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Sediment movement in a sub-alpine basin in the Coast Mountains of British Columbia Jones, Penelope Sarah Ann 1982

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SEDIMENT MOVEMENT IN A SUB-ALPINE IN THE COAST MOUNTAINS OF BRITISH COLUMBIA BASIN BY PENELOPE SARAH ANN JONES B.A., THE UNIVERSITY OF CAMBRIDGE 1979 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN THE FACULTY OF GRADUATE STUDIES (GEOGRAPHY) WE ACCEPT THIS THESIS AS CONFORMING TO THE REQUIRED STANDARD THE UNIVERSITY OF BRITISH COLUMBIA SEPTEMBER, 1982 © PENELOPE SARAH ANN JONES, 1982 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of c^ & 0 ^ CAPVW  The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date I ^ _ ? e V o W * - \°[HI-DE- 6 (3/81) i i ABSTRACT Sediment t r a n s f e r s i n a small a l p i n e v a l l e y were measured d u r i n g the summer of 1981. The sediment budget concept was used to generate three hypotheses which guided the study. Data were c o l l e c t e d at 20 s i t e s u s i n g G e r l a c h troughs, s p l a s h troughs and bulk samplers. S p a t i a l i n t e g r a t i o n of s i t e data e s t a b l i s h e d t h a t wind was o v e r a l l the most important component of the sediment budget. E o l i a n m a t e r i a l i n c l u d e d both d i r e c t d e p o s i t i o n d u r i n g the summer months and m i n e r a l m a t e r i a l s t o r e d i n the winter snowpack. Measured r a t e s of d e p o s i t i o n matched accumulation r a t e s c a l c u l a t e d from the s o i l p r o f i l e and mineralogy suggested a r e g i o n a l source f o r windblown m a t e r i a l . Animals (marmots) are the main agents of sediment t r a n s f e r on t a l u s s i t e s but as t h e i r i n f l u e n c e i s s p a t i a l l y l i m i t e d , they are l e s s important than wind over the whole b a s i n a r e a . Overland flow and r a i n s p l a s h perform some sediment t r a n s f e r on unvegetated areas of f i n e d e b r i s . The same s i t e s support needle i c e which c o n t r i b u t e s l i t t l e to the t o t a l sediment budget. T h i s ranking i s t e n t a t i v e as the f i e l d season had l a t e snowmelt, e a r l y f a l l snow accumulation and an e x c e p t i o n a l l y warm, dry August. The s t r a t i f i e d , random, r e p l i c a t e d sampling scheme employed i n t h i s study was i n e f f i c i e n t as many s i t e s i i i s t r a d d l e d t w o v e g e t a t i o n s t r a t a . U s e o f a p l a n e t a b l e m a p r a t h e r t h a n a e r i a l p h o t o g r a p h s f o r a b a s e m a p s h o u l d i m p r o v e e f f i c i e n c y . i v TABLE OF CONTENTS Page A b s t r a c t i i Table of contents i v L i s t of t a b l e s ix L i s t of f i g u r e s x Acknowledgements x i Chapter 1 I n t r o d u c t i o n 1 1 . 1 O b j e c t i v e s 1 1.2 H i s t o r i c a l P e r s p e c t i v e 2 1.3 A conceptual model 3 1.4 Agents of sediment t r a n s f e r 7 1.4.1 Overland flow 7 1.4.2 Impacted o v e r l a n d flow ; 9 1.4.3 Splash 9 1.4.4 F r o s t and needle i c e 10 1.4.5 Wind e r o s i o n and d e p o s i t i o n 11 1.4.6 Animals 12 1.4.7 S p a t i a l v a r i a b i l i t y of s o i l l o s s 13 1.5 S p a t i a l v a r i a b i l i t y of s o i l l o s s 12 1.5.1 Slope angle 13 1.5.2 V e g e t a t i o n 14 1.6 Temporal v a r i a b i l i t y 15 V 1.7 Hypothesis f o r m u l a t i o n 15 Chapter 2 D e s c r i p t i o n of the study area 17 2.1 Region a l p e r s p e c t i v e 17 2.2 L o c a l topography 17 2.3 Climate 21 2.4 Geology 21 2.5 Quaternary h i s t o r y 22 2.6 S o i l s 23 2.7 V e g e t a t i o n 25 Chapter 3 Sampling scheme, f i e l d i n s t a l l a t i o n s and a n a l y t i c a l techniques 28 3.1 S p a t i a l v a r i a b i l i t y of s o i l l o s s 28 3.2 Sampling framework 30 3.3 Sampling design 31 3.4 F i e l d i n s t a l l a t i o n s 33 3.4.1 G e r l a c h troughs 33 3.4.2 Splash troughs 34 3.4.3 Bulk c o l l e c t o r s 36 3.4.4 T r a c e r p a r t i c l e s 36 3.4.5 Standpipes 37 3.4.6 M e t e o r o l o g i c a l instruments 38 3.4.7 Snow sampling 38 3.5 Sampling frequency 39 v i 3.6 S i t e c h a r a c t e r i s t i c s 41 3.7 A n a l y s i s of sediment samples 41 3.7.1 F i e l d techniques 41 3.7*2 Laboratory techniques 42 3.7.2 S i e v i n g 43 3.7;4 P r e p a r a t i o n f o r XRD 43 Chapter 4 R e s u l t s and e r r o r a n a l y s i s 45 4.1 Data from i n d i v i d u a l apparatus 45 4.1.1 G e r l a c h troughs 45 4.1.2 Splash troughs 49 4.1.3 Bulk c o l l e c t o r s 49 4.1.4 Tra c e r p a r t i c l e s 51 4.1.5 Standpipes 53 4.1.6 Sediment c o n t a i n e d i n the snowpack 53 4.1.7 Overland flow data 54 4.2 M e t e o r o l o g i c a l summary 54 4.2.1 Temperature 54 4.2.2 Snow 56 4.2.3 R a i n f a l l 57 Chapter 5 I n t e r p r e t a t i o n of the r e s u l t s 59 5.1 S u r f i c i a l movement 59 5.2 Overland flow 67 5.3 Splash 74 v i i 5.4 F r o s t and needle i c e 78 5.5 E o l i a n d e p o s i t i o n 79 •5.5.1 P a r t i c l e s i z e d i s t r i b u t i o n and amount of wind blown m a t e r i a l 79 5.5.2 Provenance of windblown sediment 82 5.5.3 Wind d e p o s i t i o n 85 5.5.4 Sediment c o n t a i n e d i n the snowpack 88 5.5.5 Summary 92 5.6 Animals 93 5.7 S p a t i a l v a r i a t i o n of sediment y i e l d 97 Chapter 6 Conclusions and recommendations 105 6.1 The sediment budget 105 6.2 Representativeness of the f i e l d season 108 6.3 Assessment of the i n i t i a l hypotheses 110 6.4 Comparison of the r e s u l t s with other data ....112 6.5 F u r t h e r r e s e a r c h 114 v i i i B i b l i o g r a p h y 116 Appendix A Slope angles 126 Appendix B S o i l organic matter 127 Appendix C Water r e p e l l e n c y 128 Appendix D Snow cover data 129 f Appendix E Sediment c o l l e c t e d i n g e r l a c h troughs 130 Appendix F P a r t i c l e s i z e f r a c t i o n s 134 Appendix G Lognormal p l o t s of g r a i n s i z e data 138 Appendix H Sediment c o l l e c t e d i n s p l a s h troughs 161 Appendix I Bulk samplers 162 Appendix J Data from t r a c e r p a r t i c l e s 163 Appendix K Snow samples ..165 Appendix L Overland flow o b s e r v a t i o n s 166 Appendix M Thermohygrograph data 167 Appendix N Ge r l a c h trough water volumes 168 •Appendix 0 I n t e r p r e t a t i o n of XRD t r a c e s ^169 Appendix P Rock composition 171 Appendix Q C l u s t e r a n a l y s i s 172 Appendix R P r i n c i p a l components a n a l y s i s 173 Appendix S M u l t i p l e r e g r e s s i o n 174 i x LIST OF TABLES 1. A r e v i s e d model of a l p i n e sediment t r a n s f e r s 6 2. Sampling scheme 25 3. V e g e t a t i o n 26 4. T r a c e r p a r t i c l e s 37 5. Trough c o l l e c t i o n dates 40 6. Loss of sample dur i n g s i e v i n g 48 7. M e t e o r o l o g i c a l data 55 8. G e r l a c h trough c o n t r i b u t i n g areas 63 9. Organic content and p a r t i c l e s i z e d i s t r i b u t i o n of 3 s o i l p i t s 86 10. S i t e c l a s s i f i c a t i o n 97 11. F s t a t i s t i c to t e s t stratum homogeneity 101 12. The sediment budget of the s t u d y area 106 13. Estimates of sediment t r a n s f e r s 113 X LIST OF FIGURES 1. The p l o t model (Caine 1971) 5 2. Summary p l o t model (Caine 1971) 3 3. L o c a t i o n of the study area 18 4. A l l i s o n s Bowl 19 5. A e r i a l photograph of the study area 20 6. S o i l g r a i n s i z e d i s t r i b u t i o n 24 7. I n s t a l l a t i o n s at s i t e 6 34 8. Sediment c o l l e c t e d i n G e r l a c h troughs 46 9. R a i n f a l l estimates 58 10. P a t t e r n of sediment movement — l a r g e stones 60 11. P a t t e r n of sediment movement — small stones 61 12. Schematic diagram of c o n t r i b u t i n g area 64 13. Displacement of t r a c e r p a r t i c l e s 65 14. Displacement of t r a c e r p a r t i c l e s 66 15. Overland flow and v e g e t a t i o n type 71 16. CRREL snow samples — sediment c o n c e n t r a t i o n s 90 17. Dendrogram showing s i t e c l a s s i f i c a t i o n by c l u s t e r a n a l y s i s 99 18. Sediment movement and slope 103 19. A l t a Lake c l i m a t i c data 109 x i ACKNOWLEDGEMENTS F i n a n c i a l support f o r t h i s study was pr o v i d e d by a UBC graduate F e l l o w s h i p , an A r c t i c and A l p i n e Research grant and N a t i o n a l Research C o u n c i l Grant 67—7073. I would l i k e to thank my s u p e r v i s o r H.O. Slaymaker f o r h i s encouragement and d i r e c t i o n and my other committee members, Dr. M.J. Bovis and Prof J.R. Mackay f o r u s e f u l c r i t i c i s m and a d v i c e . My a s s i s t a n t s , K. Lewis and M. T y l e r , were t i r e l e s s workers and c h e e r f u l companions i n the f i e l d and A l and M a r t i S t a e h l i extended generous h o s p i t a l i t y . I am g r a t e f u l to F. Mah and E. Minchowsky of the Water Q u a l i t y Laboratory (Environment Canada) f o r use of t h e i r oxygen plasma furnace and to the S o i l Science department at U.B.C. who enabled the XRD a n a l y s i s . 1 CHAPTER I. INTRODUCTION 1.1 O b j e c t i v e s The aim of t h i s study i s to c h a r a c t e r i s e sediment movement on the s o u t h — f a c i n g slope of a small a l p i n e watershed. S u b s t a n t i a l sediment storage on the h i l l s l o p e (as l o e s s d e p o s i t s ) shows that sediment i s not d e l i v e r e d d i r e c t l y to the nearest stream channel. -As most s t u d i e s of a l p i n e sediment y i e l d analyse r i v e r — t r a n s p o r t e d c l a s t i c m a t e r i a l (Slaymaker and McPherson 1977), they do not q u e s t i o n the mechanisms i n v o l v e d in the o v e r l a n d t r a n s f e r of sediment. T h i s study, in c o n t r a s t , focuses on the h i l l s l o p e system as an e n t i t y rather than as an adjunct to a r i v e r channel. More s p e c i f i c a l l y , i t examines the i n f l u e n c e of s e v e r a l f a c t o r s which c o n t r i b u t e to h i l l s l o p e sediment movement. It a l s o makes a p r e l i m i n a r y s t a t i s t i c a l assessment of the s p a t i a l v a r i a b i l i t y of s o i l l o s s together with a q u a l i t a t i v e a n a l y s i s of temporal v a r i a b i l i t y . The study i s intended to be e x p l o r a t o r y , accomodating a wide range of p o s s i b l e mechanisms and u t i l i s i n g a number of d i f f e r e n t techniques. T h i s i s to expedite an e f f i c i e n t sampling design i n f u t u r e work and a l s o to evaluate d i s p a r a t e techniques. The o b j e c t i v e s are s t a t e d f o r m a l l y in three f a l s i f i a b l e hypotheses in s e c t i o n 1.7 a f t e r the t h e o r e t i c a l s t r u c t u r e i s j u s t i f i e d and germane p r a c t i c a l c o n s t r a i n t s are s t a t e d . The budgeting approach, used s u c c e s s f u l l y i n energy and mass balance s t u d i e s (Jordan 1978), was chosen as a powerful t h e o r e t i c a l framework. Proposed by Jahn (1968), i t p r o v i d e s a 2 strong but f l e x i b l e s t r u c t u r e with which to c o n s t r u c t an optimal experimental d e s i g n . I t a l s o p r o v i d e s f o r the subsequent i n t e g r a t i o n of d i v e r s e measurements of process and morphology. The Bubnoff (1mm lowering per year) i s the u n i t of measurement. 1.2 H i s t o r i c a l P e r s p e c t i v e s The study of sediment movement began with the work of Hutton (1785) and L y e l l (1830). Both recognised that sediment accumulations i n the g e o l o g i c r e c o r d c o u l d be i n t e r p r e t e d with r e f e r e n c e to contemporary processes. T h i s r e a l i s a t i o n r a i s e d q u e s t i o n s about the age of the e a r t h and the time s c a l e of sedimentary processes. The f i r s t t r e a t i s e s were d e s c r i p t i v e essays d e s c r i b i n g landforms on .a grandiose s c a l e : t h e i r l o g i c was i n d u c t i v e . Davis (1909), Penck (1924) and Wooldridge and L i n t o n (1955) d e s c r i b e d r i v e r t e r r a c e s , p e n e p l a i n s , slope morphology and i c e carved f e a t u r e s . The c h a r a c t e r i s a t i o n of process was s i m p l i s t i c and q u a l i t a t i v e : Davis wrote (I909p424) "no rocks are unchangeable t h e i r waste creeps and wastes d o w n h i l l as long as any h i l l s remain." Since the 1950's geomorphology has i n a d v e r t a n t l y embraced l o g i c a l p o s i t i v i s m with i t s tenet that knowledge advances by hypothesis t e s t i n g (Popper 1972) and the deductive f o r m u l a t i o n of p r o b a b i l i s t i c g eneral laws (Mann 1970). Recent geomorphological work has focused on process (mechanisms) and process-morphology l i n k a g e s which are measurable in the human time frame. Most recent work has focused on some aspect of sediment p r o d u c t i o n , storage, breakdown and t r a n s f e r . 1 .3 A conceptual model of the a l p i n e h i l l s l o p e system 3 The morphological system of an a l p i n e h i l l s l o p e i n c l u d e s g e o l o g i c , p e d o l o g i c , c l i m a t i c , h y d r o l o g i c a l and b i o l o g i c a l f a c t o r s . S t r e s s a c t i n g on morphology induces response which may lea d to sediment movement. F i g 1 1 shows the s p e c i f i c items Caine (1971) c o n s i d e r e d at the p l o t (10m 2) s c a l e - a l s o some proposed F i g 2 Summary plot model (Caine 1971) Boundary conditions Processes Responses I I • Direct important links, showing direction of influence — — — • Feedback effects l i n k a g e s ( F i g 2 ) 2 . 1Caine (1971) p 321 A conceptual model f o r a l p i n e process study. Reproduced with permission from A r c t i c and A l p i n e Research 3. 2 C a i n e (1971 ) p 325 4 The present study u t i l i s e d comparable h i l l s l o p e p l o t s and addressed the problem of s p a t i a l v a r i a b i l i t y of sediment movement. Caine's model, with a few m o d i f i c a t i o n s , was p a r t i c u l a r l y s u i t a b l e . As a process—response model i t provided a b a s i s f o r t r a c i n g sediment throughputs; i t a l s o i n d i c a t e d a wide range of background i n f o r m a t i o n which c o u l d be used to o b t a i n a more e f f i c i e n t and comprehensive sampling scheme. Th i s study was l i m i t e d to one summer season so that three c a t e g o r i e s of v a r i a b l e were e l i m i n a t e d or i n c l u d e d only i n a l i m i t e d way and one v a r i a b l e , wind, was added:— 1. V a r i a b l e s of slow mass movement It i s impossible to study slow mass movement i n a s i n g l e summer season. Whilst o b s e r v a t i o n s of rid g e d s o i l at the base of stone s t r i p e s suggested that slow mass movement co u l d be at l e a s t l o c a l l y s i g n i f i c a n t , the time c o n s t r a i n t precluded measurement. There are a few measurements which can be used comparatively (Benedict 1970,Price 1972) but these are l i m i t e d to s p e c i f i c m orphological f e a t u r e s , mainly d e b r i s lobes, whose ra t e of movement i s much g r e a t e r than average. 2. V a r i a b l e s of the snowpack The summer study p e r i o d d i d not begin u n t i l mid June and ended i n mid October once the winter snowpack covered the b a s i n . The r o l e of snow in moving sediment i s l a r g e l y s p e c u l a t i v e . The f i n d i n g s of Mackay and Matthews (1974) show snow creep i s not an important agent of sediment movement. As s l u s h a v a l a n c h i n g , found by Caine (1969) to be the dominant agent of sediment t r a n s f e r on New Zealand s c r e e s , was not observed i n the study F i g 1 The plot model (Caine 1971) Boundary conditions I. Geologic-pedologic controls (a) Mantle thickness (b) Surface shear strength (c) Bulk shear strength (d) Infiltration capacity (e) Permeability (f) Slope angle (g) Aspect (h) Slope position II. Climatic controls (a) Temperature variations (b) Rainstorm periodicity (c) Rainfall intensity - (d) Snow cover duration (e) Snow depth-density • (f) Snowdrift factors (g) Snowmelt conditions III. Biologic controls (a) Ground cover (b) Litter cover (c) Phenologic characteristics (d) Root density (e) Root strength (f) Burrowing organisms (g) Surface animal movement Processes I. Bulk mechanical stresses (a) Tangential stress (b) Particle expansion-contraction (c) Ice crystal growlh II. Surface water stresses (a) Overland (low drag (b) Rill discharge drag (c) Ground freezing III. Soil and groundwater stresses (a) Soil moisture fluctuations (h) Soil moisture gradients (t) Interflow discharge (d) I'oic water pressure (e) Water table fluctuations IV. Meteorological stresses (a) Raindrop kinetic energy (b) Snowpack pressure (c) Avalanche shear stress (d) Stem flow discharge Responses I. Soil surface set (a) Sheet erosion (b) Gully erosion (c) Surface compaction (d) Talus settling (c) Avalanche erosion deposition (f) Needle ice transport II. Bulk soil set 1 (a) Soil creep (b) Solifluction (c) I.andsliding (d) Groundw;iter solution transport (c) Frost creep III. Rock weathering set (a) Mechanical shattering (b) Solution effects (c) Mechanical corrosion 6 area i t was i n i t i a l l y concluded that the snowpack was not an important component of the sediment budget. 3. Stream e r o s i o n Drainage from the slope i s mainly by seepage except at snowmelt. The streams which run at snowmelt do not erode t h e i r banks; o f t e n they flow over a t h i c k l a y e r of moss which p r o t e c t s both streambed and banks. Elsewhere the streambed i s covered with l a r g e c o b b l e s . Wind Wind i s inc l u d e d as an a d d i t i o n a l agent of s t r e s s because the s o i l p r o f i l e shows that windblown m a t e r i a l i s accumulating in the study area. These four m o d i f i c a t i o n s give a r e v i s e d model which i s shown i n Table 1. Table 1 A r e v i s e d model of a l p i n e sediment t r a n s f e r s PROCESSES RESPONSES MORPHOLOGICAL CHARACTERISTICS Parent rock Mantle t h i c k n e s s Slope angle S o i l a t t r i b u t e s Snow f r e e p e r i o d V e g e t a t i o n cover Species type Water t a b l e p o s i t i o n Overland flow Raindrop impact F r o s t l o o s e n i n g Wind d e p o s i t i o n Animal a c t i v i t y Sediment t r a n s f e r The r e v i s e d model has e l i m i n a t e d a l l but s u r f i c i a l sediment t r a n s f e r s , because of the short d u r a t i o n of the study. Adoption of Caine's model i s only v a l i d f o r small (10m 2) p l o t s : these were the chosen sampling u n i t and a s t r a t i f i e d random design was 7 employed to a v o i d b i a s i n s i t e s e l e c t i o n yet o b t a i n maximum e f f i c i e n c y . The processes l i s t e d i n the model determined the type of apparatus to be used; G e r l a c h troughs captured a l l the m a t e r i a l p a s s i n g over a 1m width of s l o p e , s p l a s h troughs estimated the p r o p o r t i o n d i s l o d g e d by r a i n s p l a s h and bulk samplers measured wind d e p o s i t i o n . The r o l e of animals was i n f e r r e d from f i e l d o b s e r v a t i o n s of burrowing a c t i v i t y l e v e l s and sediment recorded i n the G e r l a c h troughs. These d i s p a r a t e techniques were aimed at a s s e s s i n g the s p a t i a l v a r i a b i l i t y of process and the r e s u l t i n g sediment p r o d u c t i o n . M e t e o r o l o g i c a l data (temperature, r a i n f a l l and wind) were c o l l e c t e d i n the extreme east of the basin and enabled a t e n t a t i v e a n a l y s i s of temporal v a r i a b i l i t y . Table 1 i s an enumeration and makes no assessment of the r e l a t i v e importance of the f a c t o r s , t h e i r magnitude, frequency and s p a t i a l v a r i a b i l i t y . Each of the processes l i s t e d i n the model w i l l now be examined b r i e f l y in order to o b t a i n a p r e l i m i n a r y ranking of mechanism and a c u r s o r y assessment of s p a t i a l and temporal v a r i a b i l i t y . 1.4 Agents of sediment t r a n s f e r 1.4.1 Overland flow The purpose of t h i s s e c t i o n i s to o u t l i n e a few c r i t i c a l l a b o r a t o r y experiments and f i e l d t e s t s which show that overland flow i s an important agent of sediment p r o d u c t i o n and t r a n s p o r t . L o g i s t i c a l c o n s t r a i n t s preclude d i r e c t f i e l d o b s e r v a t i o n and measurement under n a t u r a l c o n d i t i o n s . Overland flow i s s t i l l 8 p o o r l y understood, d e s p i t e 40 years of experimentation and debate and the present l e v e l of comprehension i s based on experiments using a r t i f i c i a l r a i n f a l l a p p l i e d to n a t u r a l or prepared p l o t s . Measurements of s o i l , l o s s (e.g. Bovis 1978), although nominally i n d i c e s of overland flow, e n t a i l temporally spaced measurements which embrace a number of undefined p r o c e s s e s . Overland flow i s generated by at l e a s t two mechanisms. The f i r s t type, 'Horton type'(Horton 1945) occurs when s o i l water storages are f i l l e d or when p r e c i p i t a t i o n d e l i v e r y exceeds s o i l i n f i l t r a t i o n c a p a c i t y — i t may cover a high p r o p o r t i o n of a watershed. E r o s i o n by Horton overland flow takes p l a c e only below Xc, the ' c r i t i c a l d i s t a n c e ' from the watershed d i v i d e where overland flow becomes t u r b u l e n t . The second type ' s a t u r a t i o n ' or Dunne type' (Dunne and Black 1970) i s more l i m i t e d s p a t i a l l y . I t i s found near stream channels and i n hollows where the ground water t a b l e i n t e r s e c t s the ground s u r f a c e . S p a t i a l v a r i a b i l i t y of overland flow governs the area where wash e r o s i o n can take p l a c e . Horton (1945) based h i s theory of watershed e r o s i o n on the premise that flow must be t u r b u l e n t to erode. However, f i e l d o b s e r v a t i o n s by Emmett(l970) and Dunne and D i e t r i c h ( 1 9 8 0 ) show that o v e r l a n d flow l i e s i n the laminar or t r a n s i t i o n range on the p l o t s that were i n v e s t i g a t e d . For example, Emmett (1970) found sediment c o n c e n t r a t i o n s of 2—260 mg/1 i n overland flow samples c o l l e c t e d under c o n d i t i o n s of laminar flow, showing that turbulence i s not a p r e r e q u i s i t e f o r e r o s i o n . Sheetflow alone, without r a i n d r o p impaction, i s capable of c o n s i d e r a b l e e r o s i o n 9 on unvegetated slopes steeper than 0.005 ( I z z a r d 1944, Moss, Walker and Hutka 1979) and the l a t t e r authors demonstrated that e r o s i o n on low angle slopes i s e f f e c t e d mainly by r a i n d r o p impacts not sheetwash. 1.4.2 Impacted Overland Flow R a i n f a l l impacts on low angle slopes (<1.25°) g r e a t l y i n c r e a s e the load of sheetflow in comparison with unimpacted flow at l e a s t in p o o r l y vegetated areas (Walker et a l 1977). Often r a i n f a l l impacting on low angle slopes m o b i l i s e s sediment which cannot be t r a n s p o r t e d (Farmer 1973) by ove r l a n d flow alone. B r i e f c l o u d b u r s t s i n r e a l rainstorms can r a i s e the suspended load i n sheetwash from 270 to 1600 ppm (Moss and Walker 1978). Conversion of these c o n c e n t r a t i o n s t a t i s t i c s i n t o a measure of e r o s i o n i s not p o s s i b l e with the a v a i l a b l e i n f o r m a t i o n . These data show that there i s a sound b a s i s , t h e o r e t i c a l and e m p i r i c a l , f o r assuming that overland flow i s an agent of sediment p r o d u c t i o n and t r a n s f e r at l e a s t i n unvegetated areas. 1.4.3 Splash In the absence of overland flow, for example i n areas of high i n f i l t r a t i o n c a p a c i t y , r a i n s p l a s h alone i s proposed as a mechanism of e r o s i o n . Two c a t e g o r i e s of study can be rec o g n i s e d : — 1. Those which c o n t r i b u t e to understanding the mechanisms of e r o s i o n , mostly c a r r i e d out on s p e c i a l l y prepared s o i l samples under l a b o r a t o r y c o n d i t i o n s . S t u d i e s in.the f i r s t category u s u a l l y focus on some aspect 10 of movement such as d i r e c t i o n of s p l a s h , angle of s p l a s h , d i s t a n c e of s p l a s h and exponent r e l a t i n g s p l a s h l o s s t o r a i n f a l l k i n e t i c energy. Estimates of the e f f i c i e n c y of detachment of the k i n e t i c energy may a l s o be made although l a b o r a t o r y simulated r a i n f a l l , which i s f r e q u e n t l y used, does not have the same drop s i z e , temporal u n i f o r m i t y or t e r m i n a l v e l o c i t y c h a r a c t e r i s t i c s as ' r e a l ' r a i n f a l l . An e x c e l l e n t and comprehensive summary of the r e l e v a n t l i t e r a t u r e i s given by F r o e l i c h and S l u p i k (1980). 2. F i e l d experiments u t i l i s i n g n a t u r a l r a i n f a l l ( B o l l i n n e 1978, Morgan 1978). 1.4.4 F r o s t and needle i c e The h y d r o m e t e o r o l o g i c a l regime i n a l p i n e regions of B r i t i s h Columbia causes frequent night f r o s t s i n the presence of c o n s i d e r a b l e moisture. Segregated i c e forms i n s o i l pores and cr a c k s (Skarzynska 1980) l o o s e n i n g the s o i l and i n c r e a s i n g i n f i l t r a t i o n c a p a c i t y (Schumm 1956). I t de s t r o y s s o i l c r u s t s and breaks armouring l a y e r s (Imeson 1977), rendering s o i l more v u l n e r a b l e to e r o s i o n by r a i n s p l a s h , o v e r l a n d flow and wind. Needle i c e i s a s p e c t a c u l a r form of i c e segregation and a very important agent of sediment t r a n s f e r and s e v e r a l estimates of movement r a t e s have been made. Soons and Rayner (1968) p a i n t e d stones 1.25—6 cms i n diameter and measured displacements of 5—63.5cms in 2 weeks and 11 f r e e z e thaw c y c l e s . Gradwell (1957) p a i n t e d stones 0.8cm diameter which moved 2—8cms per year on slopes of 2°—5° and 15-25cm on slopes of 10°. Mackay and Matthews (1975) made long term measurements on the Cinder Cone, G a r i b a l d i park, which demonstrated that needle i c e was more e f f i c i e n t at moving sediment than snowcreep, f r o s t heave 11 (concrete f r e e z i n g ) and s u r f a c e wash. Stone s t r i p e s gave measurements of I5cm/y for s u r f i c i a l movement of coarse m a t e r i a l and 35cm/y f o r f i n e s . Subsurface markers i n d i c a t e d that only the top 0.5cm of s o i l p a r t i c i p a t e d in mass movement. Mass t r a n s p o r t was estimated at about 3kg/y/m width of slope from a two year study of two troughs. T h i s can be converted to an a r e a l estimate of e r o s i o n (by observing the displacement of marker p a r t i c l e s ) of approximately I2kg/m 2/y or 10,000 Bubnoffs.' The amount of sediment a t t r i b u t e d to needle i c e t r a n s f e r i s s u b s t a n t i a l : i t has been reported at l e v e l s up to s e v e r a l orders of magnitude g r e a t e r than that recorded f o r e r o s i o n by overland flow. There are no s t u d i e s e x p l i c i t l y comparing sediment movement by needle i c e and overland flow i n the same area. 1.4.5 Wind e r o s i o n and d e p o s i t i o n Many a l p i n e s o i l s i n the Coast and Rocky Mountains are developed i n l o e s s r i c h d e p o s i t s o v e r l y i n g d i s c o n t i n u o u s t i l l and bedrock. Marker beds of v o l c a n i c ash i n the study area suggest gradual a c c r e t i o n of 30cm or more of windblown l o e s s over the past 10,000 years (Dumanski et a l 1980) while b u r i e d s o i l h o r i z o n s w i t h i n the l o e s s sheet (Dumanski and Pawluk 1971, van Ryswyck and Okazaki 1979) i n d i c a t e p e r i o d s of l i t t l e or no d e p o s i t i o n . S t r i c t l y the term ' l o e s s ' r e f e r s to an e o l i a n d e p o s i t p r i m a r i l y composed of m a t e r i a l in the 5—50»m s i z e range (Junge 1977) but i n t h i s study i t i s used more g e n e r a l l y , to r e f e r to the t o t a l amount of wind t r a n s p o r t e d m a t e r i a l . From an a n a l y s i s of lake sediments Caine (1971) showed that e o l i a n d e p o s i t i o n over the l a s t 10,000 years had been e q u i v a l e n t to e r o s i o n over the drainage basin (Green Lakes, Colorado) of 12 approximately 0.004mm/y or 4 Bubnoffs. G a l l i e (personal communication) caught windblown m a t e r i a l i n bulk samplers l o c a t e d w i t h i n the present study area and T e t i and Slaymaker (personal communication) r e p o r t e d duststorms on nearby n e o g l a c i a l moraines. These o b s e r v a t i o n s suggest that windblown m a t e r i a l i s a s i g n i f i c a n t component of the sediment budget. 