .5 5. 74 140680 243 7.94 2.8 14. 7 2.0 5. 95 140680 838 5.94 2.8 13. 9 1 .7 6. 39 150680 1700 7.37 2.8 13. 9 1 .7 6. 25 1 40680 1700 6.67 2.8 13. 9 1 .7 6. 41 150680 1 100 7.61 2.8 12. 6 1 .7 6. 35 1 40680 2300 9.54 2.8 13. 9 1 .5 6. 45 1 60680 1 100 5.66 2.8 14. 3 1 .7 6. 43 160680 1700 5.20 2.8 13. 0 1 .7 6. 28 150680 500 8.98 2.8 13. 9 1 .5 6. 44 150680 2300 8.02 2.8 13. 9 1 .7 6. 42 160680 500 6.97 2.8 14. 7 1 .7 6. 37 180680 1 100 4.88 2.8 13. 0 1 .7 6. 38 170680 1700 7.94 2.8 12. 1 1 .2 6. 28 180680 2300 6.37 2.8 13. 0 1 .5 6. 37 170680 2300 6.89 2.8 12. 1 1 .5 6. 36 170680 1 100 9.26 2.8 14. 7 1 .7 6. 41 180680 1 700 4.76 2.8 13. 9 1 .7 6. 40 180680 500 5.87 2.8 13. 4 1 .5 6. 35 190680 500 5.33 2.8 14. 3 2.0 6. 41 170680 500 6.22 2.8 13. 9 1.5 6. 40 160680 2300 5.66 2.8 13. 9 1 .5 6. 40 190680 1700 5.26 246 S i t e ID# Si(OH), Ca 0 80190 90 . 5 21 . 2 0 80199 8 7 . 8 21 . 4 0 801 94 95 . 8 21 . 2 0 80193 90 . 5 19. 9 0 80198 95 . 8 21 . 4 0 80195 9 5 . 8 21 . 2 0 80192 7 9 . 8 18. 7 0 801 97 9 0 . 5 2 0 . 2 0 80196 8 5 . 1 19. 2 0 80200 8 7 . 8 22 . 7 0 80216 9 3 . 1 2 3 . 9 0 80217 9 3 . 1 24 . 4 0 8021 1 8 2 . 5 19. 9 0 80218 9 3 . 1 2 3 . 9 0 8021 9 8 7 . 8 22 . 7 0 80220 8 5 . 1 22 . 4 0 80221 8 2 . 5 20 . 7 0 80224 74 . 5 19. 9 0 80222 7 9 . 8 19. 9 0 80228 8 5 . 1 22 . 4 0 80225 7 9 . 8 2 0 . 4 0 80223 74 . 5 19. 9 0 80229 9 0 . 5 2 3 . 4 0 80226 8 2 . 5 21 . 4 0 80227 8 7 . 8 22 . 9 0 80230 7 9 . 8 19. 9 0 80232 6 6 . 5 13. 9 0 80306 7 7 . 2 16. 7 0 80324 61 . 2 13. 2 0 80339 74 . 5 19. 2 0 80344 6 9 . 2 16. 9 0 80367 7 7 . 2 19. 2 0 80375 7 9 . 8 19. 9 0 80371 8 2 . 5 18. 4 0 80618 82 . 5 2 6 . 4 0 80662 8 5 . 1 24 . 9 0 80672 8 5 . 1 22 . 2 SQUITO WEIR: 1 79001 101. 1 58 . 8 1 79006 46 . 8 9. 9 1 79017 105. 4 26 . 6 1 79032 92 . 9 24 . 4 1 79049 1 0 8 . 3 35 . 9 1 79059 5 3 . 7 18. 7 1 79055 7 8 . 8 24 . 7 1 79066 77 . 4 22 . 2 1 79072 2 7 . 1 9. 7 1 79081 34 . 0 10. 4 1 79088 8 3 . 0 2 3 . 4 1 79098 35 . 6 1 1 . 41 79106 32 . 7 12. 9 Mg Na K PH Date Time Q 1/s 2.8 14. 3 1 .5 6. 38 190680 1 100 4 .40 2.8 15. 2 1 .7 240680 400 3 .98 2.8 14. 7 1 .7 6. 36 200680 1 1 00 4 .88 2.8 13. 9 1 .7 6. 33 200680 500 6 .08 2.8 15. 2 1 .7 6. 28 210680 1 100 4 . 64 2.8 14. 3 1 .7 6. 34 200680 1 700 4 .76 2.8 13. 0 1 .5 6. 32 190680 2300 7 .69 2.8 13. 9 1 .7 6. 29 210680 500 5 .87 2.8 13. 4 1 .7 6. 31 200680 2300 6 .67 3.2 15. 2 1 .7 6. 1 4 240680 600 3 .84 3.2 16. 0 1 .7 6. 26 240680 800 3 .74 3.2 16. 0 1 .7 6. 09 240680 1000 3 .63 2.8 14. 3 2 .0 6. 00 230680 1 520 3 .95 3.2 15. 6 1 .7 6. 20 240680 1 200 3 . 58 2.8 15. 6 1 .7 6. 1 6 240680 1 400 3 .58 2.8 14. 7 1 .5 6. 1 2 240680 1 600 4 .52 2.8 13. 9 1 .7 5. 98 240680 1800 5 .80 2.8 13. 9 1 .5 5. 71 250680 0 6 .89 2.8 13. 4 1 .5 6. 02 240680 2000 6 .97 2.8 15. 2 1 .7 6. 10 250680 800 4 .88 2.8 13. 9 1 .5 5. 98 250680 200 6 .37 2.8 13. 9 1 .7 6. 08 240680 2200 7 .29 2.8 15. 6 1 .7 6. 10 250680 1 000 4 .52 2.8 14. 3 1 .7 6. 1 5 250680 400 5 .73 2.8 16. 0 2 .5 6. 12 250680 600 5 .26 2.8 13. 9 1 .5 6. 14 250680 1 200 4 .23 2.0 10. 8 1 .0 5. 70 250680 2030 6 .22 2.4 12. 6 1 .5 6. 04 120780 810 4 .29 1 .6 10. 8 1 .2 6. 04 120780 21 30 7 .45 2.8 13. 9 1 .2 6. 04 130780 1 103 3 .95 3.2 12. 6 1 .2 1 40780 825 4 .64 2.4 17. 3 1 .5 10880 1 122 0 .41 2.8 2 0 . 0 1 .5 120880 959 2.8 16. 9 1 .7 20880 1 659 0 .77 2.8 16. 5 2 .0 6. 36 1 1 080 1349 0 .22 3.2 17. 8 2 .3 6. 45 21 080 1 435 0 .10 3.7 17. 3 1 .7 51080 1000 8.6 2 8 . 2 4 .3 6. 06 180579 1015 0 .02 2.0 3. 9 1 .5 5. 60 260579 820 3.2 24 . 3 0 .7 150679 915 0 .48 3.2 2 6 . 9 1 .7 180679 1 326 0 .73 4 .5 2 7 . 4 1 .7 220679 834 0 .73 2.4 16. 9 1 .2 6. 40 220679 1956 1 .04 2.8 2 0 . 0 1 .2 230679 1 150 0 .62 2.8 12. 6 1 .5 250679 1009 0 .81 1 .2 5. 6 0 .7 250679 1 757 4 .01 1 .2 2. 6 0 . 7 5. 81 290679 1742 4 .01 2.8 9. 1 2 . 3 20779 1 100 0 .29 1 .2 2. 6 0 !o 6. 07 50779 1 640 3 .90 1 .2 2. 1 0 .5 80779 1300 4 .23 t e ID# S i ( O H ) « C a Mg N a 7 9 1 1 1 7 3 . 4 2 4 . 7 2. 4 1 5 . 2 7 9 1 2 0 8 9 . 7 2 5 . 6 2 . 8 1 6 . 0 7 9 1 2 7 8 7 . 0 2 8 . 1 2 . 8 1 6 . 5 7 9 1 31 91 . 0 3 0 . 1 2 . 8 1 6 . 9 7 9 1 3 3 8 5 . 4 2 8 . 4 2 . 8 1 6 . 9 7 9 1 4 4 8 7 . 0 31 . 9 2. 8 1 7 . 8 7 9 1 4 1 91 . 0 3 0 . 9 3. 2 1 8 . 2 7 9 1 4 9 9 9 . 0 3 6 . 6 3. 2 2 0 . 4 7 9 1 4 7 1 0 7 . 2 3 4 . 4 2. 8 1 9 . 5 7 9 1 6 0 1 0 7 . 2 4 5 . 4 4. 1 21 . 7 7 9 1 7 2 7 0 . 0 2 2 . 2 2. 4 1 9 . 5 7 9 1 8 6 1 0 3 . 5 3 3 . 6 3. 2 1 9 . 5 7 9 1 9 8 1 0 5 . 1 41 . 1 3. 7 2 0 . 8 7 9 2 0 3 1 0 7 . 8 4 5 . 6 4. 1 2 2 . 6 8 0 0 0 2 8 5 . 1 3 0 . 9 4. 1 1 5 . 2 8 0 0 0 8 1 0 1 . 1 2 9 . 4 4. 1 1 5 . 6 8 0 0 2 6 8 7 . 8 2 6 . 6 4. 1 1 6 . 9 8 0 0 3 0 9 3 . 1 3 0 . 1 4. 1 1 6 . 5 8 0 0 4 9 9 5 . 8 2 9 . 9 4. 1 1 8 . 2 8 0 0 8 6 1 0 6 . 4 2 8 . 9 3. 7 1 8 . 2 8 0 0 9 0 1 0 3 . 8 2 8 . 4 3. 7 1 7 . 8 8 0 0 9 7 9 5 . 8 2 6 . 1 3 . 7 1 7 . 3 8 0 0 9 2 1 0 6 . 4 31 . 4 4. 1 1 6 . 0 8 0 0 9 9 1 0 6 . 