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Stream channel morphology : comparison of logged and unlogged watersheds in the Queen Charlotte Islands Hogan, Daniel Lewis 1985

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STREAM CHANNEL MORPHOLOGY: COMPARISON OF LOGGED AND UNLOGGED WATERSHEDS IN THE QUEEN CHARLOTTE ISLANDS By DANIEL LEWIS HOGAN B.A., The University of B r i t i s h Columbia, 1976 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department of Geography) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA September 1985 © Daniel Lewis Hogan, 1985 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Geography  The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date September 1985 DE-6 (3/81) ABSTRACT This study compares the morphology of c o a s t a l , gravel-bed streams i n two unlogged and two logged Queen Charlotte Islands watersheds. This comparison q u a n t i f i e s the influence of logging and r e l a t e d a c t i v i t i e s on channel morphology and, consequently, the f r e s h water p h y s i c a l habitat of salmonids. Further, i t provides a basis upon which to determine hab i t a t r e h a b i l i t a t i o n c r i t e r i a f o r disturbed channels. Pools and r i f f l e s are d e t a i l e d because: a) they r e f l e c t changes i n sediment supply; b) they are important f i s h h a b i t a t s , and; c) t h e i r general character has been documented i n previously published l i t e r a t u r e allowing a p p l i c a t i o n of geomorphological r e s u l t s to habitat evaluation. Longitudinal p r o f i l e s conducted over r e l a t i v e l y long channel segments located within each watershed i n d i c a t e that channels i n watersheds logged to the channel banks by old techniques have reduced pool-to-pool spacings and increased r i f f l e amplitudes and magnitudes. There i s an increase i n channel stored sediment r e s u l t i n g i n p r o p o r t i o n a l l y l a r g e r r i f f l e s and smaller pools. This represents a reduction i n a v a i l a b l e rearing h a b i t a t . No s i g n i f i c a n t d i f f e r e n c e s e x i s t i n pool and r i f f l e c h a r a c t e r i s t i c s between unlogged watersheds and those logged by contemporary techniques. In a l l cases the pool and r i f f l e character d i f f e r e d from most previously published r e s u l t s . Results obtained from d e t a i l e d study reaches located within each channel segment show that large organic debris i s a c o n t r o l l i n g f a c t o r i n f l u e n c i n g the morphology of these streams. Based upon a comparison of reaches, i t i s concluded that LOD c h a r a c t e r i s t i c s are a l t e r e d i n the - i i i -older logged channels. This includes a s h i f t i n the s i z e d i s t r i b u t i o n , with smaller material being more prevalent. Orientation of t h i s m a t erial i s also a l t e r e d ; more LOD i s l y i n g p a r a l l e l to the flow d i r e c t i o n , as opposed to the more common diagonal o r i e n t a t i o n found i n unlogged channels. This s h i f t i n o r i e n t a t i o n i s responsible f o r a reduction i n channel width and depth v a r i a b i l i t y , reduced sediment texture, fewer cut banks, smaller pool areas and decreased channel s t a b i l i t y . This r e s u l t s i n reduced habitat d i v e r s i t y and q u a l i t y . No morphological d i f f e r e n c e s were detected between unlogged and r e c e n t l y logged reaches. The a r c h i t e c t u r e of unlogged channels can be duplicated to r e h a b i l i t a t e disturbed streams. Pool and r i f f l e sequences should be spaced approximately 2^ - channel widths apart and r i f f l e magnitudes should average 0.013 m/ra. LOD should play a major r o l e i n r e h a b i l i t a t i o n . Long pieces of debris should be placed e i t h e r diagonally across the channel to increase depth and width v a r i a b i l i t y and to store sediment or p a r a l l e l to the flow i f width i s to be reduced. D i v e r s i t y can be increased by placing large root wads to produce small scour holes. Only small debris steps, accounting for approximately 10% of the o v e r a l l change i n el e v a t i o n should be used. This comparative study of channel morphology emphasizes the importance of c r i t i c a l l y evaluating basin morphometric properties and the r o l e of LOD o r i e n t a t i o n . Further, i t ind i c a t e s that previous studies reporting average values and neglecting LOD provide i n s u f f i c i e n t d e t a i l to quantify f i s h h a b i t a t . - i v -TABLE OF CONTENTS Page - ABSTRACT i i TABLE OF CONTENTS...... i v LIST OF TABLES v i i LIST OF FIGURES i x ACKNOWLEDGEMENT S x i i i 1.0 INTRODUCTION 1 1.1 Background 1 1.2 Previous Studies 4 1.2.1 Study Designs, and Channel Variables 4 1.2.2 Studies Concerned with Changes i n Independent Variables 8 1.2.3 Studies Concerned with Changes i n Dependent Variables 9 1.2.4 Studies of Flow Conditions and Habitat 15 1.2.5 Summary .. 16 1.3 Study Objectives. 17 2.0 STUDY DESIGN AND DESCRIPTION OF THE STUDY AREAS 19 2.1 Study Design 19 2.1.1 Problems Associated with Paired Watershed Designs 21 2.1.2 S t a t i s t i c a l Procedures 22 2.2 Study Watersheds 22 2.2.1 General Description of the Study Watersheds 23 2.2.2 Geology 23 2.2.3 Hydrometerology 26 2.2.4 So i l s and Vegetation 30 2.2.5 Basin Morphometry 31 2.2.6 Logging H i s t o r i e s 34 2.3 Stream Channel and Reach Study Areas 39 2.3.1 Sub-Basin C h a r a c t e r i s t i c s 39 2.3.2 Study Reach C h a r a c t e r i s t i c s 43 2.4 Summary 44 - v -Page 3.0 STUDY METHODOLOGY 48 3.1 Channel Scale Longitudinal Profiles 48 3.2 Reach Scale Morphological Studies... 52 3.2.1 Morphological Studies Conducted at Low Flow 52 3.2.2 Habltat-Streamflow Studies 57 4.0 CHANNEL SCALE LONGITUDINAL PROFILES 61 4.1 Pool and R i f f l e Spacing 66 4.2 R i f f l e Amplitude, Magnitude and Relative Relief... 75 4.3 Pool and R i f f l e Proportions 79 4.4 Summary 81 5.0 REACH SCALE MORPHOLOGICAL STUDIES 84 5.1 Large Organic Debris Characteristics 84 5.1.1 Large Organic Debris Quantities 84 5.1.2 Large Organic Debris Arrangement Within the Channel Zone 96 5.1.3 Summary of LOD Input, Storage and Output Characteristics 104 5.2 Influence of Large Organic Debris on Channel Morphology 109 5.2.1 Channel Depth and Width 109 5.2.2 Pool and R i f f l e Characteristics 118 5.2.3 Sediment Texture 123 5.2.4 Channel Gradient and stored Sediment Volumes 124 5.2.5 Summary 129 6.0 HABITAT-STREAMFLOW STUDIES 130 6.1 Hydraulic Geometry 130 6.2 Stream Flow Stage and Velocity-Depth Relations.... 