1.4.6 Animals Thorn (1978) noted that p h y s i c a l s c i e n t i s t s regard animals as an a b e r r a t i o n to be avoided i n res e a r c h s i t e s e l e c t i o n . He showed that the pocket gopher on Niwot r i d g e moved, l o c a l l y , 1000 times more sediment in one year than other tundra proc e s s e s . Furthermore, gophers were most a c t i v e i n areas of almost unbroken v e g e t a t i v e cover, s i t e s t r a d i t i o n a l l y c o n s i d e r e d the s m a l l e s t c o n t r i b u t o r s to the sediment budget. Thorn estimated that pocket gophers move 2-3 Bubnoffs or 3,900-5,800 kg/km 2/year (by counting the number of mounds). T h i s f i g u r e i s comparable to the 1829-4390 kg/km 2/y a t t r i b u t e d by Darwin (1881) to earthworms, the 926-9512 kg/km 2/y estimated by Thorp (1949) f o r p r a i r i e dogs and the 1950 kg/km2/y P r i c e (1971) found moved by a r c t i c ground s q u i r r e l s . Imeson (1976) measured 1940 m3/km2/y r a i s e d to the ground i n the Luxembourg Ardennes by moles; t h i s was a major source of sediment f o r subsequent r e d i s t r i b u t i o n by r a i n s p l a s h . Y a i r (1974) found porcupine and isopod burrows accounted f o r a l l the sediment exported by f l u v i a l processes (up to 35 Bubnoffs) in a s m a l l , f i r s t order drainage b a s i n . The Coast Mountains have a l a r g e p o p u l a t i o n of hoary marmots (Marmota c a l i q a t a c a s c a d e n s i s ) which d i g l a r g e burrows and may be an important component of the sediment budget. 13 1.5 S p a t i a l v a r i a b i l i t y of s o i l l o s s Process (mechanism) has been summarily examined in the preceding s e c t i o n but i n a process—response model morphology i s v a r i a b l e . Process i s to some extent c o n t r o l l e d by morphology, hence previous s t u d i e s of s p a t i a l v a r i a b i l i t y and process should be s y n t h e s i s e d to i n c r e a s e e f f i c i e n c y of the sampling d e s i g n . As s i t e s e l e c t i o n was made from 1;10,000 a e r i a l photographs, the i n i t i a l sampling scheme was dependent only on v e g e t a t i o n s t r a t a . Although v e g e t a t i o n has been found to be an important v a r i a b l e in p r e v i o u s e r o s i o n s t u d i e s , slope angle i s a l s o a major cause of s p a t i a l v a r i a t i o n i n e r o s i o n r a t e s . Minor f a c t o r s i n c l u d e slope l e n g t h , water r e p e l l e n c y and s o i l type. The major f a c t o r s are reviewed below to assess t h e i r l i k e l y e f f e c t on sediment p r o d u c t i o n and to examine the f e a s i b i l i t y of measurement. 1.5.1 Slope angle S o i l l o s s undoubtedly i n c r e a s e s with slope angle. A range of exponents are r e p o r t e d : 1.35(Musgrave 1947), 1.4 (Zingg 1940), 1.45 (van Doren and B a r t e l l i 1956), and 2 (d'Souza and Morgan 1976). Horton (1945) thought s o i l l o s s must decrease p r o g r e s s i v e l y f o r slopes >20° because t h e o r e t i c a l c o n s i d e r a t i o n s preclude uniform t u r b u l e n t flow. Slope angle i s e a s i l y measured at the p l o t s c a l e i n the f i e l d but i s hard to estimate from maps. Slope angle i n f l u e n c e s overland flow by i n c r e a s i n g i t s v e l o c i t y (and Reynold's number). It i n f l u e n c e s s p l a s h by determining the p r o p o r t i o n of t o t a l t r a n s p o r t which occurs downslope (100% at 37° a c c o r d i n g to Farmer and van Haveren 1971). I t a l s o i n c r e a s e s the downslope 14 t r a n s f e r of m a t e r i a l f a l l i n g or r o l l i n g under the i n f l u e n c e of g r a v i t y . 1.5.2 V e g e t a t i o n V e g e t a t i o n i s a major i n f l u e n c e on s o i l l o s s and i s r e s p o n s i b l e f o r c o n s i d e r a b l e l o c a l v a r i a t i o n i n e r o s i o n r a t e s . Carson and Kirkby (1972) s t a t e that r a t e s of wash e r o s i o n on unvegetated slopes are 1,000—10,000 times g r e a t e r than on vegetated s l o p e s . I t i s a l s o w e l l known that v e g e t a t i o n p r o t e c t s the s o i l c h i e f l y by s h i e l d i n g i t from r a i n d r o p impacts. T h i s has been demonstrated e m p i r i c a l l y by work at many d i f f e r e n t s p a t i a l s c a l e s . At a p l o t s c a l e , Bovis (1982) showed that 45—65% of the v a r i a n c e of annual s o i l l o s s can be accounted fo r by the product of %bare s o i l and s i n e of slope angle. Slaymaker (1972) demonstrated that the sediment load of small watersheds without i n c i s e d channels was e n t i r e l y accounted fo r by s o i l e r o s i o n from unvegetated areas and Bryan and Campbell (1980) found that the badlands in the Red Deer r i v e r basin c o n t r i b u t e d 64 times as much sediment per u n i t area as d i d the r e s t of the b a s i n . These data a l l s t r o n g l y r e i n f o r c e the c o n t e n t i o n that p l a n t cover i s an important determinant of s o i l l o s s . Three of the proposed e r o s i o n a l mechanisms are s t r o n g l y dependent upon ground cover; needle i c e only grows where there i s l i t t l e or no v e g e t a t i o n and s p l a s h and wash are a l s o most e f f i c i e n t in those p l a c e s . 15 1.6 Temporal v a r i a b i l i t y The study took p l a c e over one summer season between snowmelt and the f a l l snow accumulation, so a q u a l i t a t i v e a n a l y s i s of temporal v a r i a b i l i t y i s necessary to assess the r e p r e s e n t a t i v e n e s s of the season. Wash and s p l a s h depend on r a i n f a l l events: a few storms ( B r i l l and Neal 1950) cause most s o i l l o s s . Campbell (1981) demonstrated that events with a r e t u r n p e r i o d g r e a t e r than two years cause s u r f a c e degradation while l e s s e r events cause net a g g r a d a t i o n . Pearce (1976) concluded that storms of one year r e t u r n p e r i o d achieved most e r o s i o n . The apparent c o n t r a d i c t i o n i s probably the r e s u l t of d i f f e r e n t measurement techniques. A l l these s t u d i e s p o i n t e d to a t h r e s h o l d r a i n f a l l i n t e n s i t y of s p e c i f i e d r e t u r n p e r i o d , below which l i t t l e e r o s i o n i s performed. The i m p l i c a t i o n i s that a short f i e l d season of a few months may not i n c l u d e a r a i n f a l l event capable of doing measurable geomorphic work. It i s l i k e l y that temporal v a r i a b i l i t y i n v o l v e s s e v e r a l f a c t o r s besides the i n c i d e n c e of r a i n s t o r m s . For example, f a l l temperatures i n f l u e n c e needle i c e occurrence, wind s t r e n g t h may i n f l u e n c e the e o l i a n load and winter snowpack depth may have a c r i t i c a l i n f l u e n c e upon the m o r t a l i t y of burrowing animals 1.7 Hypothesis f o r m u l a t i o n Caine's model in F i g u r e 1 i s a type of process response model. The model d e r i v e d f o r t h i s t h e s i s (Table 1) i s of the same genre but l i m i t e d to i n c l u d e only v a r i a b l e s of s u r f i c i a l movement. Responses are not separated e x p l i c i t l y i n t o d i f f e r e n t 16 c a t e g o r i e s : the p r i n c i p l e of e q u i f i n a l i t y i s accepted. The b r i e f review i n the preceding three s e c t i o n s enables some hypotheses to be formulated about processes which r e g u l a t e the sediment cascade. Three hypotheses are s t a t e d , a l l s a t i s f y i n g the c r i t e r i o n of f a l s i f i a b i l i t y . The f i r s t h y p o t h e s i s ranks the proc e s s e s : — 1. Sediment i s moved by needle i c e , wash, s p l a s h and wind, ( i n descending order of importance) with animals as a p o s s i b l e but u n p r e d i c t a b l e f a c t o r . The second hypothesis i s drawn from the review of morphology i n s e c t i o n 1.5: 2. The major mo r p h o l o g i c a l f a c t o r s c o n s t r a i n i n g s o i l l o s s are slope angle and percentage bare s o i l w h i l s t minor f a c t o r s i n c l u d e water r e p e l l e n c y , s o i l o r ganic matter and s o i l p a r t i c l e s i z e d i s t r i b u t i o n . Hypothesis 1 s t a t e s that needle i c e i s the major i n f l u e n c e upon sediment p r o d u c t i o n w h i l s t s p l a s h and wash are secondary. These premises give the t h i r d h y p o t h e s i s : — 3. Sediment movement i s g r e a t e s t i n the f a l l d u r i n g needle i c e events. Smaller but s i g n i f i c a n t movement occurs d u r i n g rainstorms when the amount of movement depends on r a i n f a l l i n t e n s i t y . 1 7 CHAPTER 2. DESCRIPTION OF THE STUDY AREA 2.1 Regional p e r s p e c t i v e The study area comprises the s o u t h — f a c i n g slope of a small a l p i n e watershed (approximately 0.2km2) at 1800m a s l with map r e f e r e n c e 034832 on the 1:50,000 92J/7 sheet. The watershed d r a i n s to Ryan River and i s about 8km north west of Pemberton and 120km north of Vancouver ( F i g 3). I t i s part of the Coast mountains of B r i t i s h Columbia which form a b e l t of c o n t i n u o u s l y high rugged t e r r a i n along the mainland coast of B r i t i s h Columbia and Southern Alaska (Ryder 1981). The topography i s dominated by f e a t u r e s of P l e i s t o c e n e g l a c i a l e r o s i o n such as nunataks and steep s i d e d g l a c i a l V a l l e y s . Previous work on the b a s i n i n c l u d e s a t h e o r e t i c a l study of h y d r o p h o b i c i t y ( B a r r e t t 1981) and an a n a l y s i s of the water budget and chemical weathering of the G a l l i e pond sub—basin ( i n progress, 1982, G a l l i e ) . 2.2 L o c a l topography The study area shows marked v a l l e y asymmetry with an unvegetated t a l u s slope and rock b l u f f s on the n o r t h — f a c i n g slope and a range of cover types on the s o u t h — f a c i n g s l o p e . T h i s l a t t e r area was s e l e c t e d f o r study on the grounds that f i e l d i n s t a l l a t i o n s were e a s i l y and s a f e l y a c c e s s i b l e . T o t a l r e l i e f of the v a l l e y i s 170m and i n s p e c t i o n of the a e r i a l photograph ( F i g 5) shows the d i f f e r e n c e i n morphology of the two v a l l e y s i d e s . Slope angles measured at the study s i t e s ( F i g 4) are given i n 18 Figure 3 Location of the Study Area ON ALLISON'S BOWL Trees Rock and Scree Grass and Moss Heather Contour interval in metres a.s.l. 0 50 100 Lower Lake approximate elevation 1800m NI=needle ice study s i t e OF s i t e s (p 69) located between 2R and 1 LML=luetkea, moss, l i c h e n ! W =whaleback ((p 86) T = tree i s l a n d 21 Appendix A. 2.3 Climate The Coast Mountains r e c e i v e heavy winter p r e c i p i t a t i o n which feeds l a r g e i c e f i e l d s , v a l l e y g l a c i e r s and a l s o maintains a deep winter snowpack at high e l e v a t i o n s . Snow course data from W h i s t l e r Mountain (1450m) show an annual average snowpack of 76.6cm water e q u i v a l e n t whereas Diamond Head (1420m) has 135.4cm. The l a t t e r s t a t i o n probably r e f l e c t s the study s i t e c o n d i t i o n s (personal communication, 1981, T. G a l l i e ) . Data from the B r i t i s h Columbia F o r e s t S e r v i c e weather s t a t i o n i n Pemberton show that there i s a pronounced summer drought and p r e c i p i t a t i o n maxima in October and November. Hence the study watershed r e c e i v e s most of i t s p r e c i p i t a t i o n as snow. Pemberton r e s i d e n t s who graze t h e i r c a t t l e near the study s i t e c o n s i d e r that i t u s u a l l y becomes snow f r e e i n July^and begins accumulating a winter snowpack during October. M e t e o r o l o g i c a l data f o r the study p e r i o d are given i n s e c t i o n 4.2.' 2.4 Geology The Coast Mountains comprise a complex igneous and metamorphic core with some f l a n k i n g sedimentaries which l a r g e l y predate the c r y s t a l l i n e rocks (Roddick and Hutchinson 1972). The bedrock i n the study area i s mapped as a Gambier Group roof pendant (McKee 1972) surrounded by quartz d i o r i t e . The Gambier Group i s extremely heterogeneous with rocks of m a c r o c r y s t a l l i n e and s c h i s t o s e t e x t u r e s . There are mafic and b a s a l t i c dykes and 22 numerous shear zones. The two most abundant rocks near the G a l l i e Pond sub—basin are 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 and a d i o r i t e ( p e rsonal communication, 1981 T. G a l l i e ) . No thorough g e o l o g i c survey was made of the r e s t of the ba s i n but f i e l d o b s e r v a t i o n s i n d i c a t e Gambier Group rocks i n the south of the basi n and quartz d i o r i t e the higher northern p o r t i o n . Most of the ba s i n i s covered with one or two l a y e r s of t i l l , the upper u n i t , p o s s i b l y an a b l a t i o n t i l l , being l e s s compact than the lower u n i t . Pedogenic h o r i z o n s are developed i n e o l i a n d e p o s i t s which o v e r l i e the t i l l . 2.5 Quaternary h i s t o r y Since d e g l a c i a t i o n the Coast Mountains have seen much ' p a r a g l a c i a l ' a c t i v i t y (Church and Ryder 1972), that i s r a p i d r e d i s t r i b u t i o n of g l a c i a l sediment i n t o secondary landforms in e a r l y p o s t g l a c i a l time. Most p a r a g l a c i a l a c t i v i t y took p l a c e i n the three m i l l e n i a f o l l o w i n g d e g l a c i a t i o n . There have been s e v e r a l n e o g l a c i a l events ( A l l e y 1976, Ryder et a l 1982). The Quaternary h i s t o r y of the study basin can be i n f e r r e d from e o l i a n d e p o s i t s and from a core taken from a bog 200m west of the Lower Lake. T h i s g i v e s a b a s a l date of 10—11,000BP which r e p r e s e n t s a minimum date f o r d e g l a c i a t i o n (personal communication T. G a l l i e ) . Where l o e s s accumulations are deep and undi s t u r b e d two coarse ash l a y e r s can be seen. The lower and t h i c k e s t l a y e r i s the Mazama ash (6,600 BP) and the upper l a y e r i s probably the Bridge r i v e r ash (2,600 BP). The Mazama ash o v e r l i e s a b u r i e d s o i l h o r i z o n which marks the end of the p o s t g l a c i a l warming around 7-6000 BP ( A l l e y 1976). P r e l i m i n a r y 23 r e s u l t s from p o l l e n a n a l y s i s (personal communication, 1981, T . G a l l i e ) of the lake core show that e o l i a n sedimentation has v a r i e d temporally p o s s i b l y i n response to c y c l e s of sediment p r o d u c t i o n as nearby v a l l e y g l a c i e r s advanced and r e t r e a t e d . 2.6 S o i l s No d e t a i l e d f i e l d o b s e r v a t i o n s of s o i l s were made because excavations would have a r t i f i c i a l l y i n c r e a s e d the amount of sediment a v a i l a b l e f o r wind e r o s i o n and t r a n s p o r t , y i e l d i n g u n r e p r e s e n t a t i v e r e s u l t s from the bulk samplers. S o i l p i t s dug i n p r e v i o u s years in the upper p a r t of the b a s i n showed w e l l developed s o i l s that were mostly D y s t r i c B r u n i s o l s (L. L a v k u l i c h , 1981 personal communication) w h i l s t those under the t r e e i s l a n d s showed p o d z o l i c h o r i z o n s . Regosols develop on a c t i v e d e b r i s lobes and steep s l o p e s . Thick organic A h o r i z o n s u n d e r l i e the area mapped as heather i n F i g 4 and deep organic s o i l s surround the Lower Lake. S o i l samples were taken at each s i t e from the h o r i z o n beneath the humus l a y e r . Approximately 500g was taken from each s i t e , more from the organic s o i l s beneath 2 and 2R as these had a very high water content. The p a r t i c l e s i z e d i s t r i b u t i o n from s i e v i n g i s shown i n F i g 6 which shows that the s o i l s are coarse t e x t u r e d with >50% sand and g r a v e l . I t was not p o s s i b l e to estimate the p r o p o r t i o n of boulders without d i g g i n g a s i z e a b l e p i t . Organic contents i n Appendix B are low; however, these f i g u r e s were f o r the e n t i r e sample, i n c l u d i n g g r a v e l . The organic content i n the f i n e r f r a c t i o n s i s high (up to 30%) as shown in Table 9 (p 86) which summarises organic content i n the v a r i o u s s o i l h o r i z o n s . Many of F i g 6 S o i l grain size d i s t r i b u t i o n 24a F i g 6 S o i l grain s i z e d i s t r i b u t i o n 25 the s o i l s i n the study watershed are water r e p e l l e n t , so t h e i r s p a t i a l v a r i a b i l i t y may determine areas where h y d r o p h o b i c i t y can generate o v e r l a n d flow. Water r e p e l l e n c y data are shown i n Appendix C. Tree i s l a n d s have the most r e p e l l e n t s o i l , f o l l o w e d by heather and moss/grass/shrub areas. Earthy spreads are not water r e p e l l e n t . 2.7 Veqetat ion Four cover types were mapped i n the f i e l d : areas with l i t t l e v e g e t a t i o n , t r e e i s l a n d s , heather and sedge/grass/ spaghnum. These were mapped with a plane t a b l e and a l i d a d e and the r e s u l t i n g map i n c o r p o r a t e d i n F i g 4. P r o p o r t i o n s of the basin occupied by d i f f e r e n t v e g e t a t i o n s t r a t a are given i n Table 2. The G a l l i e Pond sub—basin was not mapped but v e g e t a t i o n s t r a t a were i n f e r r e d from a more d e t a i l e d map (T. G a l l i e , i n p r e p a r a t i o n ) . The f i r s t category, that of rock and scree areas Table 2 Sampling scheme From photograph From map % % Lake 1 1 Tree 42 26 Scree 20 18 Heather 34 , 48 Grass 4 6 101 1 00 appeared to be too broad as i t i n c l u d e d bedrock, l a r g e boulder f i e l d s , small scree and earthy spreads (unvegetated areas with no pedogenic development and s i l t y s o i l s a s s o c i a t e d with needle i c e a c t i v i t y ) . These d i s p a r a t e environments are a l l 26 c h a r a c t e r i s e d by lack of v e g e t a t i o n : only some mosses and a few shrubs t o l e r a t e these h a b i t a t s (Luetkea p e c t i n a t a , Rhosomitrium  sudeticum, Sterocaulon sp) Tree i s l a n d s (Abies l a s i o c a r p a , Tsuga  mertensiana, Pinus a l b i c a u l i s ) occupy high dry rocky s i t e s and have many krummholz specimens (mainly Abies l a s i o c a r p a ) . Table 3 V e g e t a t i o n S i t e Large L i t t e r E a r t h Moss Grass Shrub Tree Heather Stone Small Canopy Stone 1 1 3 44 0 6 0 50 20 18 2 0 0 5 1 00 95 79 3 0 2R 0 0 0 96 30 92 0 21 3 0 0 0 39 0 40 0 21 4 5 0 18 3 35 30 0 42 5 1 5 0 55 1 5 3 7 0 10 6 0 0 0 30 0 1 5 0 98 7 6 0 70 21 9 1 4 0 1 0 8 0 39 0 8 0 1 7 0 56 9 7 5 74 0 2 64 0 0 9R 4 0 65 0 3 71 0 0 10 2 70 0 0 0 100 1 5 0 1 OR 6 7 0 0 7 59 10 52 1 1 1 3 71 0 1 4 0 83 1 5 0 1 2 4 100 0 0 0 1 00 100 0 1 2R 1 4 65 0 45 1 54 1 0 0 13 8 57 0 0 0 1 00 20 0 1 3R 76 10 0 0 0 23 0 14 1 4 31 29 1 5 0 8 43 0 47 NI 3 0 96 1 0 0 0 0 The ground i s c a r p e t e d with a t h i c k l a y e r of pine n< suggesting decomposition i s slow. There are some shrubs, notably h u c k l e b e r r i e s (Phyllodoce empetriformis, Phyllodoce intermedia  Phyllodoce g l a n u l i f e r a ) but no c l o s e cover. The sedge/spaghnum/grass a s s o c i a t i o n (Carex n i g r i c u s , Carex s p e c t a b i l i s , Juncus drummondii, Phyllodoce empetriformis) occupies depressions and stream channels and i s best developed around the Lower Lake. The f o u r t h category, areas where heather 27 (Cassiope mertensia, Phyllodoce empetriformis, Phyllodoce  intermedia, Phyllodoce q l a n u l i f e r a ) i s the predominant p l a n t , covered a very wide range of h a b i t a t s and probably r e q u i r e d s u b d i v i s i o n a c c o r d i n g to moisture a v a i l a b i l i t y . A complete s p e c i e s l i s t f o r the G a l l i e Pond subbasin i s given by B a r r e t t (1981) and the l i s t r e c o g n i s e s s e v e r a l s u b - c a t e g o r i e s of the areas mapped here as 'heather' and 'rock and s c r e e ' . V e g e t a t i o n was sampled at each s i t e immediately above the G e r l a c h trough with a 1m2 sampling quadrat d i v i d e d with s t r i n g i n t o 100cm2 segments. Seven cover types were r e c o g n i s e d : grass, m o s s , s h r u b , t r e e , 1 i t t e r , s m a l l stone and e a r t h and l a r g e stone. Each was expressed according to the percentage of a 1m2 segment immediately above the trough (Table 3). Many s i t e s had >100% cover because the t o t a l s t a t i s t i c was the sum of s e v e r a l i n d i v i d u a l cover types. V e g e t a t i o n surveys were made three times d u r i n g the f i e l d season to monitor seasonal changes. Shrub and grass was the only stratum which showed s u b s t a n t i a l change as the season progressed. An average value i s t a b u l a t e d . 28 CHAPTER 3. SAMPLING SCHEME, FIELD INSTALLATIONS AND ANALYTICAL TECHNIQUES 3.1 S p a t i a l v a r i a b i l i t y of s o i l l o s s The o b j e c t i v e of a good sampling design i s to gather i n f o r m a t i o n as e f f i c i e n t l y as p o s s i b l e . T h i s study u t i l i s e d small p l o t s (10m 2) ac c o r d i n g to the framework of Caine's model. S i m i l a r small p l o t s have been used s i n c e the 1920's f o r studying the s p a t i a l v a r i a t i o n of s o i l l o s s . They have been employed on the premise that morphology c o n s t r a i n s sediment y i e l d : slope angle, slope l e n g t h , s o i l c h a r a c t e r i s t i c s and v e g e t a t i v e cover are f r e q u e n t l y c i t e d as c o n t r o l l i n g c h a r a c t e r i s t i c s . They are a l s o used because of the p h y s i c a l d i f f i c u l t y of measuring e r o s i o n from l a r g e r areas. Boughton (1967) rec o g n i s e s two types of p l o t study :— 1. Those which analyse the e f f e c t of one v a r i a b l e while the others are h e l d constant (van Doren and B a r t e l l i 1956). 2. Those which estimate t o t a l s u r f i c i a l e r o s i o n c h a r a c t e r i s t i c of c e r t a i n environments, o f t e n at a watershed s c a l e . The f i r s t type of study i s a r t i f i c i a l and s u f f e r s from s e v e r a l c o n s t r a i n t s (Riezebos and Slotbom 1974). F i r s t , p l o t s d i f f e r i n g from each other in only one c h a r a c t e r i s t i c r a r e l y e x i s t i n nature as slope angle and len g t h are c o r r e l a t e d with s o i l and v e g e t a t i o n c h a r a c t e r i s t i c s . Second, s o i l l o s s i s o f t e n e x p l i c i t l y a t t r i b u t e d to r a i n f a l l and other f a c t o r s are not co n s i d e r e d . A r t i f i c i a l r a i n f a l l i s a p p l i e d to hasten data c o l l e c t i o n although i t does not produce the same e r o s i v e c o n d i t i o n s as n a t u r a l r a i n f a l l . A t h i r d concern i s the enclo s u r e 29 of p l o t s . Besides the d i s t u r b a n c e i n i n s t a l l i n g boundary fences, e n c l o s u r e l i m i t s the b u i l d u p of depth and v e l o c i t y i n o verland flow i n t e r r u p t i n g the n a t u r a l p a t t e r n of flow (Emmett 1970). Since e r o s i v e power i s c o n t r o l l e d i n d i r e c t l y by l e n g t h of o v e r l a n d flow ( I z z a r d 1944, Horton 1945), s o i l l o s s i s probably underestimated i n enclosed p l o t s . F i n a l l y , r e g r e s s i o n a n a l y s i s i s i n v a r i a b l y used to l i n k m o r phological f a c t o r s and s o i l l o s s . While r e g r e s s i o n i s a d e s c r i p t i v e , a n a l y t i c a l t o o l , c o r r e l a t i o n does not imply a c a u s a l r e l a t i o n s h i p (Mark and Church 1971) and cannot s u b s t i t u t e f o r an understanding of the p h y s i c a l r e l a t i o n s h i p s . Hayward (1967) notes that only four out of 69 p l o t s t u d i e s he i n v e s t i g a t e d used s t a t i s t i c a l l y a c c e p t a b l e designs, a f a c t which i n v a l i d a t e s many s t a t i s t i c a l l y s i g n i f i c a n t r e s u l t s . There are fewer s t u d i e s of the second type. A l l are g eomorphologically b i a s e d and many are process o r i e n t e d (Bryan, Y a i r and Hodges 1977) rather than analyses of s p a t i a l v a r i a b i l i t y . Bovis (1978) observes that a c t i v e s i t e s y i e l d i n g measureable r e s u l t s in a short time p e r i o d have r e c e i v e d a d i s p r o p o r t i o n a t e amount of a t t e n t i o n . However, as h i s r e s u l t s and those of Thorn (1976) i n d i c a t e a c t i v e s i t e s a l s o show the g r e a t e s t v a r i a b i l i t y , a s t a t i s t i c a l l y v a l i d sampling scheme should embrace a range of s i t e s but sample most i n t e n s i v e l y in a c t i v e areas (Bovis and Thorn-1981). 