4 2 8 . 9 4. 1 1 9 . 5 8 0 0 9 3 1 0 3 . 8 31 . 1 4. 1 1 6 . 9 8 0 0 9 8 1 0 1 . 1 2 8 . 1 4. 1 1 6 . 9 8 0 0 9 6 1 0 6 . 4 3 0 . 9 4. 1 1 9 . 5 8 0 0 9 5 1 0 6 . 4 2 9 . 6 4. 1 1 7 . 8 8 0 0 9 1 1 0 3 . 8 2 9 . 1 3. 7 1 8 . 2 8 0 0 9 4 1 0 6 . 4 3 0 . 4 4. 1 1 7 . 8 8 0 1 1 3 9 3 . 1 2 6 . 6 3 . 2 1 6 . 5 8 0 1 2 4 1 0 6 . 4 2 7 . 4 4. 1 1 7 . 3 8 0 1 3 4 1 0 3 . 8 2 7 . 9 4. 1 1 9 . 1 8 0 1 4 3 8 2 . 5 2 5 . 4 3. 2 1 4 . 3 8 0 1 5 3 9 5 . 8 2 6 . 6 3 . 2 1 6 . 0 8 0 1 6 2 1 0 3 . 8 2 6 . 6 3. 7 1 6 . 0 8 0 2 0 9 1 0 6 . 4 2 8 . 1 3 . 7 1 7 . 3 8 0 2 3 3 9 3 . 1 2 4 . 9 3 . 2 1 5 . 6 8 0 3 0 5 1 0 3 . 8 2 7 . 6 3. 7 1 7 . 3 8 0 3 4 5 9 8 . 5 2 6 . 9 3 . 7 1 6 . 9 8 0 3 4 9 9 3 . 1 2 5 . 4 3 . 2 1 6 . 0 8 0 3 4 8 8 7 . 8 2 6 . 4 3. 2 1 6 . 9 8 0 3 4 7 9 5 . 8 2 6 . 4 3. 7 1 6 . 5 8 0 3 5 3 8 2 . 5 2 4 . 9 3 . 2 1 6 . 5 8 0 3 5 2 8 7 . 8 2 4 . 2 3. 2 1 5 . 6 8 0 3 5 7 9 5 . 8 2 7 . 4 3. 7 1 6 . 5 8 0 3 5 0 8 2 . 5 2 4 . 4 3. 2 1 5 . 6 8 0 3 5 5 8 5 . 1 2 6 . 4 3 . 7 1 6 . 5 8 0 3 5 1 8 5 . 1 2 4 . 4 3 . 2 1 5 . 6 8 0 3 5 8 9 8 . 5 2 7 . 1 3 . 2 1 6 . 5 8 0 3 5 9 9 3 . 1 2 7 . 4 3. 7 1 6 . 5 K p H D a t e T i m e Q 1/ s 2 .0 2 0 0 7 7 9 1 6 0 4 0 . 7 3 2 .3 2 1 0 7 7 9 1 6 5 5 0 . 5 5 2 .0 2 2 0 7 7 9 1 9 4 0 0 . 3 6 2 .0 2 3 0 7 7 9 1 0 0 0 1 . 0 3 2 .3 2 3 0 7 7 9 1 651 0 .31 2 .0 2 5 0 7 7 9 1 1 1 0 0 . 1 2 2 .5 6 . 2 0 2 4 0 7 7 9 1 0 2 0 0 . 1 3 2 .0 1 0 8 7 9 1 7 0 0 0 .02 2 .0 2 9 0 7 7 9 1 5 5 0 0 .04 2 .5 6 0 9 7 9 1 6 0 0 0 . 1 1 2 .8 8 0 9 7 9 1 3 4 5 2 . 0 9 2 .5 1 0 0 9 7 9 1 6 3 5 0 . 4 5 2 .3 2 3 0 9 7 9 1 2 3 0 0 .02 2 .5 51 0 7 9 1 9 0 0 0 .02 2 .5 1 7 0 5 8 0 1 8 4 9 0 . 9 5 2 .0 6 . 3 0 1 0 6 8 0 1 2 5 0 1 .74 2 .0 1 0 0 6 8 0 8 1 0 2 .92 2 .3 6 . 1 6 9 0 6 8 0 1 1 3 0 2 .74 2 .0 6 . 1 0 1 0 0 6 8 0 2 0 3 3 2 . 1 7 2 .3 6 .24 1 2 0 6 8 0 9 5 0 1 .68 2 .3 6 . 2 0 1 1 0 6 8 0 2 3 0 2 . 0 6 2 .3 6 . 2 7 1 2 0 6 8 0 2 2 0 0 2 .21 2 .0 6 . 2 5 1 1 0 6 8 0 1 4 3 0 1 .74 2 .3 6 .34 1 3 0 6 8 0 1 2 0 0 2 . 3 6 2 .3 6 .24 1 1 0 6 8 0 2 0 3 2 1 .68 2 .0 6 . 2 7 1 3 0 6 8 0 6 0 0 2 .57 2 .5 6 . 3 3 1 2 0 6 8 0 1 4 3 0 1 .68 2 .0 6 .32 1 2 0 6 8 0 8 3 0 1 .71 2 .3 6 . 16 1 1 0 6 8 0 8 3 0 1 . 9 5 2 .0 6 . 3 0 1 2 0 6 8 0 2 3 0 1 .68 2 .3 6 . 2 2 1 3 0 6 8 0 2 3 0 2 .74 2 .5 6 . 2 0 1 3 0 6 8 0 8 5 0 2 .41 2 .5 6 . 2 6 1 3 0 6 8 0 1 5 0 6 2 .41 2 .0 6 . 0 5 1 3 0 6 8 0 2 0 3 9 3 . 8 0 2 .3 6 . 2 2 1 4 0 6 8 0 2 3 7 3 .90 2 .3 6 . 2 6 1 4 0 6 8 0 8 3 4 3 .20 2 .0 6 . 3 2 2 3 0 6 8 0 1 5 1 4 2 . 1 7 1 .7 6 . 1 0 2 5 0 6 8 0 2 0 3 7 3 . 1 0 2 .3 6 . 3 0 1 2 0 7 8 0 8 0 2 2 . 3 3 1 .7 1 4 0 7 8 0 8 3 0 2 .41 1 .7 1 2 0 7 8 0 1 4 0 0 2 .41 1 .7 1 2 0 7 8 0 1 2 0 0 2 . 1 7 1 .7 1 2 0 7 8 0 1 0 3 0 2 . 0 9 1 .7 1 2 0 7 8 0 2 2 0 0 3 . 2 9 1 .7 1 2 0 7 8 0 2 0 0 0 3 . 4 9 1 t .7 1 3 0 7 8 0 6 0 0 2 .57 1 .7 1 2 0 7 8 0 1 6 0 0 3 . 1 0 2 .0 1 3 0 7 8 0 2 0 0 2 .92 1 .5 1 2 0 7 8 0 1 8 0 0 3 . 2 9 1 .7 1 3 0 7 8 0 8 0 0 2 .41 1 .7 1 3 0 7 8 0 1 0 0 0 2 . 2 5 248 te ID# Si(OH) « Ca Mg Na K PH Date Time Q 1/s 1 80356 85. 1 26.9 3.7 16. 5 1 .7 130780 400 2 .74 1 80354 93. 1 25.9 3.2 16. 0 1 .7 130780 0 3 .10 1 80361 82.5 26.9 3.2 16. 0 1 .7 130780 1 400 2 .25 1 80364 82.5 24.7 3.2 15. 6 1 .7 130780 2000 2 .92 1 80365 82.5 23.7 3.2 15. 6 1 .7 130780 2200 2 .92 1 80362 87.8 25.4 3.2 15. 6 1 .5 130780 1600 2 .57 1 80360 87.8 26.4 3.7 16. 5 2.0 130780 1 200 2 .09 1 80363 82.5 24.2 3.2 16. 0 2.3 1 30780 1800 3 .01 1 80368 90.5 27.9 3.2 17. 3 1 .7 1 0880 1 126 0 .51 1 80376 90.5 33.6 3.7 20. 0 2.0 120880 1 002 0 .34 1 80372 82.5 26.9 3.2 16. 9 2.0 20880 1704 0 .73 1 80385 106.4 40.4 4.1 19. 5 1 .7 280780 1 400 0 .00 1 80380 117.1 37.6 3.7 20. 8 1 .7 180780 1 726 0 .06 1 80395 106.4 43.4 4.1 20. 0 1 .2 120980 1 040 0 .01 1 80418 106.4 41.4 4. 1 20. 4 1 .7 120980 1 740 0 .01 1 80422 119.8 44. 1 4.5 21 . 7 1 .7 130980 930 0 .02 1 80479 95.8 43'. 9 4.1 19. 1 1.7 190980 1 1 00 0 .06 1 80600 95.8 29.9 3.7 16. 9 1 .7 6 . 12 300980 1 600 0 .81 1 8061 9 1 06.4 36. 1 3.7 18. 7 1 .7 6 .33 1 1080 1410 0 .45 1 80660 109. 1 35.9 4. 1 20. 4 2.3 6 .30 21 080 1428 0 .31 1 80671 114.4 39.9 4.5 20. 4 2.0 51080 1000 0 .02 1 80703 106.4 44.6 3.7 18. 7 1 .7 151080 0 0 .00 SQUITO FAN SUBSURFACE SITE • 2 79002 105.4 58.3 7.4 29. 5 2.3 5 .30 180579 1 009 2 79007 63.6 12.4 1 .6 13. 0 1 .2 5 .70 260579 830 2 79016 109.6 35.4 3.7 29. 1 1 .5 150679 915 2 79033 111.0 34.6 3.7 26. 9 1 .5 180679 1 330 2 79050 92.9 33.4 3.2 22. 1 1 .5 220679 840 2 79056 77.4 38.6 3.7 27. 8 2.0 230679 1 1 59 2 79060 46.8 26.6 2.8 19. 5 1 .5 5 .96 220679 1 954 2 79065 78.8 34.9 3.7 16. 9 2.5 250679 1 024 2 79071 25.8 11.2 1 .2 6. 9 1 .2 250679 1 750 2 79086 84.3 37.6 4.1 13. 4 2.3 20779 1 100 2 79082 80.4 35.9 3.7 12. 6 0.7 5 .93 290679 1 750 2 79097 77.4 37.9 3.7 13. 0 1 .5 5 .93 50779 1 625 2 791 07 71.8 36. 1 3.2 10. 4 2.0 80779 1 300 2 79119 120.8 42.9 4. 1 25. 2 4.8 210779 1 655 2 791 12 1 20.8 42. 