139 6.3 Summary 156 7.0 CONCLUSIONS 157 8.0 BIBLIOGRAPHY 168 - v i -Page 9.0 APPENDICES 178 Appendix A Assessment of P r e c i p i t a t i o n and Runoff V a r i a b i l i t y i n the Queen Charlotte Islands 178 A . l P r e c i p i t a t i o n 179 A.1.1 Introduction 179 A.1.2 Methods 180 A. 1.3 Results and Discussion 185 A. 2 Runoff 188 Appendix B Basin Morphometry of Selected Queen Charlotte Island Streams 193 B. l Introduction 194 B.2 Background 195 B.3 Methods 196 B. 3.1 Linear Aspects of Drainage Basins 196 B.3.2 Areal and R e l i e f Aspects of Drainage basins 198 B.4 Results and Discussion 199 B.4.1 Basin and Sub-Basin Morphometry 199 B.4.2 Basins and Sub-Basins Compared. 205 Appendix C Textural Analysis of Surface, Subsurface and McNeil Sediment Samples of Selected Queen Charlotte Island Streams 213 Appendix D AT-A-Station Hydraulic Geometries of Selected Queen Charlotte Island Streams.... 215 - v i i -LIST OF TABLES Page Table 2.1 Watershed c h a r a c t e r i s t i c s of selected Queen Charlotte Island streams 33 Table 2.2 Logging h i s t o r i e s of the study watersheds 35 Table 2.3 Sub-basin c h a r a c t e r i s t i c s 40 Table 2.4 Comparison of sub-basin c h a r a c t e r i s t i c s : r a t i o s of selected l i n e a r scale features and dimensionless numbers 42 Table 2.5 D e t a i l study reach c h a r a c t e r i s t i c s 45 Table 2.6 Summary of selected study pairs 47 Table 4.1 Summary of analysis of variance r e s u l t s for pool-to-pool spacing 70 Table 4.2 Summary of channel averaged r i f f l e amplitude, magnitude and r e l a t i v e r e l i e f 76 Table 4.3 Summary of ana l y s i s of variance for r i f f l e amplitude, magnitude and r e l a t i v e r e l i e f 77 Table 4.4 Summary of pool and r i f f l e proportions fo r i n d i v i d u a l study channels 80 Table 4.5 Summary of ana l y s i s of variance r e s u l t s for p o o l / r i f f l e r a t i o s 82 Table 5.1 Number of pieces and volumes pf large organic debris 92 Table 5.2 Summary of ana l y s i s of variance r e s u l t s f o r large organic debris volumes.... 95 Table 5.3 Summary of analysis of variance r e s u l t s f o r o r i e n t a t i o n of in-stream large organic debris by volume 103 Table 5.4 Summary of the r e l a t i o n between large organic debris c h a r a c t e r i s t i c s and channel width and depth v a r i a b i l i t y 117 - v i i i -Page Table 5.5 Summary of channel cutbanks 119 Table 5.6 Area and shape of pools and r i f f l e s 121 Table 5.7 Percentage change i n channel e l e v a t i o n due to large organic debris steps (channel scale studies) 125 Table 5.8 Volumes of sediment r e l a t e d to large organic debris 127 Table 6.1 A t - a - s t a t i o n hydraulic geometry exponents and c o e f f i c i e n t s 134 Table 7.1 Summary of channel changes associated with logging and r e l a t e d a c t i v i t i e s 159 Table 7.2 Factors not re l a t e d to logging a c t i v i t i e s which may contribute to documented channel d i f f e r e n c e s (a caveat to Table 7.1) 165 Table A . l Location of selected climate s t a t i o n s i n the Queen Charlotte Islands 183 Table B.l Summary of morphometric data: main basins 200 Table B.2 Summary of morphometric data: sub-basins 201 Table B.3 Comparison of basin c h a r a c t e r i s t i c s : r a t i o s of l i n e a r scale features and dimensionless numbers.. 210 Table C.l Summary of t e x t u r a l a n a l y s i s of surface, subsurface and McNeil sediment samples (phi units) 214 - i x -LIST OF FIGURES Page Figure 2.1 Study design using paired watersheds 20 Figure 2.2 Study watersheds on the Queen Charlotte Islands. 24 Figure 2.3 S p a t i a l v a r i a t i o n of p r e c i p i t a t i o n on the Queen Charlotte Islands 28 Figure 2.4 Drainage patterns, logging h i s t o r i e s and l o c a t i o n of study reaches i n selected Queen Charlotte Island watersheds 36 Figure 3.1 Channel morphology study procedures 49 Figure 3.2 Diagram of methods of conducting l o n g i t u d i n a l p r o f i l e surveys 51 Figure 4.1 Longitudinal p r o f i l e of channel thalweg: Government Creek 62 Figure 4.2 Longitudinal p r o f i l e of channel thalweg: Mosquito Creek 64 Figure 4.3 Longitudinal p r o f i l e of channel thalweg: Bonanza and Hangover Creeks 65 Figure 4.4 Schematic digram of pool and r i f f l e sequence and method of determining r i f f l e spacing, amplitude, r e l a t i v e r e l i e f and magnitude. 67 Figure 4.5 Frequency d i s t r i b u t i o n of pool-to-pool spacing for f i v e unlogged watershed streams and three logged watershed streams 68 Figure 4.6 Frequency d i s t r i b u t i o n of pool-to-pool spacing for streams with minimal LOD and adjusted channel widths 72 Figure 5.1 LOD, morphology and l o n g i t u d i n a l p r o f i l e of Government Reach B 85 Figure 5.2 LOD, morphology and l o n g i t u d i n a l p r o f i l e of Government Reach C 86 - x — Page Figure 5.3 LOD, morphology and l o n g i t u d i n a l p r o f i l e of Government Reach D 87 Figure 5.4 LOD, morphology and l o n g i t u d i n a l p r o f i l e of Mosquito Main 88 Figure 5.5 LOD, morphology and l o n g i t u d i n a l p r o f i l e of Mosquito Tributary 89 Figure 5.6 LOD, morphology and l o n g i t u d i n a l p r o f i l e of Hangover 90 Figure 5.7 LOD, morphology and l o n g i t u d i n a l p r o f i l e of Bonanza 91 Figure 5.8 Frequency d i s t r i b u t i o n of large organic debris by volumes.... 94 Figure 5.9 D e f i n i t i o n diagram for large organic debris o r i e n t a t i o n . 98 Figure 5.10 Orientation of LOD by volume p r i o r to rearrangement by streamf low. 99 Figure 5.11 Orientation of in-stream LOD by volume 101 Figure 5.12 Clustering of large organic debris 105 Figure 5.13 V e r t i c a l d i s t r i b u t i o n of large organic debris.. 