30 3.2 Sampling framework Hayward (1967) emphasises that r e p l i c a t i o n and randomisation are p r e r e q u i s i t e s of a s t a t i s t i c a l l y v a l i d sampling d e s i g n . R e p l i c a t i o n i s r e q u i r e d to c h a r a c t e r i s e within-groups v a r i a n c e when comparison between groups i s being made and i t i s a l s o necessary to a v o i d sampling b i a s . S t r a t i f i c a t i o n i n t o s i t e s with s i m i l a r morphological c h a r a c t e r i s t i c s i n c r e a s e s sampling e f f i c i e n c y but u n f o r t u n a t e l y s e v e r a l p l o t s t u d i e s ( E i s e l s t e i n 1967, Bovis 1978) have found subsequent r e c l a s s i f i c a t i o n by c l u s t e r a n a l y s i s i s necessary before a n a l y s i s of v a r i a n c e i s meaningful. T h i s suggests that s t r a t i f i c a t i o n c a r r i e d out p r i o r to a f i e l d examination of s i t e s i s i s o f t e n i n a c c u r a t e . The problem appears to be one of s c a l e as . s o i l l o s s c o n t r o l s cannot be i d e n t i f i e d at the s c a l e of maps and a e r i a l photographs. I t i s p o s s i b l e to compute the number of p l o t s r e q u i r e d to sample w i t h i n a s p e c i f i e d c o n f i d e n c e l i m i t : — n = t 2 s 2 E 2 where t i s the r e q u i r e d percentage poin t of the t d i s t r i b u t i o n , s 2 i s the p o p u l a t i o n v a r i a n c e and E i s the p e r m i s s i b l e e r r o r . U n f o r t u n a t e l y t h i s formula presupposes knowledge of s 2 which i s never known u n t i l completion of the study. A l s o , the s t a t i s t i c assumes that the data are normally d i s t r i b u t e d . Bovis (1978) shows that c o e f f i c i e n t s of v a r i a t i o n of s o i l l o s s from three v e g e t a t i o n s t r a t a gave values of 1.4,1.4 and 1.6 i n d i c a t i n g skewness (0.5 shows n o r m a l i t y ) . Even without t h i s second problem and with adequate knowledge of the p o p u l a t i o n , the sampling 31 equation p r e d i c t s a number of s i t e s which i s economically u n f e a s i b l e . Hence t h i s study and others have hkjh e r r o r margins and do not have enough s i t e s f o r s t a t i s t i c a l v a l i d a t i o n . However, t h i s was designed as a p i l o t study which might enable subsequent, more accurate work and any sampling d e f i c i e n c i e s c o u l d be improved i n l a t e r work. 3 . 3 Sampling design The study s i t e l a y under a deep snowpack a l l winter so i t was not p o s s i b l e to perform a d e t a i l e d f i e l d survey before s e l e c t i n g p l o t s for i n s t a l l a t i o n s . 1:10,000 i n f r a red photographs were a v a i l a b l e which enabled v e g e t a t i o n s t r a t a to be i d e n t i f i e d ( F i g 5). Four s t r a t a were i d e n t i f i e d from these photographs; t r e e i s l a n d s , rock and scree, heather and shrub/grass/spaghnum — the same u n i t s which were subsequently mapped and d e s c r i b e d p r e v i o u s l y i n more d e t a i l i n s e c t i o n 2.7. The s t r a t a , as d i s c e r n e d on the a e r i a l photograph, were mapped ( F i g 5) and d i v i d e d i n t o a numbered g r i d with each square r e p r e s e n t i n g approximately 10m2. P l o t s were s e l e c t e d randomly by drawing random numbers and l o c a t i n g s i t e s w i t h i n the numbered g r i d . A small p o r t i o n of the basin was covered by l a t e l y i n g snow patches when the photograph was taken and v e g e t a t i o n was i n f e r r e d from the surrounding areas. A g r e a t e r problem was determining the c o r r e c t c l a s s i f i c a t i o n f o r areas obscured by the shadows of t r e e s . A plane t a b l e map of the study area was made l a t e r i n the season to assess the accuracy of the o r i g i n a l sampling d e s i g n . The map ( F i g 4) and a s s o c i a t e d s t a t i s t i c s show (Table 2 pg 25) 32 that the area i n i t i a l l y a s s i g n e d to t r e e s (42%) was overestimated by 16% w h i l s t that of heather was underestimated by 14%. T h i s was p a r t i a l l y due to the tr e e shadow e f f e c t but a l s o to i n c l u s i o n of krummholz i n the t r e e stratum. F i e l d i n v e s t i g a t i o n s showed that there was a low percentage of ground covered by l i t t e r beneath these specimens and so a c l a s s i f i c a t i o n of heather was more a c c u r a t e . L o g i s t i c a l c o n s t r a i n t s l i m i t e d the number of s i t e s which c o u l d be s e r v i c e d to a maximum of 20. As s o i l l o s s i s low i n areas with a high percentage of v e g e t a t i o n cover, only two s i t e s were i n s t a l l e d in the spaghnum/grass/shrub stratum, and only three i n heather d e s p i t e the 34% area occupied by the l a t t e r . These i n s t a l l a t i o n s were not r e p l i c a t e d as low values of s o i l l o s s are a s s o c i a t e d with low w i t h i n stratum v a r i a n c e . Dry t r e e i s l a n d s and scree/rock areas were expected to show g r e a t e r v a r i a n c e , so f i v e s i t e s were l o c a t e d in each stratum and two of these were r e p l i c a t e d . An a d d i t i o n a l s i t e was s e l e c t e d s u b j e c t i v e l y at a place where needle i c e had been observed d u r i n g a b r i e f v i s i t the pr e v i o u s autumn as i t was not c e r t a i n whether the random sampling scheme encompassed any s i t e s showing needle i c e a c t i v i t y . The sampling design was implemented before snowmelt to av o i d b i a s i n s i t e l o c a t i o n . A stake was p l a c e d i n the snowpack at each s i t e as l o c a t e d with a e r i a l photographs using t r e e s and rocks f o r i d e n t i f i c a t i o n . Instrumentation was i n s t a l l e d as soon as the snowpack melted. One of the s i t e s i n the grass/shrub/spaghnum stratum had to be r e l o c a t e d because the s i t e became a meltwater channel conducting water from higher in 33 the basin to the Lower Lake. The s i t e was r e l o c a t e d as a r e p l i c a t e of the other one i n the stratum. The l o c a t i o n of each s i t e i s shown in F i g 4 and r e p l i c a t e s are denoted by the l e t t e r R. 3.4 F i e l d i n s t a l l a t i o n s 3.4.1 G e r l a c h troughs These were i n s t a l l e d at a l l 20 sampling s i t e s to c o l l e c t the t o t a l amount of sediment c r o s s i n g 1m of slope over v a r i a b l e time p e r i o d s determined by the occurrence of r a i n s t o r m s . They were designed to c o l l e c t sediment moved by overland flow, s p l a s h , wind a c t i o n and a l s o that d i s p l a c e d by animals. S i m i l a r troughs are d e s c r i b e d by G e r l a c h (1967), Leopold-and and Emmett (1967) B o v i s d 978), Campbell ( 1 974 ) , Dingwall (1972) and many ot h e r s . The troughs were c o n s t r u c t e d from 3" PVC pipe and pipe caps. A 7/8" ( i . d . ) v i n y l tube conducted water to a 2 l i t r e r e s e r v o i r . Each trough was 1m long. The troughs were cemented i n t o the ground with the a i d of l o c a l stones to supplement the cement mixture and small boulders to b u t t r e s s the troughs on steep s l o p e s . The concrete formed a smooth, g e n t l y s l o p i n g apron over which water was d i v e r t e d from the slope i n t o the trough. A small rim on e i t h e r s i d e of the apron prevented flow d i v e r g i n g around the trough. The j o i n between the troughs and concrete was se a l e d with c a u l k i n g compound and the upper edge of the apron was impregnated with ' c o l d cure' epoxy where i t met the s o i l : t h i s was to prevent e r o s i o n . F i g 7 i l l u s t r a t e s the trough and other i n s t a l l a t i o n s at s i t e 6. 35 The troughs s i t e d i n heather were the l e a s t s u c c e s s f u l because heather grew v i g o r o u s l y beneath the c o n c r e t e . Some lumps eroded but they were much l a r g e r than the other m a t e r i a l caught in the trough and were e a s i l y d i s t i n g u i s h e d and removed. A much more s e r i o u s problem was trough d e s t r u c t i o n by marmots. They were a t t r a c t e d to the troughs because of a wooden framework o r i g i n a l l y i n c l u d e d in the d e s i g n . The troughs at s i t e s 9 and 9R were twice p u l l e d out of t h e i r c oncrete moulds at the beginning of the season. Large boulders p l a c e d at e i t h e r end of both troughs prevented f u r t h e r damage and the animals appeared to l o s e i n t e r e s t once the i n s t a l l a t i o n s were secure! 3.4.2 Splash troughs Splashboards were f i r s t used by E l l i s o n (1945). They are boards with a c o l l e c t i n g trough. Refinements have i n c l u d e d c o l l e c t i n g troughs at d i f f e r e n t h e i g h t s (Gerlach 1978) and d i f f e r e n t m a t e r i a l s used as a c o l l e c t i n g board to increase the adherence of splashed m a t e r i a l . Grezs (1971) used f l a n n e l spanned in a wooden frame and Chmeilowiesz (1977) t r i e d b l o t t i n g paper. None of these a l t e r n a t i v e m a t e r i a l s was an improvement on the usual wood or metal. Apparatus c o n s i s t i n g of a funnel sunk i n t o the ground ( B o l l i n n e 1978) gave extremely high r a t e s of I0kg/m 2 or 5,000 Bubnoffs f o r a g r i c u l t u r a l l and. Morgan (1978) used c o n c e n t r i c r i n g s to d e l i n e a t e the area c o n t r i b u t i n g splashed sediment to c o l l e c t i n g t r a y s and obtained much lower values of 0.082kg/m 2/year or <40 Bubnoffs. T h i s l a t t e r apparatus was i n s t a l l e d at the study s i t e but u n f o r t u n a t e l y the f a b r i c put out to c a t c h the splashed m a t e r i a l was eaten by marmots. 36 The splashboards used i n t h i s study were c o n s t r u c t e d from 3" PVC pipe and PVC s h e e t i n g . A 1/4" diameter pipe was used to f l u s h the accumulated sediment. They were cemented i n t o the ground with the trough edge as c l o s e as p o s s i b l e to the ground s u r f a c e . They were f r e q u e n t l y d i s t u r b e d by marmots — which accounts p a r t l y f o r the small q u a n t i t y and low q u a l i t y of the r e s u l t s . A l s o the drainage tubes o f t e n became blocked — a l a r g e r diameter tube would have performed b e t t e r . 3.4.3 Bulk c o l l e c t o r s Wind d e p o s i t i o n was sampled by bulk c o l l e c t o r s . These were buckets wired to a 9" f u n n e l . The funnel was p l a c e d 30cms above the ground and so was too high to c o l l e c t splashed m a t e r i a l . The funnel c o l l e c t e d both wet and dry f a l l o u t . Mossbags (Goodman and I n s k i p 1977) were a l s o i n s t a l l e d but they d i s i n t e g r a t e d d u r i n g the dry s p e l l in August. 3.4.4 Tracer p a r t i c l e s T racer p a r t i c l e s of many substances i n c l u d i n g p a i n t e d stones (Bovis 1978), r a d i o a c t i v e l y tagged p a r t i c l e s (DePloey 1969) and crushed w i l l e m i t e ore (Fowler and Bennett 1969) have been used to t r a c e sediment movement. A l l except the r a d i o a c t i v e l y tagged p a r t i c l e s are inadequate as recovery i s l e s s than 100%. P u b l i c o p i n i o n and expense m i l i t a t e a g a i n s t the use of r a d i o a c t i v e substances. T r a c e r s were p l a c e d i n t h i s study f o r two reasons. The f i r s t was to i n v e s t i g a t e the movement of p a r t i c l e s of d i f f e r e n t s i z e s and the second to estimate the area c o n t r i b u t i n g sediment to the G e r l a c h trough. Stones from the UBC campus were s i e v e d 37 and spray p a i n t e d with f l u o r e s c e n t p a i n t as suggested by Bovis (1978). The s i z e s and c o l o u r s of stone and the s i t e s at which they were p l a c e d are shown i n Table 4. Table 4 Tracer p a r t i c l e s Size(mm) Colour Number pl a c e d S i t e s 4-8 Green 50 ALL 2-4 Yellow 1 07 ALL 1 -2 Red 200 ALL 1-0.5 Green many NI,10,2R,6,9 0.5-0.354 Yellow many NI,10,2R,6,9 0.354-0.25 Red many NI,10,2R,6,9 Three s i z e s of l a r g e r p a r t i c l e s (8—4mm 4—2mm 2—1mm) were p l a c e d at a l l s i t e s w h i l s t the smaller p a r t i c l e s (0.5—1mm 0.5—0.35, 0.35—0.25mm) were p l a c e d at a few repr e s e n t a t i v e , s i t e s because they were very time consuming to manufacture, l o c a t e and count. They were used to give only q u a l i t a t i v e data. A l a r g e p r o p o r t i o n were l o s t , probably through b u r i a l and p a i n t l o s s . 3.4.5 Standpipes 2" (5 cm) diameter standpipes were p l a c e d at 13 s i t e s to i n v e s t i g a t e the p o s i t i o n of the water t a b l e r e l a t i v e to the ground s u r f a c e . At s i t e s 7,9,9R,1 OR,13,13R and 14 the ground was too stony f o r s u c c e s s f u l i n s t a l l a t i o n . Holes were augured with a bucket auger and the standpipe pushed home. Depths of i n s t a l l a t i o n v a r i e d from 18 to 70 cms and i n many p l a c e s the ground was too stony f o r i n s t a l l a t i o n . 38 3.4.6 M e t e o r o l o g i c a l instruments Temperature and humidity were measured with a Fuess thermohygrograph which kept a continuous r e c o r d . I t was kept i n a Stevenson screen 2m above the ground. Cumulative windspeed was measured by a C a s s e l l a anemometer and rainstorms were monitored by a t i p p i n g bucket raingauge connected to an event recorder c o n s t r u c t e d by R . L e s l i e ( t e c h n i c i a n , Dept of Geography). Each bucket t i p represents 0.33mm of r a i n and the number of t i p s i n a 9.5min time p e r i o d was recorded. The intended time p e r i o d was I5mins but because moisture a t t a c k e d the c i r c u i t r y the time p e r i o d was a l t e r e d . The time p e r i o d was checked over s e v e r a l days under f i e l d c o n d i t i o n s . There i s a b a s i c u n c e r t a i n t y of 1 t i p per time p e r i o d ( B a r r e t t 1981). A l l the m e t e o r o l o g i c a l instruments were l o c a t e d in the extreme east of the b a s i n . 3.4.7 Snow sampling A Mount Rose snow sampler was used to o b t a i n snow cores f o r sediment a n a l y s i s and a CRREL snow survey k i t was used to sample sediment c o n c e n t r a t i o n with depth. The l a t t e r comprised s e v e r a l r 500ml c a p a c i t y tubes I9.5cms long which were used to take cores from the edge of snowpits. Some 18x18cm s u r f a c e samples of accumulated sediment were scraped o f f the s u r f a c e to o b t a i n a rough estimate of the amount and type of sediment d e p o s i t e d on the snowpack. 39 3.5 Sampling frequency The troughs were emptied nine times d u r i n g the season. However, the f i r s t two r a i n f a l l events (9—12 and 18—19 J u l y ) were only recorded i n a few troughs as the others were not i n s t a l l e d . A l l the troughs except those at s i t e s 5 and NI were i n s t a l l e d i n time to r e c o r d the r a i n f a l l event of J u l y 29. I t took up to 4 days to empty the troughs and process the water and sediment; t h i s meant that s e v e r a l rainstorms were i n t e g r a t e d each time the trough was emptied. On August 30 emptying was only p a r t i a l l y completed before the l a r g e r a i n s t o r m of August 31. Hence the two d a t a s e t s are summed. Data c o l l e c t e d on September 7 and September 15 are combined because the b o t t l e s were emptied on September 7 but the troughs were not emptied. Data from September 25 and October 14 are summed because snow occupied many s i t e s on September 25 and i c e i n the b o t t l e s prevented complete emptying. In October the s i t e s were dug out of the snow extremely c a r e f u l l y , u n t i l only a 5 cm l a y e r covered them. T h i s melted and enabled the troughs to be emptied with minimum d i s t u r b a n c e . The procedure was a r t i f i c i a l but the only way to o b t a i n sediment e n t r a i n e d d u r i n g the r a i n s t o r m of September 20. No r e c o r d f o r 9 and 9R i s a v a i l a b l e f o r October 14 because of access problems and the trough at s i t e 3 c o u l d not be l o c a t e d under snow cover. Although troughs were emptied a f t e r rainstorms because the c o l l e c t i n g r e s e r v o i r s were f u l l , the sediment they caught was not n e c e s s a r i l y the r e s u l t of r a i n s t o r m s . The three f a c t o r s of needle i c e , animals and e o l i a n d e p o s i t i o n are not d i r e c t l y dependent upon r a i n f a l l events. Hence a convention w i l l be 40 introduced here that i s used in the r e s t of the t h e s i s . Amounts of sediment recorded f o r a p a r t i c u l a r day r e l a t e to . the time p e r i o d s i n c e the trough was l a s t emptied. The i n f o r m a t i o n i s given i n Table 5. Splash troughs were emptied on J u l y 21, September 1 and September 15. As noted in s e c t i o n 3.4.2 many were s e v e r e l y d i s t u r b e d . Bulk samplers were emptied twice, on September 1 and September 15, with the exception of s i t e 9 which was emptied a t h i r d time on September 25. The date at which each apparatus was i n s t a l l e d and the date at which each s i t e became snow free i s shown in Appendix D. Displacement of t r a c e r s was measured only once, at the end of the season in October by f i n d i n g displacement from a s t r i n g s t r e t c h e d between two n a i l s which had p r e v i o u s l y acted as a b a s e l i n e . There are no f i g u r e s for s i t e s 3,10R,12R and which co u l d not be r e l o c a t e d . Table 5 Trough c o l l e c t i o n dates Per iod Date emptied 9-14 J u l 14- 19 J u l 19 J u l - 4 Aug 4 Aug-29 Aug 29 Aug-1 Sep 1 -7 Sep 7-15 Sep 15- 25 Sep 25 Sep-14 Oct 14 J u l 19 J u l 4 Aug 29 Aug 1 Sep 7 Sept 1 5 Sep 25 Sep 14 Oct 41 3.6 S i t e c h a r a c t e r i s t i c s M o r p h o l o g i c a l c h a r a c t e r i s t i c s were measured to check the i n i t i a l c l a s s i f i c a t i o n . Slope, v e g e t a t i o n cover and s o i l c h a r a c t e r i s t i c s have a l l been shown to be important in p r e v i o u s work. These three c h a r a c t e r i s t i c s were measured and a f o u r t h , water r e p e l l e n c y , was added as t h i s i s p o t e n t i a l l y a major f a c t o r i n g e n e r a t i n g overland flow. 3.7 A n a l y s i s of sediment samples The same techniques were a p p l i e d to sediment caught in G e r l a c h troughs, s p l a s h troughs, snow and bulk samplers. 3.7.1 F i e l d techniques Water samples, whether d e r i v e d from snow, bulk samplers, G e r l a c h troughs or s p l a s h troughs, a l l contained, some mineral m a t e r i a l and much organic matter. The l a r g e r p i e c e s of d e b r i s were f i l t e r e d out using a funnel with a p e r t u r e s which r e t a i n e d m a t e r i a l l a r g e r than 1mm diameter. Large stones and organic matter were r e t a i n e d but kept separate from the f i n e r f r a c t i o n . The water and sediment passing through the funnel were f i l t e r e d through a 0.45><m S a r t o r i u s c e l l u l o s e n i t r a t e f i l t e r paper using S a r t o r i u s SM16510 f i l t r a t i o n apparatus and a hand pump to c r e a t e a vacuum. T h i s was very time consuming as many samples took 3 hours to f i l t e r due to the c l o g g i n g of f i l t e r s by waxy and r e s i n o u s organic compounds. A l l samples were placed in p l a s t i c bags and taken back to the l a b o r a t o r y f o r f u r t h e r a n a l y s i s . 42 3.7.2 Laboratory techniques The l a r g e r p o r t i o n of the sediment was ashed i n a muffle furnace at 550°C for 2 hours. T h i s technique was u n s a t i s f a c t o r y fo r three reasons:— 1. Ash escaped from c r u c i b l e s and i t i s not known whether some mineral p a r t i c l e s were a l s o l o s t . 2. The weight of the ceramic c r u c i b l e s c o u l d not be determined to b e t t e r then ±0.0006g. As s e v e r a l small samples were of t h i s magnitude, the sediment was emptied from the c r u c i b l e s , using d i s t i l l e d water to wash out the r e s i d u e i f necessary and the oven d r i e d sediment was then weighed. 3. High temperatures used i n the M u f f l e procedure a c c e l e r a t e d mechanical weathering and caused l a r g e p a r t i c l e s to break apart both i n the furnace and upon c o o l i n g . An o x i d i s e d c r u s t formed on some p a r t i c l e s . The f i l t e r papers were ashed i n an I n t e r n a t i o n a l Plasma C o r p o r a t i o n (IPC) oxygen plasma furnace. T h i s technique u t i l i s e s i o n i s e d oxygen e n e r g i s e d by a r a d i o frequency g e n e r a t i n g u n i t . The i o n i s e d oxygen at t a c k e d organic bonds and so o x i d i s e d a l l the organic matter i n the sample and the f i l t e r paper. The r e a c t i o n products and excess oxygen were withdrawn from the system by a vacuum pump. D u p l i c a t e t e s t s on 12 blank f i l t e r papers ashed overnight showed that the papers were completely des t r o y e d . Other l i t e r a t u r e ( G l e i t t and Holland 1962) confirmed that organic matter was completely o x i d i s e d . The r e a c t i o n takes p l a c e at about 80°C (Walsh and F a s c i n g 1970) and t h i s i s v a l u a b l e in a v o i d i n g any m i n e r a l o g i c a l a l t e r a t i o n s . K and Mg s a t u r a t e d s l i d e s of k a o l i n i t e , 43 v e r m i c u l i t e , m o n t m o r i l l o n i t e and c h l o r i t e standards were t r e a t e d i n the furnace. Subsequent comparison with u n t r e a t e d s l i d e s from the same batch confirmed that there was no d e t e c t a b l e d i f f e r e n c e a f t e r exposure i n the oxygen furnace. Small g l a s s p e t r i d i s h e s were used to hold the f i l t e r papers. These showed no weight change a f t e r exposure i n the oxygen furnace and a i r c o o l i n g f o r 20 mins. Weighing of these samples was accurate to ± O.OOOlg. Hence the oxygen furnace i s c o n s i d e r a b l y more r e l i a b l e than the muffle and o f f e r s advantages of c l e a n l i n e s s and lack of m i n e r a l o g i c a l a l t e r a t i o n . However, ag a i n s t these advantages must be set the long time p e r i o d r e q u i r e d to ash samples and the requirement that samples be <1g. 3.7.3 S i e v i n g A f t e r treatment f o r the removal of or g a n i c s the samples, combined f r a c t i o n s from muffle and oxygen furnaces, were wet si e v e d through 7.5cm diameter s i e v e s i n t o 0.063mm, 0.063—0.25mm, 0.25—0.5mm, 0.5—1mm, 1—2mm, 2-4mm and 4-8mm f r a c t i o n s . Estimates of the diameters of l a r g e r p a r t i c l e s were made by measurement of i n d i v i d u a l stones. The samples were oven d r i e d at 105°C and weighed. 3.7.4 P r e p a r a t i o n f o r X Ray D i f f r a c t i o n (XRD) Each of the samples c o l l e c t e d on 1 September from the bulk samplers and a l s o two snow samples were prepared f o r XRD to i n v e s t i g a t e the m i n e r a l o g i c a l composition. One f i l t e r paper from each of the bulk samplers was pasted onto a s l i d e and analysed. The <63>im f r a c t i o n from each ashed sample was then prepared on o r i e n t e d s l i d e s by K and Mg s a t u r a t i o n i n accordance with 44 procedures o u t l i n e d i n the UBC S o i l Science Laboratory Manual. As the <63»m f r a c t i o n was very small (see Appendix I) c o n c e n t r a t i o n s i n the prepared s o l u t i o n s were low and the s l i d e s r e q u i r e d many a p p l i c a t i o n s of the s o l u t i o n to o b t a i n a f i l m t h i c k enough to give meaningful XRD peaks. U n f o r t u n a t e l y some dust a l s o s e t t l e d and t h i s r a i s e d the l e v e l of 'noise' i n the XRD peaks. 45 CHAPTER 4. RESULTS AND ERROR ANALYSIS The purpose of t h i s chapter i s to present data c o l l e c t e d in the f i e l d and processed i n the l a b o r a t o r y and to make an assessment of i t s p r e c i s i o n . I n t e r p r e t a t i o n of the r e s u l t s i s given i n chapter 5. 4.1 Data from i n d i v i d u a l apparatus 4.1.1 G e r l a c h troughs The amount of sediment caught i n each trough each time i t was emptied i s shown in Appendix E and summary s t a t i s t i c s f o r the whole season are shown i n F i g 8. Bracketed values in the Appendix i n d i c a t e s i n g l e l a r g e stones which f e l l i n t o the troughs. The data shown are the sum of f r a c t i o n s processed in the M u f f l e furnace and the oxygen plasma furnace and there i s some underestimation of the weight of organic matter because the p r o p o r t i o n caught on f i l t e r papers c o u l d not be estimated. At s i t e s where a l a r g e p r o p o r t i o n of organic matter was caught on f i l t e r " papers, the column i s l e f t blank. The l e n g t h of record v a r i e s from trough to trough because of the d i f f e r e n t times at which the troughs were i n s t a l l e d as shown i n Appendix D. The convention suggested i n Table 5 w i l l be adopted: a l l dates r e f e r to the date at which the apparatus i s emptied and not the date of the r a i n s t o r m s . Each t a b u l a t e d value in Appendix E has the same degree of u n c e r t a i n t y p l u s ±0.0002g p l u s other f a c t o r s i t was not p o s s i b l e to e v a l u a t e . Sample f r a c t i o n s processed i n muffle and oxygen furnace were both subject to ±0.000lg e r r o r due to u n c e r t a i n t i e s in the balance reading. Contamination of f i l t e r e d samples was <t F i g 8 Sediment col l e c t e d i n Gerlach troughs A break i n the graph represents a weight too large to be plotted. The appropriate s t a t i s t i c i s given. Site number 47 checked by f i l t e r i n g meltwater samples. These gave a sediment content of 0.0001—0.0003g per l i t r e of water, a c o n c e n t r a t i o n which i s a t t r i b u t e d to suspended sediment i n meltwater (see sediment c o n c e n t r a t i o n s ) t a b u l a t e d i n Appendix K. The p r o p o r t i o n processed i n the M u f f l e furnace was subject to weight l o s s due to d e f l a g r a t i o n and o x i d a t i v e r e a c t i o n s of c o n s t i t u e n t minerals at high temperatures. No values c o u l d be p l a c e d upon these two f a c t o r s but they were thought to be g r e a t e r than the balance e r r o r . The assessed e r r o r (±0.0002g) i s small when compared with both t o t a l and i n d i v i d u a l amounts of sediment c o l l e c t e d at each s i t e . There were some problems due to cement e r o s i o n , p a r t i c u l a r l y at s i t e s 6 and 3. However, the cement eroded i n l a r g e lumps and was e a s i l y d i s t i n g u i s h e d from other captured m a t e r i a l . Cement e r o s i o n was thought to be marmot damage and where cement c o u l d not be r e l i a b l y d i s t i n g u i s h e d from c a t c h , as at s i t e 6 on 15S, the d o u b t f u l q u a n t i t i e s were omitted from summary s t a t i s t i c s . In the next chapter i n f e r e n c e s w i l l be drawn from the s i z e d i s t r i b u t i o n of m a t e r i a l trapped i n the G e r l a c h troughs. A l l data are f o r oven d r i e d s o i l with f r a c t i o n s from the muffle and oxygen furnaces processed together. The amounts in each s i z e c l a s s a f t e r s i e v i n g are shown in Appendix F and as p l o t s i n Appendix G. Some e r r o r was i n c u r r e d during s i e v i n g and t h i s i s examined in Table 6. The o r i g i n a l weight of s o i l i s shown in the f i r s t column. T h i s can be compared with the weight a f t e r p r o c e s s i n g i n the muffle and oxygen furnace — seen in the second column of Table 6. The biggest e r r o r s i n terms of weight are found f o r the l a r g e s t samples —9,9R,10,11. At s i t e 9R 48 Table 6 Loss of sample durin g s i e v i n c A l l weights i n grams S i t e T o t a l T o t a l Di f ference % 1 3.9846 4.2365 0.2519 6 2 0.2779 0.3594 0.0815 23 2R 0.1037 0.1373 0.0336 24 3 • 0.0851 0.0565 0.0286 50 4 0.0393 0.0440 0.0047 1 1 5 1.5455 1.6102 0.0647 4 6 0.2741 0.2104 -0.0409 18 7 1.0127 1.0691 0.0564 5 8 0.2071 0.2104 -0.0033 2 6 54.8954 55.9416 1.0452 2 9R 22.6321 25.0723* 1.0452 2 10 6.4045 6.9683 0.5638 9 1 OR 0.4862 0.4426 -0.0436 1 0 1 1 7.4232 8.0181 0.5949 7 1 2 0.2780 0.2230 -0.0557 25 1 2R 1.4017 1.3645 -0.0372 3 1 3 0.2574 0.2563 -0.0011 0 1 3R 0.2361 0.3641 0.1280 85 1 4 0.5110 0.5371 0.0261 5 NI 3.3084 3.5460 0.2376 7 • 1 . 