1 4. 1 23. 9 4.3 200779 1 620 2 791 25 127.5 41 .4 4.1 23. 4 4.3 220779 1930 2 791 30 117.9 43. 1 4.1 23. 9 4.3 230779 1000 2 791 34 120.8 42. 1 4.1 24. 3 4.3 230779 1 654 2 79148 1 24.8 43.4 4.1 24. 7 4.0 290779 1 550 2 791 45 131.5 44. 1 4.5 24. 3 3.8 250779 1115 2 791 42 131.7 42.9 4. 1 24. 3 4.3 5 .93 240779 1030 2 79156 142.4 61 .3 5.7 34. 3 6.3 130879 1200 2 79155 139.7 58.3 5.3 30. 0 5.1 1 10879 1 200 2 79150 131.5 45.9 4.5 27. 4 5.1 1 0879 1710 249 S i t e ID# S i (OH) „ Ca Mg Na 2 791 52 1 37. 1 53. 8 5.3 28.7 2 791 58 131.5 65. 1 5.7 29. 1 2 791 61 123.5 58. 3 5.3 26.0 2 791 73 113.4 53. 3 4.9 24.7 2 79199 124.6 54. 3 4.9 25.6 2 79194 121.9 52. 6 4.9 24.7 2 79204 121.9 49. 6 4.5 24.7 2 80007 90.5 41 . 9 4.5 18.2 2 80009 87.8 40. 1 4.1 16.0 2 80029 74.5 40. 6 4. 1 26.9 2 80051 79.8' 38. 1 4. 1 17.3 2 80067 85. 1 39. 6 4.1 18.2 2 80060 82.5 37. 9 4.1 18.2 2 80069 85. 1 39. 4 4.5 16.9 2 80089 85. 1 41 . 6 4.1 18.7 2 80085 85. 1 38. 9 4.5 16.5 2 801 03 85. 1 40. 9 4.5 16.9 2 801 1 2 85. 1 38. 4 4.1 16.9 2 80123 87.8 36. 6 4. 1 19.1 2 801 33 87.8 37. 1 4. 1 17.8 2 801 42 79.8 39. 6 4.1 17.3 2 801 52 85. 1 37. 1 3.7 15.2 2 80161 85. 1 36. 6 4.1 17.8 2 8021 0 90.5 36. 1 4. 1 17.3 2 80234 85. 1 34. 9 3.7 16.0 2 80304 87.8 33. 1 3.7 16.5 2 80323 79.8 32. 9 3.7 17.8 2 80338 82.5 32. 1 3.7 16.9 2 80346 82.5 32. 6 3.7 16.5 2 80369 106.4 39. 1 4.5 24.3 2 80377 117.1 43. 4 4.9 27.8 2 80373 106.4 39. 1 4.5 24.3 2 80386 133. 1 45. 6 4.5 24.7 2 80388 127.7 45. 6 4.5 24.3 2 80381 138.4 41 . 1 4.5 25.6 2 80394 1 35.7 50. 1 5.3 26.0 2 8041 7 1 30.4 46. 9 5.3 25.6 2 80421 127.7 45. 9 4.9 24.7 2 80450 1 30.4 46. 9 4.5 24.3 2 80478 133. 1 52. 1 5.7 25.2 2 80603 114.4 49. 4 4.9 23.4 2 80620 117.1 48. 6 4.5 23.9 2 80661 122.4 46. 1 4.9 25.2 2 80670 122.4 44. 9 5.3 24.7 HUMMINGBIRD CHANNEL ARTESIAN TEST 5 80674 471 .2 56. 1 34.5 39.5 K pH Date Time Q 1/s 4.8 100879 1 030 5.1 240879 1 300 4.0 60979 1610 4.0 80979 1 350 4.3 230979 1 230 4.0 100979 1 630 4.0 51 079 1900 2.8 290580 1 650 2.8 6 .20 1 0680 1 300 2.8 5 .96 90680 1 1 25 2.8 6 .05 100680 2117 3.0 6 .00 110680 1 445 2.8 6 .30 110680 837 2.8 5 .96 110680 2040 2.8 5 .88 120680 1630 2.5 6 .05 120680 945 2.5 5 .98 120680 2025 2.8 6 .01 130680 225 3.5 6 .01 130680 844 2.8 5 .97 130680 1 506 2.5 5 .96 130680 2036 2.5 5 .96 140680 240 2.5 6 .00 140680 830 2.8 6 .05 230680 1516 2.3 6 .02 250680 2050 2.5 6 .06 120780 805 2.5 5 .99 120780 2125 2.3 5 .93 130780 1 052 2.3 140780 832 3.5 1 0880 1 1 36 4.8 120880 1014 3.5 20880 1715 4.0 280780 1 400 3.3 90980 4.0 180780 1737 3.5 120980 1 040 4.0 120980 1740 3.8 130980 930 3.5 170980 1200 3.5 190980 1 100 3.5 6 .00 300980 1 620 3.5 5 .90 1 1080 1 430 3.8 5 .96 21080 1 430 3.5 51080 1000 S ITE: 18.4 51080 1000 250 S i t e ID# S i ( O H ) „ Ca HUMMINGBIRD WEIR: 6 79003 22 . 8 7. 2 6 79008 9. 0 3. 7 6 79019 22 . 8 3. 4 6 79034 3 9 . 6 6. 4 6 79035 2 8 . 4 4. 4 6 79036 38 . 3 4. 9 6 79037 42 . 5 3. 7 6 79047 2 8 . 4 5. 4 6 79057 9. 0 3 3 . 4 6 79053 4 9 . 5 3. 7 6 79068 0. 5 2. 9 6 79074 18. 6 1 . 2 6 79089 34 . 0 7. 9 6 79083 2 5 . 8 1 . 2 6 791 09 100. 3 14. 9 6 79104 9. 0 3. 7 6 791 00 10. 3 1 . 9 6 791 77 32 . 2 5. 7 6 79182 8 6 . 7 10. 9 6 80025 3 9 . 9 7. 4 6 80032 42 . 5 7. 9 6 80052 5 0 . 5 7. 7 6 80062 5 3 . 2 7. 7 6 80068 55 . 9 8. 7 6 80078 55 . 9 8. 4 6 801 01 4 7 . 9 7. 4 6 801 10 42 . 5 7. 2 6 801 21 4 7 . 9 7. 4 6 801 31 5 3 . 2 7. 4 6 801 40 42 . 5 8. 9 6 80159 4 7 . 9 6. 4 6 801 50 34 . 6 6. 4 6 801 68 6 6 . 5 13. 7 6 80169 5 3 . 2 7. 4 6 801 70 4 7 . 9 7. 2 6 8021 4 61 . 2 6. 9 6 80237 4 7 . 9 5. 9 6 80302 5 5 . 9 6. 2 6 80318 42 . 5 5. 7 6 80337 58 . 5 6. 9 6 80342 55 . 9 6. 2 6 80366 9 8 . 5 1 1 . 96 80374 1 2 7 . 7 2 5 . 6 6 80370 9 8 . 5 12. 4 6 80601 5 8 . 5 8. 2 6 80668 8 5 . 1 12. 9 6 80673 119. 8 18. 4 Mg Na K PH D a t e T ime Q 1/s 2.4 13. 0 3.8 5 .04 180579 1 1 05 0 .77 1 .2 13. 9 2.0 5 . 1 2 260579 815 1 .2 10. 4 2.5 5 .56 150679 945 0 .03 0.8 13. 0 1 .2 190679 0 1.31 0.8 13. 9 2.0 200679 402 1.15 1 .2 12. 6 1 .7 190679 1 520 0.31 0.8 12. 6 1 .2 190679 21 32 1 .88 0.8 12. 6 1 .7 220679 830 0 .34 4 .9 15. 6 2.0 5 .30 220679 2005 0 .65 0.8 1 1 . 3 1 .7 230679 1 1 45 0.18 1 .2 13. 4 8.4 250679 1 036 0 .20 0 .4 0. 0 2.8 250679 1805 4 .35 1 .2 3. 9 1 .2 20779 1 100 0 .05 0 .4 0. 0 0.2 5 .29 290679 1 748 2.83 1 .2 2 3 . 0 2.5 200779 1 630 0.01 0 .0 0. 0 1 .5 80779 1 300 3.29 0 .0 0. 0 1 .0 5 .24 50779 1 630 3.10 0 .4 5. 6 4.8 80979 1415 0 .77 0.8 16. 0 1 .2 100979 1635 0 .03 1 .2 7. 3 0 .7 100680 750 0 .95 1 .2 7. 8 0 .7 5 .46 90680 1253 0 .79 1 .2 8. 6 1 .0 100680 201 5 0 .62 1 .2 8. 6 1 .0 5 .00 110680 815 0 .55 1 .2 10. 0 1 .2 5 .50 110680 2027 0 .42 1 .2 9. 5 1 .0 5 .60 120680 918 0 .45 1 .2 7. 8 0 .7 5 .50 120680 1 956 0 .65 1 .2 8. 2 1 .2 5 .53 130680 202 1.31 1 .2 7. 8 1 .0 5 .53 130680 810 1 .00 1 .2 10. 4 1 .5 5 .53 1 30680 1 448 0.81 1 .2 7. 