107 Figure 5.14 D e f i n i t i o n diagram for v a r i a b i l i t y of large organic debris volumes, channel widths and depths I l l Figure 5.15 V a r i a b i l i t y of channel depth, width and large organic debris 112 Figure 6.1 Definition, diagram of channel geometry 131 Figure 6.2 Reach averaged hydraulic geometry: Hangover Creeks 136 Figure 6.3 Reach averaged hydraulic geometry: Bonanza Creek 136 Figure 6.4 Habitat averaged hydraulic geometry: Hangover Creek 138 - x i -Page Figure 6.5 Lines of equal p r o b a b i l i t y of use by coho salmon for spawning, f r y rearing and egg incubation 140 Figure 6.6 D i s t r i b u t i o n of water surface area by depth-v e l o c i t y c l a s s : Hangover Creek 141 Figure 6.7 D i s t r i b u t i o n of water surface area by depth-velocity c l a s s : Bonanza Creek 144 Figure 6.8 Cumulative plots of changes i n mean depth and v e l o c i t y with changing discharge: Hangover Creek 149 Figure 6.9 Cumulative plots of changes i n mean depth and v e l o c i t y with changing discharge: Bonanza Creek 151 Figure 6.10 Weighted useable areas for coho salmon (m per 200 m of channel): Hangover Creek. 154 Figure 6.11 Weighted useable areas for coho salmon (m per 200 m of channel): Bonanza Creek 155 Figure A.l Cumulative p r e c i p i t a t i o n plots for selected AES and ASB climate stations 182 Figure A.2 Dendrogram diagram of p r e c i p i t a t i o n s t a t i o n groupings 186 Figure A.3 Cumulative plot of error indices as a r e s u l t of grouping p r e c i p i t a t i o n records 186 Figure A.4 Annual mean monthly discharge and unit discharge graphs for selected Queen Charlotte Island streams 190 Figure A.5 Relation between p r e c i p i t a t i o n and runoff for homogeneous p r e c i p i t a t i o n zones considered i n Figure 2.3 191 Figure B.l Hypsometric curves for the study basins 203 Figure B.2 Hypsometric curves for the study sub-basins.... 204 Figure B.3 Longitudinal p r o f i l e of Government Creek (Reaches A,B,C,D) 206 - x i i -Page Figure B.4 Longi t u d i n a l p r o f i l e of Mosquito Main Creek and Mosquito Tr i b u t a r y Creek 207 Figure B.5 Longi t u d i n a l p r o f i l e of Bonanza and Hangover Creek 208 Figure D.l A t - a - s t a t i o n h y d r a u l i c geometry: Government Creek 216 Figure. D.2 A t - a - s t a t i o n h y d r a u l i c geometry: Mosquito Main Creek 217 Figure D.3 A t - a - s t a t i o n h y d r a u l i c geometry: Mosquito Tr i b u t a r y Creek 218 Figure D.4 A t - a - s t a t i o n h y d r a u l i c geometry: Hangover Creek 219 Figure D.5 A t - a - s t a t i o n h y d r a u l i c geometry: Bonanza Creek 220 - x i i i -ACKNOWLEDGEMENTS I wish to s i n c e r e l y thank my supervisor, Dr. M. Church for h i s guidance and support throughout this study. Dr. H.O. Slaymaker's advice and constructive review of this thesis i s also greatly appreciated. I would l i k e to acknowledge C. Robertshaw, L. Davies, and C. Moffat for t h e i r assistance i n the f i e l d ; E. K e l l e r h a l s and C. Moffat for helping with the reduction of data; many members of the Fish/Forestry Interaction Program, p a r t i c u l a r l y V. Poulin for supporting the project and L. Beaven, T. Harding and D. Tripp, for several h e l p f u l suggestions and B. Humphrey for d r a f t i n g most of the figures i n this thesis; K. Rood for many useful discussions; and C. Moffat for a s s i s t i n g i n the f i n a l production of this t h e s i s . This research was funded by the Natural Sciences and Engineering Research Council operating grant to Dr. M. Church; the Fish/Forestry I n t e r a c t i o n Program sponsored by the B r i t i s h Columbia Ministry of Forests, B r i t i s h Columbia Ministry of Environment and the Canada Department of F i s h e r i e s and Oceans; and the Walter W. J e f f r e y Memorial Scholarship. F i n a l l y , I would l i k e to thank my wife for the A.L. Hogan Study Grant (1982-85) and my new-born daughter, Katie, for providing strong incentive to f i n i s h t his thesis and to get a r e a l job — a promotion from my present p o s i t i o n as "Mr. Mom". - 1 -1.0 INTRODUCTION 1.1 Background In 1981 the commission investigating the P a c i f i c Salmon Fishery stated i t s i n i t i a l conclusions on the economic state of the resource. In that report, Pearse (1981, p. 93) asserted that "unless the i n t e g r i t y and productivity of the aquatic habitat i s protected, even the best stock management w i l l be of no a v a i l . . . . In short, i f habitat goes so do the f i s h . " In this context the physical components of fresh water habitat are those areas of the stream used for spawning and incubation, usually the well sorted gravel and cobble material comprising r i f f l e s and those used for rearing zones, most often the pool and near bank areas (Canada Department of Fisheries and Oceans, 1980). Although the morphologic character of these habitat areas i s a direct function of channel materials and f l u v i a l processes, the 'in t e g r i t y and productivity' may be influenced by various land use a c t i v i t i e s within the watershed. This w i l l depend largely on the type of land use a c t i v i t y and the inherent s t a b i l i t y of the watershed slopes and channels. However, Pearse (1981, p. 84) concluded that " i t i s now widely agreed that logging and related a c t i v i t i e s have had a greater overall impact on the salmon stocks than any other single source of habitat damage." This statement i s extremely broad because i t does not address the highly variable nature of logging influence over both time and space scales. I t i s also very d i f f i c u l t to substantiate conclusively (cf. Hartman and Holtby, 1982). The resource manager i s - 2 -s t i l l faced with s e v e r a l , l a r g e l y unanswered, questions: i s habitat s i g n i f i c a n t l y degraded as a r e s u l t of a l t e r e d channel morphology due to logging and r e l a t e d a c t i v i t i e s ? i f a problem does e x i s t , what measures can be taken to mitigate the impact? and, what can be done to restore or r e h a b i l i t a t e habitat to most c l o s e l y approximate i t s n a t u r a l , unaltered condition? The answers to the above questions are d i f f i c u l t to determine, p a r t i c u l a r l y i n small watersheds (drainage basin areas l e s s than 100 2 km ) and i n geomorphically a c t i v e areas. The d i f f i c u l t y stems p r i m a r i l y from a general lack of information concerning the morphologic character of small streams p r i o r to logging. Apart from a l i m i t e d number of watershed studies, of which only recent work d i r e c t l y addresses the r e l a t i o n between logging and channel morphology (e.g., Madej, 1984; L i s l e , 1982), changed habitat conditions are often i n f e r r r e d s o l e l y from post-logging f i e l d i n s p e c t i o n s . Conventional a i r photographs have