5g di s c r e p a n c y due to l o s s of part of p r o c e s s i n g . approximately 2g was l o s t from the September 1 sample because sediment was s p i l t from the d i s h . The l a r g e s t d i s c r e p a n c i e s (1—0.5g) at the other s i t e s are probably because i t was harder to wash sediment o f f the s i e v e s when the sample was l a r g e . A r e l a t i v e l y high pressure j e t of water had to be used which u n f o r t u n a t e l y caused some l o s s e s by p r o j e c t i n g sediment i n t o the a i r . The s i e v e s a l s o had a tendency to overflow when l a r g e samples were being processed. The e r r o r s ranged from 50% f o r s i t e 3 to zero f o r s i t e 13. T o t a l s of s i e v e d m a t e r i a l were both l a r g e r and smal l e r than the pr e — p r o c e s s i n g t o t a l s i n d i c a t i n g that m a t e r i a l was both l o s t and 49 gained from the s i e v e s . Not a l l samples from s i t e s 13 and 13R were s i e v e d so the comparison i s made by o m i t t i n g incomplete v a l u e s . While the e r r o r s are r e g r e t t a b l y l a r g e , they were c o n s i d e r e d to be small enough to allow q u a l i t a t i v e comparison of the r e s u l t s . 4.1.2 Splash troughs The amount of m a t e r i a l c o l l e c t e d in s p l a s h troughs i s shown in Appendix H. None of the c o l l e c t i o n s was complete because a l l were made without l i f t i n g the trough out of the ground. T h i s i n e v i t a b l y l e f t some m a t e r i a l i n the trough which s e t t l e d to the bottom r a t h e r than being washed out as the o u t l e t tube g r a d u a l l y became clogged with l a r g e p a r t i c l e s . It should a l s o be s t r e s s e d that most s p l a s h troughs were s e v e r e l y d i s t u r b e d by marmots before J u l y 21 when stones were pl a c e d to prevent f u r t h e r d i s t u r b a n c e , so these f i g u r e s should be regarded as minimum v a l u e s . I t was impossible to assess the p r e c i s i o n of the apparatus without d e s t r o y i n g i t but v i s u a l i n s p e c t i o n of the troughs suggested that the true amount of splashed m a t e r i a l c o u l d have been double the recorded value. Moreover, the c o l l e c t e d m a t e r i a l would have been b i a s e d toward the f i n e r f r a c t i o n as the co a r s e r p a r t i c l e s were l e s s s u c c e s s f u l l y evacuated with wash water. 4.1.3 Bulk c o l l e c t o r s These were e s t a b l i s h e d on 2nd August and emptied twice d u r i n g the season with the exc e p t i o n of s i t e 9, which was emptied f o r a t h i r d time on 25 September. The amount of sediment c o l l e c t e d at each s i t e during the season i s shown i n Appendix I 50 together with the s i z e d i s t r i b u t i o n s of the t o t a l c a t c h at each s i t e . Although the measurements were i n t e r n a l l y c o n s i s t e n t with a minimal p r o c e s s i n g e r r o r , i t was not p o s s i b l e to e s t a b l i s h the e f f i c i e n c y of the samplers. They were probably l e s s e f f i c i e n t at t r a p p i n g s o i l than the surrounding v e g e t a t i o n with i t s s t i c k y , h a i r y s u r f a c e s and i t i s l i k e l y these undersampled at high windspeeds. D e p o s i t i o n during rainstorms, which wash out most p a r t i c l e s <30Mm(Se'infield 1975) from the atmosphere was most e f f i c i e n t because sediment e n t e r i n g the funnel would be washed immediately i n t o the r e s e r v o i r . Hence undersampling was probably most s e r i o u s f o r l a r g e r diameter p a r t i c l e s . A l l the bulk c o l l e c t o r s were processed e x c l u s i v e l y on f i l t e r papers which g r e a t l y decreased the p r o c e s s i n g e r r o r to ±0.000lg. However, one paper from each sample c o l l e c t e d on 1 September was used f o r XRD. As t h i s was pasted onto a microscope s l i d e i t was not a v a i l a b l e f o r p r o c e s s i n g i n the oxygen furnace so an estimate had to be made f o r the amount of sediment i t c a r r i e d . .The mean weight of sediment c a r r i e d by each processed f i l t e r paper was c a l c u l a t e d and the corresponding value i n Appendix I ad j u s t e d upwards. A s t e r i s k s i n d i c a t e the t o t a l s which are a f f e c t e d . I t i s l i k e l y that the adjustment was low because f i l t e r papers which appeared to c a r r y most sediment were s u b j e c t i v e l y chosen f o r a n a l y s i s . A l s o , the e r r o r i s g r e a t e s t fo r s i t e 13 with a t o t a l number of 4 f i l t e r papers compared to 9 f i l t e r papers at s i t e 9 arid 6 at the other two s i t e s . The p o s s i b l e e r r o r s were not l a r g e enough to a f f e c t the s i t e ranking of 13,2 and 6, 9 in ascending order of sediment c a t c h . 51 4.1.4 T r a c e r p a r t i c l e s Coloured stones were p l a c e d at a l l s i t e s on August 5 and t h e i r t o t a l displacement at the end of the season was measured on October 12—16. The b a s e l i n e was marked by s t r i n g s t r e t c h e d between two long n a i l s . Only the three l a r g e s t s i z e s were analysed q u a n t i t a t i v e l y and 2 cm was taken as the minimum s i g n i f i c a n t d i s t a n c e moved. T h i s was a r e g r e t t a b l y l a r g e d i s t a n c e but was necessary because many stones s e t t l e d away from the b a s e l i n e during p o s i t i o n i n g because of i r r e g u l a r i t i e s i n microtopography caused by stones and v e g e t a t i o n . The d i s t a n c e s moved by the three l a r g e r s i z e s are shown, in Appendix J . P l o t s on p r o b a b i l i t y axes (not appended) showed that the data approximate to l o g n o r m a l i t y as would be p r e d i c t e d from Caine (1968). Thus the geometric rather than a r i t h m e t i c mean i s a p p r o p r i a t e f o r a n a l y s i n g displacements. The d i f f e r e n c e between the two i n d i c a t e s the degree of skew, that i s whether movement i s due to a few p a r t i c l e s moving a long way or whether i t i s due to many p a r t i c l e s each moving a short d i s t a n c e . S i m i l a r values of the two means i n d i c a t e the l a t t e r , d i f f e r i n g values the former. In both cases stones that d i d not move were not counted. Geometric and a r i t h m e t i c means and t h e i r r a t i o s are a l s o given in Appendix J . Recovery r a t e s of the t r a c e r s vary g r e a t l y . Appendix J shows that the average recovery r a t e of l a r g e green stones was 82% and the lowest 68%. Corresponding f i g u r e s f o r red are 55% and 29% and f o r yellow 38% and 19%. T h i s was unexpected as the s m a l l e s t stones (red 1—2mm diameter) were expected to show the lowest recovery r a t e s . However, yellow stones (2—4mm) were hard 52 to d i s t i n g u i s h from v e g e t a t i o n and the poorest r e s u l t s came from s i t e s with a l a r g e amount of dead grass and shrub ( s i t e s 2R and 2). As recovery at a l l p l o t s was <100%, the r e s u l t s must be tempered by a r e a l i s a t i o n that s e v e r a l f a c t o r s i n d i v i d u a l l y or c o l l e c t i v e l y obscured the stones and so bi a s e d the r e s u l t s : 1. Coating with s o i l , seen at 9R, was e f f e c t i v e only where bare s o i l i s a v a i l a b l e f o r rain d r o p s to churn. 2. Covering by l i t t e r or other dead v e g e t a t i o n , seen at s i t e s 12 and 8. T h i s i s most s e r i o u s beneath l a r g e t r e e s . 3. B u r i a l by other stones. 4. Covering by new growth ( e s p e c i a l l y at s i t e s 2 and 10). 5. Dropping down c r e v i c e s of s i z e l a r g e r than the t r a c e r s . 6. Some p a r t i c l e s t r a v e l l e d so f a r downslope that d e t e c t i o n was u n l i k e l y (probably a f a c t o r at s i t e s 9 and 12). The f i r s t f i v e f a c t o r s were assumed to be l e s s s e r i o u s than the s i x t h because they a f f e c t e d a l l stones i r r e s p e c t i v e of t h e i r p o s i t i o n r e l a t i v e to the b a s e l i n e . However, the s i x t h p o s s i b i l i t y would l e a d to underestimation of the mean d i s t a n c e t r a v e l l e d . Hence a l l d i s t a n c e s t a t i s t i c s shown here should be regarded as minimum estimates unless there i s 100% recovery. The gr e a t e r the recovery percentage, the more r e l i a b l e the s t a t i s t i c s and hence t h e i r i n t e r p r e t a t i o n . No q u a n t i t a t i v e a n a l y s i s was attempted f o r the f i n e r p a r t i c l e s (0.25-1mm) but f i e l d i n s p e c t i o n showed that a l l f i v e problems were g r e a t l y exacerbated i n these small s i z e s and q u a n t i t a t i v e a n a l y s i s was impossible because of low recovery r a t e s . 53 4.1.5 Standpipes These were i n s t a l l e d to i n d i c a t e the l e v e l of the groundwater t a b l e r e l a t i v e to the ground s u r f a c e . T h i s showed whether ov e r l a n d flow was Dunne or Horton types. S i t e s 2 and 2R were the only ones to show a ground water t a b l e near the s u r f a c e throughout the season and B a r r e t t (1981) has shown that there are m u l t i p l e water t a b l e s i n t h i s zone. The l a r g e storm of August 31 d i d not cause any p e r c e p t i b l e r i s e in the water t a b l e except at s i t e s 2 and 2R, so i t must be concluded that the other s i t e s are only s a t u r a t e d once a year at snowmelt, i f at a l l . 4.1.6 Sediment contained i n the snowpack Measurements of sediment contained i n the snowpack were not par t of the o r i g i n a l experimental d e s i g n . However, as there was too much snow at the beginning of the season to proceed with the planned sampling scheme, 3 days were devoted to t a k i n g snow samples and making f i e l d o b s e r v a t i o n s . The weight of sediment c o l l e c t e d in the snowpack i s given in Appendix K. S i t e s 1—6 were sampled on J u l y 1 and s i t e s 7 and NI on J u l y 2. The samples were obtained by t a k i n g four cores with the Mount Rose sampler at 5m north, south, east and west of each s i t e , as i d e n t i f i e d with the a i d of the a e r i a l photograph over the snowpack s u r f a c e . Snow was taken only from p l a c e s with no obvious s u r f a c e c o n c e n t r a t i o n s of sediment. A l l four cores were melted together and f i l t e r e d except at s i t e NI where the cores were kept seperate because of t h e i r inhomogeneity. Snow p i t s were dug at s i t e s 2 and 4 to i n v e s t i g a t e the sediment d i s t r i b u t i o n with depth using the CRREL snow sampling k i t . The 54 weight of sediment, water volume and c a l c u l a t e d sediment c o n c e n t r a t i o n s for each sample are given i n Appendix K. Each f i g u r e i s thought to be accurate to ±0.000lg because the whole sample was processed on f i l t e r papers. There i s a dis c r e p a n c y between the f i g u r e s shown i n Appendix K f o r the Mount Rose and CRREL samplers. Sediment c o n c e n t r a t i o n s f o r the CRREL samples are c o n s i d e r a b l y higher (250 - 2700 x I0" 8g/cc CRREL and 90 -420 x 10" 8 Mount Rose). Contamination of the CRREL samples was r u l e d out because s i t e 4 was sampled f i r s t , g i v i n g lower c o n c e n t r a t i o n s than s i t e 2. T h i s suggests that d i r t y tubes were not the cause of the d i s c r e p a n c y . Two e x p l a n a t i o n s are p o s s i b l e : — 1. P i t samples were taken from u n r e p r e s e n t a t i v e s i t e s . S i t e 2 i n p a r t i c u l a r i s e x c e p t i o n a l . 2. The CRREL samples are too small to be r e p r e s e n t a t i v e . 4.1.7 Overland flow data Depth and v e l o c i t y readings taken at the top and bottom edges of d e l i m i t e d "plots are shown in Appendix L. Depth was measured with a m i l l i m e t r e s c a l e and v e l o c i t y by dye t r a c e s . 4.2 M e t e o r o l o g i c a l summary 4.2.1 Temperature Summary data from the Fuess thermohygrograph f o r J u l y , August, September and pa r t of October are given in Table 7. Measured temperatures were c a l i b r a t e d with c h a r t s made by Braun (1980) who checked the instrument with an Assman psychrometer over the range of i n t e r e s t . 55 The temperature data are u s e f u l f o r supplementing J u l y August September October Table 7 M e t e o r o l o g i c a l data Temperature data Max 1 2°C 17°C 1 0°C 1 2°C Min 6°C 1 2°C 2°C 0°C R a i n f a l l data Total(mm) D u r a t i o n ( h r s ) Max 30min i n t e n s i t y (mm) 31 Aug 23 1 1 3 3 Sep 5 8.7 1 .2 9 Sep 2 1 .25 1 18 Sep 6 5 1 .2 20 Sept (1) 1 .2 2 0.6 20 Sept (2) 7 2.25 2.66 o b s e r v a t i o n s of needle i c e events. Needle i c e does not grow u n t i l ground temperatures reach —2°C and i t a l s o r e q u i r e s a p l e n t i f u l water supply and" optimal h y d r a u l i c c o n d u c t i v i t y in near s u r f a c e s o i l (Outcault 1970). A l l temperature measurements were taken at 2m above the ground so that the ground i t s e l f was s u b s t a n t i a l l y c o o l e r at n i g h t . The September thermohygrograph data (Appendix M) show that only 20—30 of the month had minimum temperatures low enough to allow i c e s e g r e g a t i o n . Needle i c e was observed on September 24,25 and 26 on snowfree patches of ground. The surrounding snow pr o v i d e d p l e n t i f u l moisture. The p e r i o d September 20-23 and a l s o the 27th onwards probably d i d not allow needle i c e growth because the ground was covered by a continuous blanket of snow s h i e l d i n g i t from d i u r n a l temperature 56 v a r i a t i o n s . Some needle i c e was observed on October 15 i n a few snow f r e e patches. 4.2.2 Snow The f i e l d s i t e was f i r s t v i s i t e d on June 15. Snow cover was estimated at 99% and the only snow free areas were a few rocky outcrops. The snow was probed with a dowel rod to make an estimate of snow depths which ranged between 2.6m near the G a l l i e Pond and 1m near s i t e 2 (Appendix D). By J u l y 1 many rock outcrops, some scree and some t r e e i s l a n d s were snow f r e e . Snow cover was estimated at 90% from f i e l d o b s e r v a t i o n s and melt a c c e l e r a t e d between J u l y 1 and 14. S i t e s on s t e e p l y s l o p i n g south f a c i n g s l o p e s , e s p e c i a l l y those with scree or rock cover, melted out f i r s t (9,9R,10 and 10R). Tree i s l a n d s i t e s (1,11,12 and 12R) a l s o became snow f r e e r e l a t i v e l y e a r l y . S i t e s i n the lower part of the v a l l e y (2 and 2R) melted out around J u l y 10: snow in the v a l l e y bottom was p r o t e c t e d from the sun for much of the day by the steep north f a c i n g s l o p e. Heather covered s i t e s were the next to become snow f r e e (3,4,13,13R,14) and f i n a l l y , at the beginning of August, s i t e s 7,5 and NI, earthy spreads u n d e r l a i n by sandy m a t e r i a l , melted out. Late l y i n g snow patches decreased the p o t e n t i a l growing season on the earthy spreads, by 4 weeks out of a t o t a l season of 12 weeks. Snow f e l l on September 20. 7-lOcms remained on September 24 i n a d i s c o n t i n u o u s c o v e r i n g . Between September 26 and October 11 approximately 70cms f e l l due to the extremely high p r e c i p i t a t i o n i n the f i r s t 10 days of October (see Table 7). T h i s was too great a depth f o r 10 days of c l e a r s k i e s to melt. 57 4.2.3 Ra i n f a11 Data from the t i p p i n g bucket r a i n gauge are shown in Table 7. U n f o r t u n a t e l y the raingauge and event recorder both malfunctioned at d i f f e r e n t times. A comparison with A l t a Lake r a i n f a l l data (Figure 9) shows that the instrument recorded reasonable amounts of p r e c i p i t a t i o n as the rank o r d e r i n g of the events August 31 — September 18 i s c o r r e c t . The runoff amounts c o l l e c t e d i n the trough r e s e r v o i r s a l s o gave an i n d i c a t i o n of the t o t a l p r e c i p i t a t i o n . U n f o r t u n a t e l y the l a r g e s t events (August 31 — September 1, September 19-23 onwards) exceeded the r e s e r v o i r c a p a c i t y . However, these volumes are u s e f u l i n i n d i c a t i n g the magnitude of rainstorms which generated trough data. A comparison with A l t a Lake p r e c i p i t a t i o n ( F i g 9) shows that the study area r e c e i v e d comparable amounts on J u l y 9—12, J u l y 29 and August 23-29 but that on 18 -19 J u l y i t r e c e i v e d s i g n i f i c a n t l y higher p r e c i p i t a t i o n than the 5mm recorded at A l t a Lake. These' data were s u f f i c i e n t to conclude that the l a r g e s t r a i n f a l l event i n the whole season occurred on August 31. I t gave a r e c o r d 24 hour p r e c i p i t a t i o n t o t a l f o r A l t a Lake i n August. G a l l i e (personal communication, 1981) provided p r e c i p i t a t i o n measurements f o r the summer and f a l l of 1978 and 1979 and i n both years measured 1 or 2 storms of s i m i l a r magnitude. However, both o c c u r r e d l a t e r i n the season and f e l l as snow or mixed r a i n and snow. T h i s suggests that the r a i n f a l l event had a r e t u r n p e r i o d of more than one year. 00 Figure 9 Rainfal l Est imates Trough waier co l lec t ion ] Alta Lake CAES) Study Area (Irom tipping bucket) A break indicates that the trough overflowed or that the r a i n f a l l recorded exceeded the amounts indicated on the scale. 59 CHAPTER 5. INTERPRETATION OF THE RESULTS In s e c t i o n 1.7 three hypotheses were put forward. The f i r s t h y pothesis ranked v a r i o u s processes i n order of t h e i r impact upon sediment p r o d u c t i o n while the second and t h i r d were concerned with s p a t i a l and temporal v a r i a b i l i t y . In t h i s chapter the v a l i d i t y of a l l three hypotheses i s examined in the l i g h t of data presented in chapter 4. A l s o , the sampling scheme i s a p p r a i s e d and improvements suggested. 5.1 S u r f i c i a l movement The displacement of t r a c e r p a r t i c l e s , r e p r e s e n t i n g s u r f i c i a l movement, i s documented in Appendix J . Those f i g u r e s , w h i l s t p r e c i s e are not a c c u r a t e , as they do not r e f l e c t q u a l i t a t i v e d i f f e r e n c e s in t r a c e r p a t t e r n s between s i t e s i n d i f f e r e n t environments. As the purpose of t r a c e r s was to show the p a t t e r n of s u r f i c i a l movement as w e l l as the amount, the summary s t a t i s t i c s i n Appendix J are supplemented by an a t — a — s i t e d e s c r i p t i o n of the type of movement. The displacement of a l l s i z e s of t r a c e r p a r t i c l e s ( F i g s 10 and 11) was i l l u s t r a t e d from f i e l d sketches made with the a i d of a sampling quadrat. Most movement took p l a c e along w e l l d e f i n e d channels corresponding to microtopographic depressions c o n s t r a i n e d by l a r g e stones and heather bushes. At most s i t e s the l a r g e r p a r t i c l e s showed one or two channels of movement per metre width of slope while the f i n e r p a r t i c l e s had higher frequency. In Appendix J the number of t r a c e r s moving a s i g n i f i c a n t d i s t a n c e i s l i s t e d . In general the more a c t i v e s i t e s (9,9R,11) which c o l l e c t e d most m a t e r i a l showed most t r a c e r s 60 Pat te rns of Sediment Movement Figure 10 Large S tones \ / 8 H e a t h e r a n d L i t t e r 3 H e a t h e r Figure 11 Small Stones N e e d l e i c e S i t e • 0.5 - K g r e e n ) * 0 . 2 5 - 0 . 5 [ y e l l o w teSK--- a n 6 ' e d ' fe>.;;.; S t o n e 10 20 30 4 0 . 5 0 g o 7 0 8 0 9 0 O m s S i t e 6 X • • • «t. .It . • *> » - » S i t e 10 S i t e 2R 62 moving as w e l l as the g r e a t e s t d i f f e r e n c e s between a r i t h m e t i c and geometric means. T h i s shows s t a t i s t i c a l l y that movement at those s i t e s i s co n c e n t r a t e d i n a few channels. A c l o s e r look at pa t t e r n and v e g e t a t i o n y i e l d s some i n t e r e s t i n g r e s u l t s . At s i t e s 3 and 6 (heather bushes with depressions i n between f l o o r e d with moss), t r a c e r s 1—2mm diameter moved f u r t h e r than those 4—8mm but a l l s i z e s r e g i s t e r e d some movement along p r e f e r r e d channels. In c o n t r a s t s i t e s 2 and 2R (grass/spaghnum) showed n e g l i g i b l e movement f o r a l l s i z e s above 1mm diameter w h i l s t the smaller s i z e s ( F i g 1 1 ) , moved along flow c o n c e n t r a t i o n s . Earthy spreads showed a sheet type of movement -t h i s can be seen i n Appendix J f o r s i t e 5 by the l a r g e number of p a r t i c l e s which moved a s i g n i f i c a n t d i s t a n c e w h i l s t none moved f u r t h e r than 25cms. Movement i n the l i t t e r of t r e e i s l a n d s was most anomalous. T r a c e r s showed movement along p r e f e r r e d l i n e s r a t h e r than u n i f o r m l y a c r o s s the whole contour while the l a r g e s t (4—8mm) p a r t i c l e s moved f a r t h e r than the smaller (1—2mm). Tracer displacements were a l s o analysed to make an estimate of the area which c o n t r i b u t e d sediment to the Ge r l a c h troughs. Mean and l o g mean d i s t a n c e s were c a l c u l a t e d f o r each c o l o u r t r a c e r ( l a r g e s i z e s only) (Table 8). U n f o r t u n a t e l y t h i s ignored n o n — p a r t i c i p a t o r y p a r t i c l e s , those moving <2cms. A s a t i s f a c t o r y s o l u t i o n to the problem of i n a c t i v e t r a c e r s was the c a l c u l a t i o n of a c o n t r i b u t i n g area, f o r each stone c o l o u r f o r each trough. T h i s was achieved by a s s i g n i n g each stone a width of slope (im/number of recovered stones) and m u l t i p l y i n g by the d i s t a n c e moved. Summation of a l l stones gave a h y p o t h e t i c a l envelope which p o t e n t i a l l y d e l i v e r e d sediment to the trough. The process 63 Table 8 G e r l a c h trough c o n t r i b u t i n g areas S i t e T r a c e r C o n t r i b u t i n g Sediment Estimated (mm) Area(cm 2) Catch(g) E r o s i o n (g/m 2) 1 4.0-8.0 -359 4.2365 123.2 2 0.5-0.25 60 0.3594 599.0 2R 0.5-0.25 32 0.1373 42.9 3 0.5-0.25 1 10 0.0565 5.1 4 not measured 5 0.5-1.0 •350 1.6102 46.0 6 0.5-0.25 75(110-60) 0.2332 31 .1(21. 1-38.5) 7 0.5-1.0 600(400-600) 1.0691 17.5(17.5-20.7) 8 0.5-0.25 27(20-30) 0.2104 77.9(70.1-105.2) 9 4.0-8.0 330(400-330)55.7416 1695.2 (1398.5-1700) 9R 0.5-0.25 1300(1300- 25.0723 192.8(134.2-250.7) 1 500) 10 4.0-8 . 0 400 6.9683 174.2 1 OR not measured 1 1 0.5-1.0 852 8.0181 94. 1 1 2 0.5-1.0 - 0.2223 ? 1 2R not measured 1 3 0.5-0.25 80(20-50) 0.4546 56.8(227.3-50.8) 1 3R not measured 1 4 0.5-0.25 30(20-30) 0.5273 179(268.6-179) NI 0.5-0.25 3.5460 1 18.2(236.4-118.2) A range of values r e s u l t s from the u n c e r t a i n t y i n e x t r a p o l a t i o n from F i g s 13 and 14. i s shown s c h e m a t i c a l l y i n F i g u r e 12 and the c a l c u l a t e d c o n t r i b u t i n g area in Table 8. D i f f e r i n g behaviour of the v a r i o u s s i z e c l a s s e s at d i f f e r e n t s i t e s i s shown i n F i g u r e s 13 and 14. S i t e s 1 and 12 with heavy l i t t e r cover both have s i m i l a r c o n t r i b u t i n g areas (approximately 350cm 2 f o r green, 50cm 2 f o r r e d ) . Grass (2 and 2R) and heather (3 and 6) s i t e s show a d i f f e r e n t r e l a t i o n s h i p ; very small c o n t r i b u t i n g areas (30 and 60cm 2 f o r 1—2mm) and the l a r g e s t displacements recorded by small t r a c e r s . Earthy spreads show a s i m i l a r t r e n d . "Mixed" s i t e s (shown i n F i g 14) have l e s s c l e a r c u t r e l a t i o n s h i p s which c o u l d r e s u l t from p a r t i a l l i t t e r 64 Figure 12 Schematic diagram of contributing area Contributing Area mmmm Gerlach trough Average tracer displacement c o v e r . Two f a c t o r s lead to underestimation of c o n t r i b u t i n g a r e a s . F i r s t , the 2cm measurement minimum in t r o d u c e s l a r g e e r r o r s ; i f each p a r t i c l e moved only 1 cm a c o n t r i b u t i n g area of 100cm2 would not be recorded and second, non—recovery of p a r t i c l e s which have t r a v e l l e d f a r t h e s t . However, the p a t t e r n of movement along p r e f e r r e d l i n e s means that the e r r o r s occur f o r only a small number of t r a c e r s . A r e p r e s e n t a t i v e c o n t r i b u t i n g area f o r each s i t e was s e l e c t e d by matching d50, the median diameter of sediment caught i n the trough, with the t r a c e r c l o s e s t i n s i z e . For example, in Table 8 d50 at s i t e s 1 and 10 i s c l o s e s t to the s i z e of the 4-8mm t r a c e r s . As the small s i z e t r a c e r s were not analysed q u a n t i t a t i v e l y , an estimate was made by e x t r a p o l a t i n g the l i n e s Figure 13 D i s p l a c e m e n t of T r a c e r P a r t i c l e s L i t t e r S m a l l S t o n e s • 4 0 0 - , 3 0 0 2 0 0-^ I , , G r e e n ( G ) Y e l l o w ( Y ) H e d ( R ) Grass 4 0 0 3 0 0 2 0 0 I 00 — 5 . . . . 7 6oH 20H G V Heather Figure 14 High Sediment Yield 9R 2 0 0 0 H Moderate Sediment Yield 67 in F i g s 13 and 14 but where there was no c l e a r r e l a t i o n s h i p a range of f i g u r e s i s g i v e n . Values of s o i l movement c a l c u l a t e d on an a r e a l b a s i s from the data above (Table 8) show that movement r a t e s at s i t e s 2R,3,5,6 and 7 are <50g/m2 or <25 Bubnoffs, at 2,13 and 11 50-1OOg or 25-50 Bubnoffs and >l00g/m 2 or >50 Bubnoffs at 1,9,9R,10,14 and NI. As a l l small areas were underrepresented, the estimates from s i t e s 2,2R,8,13 and 14 are too l a r g e , those f o r 3 and 6 suspect, whereas s t a t i s t i c s f o r 1,5,7,9,9R,10,11 and NI are more r e l i a b l e . S i t e 9 i s unique i n i t s high r a t e of sediment movement but the amount of sediment i n motion on other ' a c t i v e ' p l o t s such as 9R,10 and 11 i s only about four times g r e a t e r than that on ' i n a c t i v e ' p l o t s such as 2 and 2R. T h i s was an unexpected r e s u l t and when wind d e p o s i t i o n i s taken ' i n t o account, the f i g u r e s take on a d i f f e r e n t i n t e r p r e t a t i o n as d i s c u s s e d i n s e c t i o n 5.4. 