3 1 .0 5 .46 130680 201 3 1 .37 0.8 6. 5 0 .7 5 .49 140680 809 1 .25 0.8 6. 9 1 .5 5 .43 140680 200 2.02 1 .6 10. 0 1 .2 5 .84 1 40680 1200 1 .00 1 .2 12. 6 2.0 5 .52 140680 1400 1 .02 1 .2 9. 1 1 .2 5 .58 140680 1600 1.10 0.8 9. 1 0 .5 5 .55 230680 1532 0 .62 0.8 7. 8 0 .5 5 .55 250680 2045 1 .43 0.8 9. 1 0.7 5 .61 120780 743 0.81 0.8 7. 3 0 .5 5 .94 120780 2111 1 .95 0.8 9. 5 0 .5 5 .64 130780 1 038 0 .69 1 .2 9. 1 0 .5 140780 814 0 .95 1 .6 21 . 7 1 .2 1 0880 1114 2.8 37 . 8 4.3 120880 955 1 .6 22 . 1 1.5 20880 1655 0.8 1 1 . 3 1 .5 5 .84 300980 1607 1.2 17. 8 1.5 6 .12 21080 1510 3.7 21 . 3 2.0 51080 1000 251 S i t e ID# Si(OH), Ca Mg Na K pH Date Time Q 1/s HUMMINGBIRD SURFACE DETENTION STORAGE SITE (HB POND) 7 79042 34.0 3. 7 0 .4 10. 8 1 .7 190679 1612 7 79103 4.7 2. 2 0 .4 0. 0 1 .5 50779 0 7 79190 46.3 6. 2 2 .0 4. 3 6 .9 100979 1650 7 80325 37.2 3. 7 0 .8 5. 6 0 .5 120780 2200 7 80606 13.3 3. 7 1 .6 3. 4 1 5 .3 5. 35 300980 1 740 MOSQUITO ( CHANNEL SITE #2 8 791 1 6 77.4 24. 4 2 .8 15. 6 2 .5 200779 1 650 8 791 21 82.8 23. 9 2 .8 15. 6 2 .5 210779 1 658 8 79139 93.7 27. 9 3 .7 19. 5 2 .8 230779 1 725 8 79169 65.7 22. 4 2 .0 12. 1 2 .0 80979 1 320 8 79188 99.5 29. 4 3 .2 18. 2 2 .5 100979 1 650 8 80616 98.5 29. 6 3 .2 17. 3 2 .3 6. 1 2 300980 1915 8 80622 1 03.8 32. 4 3 .7 17. 8 2 .3 6. 22 1 1 080 1 435 MOSQUITO CHANNEL SITE #1 9 79029 116.6 22. 4 3 .7 31 . 7 3 .0 180679 1 200 9 79096 3'9.6 12. 7 1 .2 2. 6 0 .7 50779 0 9 791 1 7 69.2 18. 4 2 .4 10. 8 1 .7 200779 1 655 9 79123 55.9 17. 7 2 .4 12. 1 2 .0 210779 1700 9 791 29 63.8 20. 2 2 .8 14. 3 2 .5 220779 1950 9 791 36 63.8 21 . 2 3 .7 13. 0 2 .5 230779 1710 9 79168 64.4 14. 9 2 .0 10. 8 1 .7 80979 1 325 9 79187 105.1 21 . 7 2 .8 17. 8 2 .8 100979 1 640 9 80054 117.1 28. 9 4 .5 20. 4 2 .8 100680 2045 9 80061 1 19.8 29. 6 4 .5 20. 4 2 .8 6. 25 110680 840 9 80073 1 27.7 33. 1 4 .9 22. 1 3 .0 6. 28 110680 2035 9 80084 1 30.4 28. 9 4 .9 20. 8 3 .0 6. 38 120680 940 9 801 02 1 19.8 28. 4 4 .5 22. 1 3 .5 6. 1 0 120680 201 6 9 801 1 1 114.4 27. 6 4 . 1 18. 7 2 .5 6. 20 130680 220 9 80122 125.1 29. 4 4 .5 21 . 3 3 .3 6. 20 130680 838 9 801 32 125.1 28. 6 4 .5 22. 1 3 .3 6. 28 130680 1 455 9 801 41 95.8 25. 1 4 . 1 17. 8 2 .5 6. 1 2 130680 2027 9 801 51 101.1 28. 1 4 . 1 17. 3 2 .8 6. 29 140680 230 9 801 60 119.8 28. 6 4 .5 19. 5 2 .8 6. 24 140680 822 9 80208 1 30.4 31 . 4 4 .5 21 . 7 3 .0 6. 27 230680 1 500 9 80236 111.8 28. 4 4 .5 18. 2 2 .5 6. 08 250680 2040 9 80303 1 22.4 31 . 4 4 .9 21 . 7 2 .8 6. 32 120780 759 9 80322 103.8 27. 4 4 .5 18. 2 2 .3 6. 22 120780 21 20 9 80340 114.4 30. 4 1 .6 20. 0 2 .3 6. 03 130780 1 049 9 8041 9 63.8 18. 9 3 .2 12. 1 2 .0 120980 1 740 9 8061 3 101.1 21 . 2 2 .8 15. 6 2 .3 5. 99 300980 1850 9 8061 7 101.1 0. 7 0 .4 3. 4 1 .7 4. 65 300980 0 9 80623 1 06.4 22. 9 3 .2 18. 7 2 .8 6. 22 1 1 080 1437 9 80665 109. 1 21 . 2 3 .2 18. 7 3 .0 6. 15 21080 1 452 HUMMINGBIRD CHANNEL SITE : #1(CHB1) 10 79039 9.0 36. 1 6 . 1 18. 2 2 .0 190679 2150 10 79038 27. 1 25. 9 4 .5 15. 6 2 .0 190679 1615 10 80607 47.9 5. 4 0 .8 9. 5 2 .0 5. 22 300980 1 750 252 S i t e ID# S i ( O H ) 4 Ca Mg HUMMINGBIRD CHANNEL S I T E #2 11 79041 11.7 4. 4 0. 4 11 79040 2 8 . 4 2 3 . 2 3. 2 11 791 79 37 .8 2. 4 0. 4 11 80053 29 .2 3. 2 0. 8 11 80063 3 1 . 9 2. 7 0. 4 11 80077 2 6 . 6 2. 9 0. 8 11 80109 18.6 2. 2 0. 4 11 801 00 2 3 . 9 2. 4 0. 4 11 801 20 2 9 . 2 2. 7 0. 8 11 801 39 2 3 . 9 2. 2 0. 4 11 801 30 3 1 . 9 3. 2 0. 8 11 801 49 18.6 1 . 9 0. 8 11 801 58 31 .9 2. 4 0. 4 11 8021 5 3 4 . 6 2. 4 0. 8 11 80235 2 3 . 9 2. 4 0. 8 11 80301 3"4.6 2. 4 0. 8 11 8031 7 2 3 . 9 3. 2 0. 8 11 80336 3 7 . 2 3. 2 1. 2 11 80605 3 7 . 2 2. 4 0. 8 HUMMINGBIRE P2 1 3 79043 5 0 . 8 56 . 1 8. 2 1 3 79046 5 6 . 4 20 . 7 8. 2 HUMMINGBIRE P3 1 4 7901 5 2 2 . 8 8. 7 4. 5 1 4 79045 3 7 . 0 34 . 4 3. 7 HUMMINGBIRE P1 1 22 79044 31 .4 0. 9 2. 0 POND, WEST SHORE 27 79069 2 5 . 8 7. 4 1 . 2 27 79070 10.3 3. 7 1 . 2 27 791 57 5 9 . 9 16. 2 2. 0 27 79202 6 8 . 6 27 . 1 2. 8 27 79200 7 4 . 2 24 . 2 2. 8 27 80383 9 8 . 5 24 . 4 2. 8 27 80396 9 0 . 5 22 . 7 2. 8 27 80423 9 3 . 1 21 . 4 2. 8 27 80602 71 .8 2 3 . 2 2. 8 27 80704 9 3 . 1 34 . 1 3. 2 POND, NORTH SHORE 28 79052 4 3 . 9 7. 2 1 . 2 28 79051 4 3 . 9 61 . 1 8. 2 28 791 53 7 6 . 1 19. 7 2. 0 28 791 51 6 9 . 2 21 . 7 2. 4 Na K PH D a t e T ime (CHB2) 10. 4 1 .0 190679 2200 15. 6 1 .7 190679 1625 3. 9 2.8 80979 1430 5. 2 1 .0 100680 21 30 4. 3 0.7 5 .30 1 10680 805 2 9 . 1 6.3 5 .47 120680 914 3. 4 0 .5 5 .25 130680 156 3. 4 0.5 5 .12 120680 1 948 6. 9 1 .7 5 .27 130680 804 3. 9 1 .0 5 .24 130680 2007 6. 0 1 .5 5 .30 130680 1 445 3. 4 0 .7 5 .21 140680 223 4. 3 1 .0 5 .26 140680 802 4. 3 0 .5 5 .36 230680 1 540 3. 9 0 .5 5 .22 250680 201 5 9. 5 0 .5 5 .49 120780 737 3. 4 0.2 5 .48 120780 21 07 4. 7 0.5 5 .26 130780 1033 7. 3 2.0 5 .23 300980 1730 1 4 3 . 9 16.3 190679 1540 32 . 