supplied minimal supplemental information p e r t a i n i n g to the previous conditions because they provide i n s u f f i c i e n t r e s o l u t i o n and the channel i s often obscured by the tree canopy p r i o r to logging. An a l t e r n a t i v e approach i s to estimate pre-logging conditions based on general, non-site s p e c i f i c , r e s u l t s obtained from previously published geomorphological studies. The value of general geomorphological information to habitat q u a n t i f i c a t i o n has not been s y s t e m a t i c a l l y assessed previously. However, because the p h y s i c a l nature of fresh water f i s h habitat i s defined i n terms of channel shape - 3 -(e.g., pools and r i f f l e s ) , sedimentology and flow conditions t h i s approach appears v i a b l e because these features have been shown to e x h i b i t a c e r t a i n degree of r e g u l a r i t y (e.g., c h a r a c t e r i s t i c p o o l - r i f f l e sequence spacing, areal s o r t i n g of sediment and t y p i c a l h y d raulic geometries). In order to evaluate the v a l i d i t y of applying general geomorphologic r e s u l t s f or habitat q u a n t i f i c a t i o n purposes i t i s necessary f i r s t to document both the pre-logging and post-logging channel morphological c h a r a c t e r i s t i c s , then determine i f e i t h e r , or both, are consistent with the generalized r e s u l t s obtained from other geographic areas and f o r d i f f e r e n t stream s i z e s . This t h e s i s presents an evaluation of the influence of logging and r e l a t e d a c t i v i t i e s on stream channel morphology and, therefore, on the p h y s i c a l features of salmonid f r e s h water h a b i t a t . This w i l l supplement current information on the morphology of small stream channels and represents an attempt to v e r i f y statements such as presented by Pearse. The Queen Charlotte Islands are studied because they are considered t y p i c a l of a s u b s t a n t i a l portion of the west coast of B r i t i s h Columbia. The thesis presents a test of the usefulness of applying geomorphic techniques and r e s u l t s to the q u a n i t i f i c a t i o n of f i s h h a b i t a t . Further, comparison of stream channel morphology i n unlogged and logged watershed provides the basis upon which to develop preliminary guidelines regarding habitat impact m i t i g a t i o n and channel r e h a b i l i t a t i o n measures. The Queen Charlotte Islands are characterized by abundant salmon producing streams (Northcote, 1984), large areas of steep t e r r a i n - 4 -underlain by hig h l y e r o d i b l e bedrock ( A l l e y and Thomson, 1978), and several s o i l types which are prone to mass movement (Wilford and Schwab, 1982). The Islands have a predominantly wet climate (Williams, 1968) and frequent seismic a c t i v i t y (Sutherland Brown, 1968). There are l a r g e areas of valuable commercial timber which, f o r over h a l f a century, have made logging an important economic resource. The Fis h / F o r e s t r y I n t e r a c t i o n Program (FFIP) was i n i t i a t e d to assess and resolve c o n f l i c t s between the f i s h e r y and f o r e s t r y resource users i n the Queen Charlotte Islands. The channel morphology study i s a component of the FFIP and was conducted within the o v e r a l l study design ( P o u l i n , 1983). 1.2 Previous Studies Studies of modifications i n channel c h a r a c t e r i s t i c s r e s u l t i n g from a l t e r e d land use p r a c t i c e s include large v a r i a t i o n s i n both the time periods and s p a t i a l areas considered. The purpose of the following s e c t i o n i s to i d e n t i f y the appropriate study designs and channel v a r i a b l e s and to review several relevant s t u d i e s . 1.2.1 Study Designs and Channel Variables Although the morphology of an a l l u v i a l stream channel depends upon many v a r i a b l e s , the importance of each depending on the temporal scale of concern, i t i s p r i m a r i l y a function of the nature and quantity of water and sediment moving through the stream system (Schumm and L i c h t y , 1963). Of main i n t e r e s t i n land-use issues i s the period of - 5 -time during and shortly after the resource development project i s i n operation, usually ranging from years to decades. During this period land-use a c t i v i t i e s can influence runoff, surface erosion and h i l l s o p e mass movement events; a l l influence the supply of sediment to the stream and therefore morphology. Over longer time periods, on the order of hundreds of years, the nature and quantity of sediment and water i s influenced by geology, climate, vegetation and basin c h a r a c t e r i s t i c s . This has implications with respect to study designs. Over the short term, on the order of months, channel flow conditions depend upon morphology. The influence of logging and related a c t i v i t i e s on channel morphology can begin immediately with the onset of timber harvesting or can be delayed u n t i l several years after logging has ceased. Cross-stream f e l l i n g and in-stream yarding can lead to immediate modifications of the channel (Chamberlin, 1982a; Toews and Brownlee, 1981; Slaney et a l . , 1977) but changes w i l l also continue to occur as sediment i s delivered at higher than normal rates from the side slopes into the channel. While surface erosion from logged basins can increase r a p i d l y , i n some cases by 60% over i t s previous rate (Megahan and Kidd, 1972), and very large immediate increases can occur from haul roads (Reid, 1981; Reid and Dunne, 1984), the surface sediment production rate tends to decline quickly after the completion of logging (Reid, 1981; Reid et a l . , 1981; Hornbeck and Reinhart, 1964). Conversely, sediment quantities delivered to the stream by landslides often increase to a maximum between 3 and 6 years after logging as a result of root strength - 6 -l o s s (O'Loughlin, 1974; Wilford and Schwab, 1982). Due to the Immediate and longer term e f f e c t s , a study of channel changes due to logging would need to begin before logging, include the logging period and continue for at l e a s t f i v e to ten years a f t e r logging ended. The complete study would probably require a minimum of twenty years. Because t h i s length of study i s u s u a l l y not f e a s i b l e , a l t e r n a t i v e study designs are used. Over