5.2 Overland flow Observations of overland flow were made at snowmelt at the margins of snowpatches in the lower part of the b a s i n . Tree i s l a n d s near s i t e s 1 and 2 dammed s e v e r a l shallow ponds f i l l e d by meltwater from snow patches f u r t h e r upslope. They discharged over low p o i n t s i n the rocky t r e e i s l a n d r i d g e causing c o n s i d e r a b l e o v e r l a n d flow in the area marked ' moss and grass ' in F i g 4. Three s i t e s , OF 1,2 and 3 near s i t e 1 were examined. The aim of the overland flow measurements presented in Appendix L was to determine whether the flow was laminar or t u r b u l e n t and 68 a l s o the r e s i s t a n c e to flow. At snowmelt r a i n d r o p impacts d i d not confuse the r e s u l t s by c r e a t i n g a d d i t i o n a l t u r b u l e n c e . Horton (1939) a p p l i e d the Manning equation, designed f o r open channel flow, to o v e r l a n d flow under t u r b u l e n t c o n d i t i o n s : v=r 2/ 3s V2 n A l l u n i t s are m e t r i c . T h i s equation assumes flow i s f u l l y t u r b u l e n t , a very q u e s t i o n a b l e assumption as i s shown i n the data presented below. For f u l l y t u r b u l e n t flow q=Rd 5 3 and i n laminar flow q=Kd 3. K i s determined e x p e r i m e n t a l l y . Hence in theory i t i s p o s s i b l e to d i s t i n g u i s h between laminar and t u r b u l e n t flow on the b a s i s of the depth exponent. In p r a c t i c e determining K i s problematic as i t v a r i e s with s l o p e , roughness and flow regime. Moreover, Emrnett (1970) found that i n h i s c l i p p e d p l o t experiments the depth exponent v a r i e d between 3 and 5/3 suggesting that flow was t r a n s i t i o n a l between laminar and t u r b u l e n t . Experiments on t u r f r a t h e r than c l i p p e d p l o t s found the depth 10.2 .times that p r e d i c t e d by the P o i s e i l l e formula presumably due to flow r e t a r d a t i o n by grass stems— in e f f e c t most of the depth was merely d e t e n t i o n storage and d i d not p a r t i c i p a t e i n flow. In f l u i d mechanics a dimensionless number, the Reynold's number i s used to d e s c r i b e flow. For present purposes Rn= q/n - dv/n i s a p p r o p r i a t e (Dunne and D i e t r i c h '1980) (where n i s the kinematic v i s c o s i t y ) , d i s flow depth and v i s the flow v e l o c i t y ) . Low Rn c h a r a c t e r i s e s laminar flow and high values t u r b u l e n t flow with t r a n s i t i o n flow between. Surface roughness 69 a f f e c t s the t r a n s i t i o n from laminar to t u r b u l e n t flow which has been observed between Rn values of 400 and 3,000 (Emmett 1970, M o r g a l i 1970, Woolhiser et a l 1970). None of these authors r e p o r t e d f u l l y t u r b u l e n t flow from f i e l d p l o t s . R e s i s t a n c e to flow i s u s u a l l y measured by the Darcy—Weisbach f r i c t i o n f a c t o r (Ff) Ff = 2gds In the laminar range the f r i c t i o n f a c t o r (Ff) i s r e l a t e d to the Rn by Ff = k Rn where k i s an e m p i r i c a l l y determined constant of microtopography and v e g e t a t i o n . Dunne and D i e t r i c h (1980) showed (by p l o t t i n g Ff a g a i n s t Rn) that k=13,250 f o r 77% cover on u n d i p p e d p l o t s and k=1,680 f o r the same p l o t s and c l i p p e d v e g e t a t i o n . Where v e g e t a t i o n was clumped, e n a b l i n g flow to wend around p l a n t s i n pseudo channels (Foster and Meyer 1975, Meyer and Monke 1965), k a l s o gives an i n d i c a t i o n of the amount of s u r f a c e d e t e n t i o n . Emmett (1970) notes that a densely vegetated h i l l s l o p e (k= 500) had a slowly r i s i n g hydrograph which r e q u i r e d a storm of 2.5 hours to reach a steady s t a t e . In the steady s t a t e q was only 1/6 of the discharge on a smooth h i l l s l o p e implying that v e g e t a t i o n a i d s i n f i l t r a t i o n by i n c r e a s i n g d e t e n t i o n time. It can be seen that both Rn and Ff r e q u i r e measurement of flow depth and v e l o c i t y . I d e a l l y discharge measurements should act as a check. Some s t u d i e s on a r t i f i c i a l p l o t s ( I z z a r d 1944, Emmett 1970) have measured flow depth, discharge and v e l o c i t y d i r e c t l y . The Rn and Ff were c a l c u l a t e d at OF1,2 and 3 from the data in App L. A p l o t (not appended) of Rn a g a i n s t Ff to f i n d k 70 y i e l d e d so much s c a t t e r that no meaningful d e t e r m i n a t i o n c o u l d be made. The values of the Rn range from 105—304 for s i t e s 1 and 3 to 167-1467 for s i t e OF2. T h i s p l a c e s flow at s i t e s OF1 and 3 i n the laminar range and flow at s i t e 2 i n the t r a n s i t i o n range. I t i s s i g n i f i c a n t that no flow l i e s i n the t u r b u l e n t range presumably because of the r e t a r d i n g e f f e c t of v e g e t a t i o n . T h i s agrees with other analyses (Emmett 1970, Langford and Turner 1972). As a l l the overland flow p l o t s were fed by ponded meltwater, i t i s impossible f o r a r a i n s t o r m to achieve a comparable d i s c h a r g e . Hence the most intense storm discharge c o u l d not produce t u r b u l e n t overland flow i n a h e a v i l y vegetated area unless r a i n d r o p impacts c r e a t e a d d i t i o n a l turbulence — t h i s i s c o n s i d e r e d i n the next s e c t i o n . The f i e l d sketch of the overland flow p a t t e r n s in F i g 15 was made at s i t e OF2 by p l a c i n g a sampling quadrat over the p l o t and observing the v e g e t a t i o n type and flowpaths in each quadrant. Flow c l e a r l y f o l l o wed the margins of heather bushes while moss i n h i b i t e d flow channels and encouraged slow seepage. In the bottom l e f t hand corner a seep emerged from a moss patch. The flow channels are f l o o r e d with humic slime which probably has l e s s r e s i s t a n c e to flow than mossy areas. The grass was a l l q u i t e dead and bent downslope, p r o v i d i n g l e s s r e s i s t a n c e to flow than new growth. Whilst overland flow was observed and measured at snowmelt, d i r e c t o b s e r v a t i o n s were not made durin g the r e s t of the f i e l d season. However, there are two types of i n d i r e c t evidence which suggest that overland flow takes p l a c e d u r i n g r a i n s t o r m s . The f i r s t i s the water r e p e l l e n c y data seen i n Appendix C; the Figure 15 O v e r l a n d f l o w a n d v e g e t a t i o n t y p e ^ Earth III Heather Grass/shrub Moss 0 10 Cms 72 second and stronger evidence i s found i n the p a t t e r n of displacement of the^ t r a c e r p a r t i c l e s . Observations of water t a b l e l e v e l s a f t e r the l a r g e storm of August 31 showed that any flow which occ u r r e d was not Dunne type except i n the grass/moss stratum, as over most of the basin the s u b s o i l was not s a t u r a t e d immediately a f t e r the r a i n ended. I t i s l i k e l y , then, that water r e p e l l e n c y generated Horton overland flow. If o v e r l a n d flow occurred s o i l e r o s i o n should c o r r e l a t e with the data recorded i n Appendix C which shows that the most water r e p e l l e n t s i t e s are a s s o c i a t e d with pine needles ( l i t t e r ) which have hydrophobic waxes and r e s i n s (Gieseking 1975). According to the water drop p e n e t r a t i o n t e s t t r e e i s l a n d s should generate most overland flow as they have the most water r e p e l l e n t s u r f a c e . However, s o i l h o r i z o n s beneath the t r e e s i n d i c a t e that l e a c h i n g takes p l a c e as there i s pronounced h o r i z o n a t i o n . The most water r e p e l l e n t s i t e s (12,12R,10R) a l l have w e l l developed Ae and Bfh or Bh h o r i z o n s with marked f i n g e r i n g along t r e e root channels. T h i s i n d i c a t e s i n f i l t r a t i o n through the water r e p e l l e n t l a y e r . The WDP t e s t shows that the l i t t e r l a y e r i s c o n t i n u o u s l y water r e p e l l e n t and that waxes permeate the Ae h o r i z o n making i t hydrophobic. Hence there i s no obvious mechanism by which water can pass through the l i t t e r l a y e r e i t h e r l o c a l l y through f i n g e r s or more g e n e r a l l y as a l e a c h i n g agent. Moderately water r e p e l l e n t s i t e s are c h a r a c t e r i s e d by heather with mossy depressions and the grass/spaghnum/shrub a s s o c i a t i o n . Mossy depressions i n d i c a t e where flow i s c h a n e l l e d between heather bushes as shown in the f i e l d sketch of s i t e 0F2 73 ( F i g 15). However, WDP t e s t s show that small s c a l e d i f f e r e n c e s i n water r e p e l l e n c y are marked when mossy de p r e s s i o n s dry out as dry moss i s water r e p e l l e n t but has cracks which enable r a p i d i n f i l t r a t i o n (eg s i t e 14) and prevent overland flow. T h i s o b s e r v a t i o n throws doubt upon the f e a s i b i l i t y of generating o v e r l a n d flow by water r e p e l l e n c y . Water volumes caught i n Ger l a c h trough r e s e r v o i r s underestimate o v e r l a n d flow. 2 l i t r e b o t t l e s were too small to accommodate the events of August 31, September 25 and September 27 — October 10. Data from J u l y 15—18, August 4, September 7 and September 15 do not y i e l d any c l e a r p a t t e r n of v a r i a t i o n between s i t e s but these events were too small to f i l l s u r f a c e d e t e n t i o n s t o r e s and generate overland flow. D i f f e r e n c e s i n trough apron s i z e and r a i n f a l l v a r i a b i l i t y account f o r the volume spread recorded i n Appendix N. The second and more c o n v i n c i n g type of evidence f o r ove r l a n d flow l i e s i n the p a t t e r n of displacement of t r a c e r p a r t i c l e s . D i s t i n c t channels of movement seen in F i g u r e s 10 and 11 correspond to microtopographic channels of over l a n d flow ( F i g 15) e s p e c i a l l y at s i t e s 3 and 6. If o v e r l a n d flow i s a f a c t o r i n sediment entrainment and t r a n s p o r t , smaller p a r t i c l e s should t r a v e l f a r t h e s t because they may be e n t r a i n e d at lower d i s c h a r g e s and are s u b j e c t to bouyancy e f f e c t s . T h i s i s seen at most s i t e s although the p r e c i s e s i z e e f f e c t depends upon v e g e t a t i o n ; at s i t e s 3 and 6 1—2mm t r a c e r s move much f a r t h e r than 4—8mm w h i l s t the smaller s i z e s show more movement. A l l s i t e s except 1 and 12 showed t h i s p a t t e r n and the dis c r e p a n c y was t e n t a t i v e l y a t t r i b u t e d to smaller t r a c e r s 74 adhering to res i n o u s pine needles; i t c o u l d a l s o r e f l e c t the b u r i a l of f i n e p a r t i c l e s as l i t t e r f e l l . In summary, overland flow d e f i n i t e l y occurs at snowmelt i n the lower p o r t i o n of the basin and probably occurs elsewhere d u r i n g r a i n s t o r m s . Evidence f o r the former i s unequivocal but evidence f o r the l a t t e r i s c i r c u m s t a n t i a l , depending upon t r a c e r displacements and WDP t e s t s r a t h e r than d i r e c t o b s e r v a t i o n . The c a p a c i t y of overland flow to erode i s much l e s s c e r t a i n although t r a c e r movement demonstrates that i t i s c e r t a i n l y able to t r a n s p o r t eroded m a t e r i a l . If ove r l a n d flow were capable of e r o s i o n , s u s c e p t i b l e s i t e s should experience t h e i r l a r g e s t sediment catches a f t e r the l a r g e s t r a i n f a l l event (September 1). The only s i t e s where t h i s o c c u r r e d were 5,9R and NI and i n the next s e c t i o n i t w i l l be argued that s p l a s h , r a t h e r than overland flow caused e r o s i o n and/or t r a n s p o r t at these s i t e s . 5.3 Splash Data from the s p l a s h troughs are su b j e c t to l a r g e e r r o r s ( s e c t i o n 4.1.2) because many troughs were knocked over by marmots. A f t e r August 4 the troughs were weighed down at e i t h e r end by boulders, which prevented f u r t h e r d i s t u r b a n c e . Splash e r o s i o n i s c o r r e l a t e d with r a i n f a l l i n t e n s i t y (Eckern 1950) which i n turn r e f l e c t s drop s i z e (Hudson 1961,1963). I f sp l a s h were important, the s p l a s h troughs would have c o l l e c t e d most sediment on September 1 a f t e r the he a v i e s t r a i n f a l l of the season. Appendix H shows that t h i s d i d not occur as mean values f o r September 15 and September 1 are s i m i l a r . The higher value f o r - J u l y 21 i s undoubtedly due to d i s t u r b a n c e . 75 Hence s p l a s h i s unimportant at s i t e s 2,9,10,12,12R,13 and 13R. The s i z e d i s t r i b u t i o n of the m a t e r i a l from s p l a s h troughs was p l o t t e d on a lognormal p l o t together with sediment captured in the G e r l a c h trough (Appendix G). At s i t e 13R the splashed sediment was f i n e r than that caught i n the G e r l a c h trough but at s i t e s 12R and 10R i t was not s i g n i f i c a n t l y c o a r s e r or f i n e r which suggests that s p l a s h was moving the same c a l i b r e m a t e r i a l as that washed i n t o the G e r l a c h trough. As f i n e r m a t e r i a l p l o t s higher on these graphs, i n a l l cases the splashed m a t e r i a l was much f i n e r than the s o i l sample. Hence s p l a s h e r o s i o n of the s o i l , i f i t occurs, only a f f e c t s the smaller p a r t i c l e s . Absolute amounts of s p l a s h data when converted to comparable u n i t s of slope width (Appendix J) show that s p l a s h c o u l d account f o r most of the sediment moved at 12 and 13 (Appendix E) ""and a l a r g e p r o p o r t i o n of that moved at 10R, 12R, and 13R. F i v e s i t e s (3,5,6,9R and NI) r e g i s t e r e d s i g n i f i c a n t sediment catches i n t h e i r G e r l a c h troughs on September 1. S i t e s 5,9R and NI, each showed displacement of a high percentage of t r a c e r s e s p e c i a l l y i n the 1-2mm s i z e c l a s s (Appendix J ) . As s i t e s 5,7 and NI had a low percentage v e g e t a t i o n cover and s i t e 9R had l i t t l e ground cover, s p l a s h , probably a c t i n g i n c o n j u n c t i o n with overland flow, was i n f e r r e d as a major i n f l u e n c e i n performing e r o s i o n . A s i m i l a r type of sheet movement i s evidence f o r the continuous m i g r a t i o n of microchannels which was simulated under l a b o r a t o r y c o n d i t i o n s by Meyer and Monke(l965). Grain s i z e p l o t s f o r s i t e s 5,7 and NI show a d i s t i n c t i v e p a t t e r n . V i s u a l i n s p e c t i o n of 5,7 and NI (Appendix G) r e v e a l a 76 concave upwards shape f o r most of the sediment samples which i s not seen i n the s o i l . In a l l three cases t h i s tendency i s most marked f o r the samples p l o t t e d as 29Aug + 1 Sept. At s i t e NI f o r example, d84-dl6 (sample) spans 1.2 - 0.26mm and d84 - d l 6 ( s o i l ) 2.6 — 0.063mm. S i m i l a r r e s u l t s from 5 and 7 show that m a t e r i a l eroded from the earthy spreads i s d e f i c i e n t in f i n e and coarse m a t e r i a l when compared to the parent m a t e r i a l . A d e f i c i e n c y of f i n e s can be e x p l a i n e d by winnowing of the s u r f a c e by the wind or washing out of f i n e s by p r e v i o u s storms : the s u r f a c e l a y e r appeared to have an armouring c r u s t of sand and f i n e g r a v e l . Eroded m a t e r i a l was a l s o d e f i c i e n t i n m a t e r i a l over 1 — 2mm showing that r a i n s p l a s h moves m a t e r i a l <2mm p r e f e r e n t i a l l y ( G a b r i e l s and Moldenhauer 1978). At s i t e s 5,7 and NI no l a r g e sediment was c o l l e c t e d and s i t e 9 was the only l o c a t i o n where a l a r g e number of stones over 2cms in diameter was c o l l e c t e d . Kirkby and Kirkby (1974) a t t r i b u t e 'creeping' to l u b r i c a t i o n between stone and ground by o v e r l a n d flow. As no l a r g e stones were caught on the earthy spreads overland flow i s probably absent because of high i n f i l t r a t i o n r a t e s i n the sandy, non—cohesive s o i l . Hence s p l a s h i s i d e n t i f i e d as the most important agent of e r o s i o n . R a i n f a l l i n t e n s i t y has an e f f e c t on the c a l i b r e of m a t e r i a l eroded by s p l a s h . At s i t e s , 5,7 and NI, the m a t e r i a l eroded on September 7 and September 15 combined was f i n e r than that eroded on August 29 and September 1 combined, which c o r r e l a t e s with maximum r a i n f a l l i n t e n s i t i e s ; 3mm/30mins for the storm on 30th August and 1.2mm/30min for 3rd September. During the r a i n s t o r m of August 31 s i t e 9R had a small s c a l e 77 mudflow f e a t u r e . T h i s can be seen i n Appendix E which shows that the l a r g e s t amount of sediment was caught a f t e r the storm of 31st August. Appendix G shows that the g r a i n s i z e d i s t r i b u t i o n of the eroded s o i l was c l o s e r to the p l o t s o i l than s o i l eroded d u r i n g any other storm. DePloey (1971) d e s c r i b e s s i m i l a r small s c a l e f e a t u r e s from l a b o r a t o r y experiments in noncohesive sands. They form when high porewater pre s s u r e s develop i n the s u r f a c e s o i l as water i s d e l i v e r e d to r i l l s . Hence the e x i s t e n c e of t h i s f e a t u r e i s an a d d i t i o n a l mechanism f o r e r o s i o n by s p l a s h and overland flow. No s i m i l a r f e a t u r e s were seen at any other s i t e s . S i t e s 3 and 6, both heather with mossy de p r e s s i o n s a l s o showed maximum sediment ca t c h on August 29 and September 1 combined. The depressions may have s u f f e r e d some e r o s i o n as the moss was d e s i c c a t e d by a long dry s p e l l d u r i n g August because there i s no upper sto r e y of shrub or grass in the mossy depressions which might m i t i g a t e r a i n d r o p impacts. T h i s i n f e r e n c e , however, i s based on small sediment samples c o l l e c t e d at only two s i t e s so f u r t h e r c o n f i r m a t o r y data are r e q u i r e d . Splash may be the agent moving 4—8mm t r a c e r s in l i t t e r at s i t e s 1 and 12. The small s i z e s are prevented from moving by l i t t e r b u r i a l or r e s i n entrapment, although there i s no l i t e r a t u r e the w r i t e r i s aware of which enables assessment of such a mechanism. In summary i t i s i n f e r r e d that s p l a s h i s the dominant agent of e r o s i o n in the earthy spreads as high i n f i l t r a t i o n c a p a c i t i e s render overland flow u n l i k e l y . Furthermore, the g r a i n s i z e d i s t r i b u t i o n and the amount of sediment captured can be r e l a t e d to i n d i v i d u a l r a i n s t o r m s . Tracer displacements s t r o n g l y suggest 78 e r o s i o n by r a i n s p l a s h probably with some impacted o v e r l a n d flow (Moss and Walker 1978) as the both f i n g e r and sheet movement are seen. The i n f l u e n c e of s p l a s h on vegetated s i t e s , however, i s l e s s e q u i v o c a l and the s i z e of m a t e r i a l trapped i n the G e r l a c h troughs suggests that s p l a s h t r a n s p o r t i s not important at s i t e s 12, 12R,13 and 13R as the captured p a r t i c l e s are much f i n e r than those from the earthy spreads. As the earthy spreads are armoured, t h i s c o u l d a l s o r e f l e c t the c a l i b r e of m a t e r i a l a v a i l a b l e f o r e r o s i o n . Splash may be important i n areas of l i t t e r where f i n e p a r t i c l e s are covered by r e s i n and i n mossy dep r e s s i o n s between heather bushes although these c o n c l u s i o n s are t e n t a t i v e as l i t t l e data i s a v a i l a b l e . In g e n e r a l , the r o l e of s p l a s h i n vegetated areas i s d o u b t f u l w h i l s t i t s importance in unvegetated earthy spreads i s i n d i s p u t a b l e . Another mechanism, which c o u l d not be i n v e s t i g a t e d , was l o o s e n i n g of the surface s o i l by needle i c e . T h i s may prepare m a t e r i a l in the f a l l f o r r a i n s p l a s h e r o s i o n . 5.4 F r o s t and Needle i c e The work of Mackay and Matthews (1974) reviewed i n s e c t i o n 1.4.4 showed needle i c e as a major agent of sediment t r a n s f e r capable of moving 3kg per year of sediment a c r o s s 1m of s l o p e . T h i s study does not show such l a r g e amounts being moved by needle i c e . Needle i c e was observed on only 3 n i g h t s , 23 — 25 September and the thermohygrograph minima (Appendix M) show none occur r e d e a r l i e r . A f t e r September 26 needle i c e was precluded by snow cover. Gerlach trough c o l l e c t i o n s on September 25 and October 14 d i d not show maximum sediment weights from s i t e s 79 5,7,NI and 9R where needle i c e was observed. The d i f f e r e n t c a l i b r e m a t e r i a l c o l l e c t e d on September 25 and October 14 combined at 5,7 and 9R, m a t e r i a l e n r i c h e d with f i n e p a r t i c l e s , may be due to needle i c e . However, Outcault (1970) observed that needle i c e can t r a n s p o r t m a t e r i a l up to g r a v e l s i z e , so predominantly f i n e m a t e r i a l would not n e c e s s a r i l y be expected and an e x p l a n a t i o n of s p l a s h e r o s i o n by r a i n f a l l on September 18 and 20 i s more reasonable. Most years the f i e l d s i t e would experience more than three f r o s t c y c l e s before the snowpack began accumulating so although needle i c e i s unimportant d u r i n g the study season, a d i f f e r e n t year with a long snow f r e e p e r i o d i n September and October would have up to 6 weeks of needle i c e c y c l e s . Turf e x f o l i a t i o n around earthy spreads i s c l e a r evidence that needle i c e i s a c t i v e (Gradwell 1960, Brink et a l 1967, Heine 1977). Snow cores at s i t e NI showed much sediment i n the basal 5 cms of the snowpack. T h i s was a t t r i b u t e d to snow f a l l i n g on i c e needles and may h e l p maintain the loose g r a n u l a r s o i l s t r u c t u r e of the earthy spreads. 5.5 E o l i a n d e p o s i t i o n 5.5.1 P a r t i c l e s i z e d i s t r i b u t i o n and amount of windblown mater i a l The a l p i n e s o i l r e c o r d (Bouma et a l 1969, van Ryswyck and Okazaki 1979) shows a l o e s s capping o v e r l y i n g t i l l . T h i s evidence, together with the author's o b s e r v a t i o n s of wind e r o s i o n i n the Swiss Alps ( T y l e r 1979) suggested that wind e r o s i o n and d e p o s i t i o n d u r i n g the summer months had d e p o s i t e d 80 the l o e s s y s o i l capping. Although l o e s s s t r i c t l y r e f e r s to windblown m a t e r i a l 10-50Mm diameter (Junge 1977) here i t i s used more g e n e r a l l y to r e f e r to a l l windblown m a t e r i a l . Appendix I shows that the sampler at s i t e 9 caught four times as much sediment as those at 2 and 6 while s i t e 13 recorded l e a s t . Lognormal p r o b a b i l i t y p l o t s (Appendix G) show that s i t e 9, with the highest t o t a l amount of l o e s s , a l s o caught the c o a r s e s t w h i l s t s i t e 13, with the lowest c a t c h , caught the f i n e s t . S i t e s 2 and 6 recorded comparable t o t a l s and had s i m i l a r g r a i n s i z e d i s t r i b u t i o n s . Hence the l a r g e r samples of wind blown m a t e r i a l were a l s o c o a r s e r . S i t e 9 l i e s at the c e n t r e of an area with a low percentage v e g e t a t i o n cover (Table 3) and low s o i l o r g anic content (Appendix B). Both e m p i r i c a l (Woodruff and Siddoway 1965) and t h e o r e t i c a l work ( C h e p i l 1951) show that these c o n d i t i o n s favour s o i l e r o s i o n so i t i s l i k e l y that m a t e r i a l c a r r i e d to the sampler at s i t e 9 came from l o c a l sources. T h i s c o n c l u s i o n i s r e i n f o r c e d by the l a r g e amount of coarse m a t e r i a l (1—2mm) which was c o l l e c t e d . According to Bagnold (1941) m a t e r i a l of t h i s s i z e moves by s a l t a t i o n and so cannot move f a r from i t s source a r e a . L o c a t i o n on a steep slope (Appendix A) may help l a r g e p a r t i c l e s d i s p e r s e as launching height can i n c r e a s e t r a v e l d i s t a n c e (Chamberlain and Chadwick 1977). As s i t e s 2,6 and 13 are vegetated windblown m a t e r i a l must have t r a v e l l e d some d i s t a n c e . I t i s f i n e r than t h a t c o l l e c t e d at 9 with a higher p r o p o r t i o n of p a r t i c l e s <0.5mm diameter and a smaller t o t a l amount (Appendix G). This i s a r e f l e c t i o n of sedimentation v e l o c i t y which governs the time p a r t i c l e s in 81 suspension take to s e t t l e out under g r a v i t y ( C h e p i l and Woodruff 1957) and hence t h e i r p o t e n t i a l f o r t r a v e l (Syers et a l 1969). S i t e 13 i s at a higher e l e v a t i o n than 2 and 6 ( F i g 4) and f u r t h e r from any areas bare of v e g e t a t i o n , so i t s smaller and f i n e r c a t c h are e x p l i c a b l e by supply areas not yet d i s c u s s e d . The absolute amount of m a t e r i a l <63»im i s q u i t e comparable at a l l four s i t e s — S i t e 9 c o l l e c t s twice as much as the others w h i l s t the d i f f e r e n t i a l i n the l a r g e r s i z e c l a s s e s i s much g r e a t e r . T h i s suggests that the coarse p a r t i c l e s s e t t l e out under g r a v i t y near t h e i r source w h i l s t f i n e s are d i s p e r s e d . The t o t a l estimated mass of sediment caught in the bulk samplers ranged from O.CH82g at s i t e 13, through 0.0284 and 0.0344g at s i t e s 2 and 6 to 0.1154 at 9. As the area of the bulk sampler funnel was 410cm 2 these f i g u r e s t r a n s l a t e to an input of 0.44,0.69,0.84 and 2.8g/m2 per year or <1.5 Bubnoffs. Because of the undersampling problem inherent i n the e o l i a n sampler and a l s o because of the short sampling season (August 4 —September 1 i n comparison with a snow f r e e season of mid J u l y to September 25) these estimates are minima. However, they show that a s i g n i f i c a n t p r o p o r t i o n of sediment caught i n the G e r l a c h troughs may be accounted f o r by d i r e c t e o l i a n d e p o s i t i o n . A trough has an area of 760cm 2 and the cement apron an area of approximately 1—3 times the trough area g i v i n g a combined area of 1520 - 3040cm 2 (0.15 - 0.3m 2). Wind d e p o s i t i o n on t h i s area d u r i n g the season ranges from 0.12 — 0.06g at s i t e 13, to 0.09-0.23g at s i t e s 2 and 6 and 0.38-0.76g at s i t e 9. Hence s i t e s 2,2R,3,4,6,8,12,13,13R and 14 may have d i r e c t wind d e p o s i t i o n accounting f o r 25 — 100% of t h e i r t o t a l c a t c h . 