6 14.0 190679 1800 2 3 . 4 2.8 140679 1 334 24 . 7 6.1 190679 1700 21 . 3 4 .6 190679 1 640 10. 4 2.3 250679 1 1 30 3. 0 1 .5 250679 1 1 00 2 0 . 8 3.8 240879 1 300 19. 5 2.5 51 079 1900 19. 5 3.3 230979 1 230 22 . 6 2.3 260780 1 350 2 0 . 8 2.0 120980 1 040 21 . 3 2.5 130980 930 15. 2 2.0 6 .12 300980 1650 2 0 . 8 2.8 151080 0 2 5 . 2 2.5 220679 850 24 . 7 2.8 220679 850 2 9 . 1 4.8 100879 1 040 18. 7 2.5 1 0879 1715 Q 1 / s 253 S i t e ID# Si(OH), Ca MOSQUITO STANDPIPE SI 30 79077 1 1 . 7 5 .9 30 791 63 34. 0 6 .7 30 80205 71 . 8 21 .4 30 80240 39. 9 8 .9 30 8031 3 1 22. 4 39 .4 30 80327 61 . 2 22 .9 MOSQUITO S2 31 7901 3 64. 9 82 .8 31 79021 1 20. 8 65 . 1 31 79031 115. 2 41 .4 31 79030 115. 2 32 . 1 31 79078 64. 9 16 .4 31 791 1 5 53. 2 18 .7 31 79184 113. 4 24 .7 31 8031 2 1 09. 1 29 .6 31 80335 1 17. 1 32 . 1 RESIDUAL : S4 33 79025 22. 8 6 .7 33 79174 75. 6 5 .4 HUMMINGBIRD S5 34 791 78 25. 2 2 .7 34 79185 33. 5 9 .9 34 79180 29. 5 3 .9 MOSQUITO : S8 37 7901 4 15. 9 773 .4 37 79022 53. 7 1 26 .7 37 79026 46. 8 53 .6 37 79028 1 1 . 7 76 .8 37 79023 50. 8 166 .6 37 79027 39. 6 44 .9 37 79076 13. 0 1 1 .2 37 79093 73. 2 1 3 .7 37 791 64 42. 0 4 .9 37 80206 23. 9 12 .7 37 8031 1 21 . 2 1 1 .9 37 80328 21 . 2 6 .9 37 80334 23. 9 19 .2 MOSQUITO ! S9 38 79075 71 . 8 17 .2 38 79095 18. 6 4 .9 38 791 1 4 72. 1 19 .2 38 79122 78. 8 20 .7 38 791 65 57. 5 9 .4 38 79197 61 . 7 1 1 .4 38 80207 58. 5 6 .9 38 80238 58. 5 7 .2 38 8031 0 61 . 2 8 .7 38 80329 39. 9 7 .4 Mg Na K pH Date Time head (cm) 2.0 0.0 0.7 250679' 1 927 1 .2 8.2 2.3 80979 1300153.20 4. 1 16.9 4.8 6 .15 230680 1750 1 .6 7.3 1 .2 5 .74 250680 21 20 6.5 30.8 4.0 5 .83 120780 1 200 4.9 13.9 3.3 6 .06 120780 21 40 18.5 53.0 9.9 140679 1231 9.8 36.9 5.1 160679 1225 6.1 35.6 4.8 180679 1 240 5.3 39.5 5.1 180679 1 230 3.2 10.4 0.5 250679 1930 2.4 12.6 2.5 200779 1 645 2.8 18.7 2.8 100979 1 650 4.5 24.3 3.5 6 .27 120780 1 1 45 4.9 25.6 4.6 6 .20 130780 1 1 30 3.7 25.2 6.3 180679 1230 4. 1 11.3 8.9 80979 1 355 1 .6 4.7 20.4 80979 1420154.80 9.0 11.7 19.1 1 00979 1 635 0.8 6.9 2.3 80979 1435133.80 71.1 26.0 1 .0 140679 1 1 52 37.4 13.9 0.0 160679 1249 33.3 11.7 0.2 180679 1121 52.6 22. 1 0.2 180679 1200 51 .0 16.9 0.0 160679 1330 19.3 18.2 0.0 180679 1 230 7.8 0.4 0.7 250679 1913 1 .6 3.0 0.0 50779 0 2.8 9.5 2.5 80979 1305157.80 7.4 5.2 1 .0 6 .24 230680 1 755 4.9 48.2 2.0 5 .35 1 20780 1 1 37 2.8 3.9 0.7 120780 21 46 13.1 20.8 4.6 130780 1 1 20 7.8 7.8 0.7 250679 1912 2.4 0.0 2.0 50779 0 2.0 30.0 5.6 200779 1640166.30 2.4 21.7 4.8 210779 1635173.30 0.8 10.8 1 .7 80979 1310141.80 1 .2 13.9 2.3 100979 1700165.00 1 .6 9.5 1 .0 5 .43 230680 1800 1 .6 9.1 0.0 5 .58 250680 2100 1 .6 16.0 1 .0 5 .58 120780 1 130 1 .2 7.3 0.5 5 .58 120780 2200 254 S i t e ID# S i ( O H ) u Ca Mg Na 38 80333 58.5 7. 2 1 .6 9 38 80626 61.2 8. 9 2 .4 1 6 38 80664 66.5 1 1 . 2 2 .4 1 2 MOSQUITO S10 39 79113 80. 1 30. 9 3 .2 20 39 79118 74.8 27. 6 2 .8 21 39 79128 85.4 27. 1 2 .8 20 39 79138 91.0 26. 9 2 .8 20 39 79132 91.0 26. 9 2 .4 1 9 39 79143 91.0 28. 4 3 .7 22 39 79146 91.0 27. 9 2 .8 20 39 80239 21.2 3. 9 1 .6 4 39 80309 103.8 32. 1 3 .7 20 MOSQUITO S11 40 79092 64.9 17. 9 2 .0 7 40 80204 135.7 39. 1 5 .3 30 40 80202 130.4 33. 4 4 .5 26 40 80241 74.5 28. 1 3 .2 15 40 80314 101.1 32. 6 3 .7 20 MOSQUITO S12 41 79091 25.8 7. 7 1 .2 3 41 79166 65.7 18. 2 4 .9 39 41 80203 63.8 17. 4 3 .7 1 7 41 80242 69.2 18. 9 3 .2 1 6 41 80315 79.8 19. 9 3 .2 1 3 MOSQUITO OLF SITE 45 79090 15.9 7. 4 0 .8 0 MOSQUITO OLF SITE 46 79094 25.8 2. 9 0 .8 0 46 80316 63.8 14. 2 2 .0 13 46 80326 58.5 14. 2 2 .0 1 1 46 80332 69.2 13. 4 2 .0 1 2 MOSQUITO OLF SITE 47 79167 61 .7 14. 7 2 .0 1 6 RESIDUAL OLF SITE 48 79176 40.7 2. 2 1 .6 3 48 79175 51 .9 3. 2 2 .0 4 RESIDUAL SEEP 50 80610 122.4 26. 1 2 .8 23 50 80667 130.4 22. 9 2 .8 26 RESIDUAL SEEP" 51 79171 42.0 6. 9 0 .8 1 1 51 79181 124.6 23. 4 2 .8 22 51 80611 127.7 20. 7 3 .2 21 51 80621 133.1 21 . 9 3 .2 21 51 80663 138.4 22. 2 3 .7 23 MOSQUITO SEEP 52 79192 72.9 15. 7 1 .2 1 3 52 80612 63.8 14. 2 1 .2 1 7 R pH Date Time head (cm) . 1 0.5 5 .50 130780 1 100 .0 3.3 5 .63 1 1 080 1 520 .6 1 .7 5 .85 21 080 1450 .0 3.3 200779 1630126.20 .3 3.3 210779 1640116.80 .4 3.5 220779 1945118.70 .8 3.3 230779 1720119.10 . 1 2.5 230779 1000 . 1 3.8 240779 1040119.80 .0 2.5 250779 1 120120.00 .3 0.5 5 .54 250680 2110 .4 2.0 5 .96 120780 1 100 .8 0.0 50779 0 .0 6.6 6 .26 230680 1455 .5 4.8 6 .08 230680 1412 .2 3.0 6 .10 250680 21 30 .0 3.5 6 .30 120780 1 220 .0 2.3 50779 0 .5 7.9 80979 1315154.40 .8 5.6 5 .82 230680 1 442 .5 3.3 5 .78 250680 21 40 .9 2.5 6 .28 120780 1230 .0 1 .5 50779 0 .0 0.7 50779 0 .4 1 .7 5 .94 1 20780 1 240 .7 1 .2 6 .00 120780 21 30 . 1 1 .2 5 .98 130780 1050 .0 2.8 80979 1320 .4 13.5 80979 1 407 .7 6.3 80979 1 405 .4 3.5 5 .99 300980 1815 .0 3.5 5 .94 21080 1 505 .7 4.8 80979 1 340 .6 2.8 1 00979 1 630 .3 2.5 5 .98 300980 1830 .3 2.0 6 . 