these shorter time periods several study designs are well suited to account for changes i n channel morphology. Two of the most common are the in t e n s i v e b e f o r e - a f t e r treatment design and the extensive post treatment design ( H a l l et a l . , 1978). The former involves the study of one, or a small number of watersheds before, during and a f t e r logging and comparing these to a c o n t r o l basin which has not been treated (e.g., Rodda, 1976; Hartman, 1982; H a l l and Lantz, 1968). Although the design provides the most complete record of absolute change, i t s main disadvantage i s that i t lacks g e n e r a l i t y ; r e s u l t s are not e a s i l y extended to other areas. The extensive post treatment design considers a large number of basins which have been grouped according to treatment h i s t o r y ; that i s , basins logged at d i f f e r e n t periods and with d i f f e r e n t techniques are substituted f or time. The main advantage of t h i s design i s that more g e n e r a l i t y i s gained and r e s u l t s can be more co n f i d e n t l y applied to other areas. The disadvantage i s the increased p r o b a b i l i t y of comparing areas which are d i s s i m i l a r with respect to geology and hydrology. Therefore, over time periods of years to decades, the morphology of an a l l u v i a l channel w i l l depend on the nature of sediment and water - 7 -moving through the stream system; the sediment supply to the channel depends p a r t i a l l y on land use p r a c t i c e s . The channel morphological response to changes i n sediment and water supply have been generalized by Schumm (1969) as follows: Q + = w+ d + F+ X + S -n+ » w+ d- F+ X+ S + P + s Q+ Q+ a w+ d + F+ X+ S± P~ s where Q = streamflow; Q s = bedload transport; w = width; d = depth; F = width - depth r a t i o ; X = meander wavelength; S = channel gradient; P = s i n u o s i t y ; + = increase d i r e c t i o n of change; - = decrease d i r e c t i o n of change. Due to the complex response of the dependent v a r i a b l e s (channel properties) to the changed independent v a r i a b l e s (sediment and water discharge) r e s u l t i n g from a l t e r e d land use p r a c t i c e s , only the d i r e c t i o n rather than the magnitude of the change can be predicted. Consideration of independent and dependent v a r i a b l e s leads to the p o s s i b i l i t y of studying the influence of logging and r e l a t e d a c t i v i t i e s on channel conditions by three d i f f e r e n t approaches. The f i r s t method examines the independent v a r i a b l e s of water and sediment discharge. The second method involves documentation of changes i n the dependent v a r i a b l e s , i n c l u d i n g channel width, depth and slope. The t h i r d method considers changes i n flow conditions i n the channel. Studies using these three approaches are discussed i n the following sub-sections. - 8 -1.2.2 Studies Concerned with Changes In Independent Var i ab le s An increase i n streamflow i s expected to lead to an increase i n channel width, depth, form r a t i o (width/depth r a t i o ) and meander wavelength and a decrease i n channel gradient (Schumm, 1969). Changes i n streamflow are a consequence of altered water i n f i l t r a t i o n and t r a n s p i r a t i o n rates within the logged watershed (Chamberlin, 1982a). Many previous studies of modified streamflow indicate that water y i e l d s increase, p a r t i c u l a r l y during the autumn and winter. (Rothacher, 1970; Harr, 1976), but a minimum of 20% to 40% of the forest cover must be removed before these changes i n streamflow can be detected (Rothacher, 1970, 1971; Bosch and Hewlett, 1982). Documented changes in peak flows are inconclusive (see Roberts, 1984 for a review). Peak flow c h a r a c t e r i s t i c s appear to be affected i n watersheds where roads cover more than 12% of the drainage basin (Harr et a l . , 1975, 1979). High peak flows may d e s t a b i l i z e stream banks (Anderson et a l . , 1976) leading to channel widening. High flows may influence the magnitude and frequency of sediment transporting events (Anderson et a l . , 1976) and lead to changes i n both the a v a i l a b i l i t y and composition of sediment i n the stream (Rice, 1981; Lyons and Beschta, 1983; Toews and Moore, 1982b) . An increase i n bedload transport i s expected to produce an increase i n width, form r a t i o s , meander wavelength, slope and si n u o s i t y and a decrease i n depth. Although studies have been conducted i n an attempt to document the changes i n bedload discharge due to timber harvest, r e s u l t s have been of l i m i t e d value. This i s due mainly to - 9 -problems inherent i n bedload sampling and d i f f i c u l t i e s i n maintaining c o n t r o l watersheds. In a 5 year study of several c l e a r cut logged Northwestern C a l i f o r n i a watersheds, Nolan and Janda (1981, p. 420) stated that "measurements" of bedload transport using the Helley-Smith sampler were made . . . but have not been used . . . because the frequency and v a r i a b i l i t y of movement r e s u l t In a small, hard-to-i n t e r p r e t data s e t " . Several years of bedload sampling at Carnation Creek on Vancouver Island have produced no useable data (B. Tassone, pers. comm., 1982). Evaluation of independent v a r i a b l e s i s , therefore, problematic because study programs must be continued over long periods of time. Examination of the dependent v a r i a b l e s i s a more d i r e c t approach to assessing the influence of logging and r e l a t e d a c t i v i t i e s on channel morphology. 