82 A comparison of the g r a i n s i z e d i s t r i b u t i o n of windblown m a t e r i a l and sediment weight in the troughs a l s o suggests that some sediment caught i n some troughs may have been windblown. Examples can be seen in Appendix G f o r s i t e 12 ( J u l y 14, J u l y 19, August 4, August 29 and September 1 combined, 10R ( J u l y 19 and August 4), 10 ( J u l y 14),8,6(September 25 and October 14 combined, August 29 and September 1 combined) and s i t e 1 (September 7 and September 15 combined, September 25 and October 14 combined). A number of other s i t e s captured sediment coar s e r than the windblown m a t e r i a l but c o n s i d e r a b l y f i n e r than the s o i l : f o r example s i t e s 13 and 13R. A l l the samples l i s t e d here were very small and so probably s u s c e p t i b l e to s i g n i f i c a n t weight l o s s or gain to the i n d i v i d u a l f r a c t i o n s d u r i n g s i e v i n g as difecussed i n s e c t i o n 4.1.1. S t i l l , the evidence for wind d e p o s i t i o n i s more c o n v i n c i n g than that f o r e r o s i o n by overland flow and s p l a s h as the former has been measured w h i l s t evidence for the l a t t e r i s c i r c u m s t a n t i a l . Overland flow and s p l a s h c o u l d rework windblown d e p o s i t s . . 5.5.2 Provenance of windblown sediment Loess provenance i s o f t e n a t t r i b u t e d to g l a c i a l e r o s i o n (Smalley 1968) which crushes rock to s i l t s i z e rock f l o u r . When washed out onto b r a i d e d r i v e r s and bare outwash p l a i n s , huge volumes of m a t e r i a l are a v a i l a b l e f o r wind e r o s i o n . Many r e g i o n a l l o e s s d e p o s i t s (Rieger and Juve 1961, Foss e t ' a l 1978) have d i s t a n c e dependent parameters such as median g r a i n s i z e (Krumbein et a l 1937) and t h i c k n e s s (Frazee et a l 1970) which enable t h e i r sources to be t r a c e d . T h i s i s not p o s s i b l e f o r the l o e s s y component of a l p i n e s o i l s as wind d e p o s i t i o n depends upon 83 l o c a l topography and winds. As there are two v a l l e y g l a c i e r s w i t h i n 5km of the study s i t e as w e l l as numerous snowpatches i t i s l i k e l y that there are p l e n t i f u l sources of wind t r a n s p o r t a b l e m a t e r i a l r e l a t i v e l y c l o s e . The mineralogy of samples from a l l four s i t e s was i n v e s t i g a t e d to see whether any d i s t i n c t i o n c o u l d be made between l o c a l and r e g i o n a l sources of l o e s s . The most u s e f u l data were obtained from o r i e n t e d s l i d e s (Appendix 0) prepared from the <63nm f r a c t i o n and samples from s i t e s 2,6,9 and 13 were s i m i l a r . A d e t a i l e d a n a l y s i s of the XRD data i s given i n Appendix 0. It i s impossible to conduct a q u a n t i t a t i v e a n a l y s i s on t r a c e s with small peaks and high noise l e v e l s . T e n t a t i v e l y the r e l a t i v e mineral abundances a r e : — P l a g i o c l a s e f e l s p a r .. ( l a r g e s t component) Muscovite mica K a o l i n i t e Amphibole V e r m i c u l i te C h l o r i t e O r t h o c l a s e Quartz ( s m a l l e s t component) T h i s rank o r d e r i n g shows up some d i f f e r e n c e s between the s m a l l e s t f r a c t i o n and the t r a c e s obtained from a n a l y s i s of the raw f i l t e r papers. The t o t a l sample c o l l e c t e d on the f i l t e r papers were a l s o run on the XRD apparatus. Noise l e v e l s were very high but t h i s technique had the advantage of i n c l u d i n g l a r g e r windblown 84 m a t e r i a l . At s i t e s 13, 9(25/9) and 6 d e f i n i t e quartz peaks can be seen i n the coarse f r a c t i o n (Appendix 0 ) . S i t e 9 (25/9) a l s o has a l a r g e peak at 3.18A which can be a t t r i b u t e d to a l a r g e c r y s t a l of p l a g i o c l a s e . Quartz and p l a g i o c l a s e are more abundant i n the l a r g e r s i z e s than mica and k a o l i n i t e . Comparison of rock mineral abundances and sample abundances r e v e a l s e v e r a l d i s c r e p a n c i e s . The two major rock types i n the b a s i n are quartz d i o r i t e and quartz a c t i n o l i t e c h l o r i t e s c h i s t . The percentage composition of each rock and g r a i n h a b i t determined from t h i n s e c t i o n s ( G a l l i e p e r s o n a l communication) are shown i n Appendix P. The v a l l e y comprises a roof pendant of the heterogenous Gambier Group (McKee 1972), of which the s c h i s t i s a major component, surrounded by the r e g i o n a l quartz d i o r i t e . The g e o l o g i c a l h i s t o r y of the area i s complex and to date has not been s t u d i e d . Quartz, although a major component of both major rock types (30% and 40% f o r d i o r i t e and s c h i s t r e s p e c t i v e l y ) i s only present as a very low percentage in the f i n e f r a c t i o n although the amount i s g r e a t e r i n the l a r g e r s i z e s . In the s c h i s t quartz occurs c h i e f l y as s t r i n g e r s which r e s i s t breakdown. A small amount i s present as m i c r o c r y s t a l s (<0.0lmm) which are s u s c e p t i b l e to chemical weathering because of the d i s t o r t e d s h e l l found on small quartz g r a i n s . D i o r i t i c q uartz i s found i n g r a i n s 0.05 — 0.5mm diameter. The s m a l l e s t s i z e (50 rim) i s small enough to be windblown, but c l o s e to the 63>/m e x c l u s i o n of the XRD p r e p a r a t i o n . T h i s study suggests that i t i s a more important component in the l a r g e r s i z e s i n d i c a t i n g a l a r g e r c o n t r i b u t i o n from the d i o r i t e than from the Gambier Group. 85 P l a g i o c l a s e i s the s i n g l e most abundant windblown m i n e r a l . T h i s must r e f l e c t the 30% p r o p o r t i o n i n the quartz d i o r i t e as i t i s a minor component of the Gambier group. However, i t occurs i n the d i o r i t e as g r a i n s 0.2 — 1mm i n diameter, so i n d i v i d u a l g r a i n s must be broken down i n t o smaller u n i t s ( p o s s i b l y by cleavage) amenable to wind e r o s i o n . K a o l i n i t e i s probably an a l t e r a t i o n product (Dixon and Weed 1977). Hornblende i s present as f i n e c r y s t a l s i n the s c h i s t and as f i n e g r a i n e d and f i b r o u s (0.1mm) u n i t s i n the d i o r i t e . As the a c t i n o l i t e s c h i s t i s 30% hornblende, the low p r o p o r t i o n i n windblown m a t e r i a l suggests that d i o r i t e i s the major l o e s s source. The s c h i s t i s r i c h i n c h l o r i t e as are many minor l i t h o l o g i e s in the Gambier Group. However, c h l o r i t e i s not a major component of windblown m a t e r i a l at any s i t e and i s we l l below the 20% which i t occupies in the s c h i s t . Hence the m i n e r a l o g i c a l evidence a l l c o r r o b o r a t e s a r e g i o n a l source f o r windblown m a t e r i a l as i t r e f l e c t s the r e g i o n a l quartz d i o r i t e r a t her than l o c a l Gambier group rocks. One major i n c o n g r u i t y i s the great abundance of mica and v e r m i c u l i t e i n the samples i n c o n t r a s t to t h e i r low c o n c e n t r a t i o n s i n the parent rock. T h i s probably r e f l e c t s the p l a t y nature of these minerals ( B r i n d l e y and Brown 1980) which enables them to be t r a n s p o r t e d long d i s t a n c e s by the wind. 5.5.3 Wind d e p o s i t i o n The s o i l r ecord at the study s i t e shows continuous d e p o s i t i o n s i n c e d e g l a c i a t i o n . Samples from s o i l h o rizons at three s i t e s i n the G a l l i e pond sub—basin are shown i n Table 9. 86 A l l samples were k i n d l y provided by T. G a l l i e from s o i l p i t s dug in p r e v i o u s y e a r s . A l l three pedons show a b u r i e d s o i l h o r i z o n with organic content as high or higher than contemporary A Table 9 Organic content and p a r t i c l e s i z e d i s t r i b u t i o n of 3 s o i l p i t s Tree I s l a n d P i t S i t e G ravel 0.5-0.25mm <0.0063mm Depth 1 -2mm- 0. 25-0 .125mm Org % 1 -0.5mm 0. 125-0.0063mm Ae 0-5 1 6 23 7.3 7.3 8. 4 7.9 28.1 40.9 Omb 5-1 1 32 28 11.4 12.2 19. 9 9.4 25 22.7 Bf 1 1-27 25 40 19.3 19.3 20. 9 7.7 18.1 15 BC 27-38 1 1 60 29.3 24.1 17. 2 10.3 8.6 10.3 Whaleback Topographic depression Ah 0-10 42 1 2 .8 3.5 14 .2 9. 2 35. 3 35. 7 Bm 10-14 7 1 22 .7 15.1 1 4 .6 1 1 . 6 10. 3 25. 6 Omb 14-25 36 26 7 .9 7.3 1 9 .9 9. 3 19. 3 30 Bmb125-37 30 2 0 .8 3.8 1 2 .2 10. 7 1 3 59. 6 Bmb237-40 1 2 64 22 .4 14.8 1 3 .2 1 1 10. 7 28 Bmb340-49 27 62 1 1 .9 10.2 1 1 .9 10. 9 1 1 43. 2 Luetkea/moss/1ichen (LML) Gently s l o p i n g Ah 0-3 25 2 0. 8 0. 8 5. 7 7 38.5 48.2 Bm 3-3.5 1 4 0 0. 6 0. 4 1 . 7 2. 6 37.2 58. Bmb13.5-6 1 2 0 0. 6 1 . 7 7. 3 17. 2 25.3 46 Omb 6-10 34 28 6. 6 5. 8 18. 2 19. 8 1 9 30.6 Bmb2l0-18 1 2 56 25. 6 20. 3 14. 6 9. 8 10.5 19.2 BC 18-60 5 63 24 25. 9 17. 6 8. 8 8.8 14.9 h o r i z o n s . Beneath the b u r i e d organic h o r i z o n l i e h o r i z o n s developed i n g r a v e l l y t i l l (60% g r a v e l ) . The LML and whaleback s i t e s show 2 l a y e r s of tephra juxtaposed at the LML s i t e and 87 separated by an organic h o r i z o n at the whaleback s i t e . The lower ash i s probably Mazama (6,600BP) and the upper the Bridge River (2,600BP) (Clague 1980). The whaleback s i t e shows the upper ash i s c o a r s e r which i s c o n s i s t e n t with i'ts o r i g i n from a c l o s e r source than the Mazama. O v e r a l l , (personal communication, 1981, T. G a l l i e ) , the s o i l p r o f i l e s suggest c o o l c o n d i t i o n s a f t e r d e g l a c i a t i o n f o l lowed by a warm p e r i o d around 6,600BP ending at the time of the Mazama ash f a l l . Another c o o l p e r i o d followed and present day c o n d i t i o n s are a l i t t l e warmer but not as warm as the optimum at approximately 6,000BP. The d i f f e r e n c e i n s o i l depth at the three s i t e s shows that wind d e p o s i t i o n i s not uniform. A c o n s i d e r a b l e p r o p o r t i o n of ' l o e s s ' d e p o s i t s are a c t u a l l y pure or reworked tephra . The 'whaleback' s i t e i s in a s h e l t e r e d d e p r e s s i o n which probably accounts f o r the deep accumulation. I t i s u n c e r t a i n whether sediment accumulates by d u s t f a l l or by the washing in of f i n e s . The l a t t e r i s suspected as su r f a c e d e t e n t i o n was observed at t h i s s i t e . A s i g n i f i c a n t amount of d e p o s i t i o n on the exposed t r e e i s l a n d s i t e i s evidence f o r the c a p a c i t y of v e g e t a t i o n (and/or l i t t e r ) to t r a p windblown m a t e r i a l . Chamberlain and Chadwick (1972) demonstrate the a t t r a c t i o n of h a i r y and s t i c k y v e g e t a t i o n w h i l s t Clough (1974) shows that moss i s more e f f i c i e n t than g r a s s . A comparison with the data in Appendix I shows that contemporary windblown m a t e r i a l i s of approximately the r i g h t p a r t i c l e s i z e d i s t r i b u t i o n to account f o r the s i z e d i s t r i b u t i o n of present day Ae and Ah hor i z o n s i f s i t e 13 i s taken as r e p r e s e n t a t i v e of the G a l l i e Pond subbasin because of i t s 88 s i m i l a r topographic l o c a t i o n . However, a bulk sampler i s r e q u i r e d i n the G a l l i e Pond sub—basin to make a more q u a n t i t a t i v e assessment. 5.5.4 Sediment contained in the snowpack The snowpack was not i n i t i a l l y proposed as a sediment source because there i s no l i t e r a t u r e showing that i t c o n t a i n s a s i g n i f i c a n t amount of sediment. There i s evidence f o r c o n s i d e r a b l e e r o s i o n by l a t e l y i n g snowpatches (Thorn 1979) at the i n t e r f a c e of the snowpack and u n d e r l y i n g rock but no s t u d i e s of the sediment content of the upper snow l a y e r s . I n v e s t i g a t i o n s of summer windblown m a t e r i a l d e p o s i t e d on the snow surface (Spalding 1979) show that the m a t e r i a l i s 90% o r g a n i c and during the winter season the mineral c o n t r i b u t i o n would be n e g l i g i b l e as snow bl a n k e t s a l l p o t e n t i a l source areas. In t h i s study a few samples were taken to i n v e s t i g a t e whether f u t u r e work should look more c l o s e l y at the r o l e of the snowpack i n c o l l e c t i n g and s t o r i n g wind blown m a t e r i a l d u r i n g the winter months Cores taken with the Mount Rose snow sampler showed that there was a s i g n i f i c a n t amount of sediment i n the snowpack. S t a t i s t i c s are given i n Appendix K. C o n c e n t r a t i o n s at the NI s i t e are g r e a t e r than those found elsewhere because i t was impossible to o b t a i n a core without loose m a t e r i a l frozen i n t o the base, probably because snow f r o z e onto i c e needles and they were i n c o r p o r a t e d i n t o the snowpack. Two cores from the needle i c e s i t e were abandoned because they i n c l u d e d sediment from the d e b r i s spread beneath. As the snowpack melts channels (runnels) form in the snow su r f a c e p a r t i c u l a r l y on steep s l o p e s . They are s t a i n e d by 89 sediment d e p o s i t e d on the snow s u r f a c e . A few snow samples were taken to compare the sediment content of the snow s u r f a c e w i t h i n and between the ru n n e l s . Three samples taken from d i f f e r e n t runnel s i d e s showed s i m i l a r sediment c o n c e n t r a t i o n s — a l l approximately 17 x 10" 5 g/cc. A maximum value was obtained from a s i t e where the sediment c o n c e n t r a t i o n was obvious - t h i s gave 159 x 10" 5 g/cc. The su r f a c e i n between the runnels gave a value of 5.57 x I0" 5g/cc, s u b s t a n t i a l l y higher than the c o n c e n t r a t i o n in the snowpack but lower than the runnel v a l u e s . These p r e l i m i n a r y f i n d i n g s show that sediment moves l a t e r a l l y a c r o s s the snowpack. Concen t r a t i o n s of sediment in runnels are three times g r e a t e r than i n the r e s t of the snowpack su r f a c e (although only one sample s u r v i v e d p r o c e s s i n g ) . A l l these s u r f a c e c o n c e n t r a t i o n s are 50 or more times gr e a t e r than the average e n t r a i n e d i n the snowpack. Snow p i t s at s i t e s 2 and 4 were dug to i n v e s t i g a t e c l a s t i c sediment c o n c e n t r a t i o n with depth (Figure 16). S i t e 4 had the g r e a t e s t c o n c e n t r a t i o n s near the su r f a c e (117 — 136.5cm) and near the base (19.5 — 39cm). Dye t r a c e s showed that dye p l a c e d at the s u r f a c e moved down v e r t i c a l l y to a l a y e r 30cm from the top of the snowpack, then down to the top of the ba s a l i c e l a y e r and p a r a l l e l to the ground. No dye was observed i n the b a s a l 20cm where the snowpack was s t i l l f rozen hard. Two. l a y e r s of r e l a t i v e l y high dye c o n c e n t r a t i o n and a l s o sediment c o n c e n t r a t i o n corresponded with i c e l a y e r s in the snowpack. At s i t e 2 the snowpack was r i p e throughout and appeared to be d i s c o l o u r e d at the base. T h i s i s c l e a r l y the r e s u l t of i n c r e a s e d sediment c o n c e n t r a t i o n ( F i g 16). The snowpit s i t e evolved i n t o a Figure 16 CRREL Snow Samples S n o w p i t 2 Sediment Concent ra t ions S o d C o n e ( g x 1 0 / c c ) 91 r a p i d l y f l o w i n g stream two weeks l a t e r conducting meltwater to the Lower Lake. It i s l i k e l y that the s t a i n i n g was caused by a seepage channel. These t e n t a t i v e r e s u l t s suggest that water seeps through the snowpack by way of p r e f e r r e d pathways — a f i n d i n g i n agreement with Jordan (1978) and Woo and Slaymaker (1971). Sediment i s d e p o s i t e d i n p r e f e r r e d channels w i t h i n the snowpack as water f i l t e r s through. The l o c a t i o n of these channels i s determined by the p o s i t i o n of i c e l a y e r s i n the snowpack and probably a l s o by ground topography. C o n s i d e r a b l e seepage i n the snowpack feeds these p r e f e r r e d channels (Jordan 1978). These o b s e r v a t i o n s suggest that meltwater does not erode beneath the snowpack although the s i t u a t i o n may vary from year to year. R e l i a b l e g r a i n s i z e data (Appendix G) were not obtained from sediment i n the snowpack because of the very small s i z e of samples. However, the a v a i l a b l e data suggest (Appendix G) that snowpack m a t e r i a l i s f i n e r than windblown m a t e r i a l during the summer although XRD shows that the mineralogy was s i m i l a r . Hence sediment accumulation i n the snowpack i s probably due to d u s t f a l l but c o n t r i b u t i o n s from nearby source areas are precluded by the heavy winter snowpack (o f t e n up to 4m). Depostion i n the s p r i n g when l o c a l sources are snow—free may be important but t h i s needs f u r t h e r i n v e s t i g a t i o n . The f i g u r e s enable a t e n t a t i v e estimate to be made of the c o n t r i b u t i o n of the snowpack to the t o t a l sediment budget. Appendix K shows that the average sediment c o n c e n t r a t i o n of the snowpack in the e a r l y summer i s 100 — 1OOOgx10"5/cc water e q u i v a l e n t . Assuming the sediment i n J u l y i s the t o t a l c o l l e c t e d over the whole snow 92 season and the amount of snow remaining i s 40cm water e q u i v a l e n t , the snowpack d e l i v e r s 100 X100 x40 x 1000 x I0" 8g/m 2 of c l a s t i c sediment to the s o i l (0.4-4g/m 2) or <2 Bubnoffs. The f i g u r e s are c o n s e r v a t i v e as they do not take i n t o account the amount of sediment which has moved l a t e r a l l y i n runnels over the su r f a c e of the snowpack. T h i s type of t r a n s f e r i s another mechanism f o r the accumulation of lo e s s y m a t e r i a l s i n topographic lows. 5.5.5 Summary Wind d e p o s i t i o n i s confirmed as a major sediment source by the amount of sediment caught i n the bulk samplers and e x t r a c t e d from the snowpack. D i r e c t e o l i a n d e p o s i t i o n may account f o r 25 —. 100% of sediment caught at the l e s s a c t i v e s i t e s d u r i n g the summer season. V a r i a t i o n in the amount of d e p o s i t i o n can be r e l a t e d to sediment a v a i l a b i l i t y . Within the basin earthy spreads are sediment sources but i t i s l i k e l y that there i s net import i n t o the basin from nearby N e o g l a c i a l moraines, outwash p l a i n s and general, r e g i o n a l d u s t f a l l . The g r a i n s i z e data show that the north part of the b a s i n , remote from any source area, r e c e i v e s f i n e r and f u r t h e r t r a v e l l e d m a t e r i a l than do the other s i t e s as i s p r e d i c t e d from the concept of s e t t i n g v e l o c i t y . The amount of sediment e n t r a i n e d i n the snowpack i s s u r p r i s i n g l y high: the snowpack i s a l a r g e r sediment source than summer e o l i a n d e p o s i t i o n . However, the snowpack samples are extremely v a r i a b l e and r e q u i r e v e r i f i c a t i o n by r e p l i c a t i o n . If the snow i s a major sediment source, movement through the pack should be i n v e s t i g a t e d more c l o s e l y as t h i s may be a more e f f e c t i v e agent of r e d i s t r i b u t i o n than o v e r l a n d flow a c t i n g upon e o l i a n sediment 93 in the summer months. 5.6 Animals There are number of anomalies i n recorded sediment volumes. They are g r e a t e s t at s i t e s 9 and 10 where 3 stones (Appendix E ) , too l a r g e to be moved by overland flow, s p l a s h or wind, were caught in the G e r l a c h troughs. Two had an o x i d i s e d c r u s t i n d i c a t i n g complete b u r i a l p r i o r to movement and one was h a l f b u r i e d before movement as shown by an o x i d i s e d c r u s t on one s i d e and moss growing on the other. At both s i t e s movement occurred near the beginning of the season and decreased during August. Other anomalies were s i n g l e l a r g e sediment catches at s i t e 1 on August 4, s i t e 2R on August 4, s i t e 8 on August 4, s i t e 11 on J u l y 19 and September 15, s i t e 12R on August 4 and s i t e 14 on J u l y 20, which c o u l d not be e x p l a i n e d by the mechanisms of o v e r l a n d flow, s p l a s h , wind or f r o s t a c t i v i t y . The study area has a l a r g e p o p u l a t i o n of hoary marmots (Marmota c a l i q a t a  c a s c a d e n s i s ) and the f o l l o w i n g d i s c u s s i o n puts forward c i r c u m s t a n t i a l evidence showing that marmots are probably r e s p o n s i b l e . The reported h a b i t s of s i m i l a r c r e a t u r e s agreed with f i e l d o b s e r v a t i o n s (Svendson 1974, Barash 1973) of hoary marmot p o p u l a t i o n d e n s i t i e s , h a b i t a t s and burrowing frequency. Marmots favour open areas f r e e of t r e e s with rocky outcrops which can.be used f o r burrowing, lookouts and sunning. The study area p r o v i d e s an i d e a l h a b i t a t . P o p u l a t i o n d e n s i t i e s have been measured as 1 female a d u l t per 330m2 although ranges only occupy a small p r o p o r t i o n of the t o t a l area and in most cases are not contiguous. Marmot d e n s i t i e s were observed to be highest on the 94 t a l u s and rock areas which commanded a good view. Burrows are dug i n areas where . the rocks are >40cms in diameter or i n areas of coarse and porous s o i l (Armitage 1973) with smaller rocks which act as burrow supports. Optimal s i t e s have many burrows. Svendson (1974) records 78 i n 0.85ha and found that they were l o c a t e d where lookouts had a 340 — 360° f i e l d of view. For t h i s reason burrows were u s u a l l y l o c a t e d on steep slopes (21—45°). Only one o b s e r v a t i o n of burrow d i g g i n g frequency i s a v a i l a b l e : Svendson observed 4 burrows dug i n one year in one range occupied by 8 females. These were mainly the ' a u x i l i a r y burrow' type with 1 or 2 entrances and only 120 — I80cms long. S l e e p i n g burrows, with three or more entrances and a l a b y r i n t h of t u n n e l s were f r e q u e n t l y e n l a r g e d . S o i l was excavated from the burrow with the hind l e g s and pushed away from the burrow entrance by the forepaws and c h e s t . S i t e s 9 and 10 are both i d e a l l o c a t i o n s f o r burrowing. They are both on steep slopes (32° and 28° r e s p e c t i v e l y ) which command a good view (see F i g 9) and have good drainage because of t h e i r rocky s o i l ( s i t e 9 i n p a r t i c u l a r ) . A c a t c h of l a r g e stones and r e l a t i v e l y few f i n e s i s a t t r i b u t e d to pushing of stones. Fines are caught by the surrounding v e g e t a t i o n and l a r g e boulders, while the l a r g e stones, once given an i n i t i a l impetus, have too much momentum to be stopped by minor topographic i r r e g u l a r i t i e s . A s i m i l a r s o r t i n g e f f e c t , on a much l a r g e r s c a l e , i s seen on t a l u s s l o p e s . D r i e d grass and shoots are c o l l e c t e d to l i n e the burrows ( B e l t z and Booth 1952) when females are parous and takes place i n June and J u l y . As the area c a r r i e s a snowpack u n t i l e a r l y 95 August, compared with J u l y i n the r e f e r e n c e d s t u d i e s , grass g a t h e r i n g would be expected to take place a month l a t e r i n the study a r e a . T h i s timing c o i n c i d e s with e r o s i o n maxima f o r s e v e r a l s i t e s (1,2R,8,11,12R and 14) implying that some s o i l may have been loosened in the g a t h e r i n g process. The epoxy used to s e a l the trough apron k i l l e d the surrounding v e g e t a t i o n which made i t a t t r a c t i v e as dry bedding m a t e r i a l when the surrounding shrubs were l u s h . The same e f f e c t was not seen at s i t e 2 because v e g e t a t i o n there remained l u x u r i a n t throughout the season. The percentage organic matter c o l l e c t e d on these dates i s lower than the average f o r the s i t e (23% at s i t e 1, 14% at s i t e 8, 1% at 12R, 8% at 14) implying that some mineral s o i l was loosened in the grass g a t h e r i n g p r o c e s s . Grain s i z e data (Appendix F) show that s i t e s 1,11 and 14 have anomalous c o a r s e — g r a i n e d sediment when hig h y i e l d s were recorded w h i l s t 8 and 2R do not show t h i s r e l a t i o n s h i p . A u x i l i a r y burrows are spaced so that one can be reached q u i c k l y i f a predator appears. They are connected by paths which are t r a v e l l e d so f r e q u e n t l y that they are devoid of v e g e t a t i o n . A network of paths was worn ac c r o s s the scree around s i t e s 9 and 9R and i t i s p o s s i b l e that marmots hopping along these paths c o u l d have loosened sediment. C e s s a t i o n of a c t i v i t y d u r i n g August i s e x p l a i n e d by high temperatures. Marmots cannot f u n c t i o n above ground once a i r temperatures exceed 20°C. Thermohygrograph data (Appendix M) show that average maximum temperature on the r i d g e as 17°C so those i n the v a l l e y were undoubtedly h i g h e r . A s l i g h t r i s e in sediment p r o d u c t i o n was noted at s i t e 9 in September. T h i s was 96 probably a r e s u l t of marmot a c t i v i t y due to animals seeking optimal h i b e r n a t i o n s i t e s as w e l l as parous females and babies e a t i n g l a t e i n the season i n order to have s u f f i c i e n t food r e s e r v e s to l a s t through the winter. F i e l d o b s e r v a t i o n s show that the marmot p o p u l a t i o n s i n these areas were high and a t e n t a t i v e estimate would put the p o p u l a t i o n at 75 female a d u l t s assuming the rocky areas only were f u l l y populated. The t o t a l p o p u l a t i o n would be two to three times t h i s f i g u r e . Marmots were observed at a l l l o c a t i o n s where t h e i r i n f l u e n c e i s suspected. They were observed near s i t e 9 on a l l o c c a s i o n s the trough was v i s i t e d d u r i n g J u l y and August and at s i t e 10 the l a r g e sediment y i e l d was o b v i o u s l y d e r i v e d from a hole dug about 2m upslope from the trough a f t e r i t was i n s t a l l e d . *• It i s impossible to estimate r e l i a b l y the e f f e c t of marmots on sediment t r a n s f e r . Undoubtedly sediment y i e l d i s d i s c o n t i n u o u s l y high because of the excavation of holes at d i s c r e t e l o c a t i o n s . I n t e g r a t i o n on .an a r e a l b a s i s i s made using Svendson's estimate of 1 burrow dug per 2 females t e r r i t o r y per year. T h i s g i v e s an a r e a l estimate of 163kg/y/km 2 i f each burrow i s assumed to have dimensions of 0.4x0.2x1.2m 3. In a d d i t i o n some sediment i s added by r e — e x c a v a t i o n of e x i s t i n g burrows although t h i s amount i s s m a l l e r . Hence an estimate of about 300kg/km 2/y or 0.3 Bubnoffs can be made for sediment production from marmot burrows. T h i s i s small i n comparison with Thorn's estimates of 3,900 -5,800kg/km 2/y for the pocket gopher. However, the d i s c r e p a n c y i s r a t i o n a l i s e d by the d i f f e r e n c e i n burrowing h a b i t s : pocket gophers burrow every year w h i l s t marmots reoccupy 97 the same burrows i n d e f i n i t e l y and only enlarge e x i s t i n g burrows or d i g a few small a u x i l i a r y ones each year. I t was not p o s s i b l e to estimate sediment t r a n s f e r s from trough data because a r e a l i s t i c c o n t r i b u t i n g area c o u l d not be estimated. 