12 1 1080 1430 .9 2.8 6 .05 21080 1 445 .0 3.0 100979 1 700 .3 3.5 5 .76 300980 1830 255 S i t e ID# Si(OH) „ Ca Mg Na K pH Date Time HUMMINGBIRD SUBSURFACE CHANNEL NEAR WEIR 53 80609 93. 1 16.4 2.4 18.7 4.0 6 .01 300980 1812 MOSQUITO 1 TALUS PIT 63 791 24 1 24.8 27.9 9.4 20.4 4.8 220779 1 920 63 791 37 96.3 24.9 3.2 19.5 3.8 230779 1715 MOSQUITO : FAN PIT 64 791 54 1 04.6 50.6 4.1 22.6 2.5 100879 1 050 RESIDUAL < OUTLET BEACH PIT 66 79183 63.0 8.4 2.4 10.4 10.2 100979 1 640 66 791 93 44.7 9.9 4.5 3.4 10.2 100979 1 700 RESIDUAL 1 MONOLITH PIT 67 79189 113.4 12.7 1 .2 17.8 2.5 100979 1700 MOSQUITO 1 WHALEBACK PIT 68 79191 74.2 2.9 1 .2 9.5 4.8 100979 1 700 68 80420 29.2 3.4 1 .6 4.7 4.6 120980 1740 68 80614 63.8 2.2 0.8 7.3 0.7 5 .00 300980 1905 68 80625 66.5 2.9 1.2 5.2 1 .2 5 .01 1 1 080 1 445 MOSQUITO : S52 71 80071 31.9 2.4 0.4 5.2 0.7 5 .35 110680 201 5 BRUNISOLIC PLOT LOWER GUTTER : STF ABOVE TILL 96 80006 26.6 5.7 2.4 15.6 2.8 170580 0 96 8001 2 29.2 1 .7 2.0 8.6 1 .2 5 .35 1 0680 1 330 96 80024 37.2 0.9 1 .6 4.3 0.5 100680 800 96 80028 29.2 0.9 1 .6 4.3 0.5 90680 1 300 96 80058 37.2 1 .4 1 .6 5.2 0.2 5 .30 100680 21 00 96 80066 37.2 1 .4 1 .6 5.6 0.5 5 .40 110680 400 96 80076 31 .9 1 .2 1 .2 5.2 0.2 5 .49 110680 0 96 80082 26.6 1 .2 1 .2 4.7 0.5 5 .48 120680 0 96 80088 26.6 1 .4 1 .2 4.7 0.5 5 .50 120680 945 96 801 0.6 23.9 1 .7 1 .2 7.3 1 .2 5 .46 120680 1830 96 801 1 9 0.0 1 .2 0.0 4.7 0.5 5 .53 130680 250 96 801 27 39.9 1 .2 1 .2 6.5 1 .0 5 .50 130680 900 96 801 38 31 .9 1 .2 1 .2 5.2 0.7 5 .20 1 30680 1 545 96 801 46 31.9 0.9 1 .2 4.7 0.5 5 .35 130680 21 00 96 801 55 42.5 1 .2 1 .2 5.2 0.5 5 .43 140680 245 96 801 65 42.5 0.9 1 .2 7.8 1 .0 5 .52 140680 830 96 8021 2 29.2 1 .2 1 .2 5.2 0.5 5 .54 230680 0 96 80244 34.6 1 .2 1 .2 5.2 0.0 5 .35 250680 21 50 96 80307 29.2 1 .4 1 .2 5.2 0.5 5 .55 120780 900 96 8031 9 26.6 1 .2 0.8 5.2 0.7 120780 2200 96 80321 31 .9 1 .2 1 .2 5.2 0.5 120780 0 96 80331 31.9 1 .2 1 .2 4.7 0.2 130780 400 96 80343 29.2 1 .4 2.0 6.0 0.7 140780 820 96 80629 58.5 2.4 3.2 14.3 5.3 5 .24 1 1080 0 REGOSOLIC PLOT SUBSURFACE CHANNEL: STF ABOVE TILL 97 80248 58.5 8.9 1 .6 16.0 3.0 250680 2155 97 80300 74.5 11.2 1 .6 13.9 1 .7 6 .06 1 20780 732 97 80320 53.2 9.4 1 .2 11.7 1 .5 120780 21 03 97 80330 71 .8 11.4 1 .6 13.0 1.5 130780 1 025 1/hr 12.00 7.00 12.00 1/hr 1 .50 2.44 1 .36 256 S i t e ID# S i ( O H ) , Ca Mg Na K pH D a t e T i m e Q 1/hr 97 80341 97 80389 97 80387 6 6 . 5 2 3 . 9 3 4 . 6 10 .4 7 .2 2 4 . 9 0 .8 2 .0 8 .2 12 .6 10 .0 3 5 . 6 2 .0 4 . 8 2 7 . 1 1 4078.0 90980 280780 807 0 0 1 .72 97 80627 7 1 . 8 6 .4 0 .8 1 1 .3 1 . 7 5. 86 1 1080 1 630 97 80669 85.1 6 .7 1 .2 1 3 .9 2 . 0 5. 90 21080 1 520 UPPER HUMMINGBIRD SDS S I TE 130 80604 85.1 3 .4 3.2 8 .6 2 . 5 4 . 82 300980 1710 MOSQUITO U5 SDS S I TE 131 80608 2 1 . 2 2 .4 2 .0 2 . 1 13 . 5 5. 1 1 300980 1805 131 80658 2 1 . 2 2 .7 2 .4 3 .9 14. 8 21080 0 MOSQUITO CHANNEL S I TE #3 133 80615 117.1 2 0 . 7 3.2 18 .7 2 . 5 6 . 18 300980 1910 133 80666 141.1 2 2 . 9 4.1 21 .3 2 . 8 6 . 1 5 21080 1 455 BULK P R E C I P I T A T I O N AND SNOWMELT S i t e l d # S i ( O H ) 4 Ca Mg 3 79020 2 9 . 8 6.7 1 .6 3 79024 9 . 0 2 .9 0 . 4 3 79064 1 .8 4 . 9 3.2 3 79084 4 2 . 5 0 .7 0 . 4 3 79085 4 2 . 5 0 .4 0 . 4 3 791 01 0 . 5 1 .7 0 . 4 3 791 02 0 . 5 2 .4 0 . 4 3 791 08 4 . 7 4 . 7 0 .8 3 79159 4 . 7 5.4 0 .8 3 791 62 4.7- 1 .4 0 .8 3 791 96 8 . 5 3.4 0 .8 3 79201 5 .5 4 .2 0 . 8 3 80004 2 . 6 3 6 . 9 3.2 3 80013 2 . 6 4 .7 0 . 4 3 80035 2". 6 6 .2 0 . 8 3 80201 2 . 6 4 . 7 0 .8 3 80254 2 . 6 1 .9 0 .4 3 80308 2 . 6 4 . 2 0 .8 3 80382 2 . 6 2 .4 0 .8 3 80390 2 . 6 6 .4 0 .4 4 79009 3 .4 1 .9 0 . 4 4 7901 0 3 2 . 7 1 .4 0 . 4 4 7901 1 1 8 . 6 1 . 4 0 . 4 4 79061 0 . 5 1 .4 0 . 4 4 79062 3 .4 1 .9 0 . 4 4 79063 11 . 7 2 .2 0 .4 4 79079 6. 1 2 .2 0 .4 91 80022 2 . 6 0 .2 0 . 4 91 80033 2 . 6 0 .2 0 . 4 91 80056 2 . 6 0 .4 0 . 4 91 80064 2 . 6 0 .4 0 . 4 91 80072 2 . 6 0 .4 0 . 4 91 80080 2 . 6 0 .4 0 . 4 91 801 07 2 . 6 0 .4 0 . 4 91 801 15 5 .3 0 .4 0 .4 91 801 28 5 .3 0 .2 0 . 4 91 801 36 5 .3 0 .4 0 . 4 91 801 47 5 .3 0 .2 0 . 4 91 801 56 7 . 9 0 .2 0 . 4 91 801 66 2 . 6 0 .2 0 .4 91 80246 2 . 6 0 .2 0 . 4 94 80001 2 . 6 0 .4 0 . 4 94 8001 1 2 . 6 0 .4 0 . 4 94 8021 3 2 . 6 0 .2 0 . 4 94 80245 2 . 6 0 .2 0 . 4 Na K Date . 2 5 . 6 2 . 5 150679 10 .0 2 . 5 170679 4 6 . 5 15 .3 230679 4 6 . 5 1 .5 300679 4 6 . 5 2 .0 10779 4 6 . 5 0 .7 30779 4 6 . 5 2 .8 40779 8 .6 3 .5 80779 8 .2 2 . 5 240879 1 .7 0 . 5 60979 5.6 0 . 2 100979 7.8 0 . 5 51079 4 6 . 1 8 .6 170580 6 .0 1 .7 20680 4 . 3 1 .0 90680 5.2 1 .0 210680 3.0 1 .5 260680 3.9 2 .3 120780 5.6 2 . 3 180780 3.0 0 . 5 90980 13 .0 0 .2 310579 12 .6 0 .2 310579 8 .2 0 .2 310579 12.1 0 .2 230679 2 0 . 0 1.0 230679 5 6 . 5 9 . 4 230679 5 6 . 5 0 .7 250679 0 .4 0 . 