1.2.3 Studies Concerned w i th Changes In Dependent V a r i a b l e s I f timber harvesting causes an increase i n both water and sediment discharge then i t i s expected that channel width, form r a t i o and meander wavelength w i l l increase, and channel depth and gradient w i l l remain approximately constant; i f s i n u o s i t y decreases the gradient should increase (Schumm, 1969). Many previous studies i n d i c a t e that an increase i n sediment leads to channel widening by l a t e r a l channel migration and bank erosion (Madej, 1978; 1982; Kelsey, 1980;Bourgeois, 1981; L i s l e , 1981; Lyons and Beschta, 1983) and channel aggradation (Narver, 1972; L i s l e , 1982; Toews and Moore, 1982b). Logging p r a c t i c e s - 10 -can have a d i r e c t influence on channel widening and aggradation by disturbing bank i n t e g r i t y during f e l l i n g and yarding and by increasing erosion around channel debris (Narver, 1972; Bryant, 1980; Bourgeois, 1981; Chamberlin, 1982a; Toews and Moore, 1982b). Changes i n channel width-depth r a t i o s depend p a r t i a l l y upon the type of material transported by the stream; coarser material tends to be associated with larger width-depth r a t i o s (Schumn, 1977). The change i n the r a t i o values w i l l depend on the composition of introduced sediment and on the texture of channel bed and bank material. In terms of f i s h habitat, the increased width-depth r a t i o can have diverse impacts. In some cases an increase may be b e n e f i c i a l because a wider area of more suitable flow depth i s available for f i s h use. Conversely, an increase may be detrimental because of a reduction i n channel area characterized by suitable flow depths. Therefore, a change i n width-depth r a t i o does not necess a r i l y imply change i n habitat q u a l i t y or quantity. Meander wavelength i s expected to increase i n response to sediment and water increases. Because the p o o l - r i f f l e sequence i s a primary feature i n the development of a meandering pattern (Leopold et a l . , 1964), i t i s anticipated that the spacing of pools and r i f f l e s should increase s i m i l a r l y i n response to longer meander wavelengths. The unusually consistent average spacing of one pool and r i f f l e sequence for every 5 to 7 bankfull widths, documented for a wide range of geographic settings (Leopold et a l . , 1964) and shown to be independent of channel pattern ( K e l l e r and Melhorn, 1973) and channel material ( K e l l e r and Melhorn, 1978) tends to support.the contention that pool and - 11 -r i f f l e lengths are adjusted to channel width and meander wavelength. This suggests that the length of a p o o l - r i f f l e sequence should adjust, that i s , increase so that spacing, i n standardized units of channel b a n k f u l l widths, does not change s i g n i f i c a n t l y . Church and Jones (1982) i d e n t i f y the fundamental channel morphology unit as a p o o l - r i f f l e - b a r sequence. They i n d i c a t e that the bar represents the major storage place for t r a c t i o n load sediments which are moved s p o r a d i c a l l y at high flows and suggest that as sediment loads increase the bar component w i l l become l a r g e r and may advance in t o the next pool to bury the proximal end of the downstream r i f f l e . This implies that the actual spacing of pool and r i f f l e sequences, disregarding standardization by b a n k f u l l width, w i l l be a l t e r e d by increases i n sediment loads. In terms of f i s h h a b i t a t , the proportional change i n pool or r i f f l e component Is important. L i s l e (1982), working i n c o a s t a l C a l i f o r n i a , confirmed that pools become more r i f f l e - l i k e i n response to increased sediment loading from l a n d s l i d e s . In the same area, Kelsey (1980) documented a reduction i n p o o l - r i f f l e spacing. These observations apparently i n d i c a t e a net l o s s i n pool area and hence, i n over-wintering and rearing h a b i t a t . Very l i t t l e work has addressed the change i n pool and r i f f l e c h a r a c t e r i s t i c s (spacing, proportion, shape) r e s u l t i n g from logging and r e l a t e d a c t i v i t i e s . Since pool, r i f f l e , and bar c h a r a c t e r i s t i c s e x h i b i t regular patterns, and because they respond to changing sediment loads, they are well suited fo r study. Pool, r i f f l e , and bar c h a r a c t e r i s t i c s of streams i n logged areas may be compared with those i n unlogged conditions or with the - 12 -gen e r a l l y quoted average values. One study which does consider the spacing of pool and r i f f l e sequences i n logged and unlogged watersheds i s reported by K e l l e r et a l . (1981). This study, which was c a r r i e d out i n old growth redwood f o r e s t s i n c o a s t a l C a l i f o r n i a , i s of i n t e r e s t because i t considers the influence of large organic debris on p o o l - r i f f l e spacing. Large organic debris (LOD) i s defined as a l l trees, logs, root wads and branches greater than 0.1 m i n diameter. Their r e s u l t s i n d i c a t e that on average, spacing i s equal to 6 widths i n a channel which has minimal in-stream LOD. In channels with abundant woody debris, the spacing averages 4 widths i n unlogged basins and 3y widths i n logged basins. In these h e a v i l y forested channels, pool and r i f f l e spacing appears to depend l a r g e l y on in-stream woody m a t e r i a l . The abundance and character of the instream woody material w i l l depend to a large extent on the logging-h i s t o r y of the watershed. In unlogged watersheds, in-stream woody material becomes an independent v a r i a b l e c o n t r o l l i n g morphology over time periods equal to the residence times of the d e b r i s . The residence period can exceed 200 years for some tree types ( K e l l e r and Swanson, 1979). The b i o p h y s i c a l importance of large organic debris to stream channel morphology has received considerable a t t e n t i o n . Studies have dealt with the influence of LOD on flow v e l o c i t i e s and on the l o c a l i z e d d i s s i p a t i o n of p o t e n t i a l energy at log steps (Heede, 1972; Marston, 1982) which r e s u l t s i n reduced channel erosion, d i f f e r e n t i a l movement and storage of c l a s t i c sediment (Swanson and Lienkaemper, 1978; Megahan - 13 -and Nowlin, 1976; Mosley, 1982). The delivery of woody debris to the channel zone has been shown to depend upon drainage basin conditions. Organic debris input should r e s u l t from slope processes i n smaller streams, while i n higher order streams (orders greater than three) input should be favoured by bank erosion and f l o t a t i o n of material from upstream (Swanson et a l . , 1976; K e l l e r and Swanson, 1979). Stream size also influences the storage and output of LOD. In larger streams the woody material i s more frequently moved during flood flows and log jams tend to be more prevalent downstream. The di r e c t influence of LOD on channel form has been discussed by K e l l e r and T a l l y (1979), K e l l e r and Swanson (1979), K e l l e r et a l . (1981) and Toews and Moore (1982a). Findings suggest that woody debris contributes s i g n i f i c a n t l y to l o c a l channel gradient and bed topography. Hence, streams with abundant in-stream woody material exhibit more variable channel depths and widths because of bed scour, bank erosion and deposition of gravel bars. The b i o l o g i c a l c h a r a c t e r i s t i c s of large woody debris studied i n the past include salmonid preferences for s p e c i f i c habitat types (Bisson et a l . , 1982; Bustard and Narver, 1975) and the role of organic debris on salmonid f r y production and populations (Hall and Baker, 1975). The influence of streamside logging a c t i v i t i e s on the character of LOD has been studied by Meehan et a l . (1969) and Swanson et a l . , (1981). Toews and Moore (1982b) have considered the impact of a range of streamside logging techniques on channel morphology. Generally, th e i r findings indicate that certain streamside timber harvesting a c t i v i t i e s lead to less stable in-stream material. In addition, a s h i f t occurs i n the - 14 -debris s i z e d i s t r i b u t i o n towards a higher frequency of small pieces which are le s s e f f e c t i v e i n terms of trapping and s t o r i n g sediment. Large organic debris acts as a buffer to bedload transport by providing r e l a t i v e l y l a r g e , frequent storage s i t e s f o r sediment. LOD 3 storage accounts for between 0.3 m of sediment per 30 m of channel i n 3 some small cobble-bed New Zealand streams (Mosley, 1981) and 6.0 m /30 m of channel i n the Coast Range of Oregon (Swanston et a l . , 1982). Stored 3 volumes can reach approximately 52 m /30m of channel i n areas with high rates of h i l l s l o p e erosion ( P i t l i c k , 1982). It i s apparent that large organic debris exerts s i g n i f i c a n t c o n t r o l over channel morphology. Also, the input, storage and output of LOD i s influenced strongly by c e r t a i n logging p r a c t i c e s . Therefore, i f LOD c h a r a c t e r i s t i c s i n unlogged channels can be documented, these can be used as a basis f or evaluating changes due to logging. Hence, LOD represents a useful i n d i c a t o r of the impact of logging a c t i v i t i e s on channel morphology. Further study i s required to document more completely the large organic debris c h a r a c t e r i s t i c s i n both unlogged and logged watersheds. In summary, logging and re l a t e d a c t i v i t i e s appear to a l t e r sediment t r a n s f e r , large organic debris and channel flow character-i s t i c s . In turn, t h i s d i r e c t l y influences channel morphology as evident i n a l t e r e d p o o l - r i f f l e sequence spacing, channel width, depth and gradient. - 15. -1.2.4 Studies of Flow Condi t ions and Hab i ta t As opposed to observing changes i n i n d i v i d u a l channel morphological properties, many previous studies have considered the d i f f e r e n c e i n channel flow c h a r a c t e r i s t i c s i n streams before and a f t e r land use changes. The most s o p h i s t i c a t e d technique i s the In-Stream Flow Group method (see Orsborn and Allman, 1976; Bovee and Milhous, 1978; Trihey and Wagner, 1981). However, t h i s technique i s not s u i t e d to a p p l i c a t i o n s concerning timber harvesting impacts. The technique used most often to assess changes i n composite channel conditions i n t h i s case i s the habitat inventory as presented by DeLeeuw (1981) and Toews and Brownlee (1981). This involves c o l l e c t i o n of f i e l d data from designated stream reaches. These data include a wide array of p h y s i c a l c h a r a c t e r i s t i c s , ranging from channel width to v i s u a l estimates of t u r b i d i t y , streambed substrate and flow v e l o c i t y . Measurements and v i s u a l observations are obtained within s p e c i f i c 'hydraulic types' which include pools, r i f f l e s , g l i d e s , chutes and back channels. The s i t e s p e c i f i c f i e l d data are extrapolated to the e n t i r e reach, stream and drainage basin. The compiled information i s then used to compare d i f f e r e n t stream systems. Several problems are inherent i n t h i s technique. In most cases habitat inventories are compiled without reference to s p e c i f i c streamflow stage ( u s u a l l y a q u a l i t a t i v e r a t i n g of low, moderate or high stage i s assigned to each survey). Both the amount and proportion of the primary habitat u n i t s (pools and r i f f l e s ) vary with flow stage; pools are drowned at high flows ( L i s l e , 1982; Leopold et a l . , 1964) - 16 -so that they more c l o s e l y resemble r i f f l e s . Therefore comparisons over time and between streams are tenuous. Even the d e l i n e a t i o n of the primary habitat components appears to s u f f e r from i n c o n s i s t e n t f i e l d i d e n t i f i c a t i o n . For example, i t i s not cl e a r i n most inventories which c r i t e r i a , whether morphologic-topographic, sedimentologic or hy d r a u l i c , are used to d i s t i n g u i s h between pools, r i f f l e s , chutes, g l i d e s , and runs. Topographic d e l i n e a t i o n may be used at low flow but hyd r a u l i c c r i t e r i a may be used instead at higher flows when the bedforms are obscured. 1.2.5 Summary Most previous studies of channel change i n r e l a t i o n to logging a c t i v i t i e s have concentrated on measurements of sediment transport and changes i n c r o s s - s e c t i o n a l and l o n g i t u d i n a l p r o f i l e s . Studies u s u a l l y included e i t h e r periods before and a f t e r logging or considered d i f f e r e n t areas, each with a d i f f e r e n t logging h i s t o r y . Studies of sediment transport changes are d i f f i c u l t . Although changes i n i n d i v i d u a l dependent v a r i a b l e s , such as channel width, depth and slope can be examined, they i n d i c a t e l i t t l e about actual changes i n useable f i s h h a b i t a t . Therefore, a better approach appears to be a study of the composite nature of the channel, i n c l u d i n g a consideration of streamflow stage. The pool, r i f f l e , and bar sequence co n s t i t u t e s the fundamental un i t of channel morphology, r e f l e c t i n g conditions during high flows. The close examination of t h e i r s p a t i a l organization should be productive i n terms of d i s t i n g u i s h i n g the influence of logging and r e l