5.7 S p a t i a l v a r i a t i o n of sediment y i e l d The i n i t i a l sampling scheme was inadequate because the t r e e stratum was overrepresented and heather was underrepresented (Table 2) on the a e r i a l photograph. The plane t a b l e map prepared in the f i e l d was intended as a b a s i s f o r f u t u r e sampling. T h i s s e c t i o n analyses whether s i t e r e c o g n i t i o n using the map i s b e t t e r than that from the a e r i a l photograph and a l s o how near both compare with a t — a — s i t e data. R e c l a s s i f i c a t i o n of s i t e s using the plane t a b l e map ( F i g 4) i s shown i n Table 10. The main Table 10 S i t e C l a s s i f i c a t i o n I n i t i a l c l a s s i f i c a t i o n Subsequent f i e l d (from a e r i a l p h o t o g r a p h ) c l a s s i f i c a t i o n Tree 1,8,10,1 OR,11 ,12,12R 1 ,10,1 OR,11,12,12R Grass 2,2R 2,2R Heather3,4,6 3,4,6,8,13,13R,13 Rock 5,7,9,9R,13,13R,14,NI 5,7,9,9R,NI change i s a r e c l a s s i f i c a t i o n of l a r g e boulders and rock i n t e r s p e r s e d with v e g e t a t i o n . As these are not a c t i v e i n sediment p r o d u c t i o n they were mapped as heather ( s i t e s 13,13R and 14) w h i l s t they were i n d i s t i n g u i s h a b l e from rock,scree and earthy spreads on the a e r i a l photograph. A c l u s t e r a n a l y s i s was 98 run to t e s t the homogeneity of the s t r a t a r e cognised on the plane t a b l e map given that f i e l d i d e n t i f i c a t i o n was s u b j e c t i v e . The approach i s s i m i l a r to that used by Bovis (1978). V a r i a b l e s used i n the a n a l y s i s were sine of slope angle, percentage small stones and e a r t h , percentage moss, percentage heather, percentage l i t t e r , percentage organic matter and water drop p e n e t r a t i o n t e s t . S o i l g r a i n s i z e parameters were not used because of the d i f f i c u l t y of o b t a i n i n g uniform and comparable samples at each s i t e . The i n t e n t i o n of a c l u s t e r a n a l y s i s i s to group s u b j e c t s ( s i t e s ) a c c o r d i n g to s i m i l a r i t i e s in t h e i r c h a r a c t e r i s t i c s ( s i n e slope angle e t c ) . The UBC %CGROUP r o u t i n e converts each c h a r a c t e r i s t i c to a score between 0 and 1, e f f e c t i v e l y s c a l i n g a l l the c h a r a c t e r i s t i c s so t h a t they have equal weight. A l l c h a r a c t e r i s t i c s do not have equal weight and t h i s l i m i t s the v a l i d i t y of the r e s u l t s . Optimum groupings are obtained by d e f i n i n g each s i t e as a s i n g l e group then combining groups i n t o c l u s t e r s i n such a way that v a r i a n c e w i t h i n c l u s t e r s i s minimised. The dendrogram ( F i g 17) shows that there i s a great i n c r e a s e i n e r r o r between steps 15 and 16 and 16 and 17 suggesting that 4 or 5 n a t u r a l groups e x i s t . S i t e s 2 and 2R, designated grass and moss, stand out as a d i s t i n c t stratum, s i t e s 5,7,9,9R and NI as another (rock and s c r e e ) , s i t e s 10,11,12,12R and 13 as t r e e s , w h i l s t s i t e s 1,4,1 OR,13R,14 and 3,6,8 stand out as two subgroups r e p r e s e n t i n g dry heather areas with some l i t t e r (1,4,1 OR,13R,14) and damp heather with mossy depressions (3,6,8). Table 11 shows that three s i t e s were m i s c l a s s i f i e d on the plane t a b l e map (1,10R and 13) but t h i s compares with s i x (1,8,1 OR,13,13R,14) in the Figure 17 99 Dendrogram showing site classif ication by cluster analysis I T E M S G R O U P E D S T E P ERROR 1 2 3 0 3 5 6 0 4 2 3 2 13 19 0 4 3 3 7 4 2 6 3 e 2 0 1 1411695 - 12 14 1 2 2 0 2 5 2 0 e 16 1 7 1 4 4 9 5 3 2 8 6 13 18 1 . 6 8 7 6 2 3 0 7 6 10 2 1 I C 1 3 5 1 e 1 13 2 . 4 4 6 0 4 3 0 9 15 16 2 . 6 5 2 7 0 4 2 10 1 5 3 5 9 4 3 3 9 4 1 1 4 9 4 . 0 8 8 3 5 7 0 12 6 8 4 2e 4 0 5 0 - 0 1 3 12 15 7 6 3 3 5 5 4 5 1 4 4 7 7 8 9 4 2 4 8 0 15 6 1 1 8 3 5 8 8 6 4 8 16 1 4 1 1 6 4 4 0 9 8 1 7 » 1 2 2 3 12 5 3 6 6 1 S 1 1 2 2 5 2 5 12 2 1 1 9 1 6 3 0 6 2 3 6 6 2 10R 13R 3 6 2R II 1* R 5 9 9R 1 14 4 6 2 1 0 12 13 N» 7 3 100 c l a s s i f i c a t i o n made from the a e r i a l photograph. Hence c l a s s i f i c a t i o n from the map i s b e t t e r than that from the a e r i a l photograph but there i s s t i l l a s i g n i f i c a n t number of s i t e s which are m i s c l a s s i f i e d . Of the three s i t e s m i s c l a s s i f i e d , 1 and 10R belonged to the 'dry heather' group with some l i t t e r , w h i l s t 13 was c l a s s i f i e d as ' t r e e ' . The intimate mixture of krummholz, boulders and heather i s not amenable to l a r g e s c a l e c l a s s i f i c a t i o n . Instead, some c r i t e r i o n , such as 55% l i t t e r cover may be a p p l i e d i n the f i e l d to enable a quick s i t e c l a s s i f i c a t i o n where the c o r r e c t stratum i s not obvious. The plane t a b l e map was much more s u c c e s s f u l at d i f f e r e n t i a t i n g 'rock and scree ' s i t e s than was the a e r i a l photograph. The c l u s t e r a n a l y s i s a l s o shows that r e p l i c a t e s i t e s (2,2R,9,9R,10,1 OR,12,12R,13,13R) v a r i e d - in t h e i r degree of s i m i l a r i t y . For example, 10 and 10R f e l l i n t o d i f f e r e n t c a t e g o r i e s and d i d not j o i n u n t i l the 18th step w h i l s t 2 arid 2R were very s i m i l a r , j o i n i n g in the f i r s t grouping step. T h i s demonstrates a great deal of v a r i a b i l i t y w i t h i n s i t e s and suggests that a smaller sampling u n i t then 10m2 may be more e f f i c i e n t . A l s o there should be a mechanism f o r s c r u t i n i s i n g r e p l i c a t e s i t e s to ensure that they do not s t r a d d l e v e g e t a t i o n boundaries. A comparison of sediment y i e l d s f o r the d i f f e r e n t c l u s t e r s shows that s i t e s with the highest y i e l d s are not a l l i n the 'rock and scree' stratum but that some are i n the t r e e i s l a n d group. T h i s i s probably because dry t r e e i s l a n d s a t t r a c t marmots. An F s t a t i s t i c was c a l c u l a t e d to t e s t whether the 101 groups recognised i n the c l u s t e r a n a l y s i s had s i g n i f i c a n t l y d i f f e r e n t means. Table 11 shows that some s t r a t a means vary s i g n i f i c a n t l y as t h e i r F r a t i o i s more than the 95% val u e . T h i s Table 11 F s t a t i s t i c to t e s t stratum homogeneity Stratum T R G H1 H2 R 0 R E E E C A A A E K S T T S H H E E R R 1 0 5 2 3 4 1 1 NI 2R 6 1 1 2 9 8 1 OR 1 2R 7 1 4 1 3 9R 1 3R 6.9653 1 ..6102 0 .3594 0. 0565 4.2365 8.0151 3 .5460 0 . 1 373 0. 2104 0.0440 0.2223 55 .9416 0. 2332 0.4426 1.3645 1 .0691 0.5371 0.4546 25 .0723 0.4664 T o t a l 17.0278 87 .2392 0.4967 0.5061 Mean 3.4056 1 7 .4478 0.2454 0.1847 D.F SUM OF MEAN 5.7266 1 . 1453 F VALUE Grand CATEGORY MEANS 4 WITHIN 15 SQUARES 3292 2321 SQUARES 823 1 55 5.32 j u s t i f i e s use of the c l a s s i f i c a t i o n i n f u t u r e sampling designs. A p r i n c i p a l components a n a l y s i s was run on the same data to i d e n t i f y c o r r e l a t i o n s between d i f f e r e n t f a c t o r s which made the grouping s t a t i s t i c a r t i f i c i a l l y s u c c e s s f u l . Appendix Q shows that the str o n g e s t c o r r e l a t i o n s occur between percentage moss 102 and s i n e of slope angle, water r e p e l l e n c y and s l o p e , water r e p e l l e n c y and moss and %bare s o i l and % l i t t e r . A l l the c o r r e l a t i o n s were i n v e r s e . I t seems that moss and water r e p e l l e n c y are s i m i l a r i n d i c e s and may cause a r t i f i c i a l l y low t o t a l e r r o r i n the c l u s t e r a n a l y s i s . However, the e r r o r jump between steps 16 and 17 was very l a r g e and so the c l u s t e r s are s t i l l c o n s i d e r e d to be v a l i d . In a second t e s t t o t a l s o i l e r o s i o n was i n c l u d e d and App R shows that i t i s h i g h l y c o r r e l a t e d with %bare s o i l and the sine of slope angle. These data a l l suggest that s i t e s e l e c t i o n from the plane t a b l e map w i l l be more accurate than from the a e r i a l photograph but that there i s a problem in d i f f e r e n t i a t i n g between the two heather s t r a t a and t r e e i s l a n d s . A u s e f u l and quick f i e l d c r i t e r i o n would be a p p l i c a t i o n of a 55% l i t t e r cover estimate. R e p l i c a t e s i t e s are not u s e f u l because of the i n t i m a t e l y mixed v e g e t a t i o n s t r a t a . Many s t u d i e s show that bare s o i l and slope angle are the most important f a c t o r s i n f l u e n c i n g s o i l l o s s . F i g u r e 18 demonstrates the i n f l u e n c e of these two f a c t o r s on s o i l l o s s . There i s a l o t of s c a t t e r when the two f a c t o r s are taken i n d i v i d u a l l y . Percentage bare s o i l and s i n e of slope were regressed on t o t a l sediment caught (Appendix E) to i n v e s t i g a t e the e f f e c t of these two f a c t o r s on t o t a l sediment caught was performed (Appendix S) to i n v e s t i g a t e the degree of s t a t i s t i c a l e x p l a n a t i o n . The m u l t i p l e c o r r e l a t i o n c o e f f i c i e n t , R, i n d i c a t i n g the degree of l i n e a r a s s o c i a t i o n between the estimated value from the r e g r e s s i o n equation and the observed value of the independent v a r i a b l e ( O s t l e 1954) was 0.6374. The c o e f f i c i e n t of F i g 18 The r e l a t i o n s h i p between sediment movement,  slope and vegetation 0.7 0.6'J 0.5 0.4 0.3^ CD c •H tn • IOR • 8 ,l?R. 0.2 0 100-1 . 5 • ? •I2.R . rvi .10 0.5 1 5 10 Sediment movement (grams) • NX 50 •H O CO 0) 80J 60 40 20'J • 5 IK 0.2 0.5 UK. J 10'II 10 50 Sediment movement (grams) 1 04 deter m i n a t i o n (R 2) was 0.4063. R 2 i n d i c a t e s the p r o p o r t i o n of the t o t a l sum of squares e x p l a i n e d by the m u l t i p l e r e g r e s s i o n and can be t e s t e d f o r a Type I e r r o r with an F t e s t . The F value, 5.8166, i s s i g n i f i c a n t at the 5% l e v e l but not at the 1% l e v e l . R 2 and i t s a s s o c i a t e d degree of e x p l a n a t i o n , i s v a l i d at the 95% confidence l e v e l . Hence a r e a l measurement of percentage bare ground and slope angle would provide an a l t e r n a t i v e approach f o r a sampling design but one which cannot be implemented without d e t a i l e d f i e l d examination. However, the plane t a b l e map would supply the necessary i n f o r m a t i o n i f t h i s approach were adopted. 105 CHAPTER 6. CONCLUSIONS AND RECOMMENDATIONS 6.1 The sediment budget In the p r e v i o u s chapter f i v e agents, overland flow, s p l a s h , wind, f r o s t and animals were c o n s i d e r e d as components of the sediment budget of the a l p i n e . P r e l i m i n a r y r e s u l t s from one f i e l d season show that animals are l o c a l l y the most important agents of e r o s i o n at i n d i v i d u a l s i t e s f o l l o w e d by splash/wash, wind and needle i c e . Summary e r o s i o n s t a t i s t i c s are given i n Table 12. S p a t i a l l y i n t e g r a t e d f i e l d measurements demonstrate that marmots are capable of moving 300kg/km 2/y or 0.15B w i t h i n t h e i r ranges. Assuming f u l l occupancy of the rock/scree s i t e s , (approximately 10% of basin) average sediment p r o d u c t i o n over the whole b a s i n i s only 0.3g/m2 per year or 0.015B although estimates of p o p u l a t i o n d e n s i t y and burrowing frequency based on l i t e r a t u r e r e p o r t s are u n r e l i a b l e . Marmots are the only agent apart from g r a v i t y which i s capable of moving sediment >2cm diameter — indeed stones up to 200g' are r e g u l a r l y moved as burrows are dug i n stony, w e l l d r a i n e d areas. The study watershed does not have an o u t l e t stream except when the Lower Lake overflows b r i e f l y at snowmelt. Overland flow i s i n f e r r e d at most s i t e s from the p a t t e r n of d i s p l a c e d t r a c e r p a r t i c l e s and may account f o r sediment accumulation around the Lower Lake. However, no t u r b u l e n t o verland flow was observed dur i n g the season so sediment a t t r i b u t e d to o v e r l a n d flow e r o s i o n i s probably d u s t f a l l t r a n s p o r t e d by overland flow. S e c t i o n 5.5 shows that mass balance and g r a i n s i z e data support t h i s a s s e r t i o n . As sediment y i e l d s are g e n e r a l l y a l i t t l e 1 06 c o a r s e r than d u s t f a l l the f i n e s t p a r t i c l e s may be trapped by v e g e t a t i o n . R a i n s p l a s h i s l o c a l l y important on earthy spreads bare of v e g e t a t i o n . T h i s i s shown by the g r a i n s i z e d i s t r i b u t i o n of splashed s o i l which shows a c h a r a c t e r i s t i c maximum s i z e which depends upon r a i n f a l l i n t e n s i t y . S i t e s 5 and 7, which were randomly s e l e c t e d , y i e l d 8 and 23 B r e s p e c t i v e l y . As earthy spreads occupy approximately 2% of the study area, t h i s g i v e s a s p a t i a l l y i n t e g r a t e d f i g u r e of 0.16-0.46B. S i t e NI, which was s u b j e c t i v e l y chosen as an example of needle i c e a c t i v i t y , showed a much higher sediment y i e l d . However, i t was not r e p r e s e n t a t i v e of the stratum but an ' i d e a l ' s i t e so the t a b u l a t e d f i g u r e i s c o n s i d e r e d to be a f a i r e v a l u a t i o n of r a i n s p l a s h e r o s i o n . Overland flow was i n f e r r e d at most s i t e s from the p a t t e r n of d i s p l a c e d t r a c e r p a r t i c l e s . Table 12 The sediment budget of the study area 1 Bubnoff=2,000 kg/km" 2/year or 2g/m 2/year assuming a rock d e n s i t y of 2. Animals 0.015-0.15B Wind(summer) 0.4B ' Snowpack 0.2-2B Splash 0.16-0.46B Wind accumulation 4B (from s o i l ) Wind d e p o s i t i o n i s unique because i t i s not concerned only with t r a n s f e r of sediment w i t h i n the drainage b a s i n : i t has the c a p a b i l i t y to t r a n s f e r sediment a c r o s s drainage d i v i d e s . R e s u l t s from the bulk samplers show that 0.44 - 2.8g/m2 (0.4-1.4B) of sediment are added each summer to the s o i l . 0.75g/m2 (0.4B) i s a reasonable average as the higher f i g u r e i s f o r a s i t e l o c a t e d i n 107 the middle of a source a r e a . In a d d i t i o n m a t e r i a l i s s t o r e d by the snowpack; t h i s c o n t r i b u t e s 0.4 — 4g/m2 per year (0.2—2B). These f i g u r e s are low estimates (see next s e c t i o n ) g i v i n g a minimum e o l i a n input of 1—5g/m2 per year (0.5—2.5B). The s o i l p r o f i l e s d e s c r i b e d i n Table 9 show 10—40cms accumulation of e o l i a n m a t e r i a l over the past 10,000 years. A reasonable s o i l p r o f i l e depth, c a l c u l a t e d from 7 s o i l p i t s , i s 20 cms. However, approximately 33% of t h i s i s ash and 25—30% of the f r a c t i o n <2mm i s o r g a n i c . Hence, i f p r e — e x i s t i n g g r a v e l i s 10% and boulders 30% only about 30% of the ' l o e s s ' capping can be a s c r i b e d to wind d e p o s i t i o n . An average bulk d e n s i t y i s 1.1 (T. G a l l i e p e r s o n a l communication) because of the high organic content, so there has been an accumulation of approximately 1.1x7xl00xl00g/m 2 s i n c e d e g l a c i a t i o n - about 77,000g/m 2. T h i s g i v e s an annual accumulation of 8g/year (or 4B) which i s s l i g h t l y higher than c u r r e n t accumulation r a t e s i f the snowpack measurements are v a l i d . These d i s p a r a t e estimates of process give i n t e r e s t i n g r e s u l t s when viewed as components of the sediment budget. Wind d e p o s i t i o n , which i s assumed to act un i f o r m l y over the whole watershed at 1 — 6 g/m2/y (0.5—3B) c o n t r i b u t e s more to the sediment budget than do animals which have a dramatic l o c a l i n f l u e n c e but a l i m i t e d sphere of a c t i v i t y . The r e s u l t s are p r e l i m i n a r y , based on a few and u n r e l i a b l e samples ( e s p e c i a l l y the snow data) and l i t e r a t u r e r a t h e r than f i e l d survey (animal a c t i v i t y ) . 108 6.2 R e p r e s entativeness of the f i e l d season As t h i s study l a s t e d only one f i e l d season i t i s important to assess the r e p r e s e n t a t i v e n e s s of the season when drawing c o n c l u s i o n s from f i e l d measurements. C l i m a t i c data were not recorded d u r i n g the summer of 1982 at the BCFS s t a t i o n at Pemberton so records from the s t a t i o n at A l t a Lake (660m) were used. I t i s 25km from the study s i t e . Averages from the maximum and minimum temperatures were c a l c u l a t e d from the AES summary data up to 1970 and from annual s t a t i s t i c s t h e r e a f t e r . Three q u a l i f i c a t i o n s are necessary:— 1. The r e c o r d i s of d i f f e r e n t l e n g t h f o r d i f f e r e n t months, ranging from 26 — 29 y e a r s . 2. The s i t e moved in 1976. There was an e l e v a t i o n change of 9m and a s h i f t of 200m in d i s t a n c e . The AES recommend that t h e i r data were u n a f f e c t e d by t h i s move. 3. Data f o r 1976 are m i s s i n g . Average v a l u e s are shown in F i g 18 together with 1981 data which the AES k i n d l y p rovided before p u b l i c a t i o n . D e v i a t i o n s of the 1981 data from the mean values are a l s o t a b u l a t e d . R a i n f a l l t o t a l s are shown in F i g 19 f o r the e n t i r e r e c o r d averaged f o r 1981. The temperature and r a i n f a l l s t a t i s t i c s taken together show that 1981 had a c o o l June with p r e c i p i t a t i o n double the average value, a warm and dry August and a c o o l and e x c e p t i o n a l l y wet October. August r e c e i v e d 2/3 of i t s r a i n f a l l on the 31st i n a s i n g l e storm which gave the h i g h e s t August 24hr p r e c i p i t a t i o n ever recorded at A l t a lake i n August. I t i s not p o s s i b l e to e x t r a p o l a t e p r e c i p i t a t i o n and f i g u r e 19 A l t a L a k e C l i m a t i c D a t a 109 Temperature Ra i n f a l l 250 200 1 J u n e Ju ly A u g S e p t Oc' i J u n e J u l y A u g S e p t 0 c t 1981 J Mean 110 temperature data r e l i a b l y from A l t a Lake to the study area watershed. However, i t i s u s e f u l to combine seasonal trends with o b s e r v a t i o n s made durin g the f i e l d season. At the end of May the Coast Mountain snowpack was below average because of a month of f a i r l y high temperatures (Snow Survey r e p o r t ) . However, c o o l , damp June weather r e s u l t e d i n r e l a t i v e l y l i t t l e a b l a t i o n d u r i n g the month at high e l e v a t i o n s so the ground was not uncovered u n t i l mid — J u l y . August and J u l y were both mainly dry and warm. F i v e rainstorms were recorded between August 31 and September 20. A l l subsequent p r e c i p i t a t i o n f e l l as snow. Low temperatures and e x c e p t i o n a l l y high p r e c i p i t a t i o n from September 25 to October 10 r e s u l t e d i n 70cms snow accumulation which d i d not melt under 12 days of c l e a r sky c o n d i t i o n s . Pemberton r e s i d e n t s s t a t e d that September 20 i s e x c e p t i o n a l l y e a r l y f o r winter snowpack accumulation to s t a r t . The probable e f f e c t of the season on my r e s u l t s i s t o : — 1. Overestimate wind e r o s i o n and d e p o s i t i o n d u r i n g August because of dry dusty c o n d i t i o n s . 2. Underestimate s p l a s h e r o s i o n and e r o s i o n due to overland flow duri n g September because of the small number and magnitude of rain s t o r m s . 3. Underestimate needle i c e a c t i v i t y because snow cover from 20 September onwards p r o t e c t e d the ground from f r o s t . 111 6.3 Assessment of the i n i t i a l hypotheses The data presented above enable c o n f i r m a t i o n or f a l s i f i c a t i o n of the three i n i t i a l hypotheses ( s e c t i o n 1.7). In the f i r s t h y p o t hesis needle i c e , wash, s p l a s h and wind, i n that order of importance, were c i t e d as components of the sediment budget. The ranking was i n f e r r e d from l i t e r a t u r e reviewed i n chapter 1 and v a l u e s are t a b u l a t e d i n Table 13. However, t h i s review of s u r f i c i a l movement shows very d i f f e r e n t r e l a t i o n s h i p s . Wind d e p o s i t i o n i s the s i n g l e most important component of the s p a t i a l l y i n t e g r a t e d sediment budget (Table 12). T h i s i m p l i e s that the basin i s undergoing net accumulation r a t h e r than e r o s i o n , a f i n d i n g confirmed by the b u r i a l of s o i l h o r i z o n s and tephra l a y e r s . Reworking of wind d e p o s i t s by o v e r l a n d flow can be i n f e r r e d from the amount and c a l i b r e of m a t e r i a l d e p o s i t e d i n the G e r l a c h troughs. The e f f e c t of s p l a s h i s n e g l i g i b l e i n vegetated areas, at l e a s t by i n f e r e n c e from u n r e l i a b l e s p l a s h trough data. Splash may be l a r g e l y reworked windblown m a t e r i a l The only e x c e p t i o n to t h i s a n a l y s i s are the areas of earthy spread where s p l a s h / o v e r l a n d flow i s the dominant agent of sediment movement. Table 12 shows that the s p a t i a l s i g n i f i c a n c e of s p l a s h (0.16—0.46B) i s l e s s than that of wind. Animals, at 0.015—0.15B are, on a s p a t i a l l y i n t e g r a t e d b a s i s , l e s s important components of the sediment budget than e i t h e r wind or s p l a s h / o v e r l a n d flow (0.16—0.46). Hence the f i r s t h y p othesis ranking needle i c e , wash/splash and wind in that order i s f a l s i f i e d . A more accurate ranking i s wind, splash/wash, animals, needle i c e . The second hypothesis i s confirmed as slope angle and % 1 12 bare s o i l are i d e n t i f i e d as major f a c t o r s i n f l u e n c i n g s o i l l o s s . The degree of e x p l a n a t i o n of s o i l l o s s by these two f a c t o r s ( r 2 ) i s 41% which i s s i g n i f i c a n t at the 95% l e v e l . I t was i n i t i a l l y proposed that sediment p r o d u c t i o n would peak i n the f a l l due to needle i c e a c t i v i t y . T h i s p a t t e r n was not seen at any s i t e . S i t e s a f f e c t e d by marmots showed two peaks of sediment p r o d u c t i o n i n J u l y / e a r l y August and September. These correspond to marmot metabolism as a c t i v i t y slows dur i n g s p e l l s of warm weather. Sediment p r o d u c t i o n on unvegetated s i t e s was i n response to r a i n f a l l . However, many s i t e s showed a continuous background of sediment movement which was probably a response to wind d e p o s i t i o n . Thus the t h i r d hypothesis i s a l s o f a l s i f i e d as the temporal v a r i a b i l i t y of sediment p r o d u c t i o n i s s i t e s p e c i f i c and depends on the domitiant a t — a — s i t e p r o c e s s e s . 6.4 Comparison of the r e s u l t s with other data Slaymaker (1977) notes that a l p i n e areas have been c h a r a c t e r i s e d as y i e l d i n g l a r g e volumes of sediment. Regional estimates of denudation range from 40 — 200 Bubnoff (St r a k h o f f 1967) to 90 - 2000 (Fournier l960)(Table 13). However, l o c a l e stimates from measurements near the study s i t e show that a l p i n e streams export only 5 — 21 B (both suspended and d i s s o l v e d l o a d ) . T h i s compares with 487B f o r the lowland L i l l o o e t r i v e r to which the study s i t e d r a i n s (Slaymaker and McPherson 1977). Hence high sediment y i e l d s i n g l a c i a t e d areas may not o r i g i n a t e from the a l p i n e zone but from v a l l e y e r o s i o n . T h i s study shows that i n t e r n a l sediment t r a n s f e r s i n a l p i n e b asins are extremely low and that e o l i a n d e p o s i t i o n over the Table 13 Estimates of sediment t r a n s f e r s ( A l l i n Bubnoffs 1 Bubnof f = 2 , OOOkg/kirr 2 / y or 2g/m2) Regional (from r i v e r s ) Strakhov 40->200 Corbel 184-770 Fo u r n i e r 90-2,000 Young 1,000 Slaymaker ( L i l l o o e t r i v e r ) 487 L o c a l ( f r o m r i v e r s ) Coast mountains(Slaymaker) 7-21 -subalpine system Small s c a l e ( f r a c t i o n a l p l o t s ) Badlands Sandstone 17,300 (Campbell)Shale 540 Subsurface pipes 540 Shale(steep) 2,835 S i d e r i t e capped 182 A l l u v i a l fans 3,196 (Pearce) 0.6-1.4 A l p i n e Tundra meadow ) (Bovis) Dry a l p i n e tundra ) 7-80 Average 40 (Thorn) Snowpatch 4,600 (Jones) A l p i n e tundra 0.2-4 Process estimates Needle ice(Mackay and Matthews) 3,400 Wind d e p o s i t i o n ( C a i n e ) 4 Animals - pocket gophers(Thorn) 2-3 earthworms 1-2 p r a i r i e dogs 0.5-1 ground s q u i r r e l s 1 moles 1 whole basin i s more than s u f f i c i e n t to account f o r sediment f l u x e s recorded i n the Ge r l a c h troughs. Net accumulation, not e r o s i o n i s t a k i n g p l a c e . The slow r a t e s of downslope sediment t r a n s f e r r e g i s t e r e d i n areas of spaghnum/grass/shrub v e g e t a t i o n 1 1 4 i n d i c a t e that sediment t r a n s p o r t e d over the v a l l e y s i d e s t r a v e l s at a d e c r e a s i n g r a t e as i t nears the v a l l e y f l o o r . The p a t t e r n of slowing t r a n s f e r s towards the v a l l e y f l o o r may not be a p p r o p r i a t e f o r watersheds with a stream e x p o r t i n g sediment. A comparison of sediment f l u x e s i n t h i s area (Tables 12 and 13) with other data from f r a c t i o n a l p l o t s (Table 13) show that the sediment f l u x e s from the Coast mountains are lower by an order of magnitude than those from the Colorado Front Range. O v e r a l l , data from a l p i n e areas show low r a t e s of sediment movement — maximum r a t e s f o r temperate badlands are given by Campbell (1974) (Table 13). I n d i v i d u a l process e s t i m a t e s i n the study area are a l s o lower than those p r e v i o u s l y r e p o r t e d . The e f f e c t of needle i c e i n t h i s area was n e g l i g i b l e and estimates of marmot e r o s i o n , at 0.015—0.15 B are very c o n s e r v a t i v e in comparison with Thorn's estimates f o r pocket gophers (2-3B). Wind e r o s i o n , i n the study watershed i s comparable with Caine's f i g u r e (4B). 