7 100680 0 .4 0 .7 90680 0 .4 0 . 7 100680 2 .6 0 .2 110680 0 .8 0 .2 110680 2.1 0 . 5 120680 1 .3 0 . 5 120680 0 .4 0 . 5 130680 0 .8 0 . 2 130680 5.2 1 .2 130680 5.2 1 .2 130680 5.2 1 .2 140680 0 .8 1 .2 140680 0 .4 1 .2 250680 0 .8 1 .2 170580 3.0 0 .2 1 0680 0 .4 0 .2 230680 4 . 7 0 . 2 250680 C A P I L L A R Y SO IL WATER SAMPLES S i t e Id# S i ( O H ) a Ca Mg 101 80397 141. 1 32. 1 20. 5 101 80424 117. 1 16. 2 14. 8 101 80456 1 49. 0 12. 4 1 1 . 9101 80630 1 38. 4 7. 2 6. 5 101 80675 220. 9 6. 7 10. 6 101 80705 266. 2 12. 7 16. 4 102 80425 141. 1 63. 8 25. 5 1 02 80631 189. 0 34. 4 14. 8 103 80398 90. 5 15. 7 7. 8 103 80426 61 . 2 8. 2 6. 5 103 80457 71 . 8 5. 4 5. 3 103 80632 69. 2 5. 2 4. 5 1 03 80677 69. 2 3. 2 3. 7 103 80706 71 . 8 3. 9 4. 9 104 80399 1 51 . 7 r r . 9' 9*. 8 104 80427 101. 1 14. 9 14. 4 104 80458 1 38. 4 12. 4 12. 7 104 80633 87. 8 1 1 . 7 9. 4 104 80678 103. 8 8. 9 8. 2 104 80707 1 30. 4 13. 2 1 1 . 1 1 05 80400 85. 1 26. 1 1 1 . 1 1 05 80428 98. 5 18. 4 10. 2 1 05 80459 226. 3 16. 2 9. 4 1 05 80634 71 . 8 18. 4 1 1 . 5105 80679 98. 5 13. 4 10. 6 106 8041 6 141 . 1 18. 9 9. 4 106 80429 143. 7 12. 4 6. 5 106 80460 220. 9 1 4'. 4 8. 2 106 80635 194. 3 1 1 . 9 5. 7 106 80680 1 94. 3 5. 9 3. 2 107 80401 93. 1 27. 9 13. 9 107 80430 63. 8 10. 7 5. 3 107 80461 266. 2 14. 7 8. 6 107 80636 127. 7 9. 9 4. 5 107 80681 239. 6 12. 2 9. 0 107 80709 1 35. 7 17. 4 12. 7 108 80431 282. 2 72. 6 38. 6 108 80637 141 . 1 27. 9 1 1 . 9108 80659 207. 6 40. 4 17. 6 108 80682 266. 2 34. 9 16. 4 108 80710 127. 7 22. 4 10. 2 109 80391 162. 4 16. 2 8. 6 109 80432 1 33. 1 13. 2 6. 9 109 80462 1 25. 1 9. 9 5. 3 109 80638 125. 1 10. 2 5. 3 109 80683 117. 1 6. 4 3. 7 109 8071 1 143. 7 8. 7 7. 4 1 10 80392 215. 6 10. 2 6. 1 1 10 80402 207. 6 9. 2 6. 9 1 10 80433 167. 7 10. 2 6. 5 Na K D a t e 113.9 61.1 120980 65.6 50.6 130980 63.0 34.7 170980 40.0 15.0 21080 48.7 14.8 51 080 80.4 18.6 161080 174.4 48.8 130980 70.4 16.3 21 080 51 .3 17.3 120980 20.8 9.4 1 30980 19 .5 7.6 170980 13.9 4.8 21080 12.1 4.6 51080 13.4 4.0 161080 50.4 13.5 120980 28.7 10.4 130980 36.9 9.9 170980 21 .7 5.8 21 080 23.4 6.6 51080 30.8 6.9 161080 56.9 28.3 120980 30.8 25.3 130980 66. 1 27.3 170980 26.0 17.9 21080 24.3 19.4 51080 93.5 27.8 1 20980 66. 5 19.9 130980 85.6 19.4 170980 33.9 7.9 21 080 43.0 8.9 51 080 93.5 27.8 120980 34.3 12.0 130980 87.4 16.6 170980 43.9 10.2 21 080 68.7 25.3 51080 67.8 13.8 161080 207.0 53. 1 130980 60.8 15.0 21 080 117.4 24.2 1 1080 90.9 18.6 51 080 46.5 10.7 161080 1 04.8 17.3 110980 79. 1 13.0 130980 63.5 10.2 170980 59. 1 7.6 21080 50.0 7.6 51080 54.3 7.1 161080 1 08.3 34.7 1 10980 91 .7 26.8 120980 81 .3 23.2 130980 S i t e I d # S i ( O H ) a 1 1 0 80463 202. 3 1 10 80639 1 59. 7 1 1 0 80684 1 65. 0 1 10 8071 2 162. 4 111 80403 71 . 8 111 80434 50. 5 111 80464 1 70. 3 111 80640 55. 9 111 80685 55. 9 111 8071 3 55. 9 1 12 80404 101. 1 1 1 2 80435 66. 5 1 1 2 80465 114. 4 1 1 2 80641 63. 8 1 1 2 80686 95. 8 1 1 2 8071 4 79. 8 1 1 4 80405 1 17. 1 1 1 4 80436 103. 8 1 1 4 80466 111. 8 1 1 4 80642 98. 5 1 1 4 80688 1 09. 1 1 14 8071 5 1 38. 4 1 1 5 80643 212. 9 1 1 5 80689 244. 9 1 1 5 8071 6 343. 4 1 1 6 80406 266. 2 1 1 6 80437 212. 9 1 1 6 80644 98. 5 1 1 6 80690 117. 1 1 1 6 80717 1 33. 1 1 1 7 80438 212. 9 1 17 80645 306. 1 1 18 80393 111. 8 1 18 80407 98. 5 1 18 80439 87. 8 1 18 80467 93. 1 1 18 80647 71 . 8 1 18 80692 87. 8 1 18 80718 82. 5 1 19 80408 125. 1 1 19 80440 93. 1 119 80468 1 25. 1 1 19 80648 93. 1 1 19 80693 90. 5 1 19 8071 9 93. 1 120 80409 133. 1 120 80441 37. 2 120 80469 45. 2 120 80649 34. 6 120 80694 37. 2 Ca Mg Na 9.2 5.3 80.0 9.9 4.9 63.5 6.7 4.1 56.9 7.7 4.9 53.9 11.2 5.7 36. 1 9.9 5.3 17.8 8.4 5.7 21.7 7.2 5.3 18.2 6.2 4.5 16.0 8.4 6.9 14.3 13.7 7.4 55.6 7.4 5.3 22.6 8.9 6.5 40.8 7.4 4.5 15.6 5.7 4.5 20.8 9.2 6.1 17.8 8.7 4.5 45*. 6 8.7 4.9 33.4 5.7 3.7 29.5 5.2 3.2 25.2 3.4 2.8 24.7 8.7 5.7 34.3 18.4 8.2 36.5 12.9 6.1 35.6 23.2 10.6 56.9 29.9 27.5 171 .8 16.7 10.6 126.1 7.4 4.5 23.9 4.7 3.2 24.3 5.2 3.7 27.4 25.6 12.3 158.7 15.9 8.2 108.3 20.2 10.2 76.5 13.9 7.4 56.5 11.7 6. 1 46. 1 10.7 6.5 42.6 9.4 5.3 28.7 10.2 5.3 33.0 9.2 4.5 28.7 13.9 5.7 53.0 19.9 4.9 29.1 19.2 5.3 35.6 19.9 5.3 22.1 17.2 3.7 20.0 21.9 4.9 26.0 17.2 9.0 70.4 8.2 5.7 21.7 5.7 7.4 21.3 4.9 7.4 13.9 3.4 6.1 14.3 K Date 20.2 170980. 1 2. 0 2'1 OBO 11.7 51 080 9.4 161080 12.2 120980 7.1 130980 6.9 170980 4.3 21 080 4.8 51080 3.8 161080 15.8 120980 7.6 130980 10.4 170980 5.1 21 080 6.6 51 080 5.8 161080 10.4 120980 7. 1 130980 5.3 170980 3.5 21080 4.0 51080 5.1 161080 12.5 21 080 11.7 51080 14.8 161080 44.2 120980 29.4 130980 6.3 21080 6.3 51 080 5.6 161080 38.3 130980 19.4 21 080 19.9 110980 14.8 120980 12.2 130980 10.9 170980 6.6 21080 8.4 51080 6.1 161080 15.8 120980 9.4 130980 9.7 170980 5.3 21080 5.3 51080 8.1 161080 22.2 120980 8.1 130980 6.3 170980 3.8 21080 3.8 51080 S i t e ld# ! S i ( O H ) , Ca Mg 1 20 80720 42. 5 5. 2 4. 9 121 8041 0 82. 5 12. 2 6. 5 121 80442 69. 2 13. 2 6. 5 121 80470 93. 1 10. 7 5. 3 121 80650 69. 2 1 1 . 9 5. 3 121 80695 93. 1 10. 7 4. 9 121 80721 292. 8 56. 1 37. 8 1 22 80443 311. 5 133. 4 45. 2 1 22 80471 386. 0 1 49. 4 56. 3 1 22 80651 1 43. 7 60. 3 20. 9 1 22 80696 197. 0 56. 1 20. 1 1 22 80722 228. 9 61 . 6 24. 2 1 23 8041 1 1 06. 4 92. 8 1 1 . 91 23 80444 79. 8 63. 8 9. 8 1 23 80472 1 54. 4 42. 1 8. 6 1 23 80652 71 . 8 44. 1 10. 2 1 23 80697 74. 5 31 . 6 9. 0 1 23 80723 98. 5 22. 4 6. 5 1 24 80412 1 06. 4 56. 6 6. 9 1 24 80445 87. 8 33. 9 5. 3 1 24 80473 98. 5 20. 2 4. 1 1 24 80653 82. 5 21 . 2 4. 5 1 24 80698 90. 5 14. 4 3. 2 1 24 80724 1 03. 8 12. 7 2. 8 1 25 80446 1 03. 8 71 . 1 10. 2 1 25 80474 244. 9 52. 8 9. 4 1 25 80654 95. 8 41 . 4 9. 4 1 25 80699 1 30. 4 30. 1 7. 8 1 26 8041 3 228. 9 259. 7 33. 3 1 26 80447 1 94. 3 182. 8 26. 3 126 80655 1 03. 8 53. 6 1 1 . 1 1 26 80700 98. 5 40. 9 8. 6 1 27 8041 4 1 75. 7 149. 4 15. 2 1 27 80448 93. 1 114. 5 12. 7 1 27 80475 1 17. 1 75. 3 7. 4 1 27 80656 69. 2 38. 6 3. 2 1 27 80701 87. 8 40. 4 3. 7 1 27 80726 85 . 1 49. 4 3. 7 1 28 8041 5 1 49. 0 53. 6 5. 7 1 28 80449 117. 1 35. 4 4. 5 128 80476 292. 8 58. 1 12. 7 1 28 80657 215. 6 39. 6 8. 6 Na K Date 15.2 3.5 161080 39. 1 13.5 120980 29. 1 9.2 130980 29. 1 8.1 170980 19.5 5.3 21 080 23.4 5.8 51080 77.4 15.8 161080 185.2 1 36.8 130980 210.9 190.5 170980 65.2 62.6 21 080 66.9 80.0 51 080 74.8 71.0 161080 78.2 53.7 120980 42. 1 44.7 130980 55.6 39.3 170980 27.8 28.3 21 080 25.2 29.9 51080 26.0 20.2 161080 60.0 44.7 120980 29. 1 25.5 130980 27.8 16.6 170980 21.7 9.7 21 080 22 . 1 9.9 51 080 24.3 9.2 161080 65.2 24.8 1 30980 75.6 21.2 170980 30.8 8.9 21080 37.4 9.4 • 51080 326.2 152.6 120980 208.3 91 .0 130980 52.6 16.6 21 080 41 .3 12.5 51 080 186. 1 45.2 120980 71.3 20.4 130980 36.5 9.4 170980 20.4 4.8 21 080 20.0 4.8 51080 20.8 4.3 161080 81 . 3 29.4 120980 37.4 13.0 130980 59. 1 21.4 170980 43.4 11.2 21 080 WATER SOLUBLE SALT EXTRACTS Hcode ID# pH Si(OH) 4 Ca Mg Na K s i t e Horizon (microinoles/1 00 g s o i l ) 1 2 80800 4.8 15.2 2.5 3.3 6.9 3. 1 S79- •9a Ahj 7 80801 4.8 17.6 2.2 8.6 6.5 1 . 5 Bm 12 80802 4.3 14.4 17.5 4.9 15.6 10. 5 S79- 2 Ahj 7 80803 4.8 35. 1 5.2 4. 1 15.6 4. 8 Bm 12 80804 5.3 21.6 3.5 2.9 6.9 3. 1 S80- •SI Ah 7 80805 5.2 21.6 0.7 0.4 3.0 1 . 0 Bm1 7 80806 5.1 17.0 0.7 0.4 3.0 0. 8 Bm2 1 1 80807 5.4 36.7 2.0 0.8 3.5 1 . 3 C 2 80808 4.7 26.6 65.9 8.6 25.2 8. 4 S79- •1 1 Ah 1 0 80809 5.9 47. 1 16.5 51 .8 47.4 33. 0 eg 1 1 80810 4.9 22.4 18.7 0.4 4.3 1 . 5 S79- •9b C 1 8081 1 5.3 94.5 1 .2 6.1 115.3 239. 1 S79- •6 Ah 7 8081 2 4.7 31.1 4.5 3.7 32.2 23. 0 Bm1 7 8081 3 4.5 28.2 5.2 2.5 12.2 2. 3 Bm2 1 1 8081 4 5.0 23.2 2.2 0.8 10.0 2. 0 C 1 8081 5 4.0 187.7 113.5 41.1 60.8 370. 8 S79- •3 LFH 3 8081 6 4.1 33.5 9.0 7.4 42.6 31 . 2 Ae 5 8081 7 4.7 57.5 2.5 0.8 24.3 8. 2 Bhf 6 80818 4.2 18.9 9.0 4.9 33.0 6. 6 Bf 8 8081 9 4.6 15.4 2.7 2.0 16.5 1 . 3 BC 1 80820 5.4 1 50.4 1 39.7 34.9 78.3 485. 9 S78- •14 LFH 3 80821 4.5 30.1 9.5 4.9 51 .3 16. 4 Ae 5 80822 4.8 42.3 4.5 1 .6 24.8 15. 3 Bh 6 80823 4.5 39.9 6.5 . 4.9 21.3 17. 9 Bf 1 80824 4.5 85. 1 239.5 14.4 56.5 997. 3 S79- 7 LH 2 80825 4.2 24.0 35.4 20.6 40.0 31 . 7 Ahe 7 80826 4.4 18.6 8.5 4.9 18.3 9. 7 Bm 6 80827 4.1 23.2 8.0 13.2 44.8 7. 7 Bfb 8 80828 4.6 31.1 2.2 4.5 9.1 0. 8 BC 2 80829 4.5 30.3 7.5 13.2 49.6 91 . 0 S79- •5 Ah 7 80830 4.3 27.9 5.7 8.6 36.5 25. 1 Bm1 9 80831 4.2 28.2 15.5 18.9 64.4 31 . 7 Omb 7 80832 4.3 17.0 6.7 4.1 17.0 4. 6 Bmb 8 80833 4.5 8.5 4.0 2.5 8.7 2. 8 BC 2 80834 4.1 22.4 16.5 28.8 45.2 56. 3 S79- 4 Ah 7 80835 4.9 20.8 2.0 2.5 24.3 5. 1 Bm1 4 80836 5.0 55.9 2.5 6.6 34.8 9. 7 Bm2 5 80837 4.2 18.6 7.5 16.4 32.2 1 1 . 5 Omb 6 80838 4.6 22. 1 3.5 4. 1 12.6 1 . 5 Bm3 8 80839 5. 1 29.8 0.2 22.6 8.7 1 . 8 BC 1 80840 4.7 167.7 47.4 67.8 1 56.5 652. 1 S78- P3 LFH 3 80841 4.6 70.3 18.5 34.6 60.9 250. 6 Ae 5 80842 4.2 22.9 24.4 25.5 77.4 38. 9 Omb 6 80843 4.2 29.3 10.5 13.6 32.6 7. 9 Bm 1 1 80844 5.1 19.2 5.0 2.5 15.6 2. 5 BC 262 Hcode ID# PH S i(OH) „ Ca Mg Na K s i t e Horizon (micromoles/100 g s o i l ) 1 80845 5.8 71.8 8.7 4. 1 76.1 306. 8 S79-8 LFH 2 80846 5.0 59. 1 4.0 3.3 48.7 92. 1 Whale Ah 7 80847 4.3 22.6 8.0 7.4 27.8 12. 0 back Bm 9 80848 4.4 12.2 10.0 8.2 59. 1 12. 3 p i t Omb 7 80849 5.1 52.2 3.0 1 .6 47.8 15. 8 Bm1 7 80850 4.6 8.5 4.0 3.3 16.5 2. 5 Bm2 2 80851 4. 1 35.1 18.7 7.8 34.8 6. 4 S79-10 Ah 7 80852 4.6 22.4 1 .5 1 .2 8.3 1 . 0 Bm 1 1 80853 4.9 21.3 2.0 2.9 5.2 1 . 5 C 9 80854 4.4 14.9 10.0 4.9 50.4 25. 6 S80-12 Om2 9 80855 4.5 57.0 12.0 5.8 50.4 12. 8 Om3 8 80856 5.0 33.3 3.7 1 .6 6.9 1 . 3 BC 1 5 80857 5.2 30.3 52.4 7.0 59.6 6. 6 Ash Pond Ash 9 80858 4.8 61 .2 2.0 2.5 8.7 24. 0 Heather p i t Omb 

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