6.4 Further research The o r i g i n a l o b j e c t i v e of t h i s study was to i n d i c a t e an a p p r o p r i a t e sampling design f o r f u r t h e r study. Besides i n d i c a t i n g areas of i n t e r e s t which c o u l d be e x p l o r e d — the snowpack as a sediment source f o r example — the study a l s o i n d i c a t e s an a p p r o p r i a t e r e s e a r c h design for f u r t h e r s t u d i e s of s o i l l o s s . The f i v e c l u s t e r s in s e c t i o n 5.6 comprise homogeneous s t r a t a w i t h i n which sampling should take p l a c e . Those with h i g h e s t sediment y i e l d a l s o had h i g h e s t v a r i a t i o n s . Scree and rock areas and t r e e i s l a n d s should have most s i t e s i n order to 115 make an estimate of the v a r i a n c e . I t would be extremely d e s i r a b l e to b u i l d i n t o the design some p r o v i s i o n f o r sampling the l a r g e marmot p o p u l a t i o n adequately. Bovis (1978) w r i t e s that s i t e r e p l i c a t i o n i s a n e c e s s i t y . T h i s study shows that at the s c a l e employed (quadrats 10m2) d u p l i c a t e s were not u s e f u l . Instead, s m a l l e r sampling u n i t s should be used and d u p l i c a t e s s e l e c t e d only w i t h i n v e g e t a t i o n s t r a t a . T h i s should prevent r e p l i c a t e s s t r a d d l i n g two v e g e t a t i o n s t r a t a . E o l i a n d e p o s i t i o n i s the most important component of the s p a t i a l l y i n t e g r a t e d sediment budget. T h i s c o n c l u s i o n was unexpected and more research i s r e q u i r e d to confirm the c o n c l u s i o n . The r o l e of the snowpack in s t o r i n g sediment deserves a t t e n t i o n as does r e d i s t r i b u t i o n of the l o a d at snowmelt. Provenance of e o l i a n sediment i s unknown: i t s mineralogy r e f l e c t s the r e g i o n a l quartz d i o r i t e - r a ther than l o c a l Gambier group rocks. T h i s , together with the l a r g e snowpack load, suggests that nearby outwash p l a i n s and N e o g l a c i a l moraines are not the only sediment source. The sediment budget framework proved v a l u a b l e . It enabled f o r m u l a t i o n of i n i t i a l hypotheses which d i r e c t e d the sampling scheme. I t a l s o enabled a r e a l l y averaged estimates of process to be compared. I n c l u s i o n of a v a r i e t y of processes showed that sediment movement which might otherwise have been a t t r i b u t e d to needle i c e and overland flow, was a t t r i b u t e d to r a i n s p l a s h and e o l i a n p r o c e s s e s . Hence the budget s t r u c t u r e , besides a i d i n g an o b j e c t i v e sampling design, a l s o gave a h o l i s t i c view of sediment t r a n s f e r , a p e r s p e c t i v e l a c k i n g i n many s i n g l e process b i a s e d s t u d i e s . 1 1 6 B i b l i o g r a p h y (AES)Atmospheric Environment S e r v i c e (Environment Canada) Monthly r e c o r d . M e t e o r o l o g i c a l o b s e r v a t i o n s i n Western Canada. A l l e y , N.F., 1976, P o s t — P l e i s t o c e n e g l a c i a t i o n s i n the i n t e r i o r of B r i t i s h Columbia: Geomorphology of the Canadian- C o r d i l l e r a , ( a b s t r a c t s ) , ed J.E Armstrong, pp6—7. 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B o l l i n n e , A., 1978, Study of the importance of s p l a s h and wash on c u l t i v a t e d loamy s o i l s of Hesbaye (Belgium): E a r t h Surface  Processes, 3, pp7l-84. Boughton, W.C., 1967, P l o t s f o r e v a l u a t i n g the catchment c h a r a c t e r i s t i c s a f f e c t i n g s o i l l o s s : J . Hydrol (N.Z.), 26, pp113-119. Bouma, J . , Hoeks, J . , van der P l a s , L . J . , van Scherrenberg, B., 1969, Genesis and morphology of some a l p i n e podzol p r o f i l e s : J o u r n a l of S o i l Science, 20, pp384-398. Bovis, M.J., 1978, S o i l l o s s i n the Colorado Front Range, sampling design and a r e a l v a r i a t i o n : Z e i t s c h r i f t f u r  Geomorphologie, Suppl 29, pplO—21. Bovis, M.J. and Thorn, C.E., 1981, S o i l l o s s v a r i a t i o n s w i t h i n a Colorado A l p i n e area: E a r t h Surface Processes and Landforms, 6, ppl51—163. Braun, L.M., 1980, Scale dependence of f a c t o r s c o n t r o l l i n g the  r e l e a s e of water from snow and i c e storage, MSc t h e s i s , U n i v e r s i t y of B r i t i s h Columbia, 142p. B r i l l , G.D. and Neal, O.R., 1950, Seasonal occurrence of runoff 1 1 7 and e r o s i o n from a sandy s o i l i n vegetable p r o d u c t i o n : Agronomy  J o u r n a l , 42, p p l 9 2 - l 9 5 . B r i n d l e y , G.W. and Brown, G., 1980, C r y s t a l s t r u c t u r e s of c l a y  m i n e r a l s and t h e i r X—ray i n t e r p r e t a t i o n , M i n e r a l o g i c a l S o c i e t y , London, 495p. Br i n k , V.C., Mackay, J.R., Freyman, S., and Pearce, D.G., 1967, Needle i c e and s e e d l i n g establishment i n SW BC: Canadian J o u r n a l  of P l a n t Science, 47, pp135—139. 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Woolhiser, D.A., Hanson, C.L. and Kuhlman, A.R., 1970, Overland flow on rangeland watersheds: J Hydrology (New Zealand), 9, pp336-356. 125 Y a i r , A., 1974, Sources of runoff and sediment s u p p l i e d by the slopes of a 1st order drainage basin in an a r i d environment (Northern Negev, I s r a e l : Geomorphologische prozesse und  prozesscombinationen i n der qeqenwart unter v e r s c i e d e n  Rlimabeqingungen, I.G.U. Commission r e p o r t on present day processes ed H. Poser. Yoon, Y.N. and Wenzel, H.G., 1971, Mechanics of sheetflow under simulated r a i n f a l l : Proc Am Soc C i v Eng J Hydr Div, 9, ppl367-1386. Zingg, H.W., 1940, Degree and length of l a n d slope as i t a f f e c t s s o i l l o s s in r u n o f f : Aq Eng, 21, pp59—64. Appendix A Slope angles S i t e Slope Sin 6 1 16° 0.27 2 15° 0.25 2R 17° 0.29 3 13° 0.22 4 29° 0.48 5 20° 0.34 6 12° 0.21 7 18° 0.31 8 27° 0.45 9 32° 0.53 9R 39° 0.63 10 28° 0.47 1 OR 29° 0.48 1 1 37° 0.61 1 2 30° 0.50 1 2R 17° 0.29 1 3 21 ° 0.36 1 3R 24° 0.41 1 4 27° 0.45 NI 23° 0.39 127 Appendix B S o i l o rganic matter 500g (approx) s o i l samples from each s i t e were taken from the A h o r i z o n . % organic matter by weight was determined by ashing i n a muffle furnace at 500°C f o r 2 hours. S i t e 1 mi s s i n g 2 16 3 missing 4 1 7 5 1 0 6 3 7 3 8 missing 9 5 9R 5 1 0 1 1 1 1 7 12 1 1 1 3 1 3 1 3R 7 1 4 10 NI 9 128 Appendix C Water Repellency Undisturbed samples from the s u r f a c e l a y e r were-taken at each sampling s i t e and a i r d r i e d . T h i s was e a s i l y achieved at s i t e s with a t u r f y s u r f a c e , d i f f i c u l t where there was a l i t t e r cover and almost impossible where the ground was bare. The q u i c k e s t and simplest t e s t f o r water r e p e l l e n c y i s the water drop p e n e t r a t i o n t e s t (WDPT) which e n t a i l s t i ming the i n f i l t r a t i o n of small water drops. Debano (1981) suggests that s o i l s be c l a s s i f i e d a c c o r d i n g to Letey et a l ( l 9 7 5 ) such that a value of >10mins i n d i c a t e s a h i g h l y water r e p e l l e n t s o i l , a value of 1—lOmins moderate water r e p e l l e n c y , 0.1—1 s l i g h t water r e p e l l e n c y and s o i l <0.1 mins i s wettable. S i t e Av of 5 drops I n d i v i d u a l (mins) values (mins) 1 2.4 0,1,3,2,3,3. 2 and 2R 4 3 5.3 2,3,4.5,6,6.5,7,8. 4 2.6 5 0 0,0,0,0,0. 6 3 0.25,0.3,0.25,0.15,0.25 7 3.3 1 .33, 1 .75,0.5,10,3. 8 10 + 4,8,8,10+,10+. 9 1 .9 0.5,1,2,2,4. 9R 1 0 + 10+,10+,10+,10+,10+. 1 0 1 .7 3,1.5,1.5,1.25,0.25,2.5. 1 OR 0.4 0.25,0.3,0.5,0.7,0.15. 1 1 3. 1 1 •5j2«5jr3^4'j4»5» 1 2 1 0 + 10+,10+,10+,10+,10+. 1 2R 1 0 + 5,5,6,10+,10+. 1 3 1 0 + 1,2,3,10+,10+. 1 3R 1 2.5,1.05,0.7,0.75,0. 1 . 1 4 1 0.1,0.7,1,1,2. NI 0 0,0,0,0,0. Appendix D Snow cover data S i t e Date s i t e s Date trough snowfree i n s t a l l e d 1 1 J u l y 1 J u l y 2 10 J u l y 1 7 J u l y 3 24 J u l y 3 August 4 1 6 J u l y 1 7 J u l y 5 28 J u l y 3 August 6 1 7 J u l y 22 J u l y 7 2 August 2 August 8 1 4 J u l y 1 5 J u l y 9 5 J u l y 5 J u l y 9R 6 J u l y 6 J u l y 10 5 J u l y 5 J u l y 1 OR 5 J u l y 5 J u l y 1 1 5 J u l y 5 J u l y 1 2 6 J u l y 6 J u l y 1 2R 6 J u l y 6 J u l y 1 3 1 2 J u l y 1 4 J u l y 1 3R 1 2 J u l y 1 4 J u l y 1 4 1 5 J u l y 1 6 J u l y NI • 1 August 3 August Snowdepth 17 June (metres) 2 1 . 0 4 1 . 75 5 1 . 75 6 1 . 6 1 4 2. 0 NI 2. 6 1 30 Appendix E Sediment c o l l e c t e d in Ge r l a c h troughs The p r o p o r t i o n of organic matter caught on f i l t e r papers c o u l d not be estimated. At s i t e s 2 and 2R very l i t t l e o r g a n i c matter was c o l l e c t e d and i t was mostly processed on f i l t e r papers. Hence no meaningful d e t e r m i n a t i o n of organic content c o u l d be made f o r samples c o l l e c t e d at these two s i t e s . Data f o r s i t e 4 were scanty because of repeated marmot a t t a c k s to the trough during the season. The f o l l o w i n g a b b r e v i a t i o n s are used: 14J = 14 J u l y 19J = 19 J u l y 4A = 4 August 29A = 29 August I S = 1 September 7S = 7 September 15S = 15 September 25S = 25 September 140 = 1 4 October • marmot d i sturbance A l l weights are given i n grams S i t e 1 DATE ORGANIC MINERAL ORGANIC(%) 19J 0.03967 0.1106 78 4A 3.1490 3.8924 45 29A+1S 0.6866 0.0894 88 7S+15S 0.3577 0.0940 80 25S 0.0060 0.0092 61 140 4.3017 0.0409 99 T o t a l 8.8977 4.2365 68 S i t e 2 19J 0.0041 4A 0.0171 7S 0.0088 15S 0.0527 140 0.2767 T o t a l 0.3594 S i t e 2R 19J 0.0016 4A 0.1071 I S - 0.0266 7S 0.0020 T o t a l 0.1373 S i t e 3 I S 1.8868 0.0469 7S 0.0069 15S 0.0696 0.0027 T o t a l 1.9564 0.0565 131 S i t e 4 1 5S 0.0055 150 0.1170 0.0385 T o t a l 0.0440 S i t e 5 1S 0. 1834 0.9860 16 7S+15S 0.0090 0.3113 3 1 50 0.0464 0.3127 1 3 T o t a l 0.2388 1.6102 13 S i t e 6 2 9A 0.0800 0.0371 68 1S 0.3573 0.1634 69 7S 30.0028 1 5S 0.0034 0.1388* 2 1 40 0.6457 0.0299 96 T o t a l 1.0864 0.2332 82 S i t e 7 29A+1S 0.0242 0.3435 7 1 6S 0.0540 0.5592 8 1 50 0.0431 0.1674 20 T o t a l 0.1213 1.0691 1 0 S i t e 8 1 9J 0. 1876 0.0379 39 4A 0.3391 0.0961 78 29A 0.9354 1S . 0.5664 0.0131 99 7S 0.0114 1 5S 0.2621 0.0071 93 1 40 0.0590 0.0448 57 T o t a l 2.3496 0.2104 92 S i t e 9 1 9J 0.5203 11.0000 5 4A 0.6191 14.3285 4 29A 2.3925 5.3778 31 (+126.5639) 1 S 0.9266 3.4938 21 7S 0.2221 1 5S 0.7927 20.4705 4 25S 0.7939 1.0489 43 T o t a l 26.0451 55.9416 1 0 (+126.5639) S i t e 9R 1 5J 0.2224 1 9J 0.1627 4A 1.1896 3.8197 24 29A 0.8653 1.4656 37 1S 2.5104 16.6485 13 7S 0.0054 0.0399 1 2 1 5S 1.0823 1.7687 38 25S 0.5710 0.9448 38 132 T o t a l 6.2240 25.0723 20 S i t e 10 H J 0.0634* 4 (+171.682) 19J 1.0080 1.9812 33 4A 0.2223 2.0901 10 29A 0.2425 0.0324 88 (+300.09) 1S 0.0629 0.0103 86 7S 0.0521 1 5S 0.0213 0.0281 1 50 2.3300 1 T o t a l 2.5535 6.9683 27 (+471.772) S i t e 10R 19J 0.1000 0.0677 60 4A 0.0140 29A 1 .2635 0.0536 96 1S 0.3116 0.0810 79 7S 0.0023 1 5S 1 .2034 0.0828 94 25S 0.0415 0.0669 38 1 50 0.9365 0.0743 93 T o t a l 3.8556 0.4426 90 S i t e -1 1 1 4J 0.1745 0. 1736 50 1 9J 4.0954 3.6434 53 4A 0.6568 0.6339 51 2 9A 0.6927 0.2047 58 1S 0.306 7S 0.595 2.5367 1 5S 2.5267 25S 0.0030 93 1 50 4.5352 0.3327 T o t a l 10.2141 8.0181 56 S i t e 12 1 4J 1 .2001 0.0090 99 1 9J 9.1901 0.0431 99 4A 0.9049 0.0202 98 1 S 4.8469 0.0044 1 00 7S 0.0087 1 5S 12.0177 0.0569 99 1 40 9.7955 0.0800 99 T o t a l 36.9553 0.2223 99 S i t e 12R 20J 0.7459 0.2236 77 4A 3.4465 0.7429 82 1S miss i n g 7S 0.3892 0.1148 77 140 1.9249 0.2832 87 T o t a l 6.5065 1.3645 83 S i t e 13 20J 1.0392 0.0684 93 4A 0.2965 0.1299 79 1S 0.4918 0.1299 79 7S 0.3331 0.1834 65 1 40 0.2720 0.0288 90 T o t a l 2.4326 0.4546 84 S i t e 13R 20J 1.2427 0.2042 86 4A 0.2769 0.0950 74 1S missing 7S+15S 0.0649 1 40 1.5787 0.1023 94 T o t a l 3.0983 0.4664 87 S i t e 14 20J 0.7804 0.3489 69 4A 0.3501 0.0608 85 1S 0.2736 0.0273 91 7S+15S 0.0416 0.0147 74 1 40 0.3931 0.0854 82 T o t a l 1.8388 0.5371 77 S i t e NI IS 0.5512 3.0937 23 1 5S 0.0038 0.1017 4 1 50 0.0070 0.3506 2 T o t a l 0.5620 3.5460 1 3 Appendix F Grain size distribution of samples caught in the Gerlach troughs (a l l measurements in millimetres and grams) Part ic le sizes (mm) Date Site 0.063 0.063-0. 25 0.25-0 .5 0.5-1 1-2 2-4 4-8 8-16 14 July 9 0.0022 0.0063 0.0015 10 0.0142 0.0096 0.0057 11 0.0328 0.0186 0.0109 0.0387 0.0524 12 0.0078 0.0036 0.0022 0.0026 19 July 8 0.0057 0.0036 0.0024 9 0.0828 0.0381 0.0321 0.0650 0.0729 1. 2047 1.6571 7 .3692 9R 0.1851 0.0673 0.0401 0.0365 0.0057 10 0.0084 0.0058 0.0047 0.0218 0.0183 0. 0130 0.9148 0 .9741 10R 0.0156 0.0091 0.0122 0.0123 11 0.2860 0.2209 0.3984 0.5425 0.4254 0. 4265 0.0000 1 .1894 12 0.0176 0.0063 0.0055 0.0028 12R 0.0342 0.0321 0.0210 0.0721 13R 0.0075 0.0150 0.0139 0.0483 4 August u 0.1293 0.1144 0.0440 0.0630 0.1005 0. 1264 1.1344 2 .0928 .2 0.0200 0.0010 0.0107 2R 0.0034 0.0122 0.0176 0.0476 8 0.0153 0.2177 0.0046 0.0090 0.0261 9 0.0086 0.0082 0.0039 0.0152 0.0311 0. 5368 2.2223 11 .4744 9R 0.1848 0.1656 0.1538 0.4012 0.4799 0. 6336 0.1925 1 .2329 10 0.0043 0.0039 0.0101 0.0142 0.0130 0. 0140 0.0000 1 .9699 10R 0.0048 0.0033 0.0053 11 0.0351 0.0192 0.0697 0.0962 0.1152 0. 1792 12 0.0058 0.0063 0.0019 0.0031 12R 0.0109 0.0136 0.0139 0.0135 0.0115 0. 0410 0.6434 13 0.0047 0.0041 0.0021 0.0029 0.0229 13R 0.0144 0.0028 0.0053 0.0517 16+ Date Site 0.063 0.063-0.25 0.25-0.5 0.5-1 1-2 2-4 4-8 8-16 29 August 6 7 8 9 9R 10 10R 1 September 1 2R 3 5 6 9 9R 10 10R 11 12 13R 7 September 1 2 2R 3 6 7 8 9 9R 10 10R 11 12 12R 13 0.0035 0.0068 0.0050 0.0202 0.0018 0.0004 0.0013 0.0221 0. 0077 0.0073 0.0055 0.0023 0.0061 0.0018 0.0029 0.0030 0.0052 0. 0126 0.3196 2. 1990 0.3170 0.2467 0.1068 0.1871 0. 0819 0.1673 0. 1478 0.0065 0.0043 0.0060 0.0030 0.0024 0.0113 0.0300 0.0030 0.0053 0.0034 0. 0194 0.0102 0.0023 0.0026 0.0091 0.0097 0.0061 0.0054 0. 0215 0.0632 0.1238 0.1157 0. 2917 0.2902 0. 0379 0.0473 0.0076 0.0095 0. 0176 0.0843 0.0336 0.0186 0. 0373 0.0769 0. 4392 3.6781 3.5216 1.7709 2. 6004 2.4449 1. 0665 0.0002 0.0011 0.0004 0. 0005 0.0160 0.0140 0.0038 0. 0055 0.0418 0.0396 0.0377 0. 0752 0.0452 0. 1025 0.0067 0.0004 0.0010 0. 0023 0.0052 0.0028 0.0060 0. 0129 0.0195 0.4090 0.0737 2.2541 0. 0009 0. 0011 0. 0021 0. 0017 0. 0017 0. 0041 0. 0018 0. 0011 0.0022 0. 0059 0. 0022 0. 0026 0. 0022 0. 0055 0. 0042 0. 0040 0. 0051 0. 0053 0. 0139 0. 0203 0. 0315 0. 0249 0. 0012 0. 0018 0. 0013 0. 0104 0. 0109 0. 0044 0. 0011 0. 0013 0. 0013 0. 0039 0. 0048 0. 0179 0. 0012 0. 0049 0. 0080 0. 0016 0. 0011 0. 0017 0. 0012 0. 0008 0.0511 0.0088 0.0045 0.0382 0.0107 0.0342 0.0473 0.0231 0.0378 Date S i t e 15 September 0.063 0^063-0.25 0.25-0.5 0.5-1 1-2 2-4 4-8 8-16 1 0.0212 0.0244 0.0086 0.0360 2 0.0057 0.0058 0.0161 3 0.0018 0.0017 0.0020 0.0014 0 .0252 4 0.0011 0.0014 0.0018 0.0016 5 0.0158 0.0498 0.0831 0.1474 0 .0323 6 0.0067 0.0026 0.0161 0.0931 0 .1099 7 0.0009 0.0020 0.0029 0.0158 0. .0321 8 0.0034 0.0009 0.0000 0.0030 0. .0075 9 0.0231 0.0192 0.1246 0.0797 0 .2996 9R 0.0000 0.0000 0.0000 0.0000 0, .0145 10 0.0028 0.0117 0.0137 0.0499 10R 0.0032 0.0023 0.0031 0.0092 0, .0523 11 0.0665 0.2225 0.1477 0.1977 0, .2870 12 0.0012 0.0023 0.0014 0.0008 0. .1177 12R 0.0088 0.0041 0.0024 0.0252 0. .0865 13 0.0258 0.0139 0.0123 0.0170 0. .0140 14 0.0055 0.6033 0.0042 0.0084 0. .0100 September 1 0.0084 0.0005 0.0010 0.0041 7 0.0020 0.0011 0.0013 9 0.0449 0.430 0.0223 0.0256 0. 0093 .9R 0.3219 0.1460 0.0805 0.1494 0. 0184 10 0.0124 0.0100 0.0031 0.0024 10R 0.0067 0.0108 0.0140 0.0155 0. 0042 11 0.0025 0.0011 0.0021 12 0.0026 0.0017 0.0029 October 1 0.0059 0.0057 0.0051 0.0143 2 0.0154 0.0213 0.0381 0.0903 0. 0443 2R 0.0330 0.0454 0.0191 4 0.0031 0.0039 0.0140 0.0211 5 0.0172 0.0326 0.0277 0.0020 6 0.0070 0.0051 0.0025 0.0052 7 0.0271 0.0192 0.0087 0.0163 8 0.0064 0.0087 0.0106 0.0103 10 0.0104 0.0203 0.0?"^ 0.0613 0.0189 0.5593 0.1140 0.2440 0.6683 8.7150 0.8890 0.3664 1.0064 0.0521 0.0171 0.0833 0.7914 ro Date Si t e 0.063 0.063-0. 25 0.25-0. 5 0.5-1 1-2 2-4 10R 0.0067 0.0068 0.0227 0.0063 0. ,0360 0.1389 11 0.0598 0.0593 0.0438 0.0487 0. .0413 0.0666 12 0.0119 0.0056 0.0122 0.0298 12R 0.0054 0.0053 0.0035 0.0091 0. .0164 0.0982 13 0.0084 0.0097 0.0083 0.0360 13R 0.0059 0.0006 0.0010 0.0218 14 0.0160 0.0121 0.0091 0.0110 NI 0.0337 0.0445 0.0253 0.0424 0. .0472 0.1455 4-8 2.1118 8-16 16+ 1 38 Appendix G G r a i n s i z e d i s t r i b u t i o n of i n d i v i d u a l samples at each s i t e The f o l l o w i n g a b b r e v i a t i o n s are used: 14J = 14 J u l y 1 9 J = 19 J u l y 1A = 1 August 4A = 4 August 16A = 16 August 29A = 29 August 1S = 1 September 7S = 7 September 15S = 15 September 25S = 25 September 140 = 14 October NI = Needle i c e s i t e BS = Bulk sampler SU = s p l a s h up SD = s p l a s h down RH = runnel hump ss = snow sample RS = runnel s i d e RA = red algae 1,5,7 etc r e f e r to s i t e s 29A+1Setc = .combined data f o r these two dates. S o i l = g r a i n s i z e d i s t r i b u t i o n of s o i l from beneath the uppermost organic organic h o r i z o n or from the ground s u r f a c e where a t u r f or l i t t e r l a y e r i s absent. BULK SRHPLERS T 1 1 1 1 1 1 r 0 . 0 6 3 0 . 2 5 1 4 SIZE OF PARTICLES (mm) 140 (mm) 141 142 143 i i i 1 1 — i 1 0 . 2 5 0 1 4 ' 6 SIZE O F P A R T I C L E S (mm) 144 ~1 1 1 1 1—• r ~ ' i ~ ~ i 1 0 . 0 6 3 0 . 2 5 0 1 4 1 6 S I Z E O F P A R T I C L E S (mm) 145 I I 1 1 1 1 1 ; — ; 0.063 0.260 * 16 SIZE OF PARTICLES (mm) 1 4 6 ^ i i i 1 1 1 1 , 0.063 0.250 1 4 II SJZE 0F PARTICLES (mm) 9B% 1 i 1 1 1 1 1 1 r 0.063 0.250 1 4 16 SIZE OF PARTICLES (mm) 98* -i 98*-j (mm] 153 B4 ! s H i i 1 r- 1 1 r 0.250 1 4 !6 S IZE OF PARTICLES (mm) 98X-J r I — I 1 1 r- 1 1 1 0.063 0.250 1 4 ft SIZE OF PARTICLES (mm) 98*' 98% 98% 159 Appendix H Sediment c o l l e c t e d i n s p l a s h troughs A l l weights are i n grams 21st J u l y 9su 0.0010 9sd 0.0178 10RSU 0.0010 lORsd 0.0006 13su 0.1181 13sd 0.0011 Mean 0.0233 0.0777 per m 1st September 2su 0.0246 2sd 0.0039 10SU 0.0183 10sd 0.0018 1ORsu 0.0276 lORsd 0.0021 12su 0.0678 I2sd 0.0035 12Rsu 0.0181 l2Rsd 0.0048 13su 0.0211 13sd' 0.0027 * 13Rsu 0.0238 l3Rsd 0.0011 Mean 0.0158 0.0327 per m 15th September 2su 0.0071 2sd 0.0039 10SU 0.0619 10sd 0.0017 1ORsu 0.0170 lORsd 0.0139 12su 0.0383 12sd 0.0150 12Rsu 0.0475 12Rsd 0.0230 13Rsu 0.0040 13Rsd missing Mean 0.0159 0.0053 per m 1 62 Appendix I BULK SAMPLERS A l l weights are i n grams S i t e 2 1 September 1 5 September T o t a l 0.0259* 0.0025 0.0284 S i t e 6 1 September 15 September T o t a l 0.0283' 0.0061 0.0344 S i t e 9 1 September 15 September 25 September T o t a l 0.083H 0.0268 0.0055< 0.1154 S i t e 13 1 September 15 September T o t a l 0.01 02< 0.0080 0.0182 One f i l t e r used f o r XRD Si z e d i s t r i b u t i o n a f t e r s i e v i n q S i t e <63>*m 63-250»im .25—.5mm .5 — 1 mm 1—2mm T o t a l 2 0.0048 0.0025 0.0012 0. 0001 0.0046 0.0132 6 0.0065 0.0025 0033 0. 001 6 0.0049 0.0188 9 0.0134 0.0119 0.0146 0. 01 49 0.0213 0.0761 1 3 0.0069 0.0018 0.0024 0-0111 As % 2 36 1 9 9 1 35 1 00 6 35 1 3 18 9 26 100 9 18 1 6 19 20 28 100 1 3 62 1 6 22 1 00 163 Appendix J Data from t r a c e r p a r t i c l e s A l l measurements are i n cms Green T r a c e r s (4-8mm) S i t e Recov--Recov- Movement Geom A r i t h R a t i o ery # ery % down up % mean mean 1 33 66 22 3 76 4.4 3.0 1 .5 2 39 78 0 0 0 — 2R 44 88 1 0 2 3 47 94 4 1 9 4 40 80 1 0 3 — 5 46 92 5 0 1 1 4.2 3.6 1 .2 6 49 98 3 0 6 2.3 2.3 1 7 34 68 30 0 88 4.8 4. 1 1 .2 8 33 66 2 0 6 — 9 37 74 28 0 100 13.1 6. 1 2.1 9R 37 74 28 0 76 42.8 23.9 1 .8 1 0 39 78 9 0 23 17.2 15.2 1 . 1 1 1 49 98 28 0 57 13.6 8.1 1 .7 1 2 47 94 28 0 60 6. 1 5.3 1 .2 1 3 40 80 1 4 0 35 7.6 6.9 1 . 1 1 4 42 84 2 0 5 — NI 42 84 1 2 1 29 2.3 2.2 1 Yellow Tracers ; (2--4mm) S i t e Recov--Recov- Movement Geom A r i t h Rat i o ery # ery % down up % mean mean 1 40 37 1 0 6 40 1 . 3 1 .5 0.9 2 34 35 1 0 3 — 2R 21 20 0 0 0 3 48 49 3 0 9 8 5.2 1 .5 4 50 47 1 0 2 — 5 34 32 8 0 24 4 3.3 1 .2 6 51 48 1 0 2 — 7 62 58 30 0 49 4.5 3.9 1 .2 8 36 34 1 0 3 — 9 20 1 9 1 7 0 85 4.3 3.8 1 . 1 9R 33 31 27 0 82 30.8 23.7 1 .3 1 0 21 20 3 0 1 4 1 3 7. 1 1 .8 1 1 38 36 13 0 34 12.3 8 1 .5 1 2 46 43 18 1 39 5 4. 1 1 .2 1 3 44 41 8 0 18 3.3 3.4 1 1 4 48 45 1 1 2 — NI 58 54 5 1 9 3.4 3.2 1 . 1 1 64 Red T r a c e r s S i t e Recov--Recov- Movement Geom A r i t h R a t i o ery # ery % down up % mean mean 1 1 24 62 20 3 19 3.6 3.2 1 .1 2 1 24 62 2 0 2 3.5 3.5 1 2R 1 26 63 4 0 3 — — 3 184 92 7 0 4 58. 1 5.9 1 .4 4 98 49 5 0 5 4.2 3.9 1 . 1 5 90 45 63 0 70 3.3 2.3 1 .4 6 101 51 4 2 4 9.6 6.7 1 .4 7 106 53 1 06 0 100 5.3 4.3 1 .2 8 58 29 2 1 3 — — — 9 73 36 1 7 1 23 76.6 4.4 1 .5 9R 90 45 71 0 79 20.7 13.3 1 .6 1 0 1 1 6 58 26 1 22 11.5 9.6 1 .2 1 1 1 32 66 45 0 34 25. 1 12.2 2.1 1 2 67 33 3 0 4 2.7 2.6 1 1 3 1 06 53 27 0 25 7.2 5.6 1 .3 1 4 121 60 8 0 7 3.6 3.5 1 NI 1 62 81 21 0 1 3 5.8 5. 1 1 . 1 Appendix K Sediment e n t r a i n e d i n the snowpack S i t e Sediment (grams) Mount Rose 1 0. 0093 2 0. 0093 3 0. 01 46 4 0. 0054 5 0. 0052 6 0. 0029 7 0. 0051 NI ( 1 ) 0. 0084 NI (2) 0. 0111 Snow s u r f a c e Between 0.0064 runnels Runnel 0.2146 hump Runnel 0.0231 s i d e 0.0168 0.0198 Red algae 0.0035 CRREL snow sampler Snowpit 2 0.0007 0.0006 0. 001 5 0.0073 0.0062 0.0018 Snowpit 4 0.0014 0.0067 0.0019 0.001 1 0.0008 0.0010 0.0030 0.0007 Water Sed cone Depth volume (gxlO /cc) (cms) (cc) 1 440 3220 28 3454 420 3893 140 3540 150 3208 90 1855 270 1087 770 964 1150 115 5570 135 159,000 131 17,600 95 17,700 123 16,100 160 220 152 460 86.5-115 197 300 69.0-88.5 196 770 49.5-69.0 158 4620 230 2700 10.5-30 68 2650 0-10.5 200 700 136.5-156 197 2480 117.0-136.5 240 790 97.5-119 202 540 78.0-97.5 223 360 58.5-78.0 234 430 39.0-58.5 255 1180 19.5-39.0 275 250 0-19.5 Appendix L Overland flow o b s e r v a t i o n s S i t e d(mm) v e l o c i t y Reynolds F r i c t i o n (cm/sec) number f a c t o r 0F1 4 4 126 0.833 4 4 126 . 0.833 4 4 126 0.833 4 4 126 0.833 7 5.7 234 16.9 18 5.7 602 43.4 1 7 7. 1 608 26.4 7 20.0 821 1 .3 9 15.3 808 3.0 1 2 25.0 1 760 1 .5 1 2 15.3 1 077 4.0 1 9.1 53 0.95 7 5.7 234 16.9 5 5.7 1 64 12.1 10 7. 1 417 15.6 10 20.0 1 173 19.6 1 1 20.0 1 290 2. 1 1 0 25.0 1 467 1 .25 1 4 15.3 1 256 4.7 1 2 22.0 641 11.3 5 10.5 308 3.6 5 3.6 1 05 0.3 3 16.7 294 0.84 9 9. 1 481 8.5 7 6.3 257 13.8 7 7.4 304 10.0 2 10.5 1 23 1 . 4 5 9.1 481 8.5 2 5.6 1 7 5.0 6 16.7 588 1 .7 2 9. 1 1 07 0.02 7 7.4 304 10.0 7 10.5 431 5.0 2 10.5 1 23 1.4 2 9.1 1 07 0.02 Appendix M Thermohygroqraph data Date °C Data °C Date °C Date °C Max Min Max Min Max Min Max Min J u l y Aug Sept Oct 1 9 — 1 19 1 2 1 1 2 6 1 1 -3 2 1 4 6 2 — 1 5 2 1 1 6 2 1 0 3 1 2 6 3 1 6 6 3 1 1 3 3 1 — 1 4 1 4 6 4 1 6 6 4 1 0 6 4 6 1 5 9 6 5 19 6 5 6 4 5 2 1 6 6 0 6 23 7 6 7 4 6 2 1 7 6 2 7 24 1 7 7 22 7 7 4 1 8 9 2 8 26 18 8 1 2 5 8 4 1 9 6 4 9 26 18 9 1 2 5 9 — 2 1 0 1 1 3 10 26 19 1 0 1 2 6 10 — — 1 1 1 4 6 1 1 24 20 1 1 1 3 8 1 1 — — 1 2 1 1 5 1 2 24 1 7 1 2 1 2 6 1 2 1 -5 1 3 1 2 6 1 3 24 1 7 1 3 1 2 6 1 3 6 -2 1 4 1 4 5 1 4 24 19 1 4 1 6 7 1 4 1 2 4 1 5 1 7 9 1 5 22 1 4 1 5 22 1 4 1 5 8 6 1 6 1 6 1 2 1 6 1 4 1 6 22 1 6 16 7 3 1 7 — 1 2 1 7 21 1 4 1 7 23 1 4 1 7 7 4 18 — — 18 20 1 4 18 1 4 1 2 1 9 — — 19 21 1 2 19 6 2 • 20 — — 20 1 2 ? 20 4 1 21 1 6 7 21 1 4 6 21 — 1 22 1 6 8 22 1 7 7 22 — — 23 1 5 9 23 22 1 2 23 — — 24 1 6 7 24 1 2 6 24 2 0 25 22 8 25 6 4 25 0 -3 26 1 9 1 2 26 1 1 4 26 0 -3 27 1 4 11 27 8 5 27 0 -3 28 5 6 28 9 5 28 1 1 29 1 4 6 29 1 1 6 29 2 1 30 1 2 6 30 1 1 4 30 1 1 31 1 6 5 31 8 6 31 168 Appendix N Gerlach trough water volumes A l l volumes i n m i l l i l i t r e s s i t e 14 19 4 29 1 7 15 25 14 J u l y J u l y Aug Aug Sept Sept Sept Sept Oct 1 445 203 2 626 210 2R 785 220 3 4 5 6 1 700 7 885 8 1 200 204 830 9 206 1 500 200 21 50 9R 28 1 726 200 1 650 1 0 836 1417 250 1 233 1810 1 OR 697 2001 272 1880 1 1 1 322 961 241 1 260 1 2 519 1000 80 1 2R 1 250 189 1 3- 1310 215 1 3R 1310 31 1 1 4 1216 1 50 NI 1 720 480 90 1 1 20 1360 530 180 1 320 1 650 600 31 50 500 1 90 1 70 1910 1950 490 160 271 0 1 270 910 270 1 960 1880 550 1 20 1 325 1 490 1 900 480 1 40 2300 2100 770 170 21 70 2050 910 170 2220 660 1 70 1710 2330 2000 930 250 1 751 2200 2000 640 1 30 910 890 2000 780 80 880 1 1 70 2000 540 1 00 1 990 2000 520 300 21 60 1 700 560 2920 21 50 640 1 60 2290 635 3640 169 Appendix 0 I n t e r p r e t a t i o n of XRD t r a c e s K a o l i n i t e was present i n a p p r e c i a b l e q u a n t i t y i n a l l the samples, shown by c o l l a p s e of the 7A peak on h e a t i n g to 550°C. S i t e s 2 and 9 both showed a r e s i d u a l peak a f t e r h e a t i n g e i t h e r because the k a o l i n i t e was not completely broken down or because c h l o r i t e was pre s e n t . No enhancement of the 14.2A peak was seen on h e a t i n g to 550°C so c h l o r i t e , i f present, was a small component of the system. A l l s i t e s show f e l s p a r . T h i s was shown by s e v e r a l sharp strong r e f l e c t i o n s at 3.18 — 3.25A, a strong r e f l e c t i o n around 4.03A and weak r e f l e c t i o n s i n some samples at 6.4 — 6.5A. The p r e c i s e peak p o s i t i o n s p l a c e the f e l s p a r s as p l a g i o c l a s e — i n c l u d i n g some Ca r i c h f e l s p a r s s i g n i f i e d by a peak at 3.13. There may be some K f e l s p a r but the two major r e f l e c t i o n s at 3.31 and 4.2A are masked by q u a r t z . S i t e s 13 and 6 a l l suggest the presence of K f e l s p a r because the c h a r a c t e r i s t i c a l l y sharp quartz peak at 3.34 i s broadened towards the 3.31A of K f e l s p a r . A l s o there are peaks above the 3.22 upper range of p l a g i o c l a s e f e l s p a r . Amphibole i s i n d i c a t e d by a peak at about 8.4 on a l l t r a c e s . In no case i s t h i s peak l a r g e and lower order r e f l e c t i o n s i n t e r f e r e with f e l s p a r and cannot be d i s c r i m i n a t e d . Quartz i s present i n very small amounts; i t i s commonly used i n q u a n t i t a t i v e a n a l y s i s . However, i t seems to be absent at 9 and only j u s t d e t e c t a b l e at s i t e 2. Even s i t e s 6,13 and RS have only a small percentage. Trace from site 9 - all sizes Trace from site 13CK saturated <0.0063 fraction) 171 Appendix P Rock composition (courtesy T. G a l l i e ) Quartz, a c t i n o l i t e c h l o r i t e s c h i s t Quartz 30% A c t i n o l i t e (horneblende) 30% C h l o r i t e 20% Ep i d o t e 5% Diops i d e 2% Sphene 2% B i o t i t e 1% P l a g i o c l a s e t r a c e Comments C h l o r i t e — very f i n e g r a i n e d , f i b r o u s and i n t e r l a c i n g g r a i n s , i n t e r l a y e r e d with c o a r s e r g r a i n e d a c t i n o l i t e and granular e p i d o t e . A c t i n o l i t e — elongate bladed c r y s t a l s , form d i s c r e t e meshed l a y e r s . Wrapped around small masses of m i c r o c r y s t a l l i n e quartz and e p i d o t e . Quartz — some f i n e g r a i n s , mainly as s t r i n g e r s . Quartz d i o r i t e Quartz 30% P l a g i o c l a s e 30% Horneblende 15% Ep i d o t e 10% K—spar 5% S e r i c i t e 3% Opaques 2% C h l o r i t e , muscovite, c1inopyroxene 5% Comments Quartz — f i n e to medium g r a i n e d (0.05—0.5mm), s t r o n g l y r e c r y s t a l l i s e d , s e r i c i t e g r a i n boundaries. P l a g i o c l a s e and K—spar — medium to coarse g r a i n e d , g r a n u l a r t e x t u r e (0.2—1mm). I n d e f i n i t e g r a i n boundaries, s e r i c i t e a l t e r a t i o n , some mafic a l t e r a t i o n . Horneblende — f i n e to medium g r a i n 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 quart< and f e l s p a r . Primary g r a i n s have r e c r y s t a l l i s e d . E p i dote — g e n e r a l l y f i n e g r a i n e d , a l s o developed along f r a c t u r e s in m i c r o — v e i n l e t s . » 

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