a t e d - 17 -a c t i v i t i e s . Because s p e c i f i c p o o l - r i f f l e c h a r a c t e r i s t i c s are strongly c o r r e l a t e d with channel and watershed properties, general r e s u l t s may be obtained. Large organic debris must also be considered because i t exerts considerable c o n t r o l over channel features and can be a l t e r e d s u b s t a n t i a l l y by logging and r e l a t e d a c t i v i t i e s . Documentation of p o o l - r i f f l e and large organic debris c h a r a c t e r i s t i c s i n unlogged and logged watershed channels c o n s t i t u t e s the i n i t i a l step i n designing habitat impact m i t i g a t i o n and r e h a b i l i t a t i o n techniques. With the exception of spacing lengths, there has been very l i t t l e work concerned with pool and r i f f l e proportions, shapes and v e r t i c a l dimensions. Also, to-date minimal information regarding the actual placement of LOD i s a v a i l a b l e . Study of these features may provide useful design requirements for channels disturbed by logging and other events. 1.3 Study Objectives The present study considers the morphology of stream channels i n logged and unlogged watersheds. The c h a r a c t e r i s t i c s of s p e c i f i c i n t e r e s t include c l a s t i c sediment and organic debris arrangement within the channel zone and flow conditions within f i s h habitat areas. The l i m i t e d time a v a i l a b l e for study necessitates the comparison of stream reach p a i r s , each with s i m i l a r b i o p h y s i c a l conditions but d i f f e r e n t land use p r a c t i c e s . Studies of channel morphology as a function of streamflow stage are undertaken to integrate the various c r i t e r i a upon which habitat - 18 -elements are delineated. This also allows evaluation of the v a r i a b i l i t y of inventory schemes which do not incorporate streamflow stage. Assessment of the within reach v a r i a b i l i t y i s undertaken i n order to determine whether the frequently conducted habitat inventories are s u f f i c i e n t l y s e n s i t i v e to unequivocally i d e n t i f y logging induced impacts on channel morphology. The study objectives are as follows: 1. To i n v e s t i g a t e and compare the channel morphology of several logged and unlogged watersheds i n the Queen Charlotte Islands by use of appropriately paired reaches. 2. To integrate morphology with salmonid fresh water habitat assessments at d i f f e r e n t streamflow stages. 3. To e s t a b l i s h appropriate channel s t a b i l i z a t i o n (habitat r e h a b i l i t a t i o n ) c r i t e r i a . - 19 -2.0 STUDY DESIGN AND DESCRIPTION OF THE STUDY AREAS 2.1 Study Design This study adopts a paired watershed design, as depicted i n Figure 2.1. In thi s idealized case Basin A constitutes the closest approximation to a control watershed available within the available study period. Measurements of channel morphology acquired i n such a basin are used to characterize the normal f l u v i a l environment of the study area. I f the entire basin Is homogeneous with respect to biophysical conditions (climate, geology, vegetation and sub-basin morphometry, as outlined by Rodda, 1976), then morphological measurements obtained for sub-basin stream A i should be si m i l a r to those for sub-basin A£. The within reach variance determines whether between reach comparisons are v a l i d . Basin B (Figure 2.1) represents a case study of channel morphology i n logged and unlogged watersheds. I f A^ and A2 are s i m i l a r , and biophysical conditions i n sub-basins 3\ and B2 are s i m i l a r , i t i s assumed that the channel morphology of streams i n B^ and B 2 would be comparable i f sub-basin B2 had not been logged. Hence, i f a measured difference exists between B^ and B2, i t i s assumed to be a resul t of logging and related a c t i v i t i e s . In practice i t i s d i f f i c u l t to locate a watershed with only one of two sim i l a r t r i b u t a r i e s logged. In thi s case the channel c h a r a c t e r i s t i c s of streams i n Basin B can be compared with Ai and A2 as long as si m i l a r biophysical basin conditions e x i s t . The Queen Charlotte Islands watersheds selected for t h i s - 20 -BASIN A "NORMAL" FLUVIAL GEOMORPHOLOGY BASIN B LAND USE STUDIES DRAINAGE DIVIDE " > STREAM CHANNEL UNLOGGED A \ \ \ \ L 0 G G E D ASSESS WITHIN REACH VARIABILITY CHARACTERIZE NATURAL STREAM MORPHOLOGY ANALYSIS IS A, = A 2? YES ASSESS BETWEEN REACH VARIABILITY CHARACTERIZE LOGGED BASIN STREAM MORPHOLOGY ANALYSIS IS B,= B 2? NO NO CONCLUSIONS YES FIGURE 2.1: STUDY DESIGN USING PAIRED WATERSHEDS. - 21 -comparative study are deta i l e d i n Section 2.2. Within these study watersheds smaller areas (sub-basins) were part i t i o n e d for the purpose of conducting studies of r e l a t i v e l y long segments of the stream (channel scale s t u d i e s ) . The biophysical conditions of each sub-basin are characterized i n Section 2.3. Also, within each sub-basin a short section of channel was selected for deta i l e d morphological studies (reach scale s t u d i e s ) . These areas are considered i n Section 2.3. A summary of a l l basin, channel and reach scale study areas i s presented i n Section 2.4 (Table 2.6). 2.1.1 Problems Assoc iated with Pa i red Watershed Designs The success of a l l paired watershed studies depends c l e a r l y upon the biophysical s i m i l a r i t y of the drainage basins to be compared. However, because no two watersheds are i d e n t i c a l i n a l l aspects, i t i s necessary to accept a c e r t a i n degree of d i s s i m i l a r i t y . Problems a r i s e when trying to decide which factors are the most important to the study and p a r t i c u l a r l y when attempting to determine an acceptable degree of s i m i l a r i t y . It i s the usual convention to evaluate s i m i l a r i t y based upon a l i m i t e d number of general f a c t o r s . For instance, geological s i m i l a r i t y i s often determined from maps surveyed at a smaller scale than that of the paired watershed study and s u r f i c i a l materials are not always assessed. Also, drainage basin area i s commonly the only morphometric parameter considered. Although the use of rather general categories Is usually a r e s u l t of a l i m i t e d data base there are several other useful parameters r e a d i l y obtained from standard topographic - 22 -maps and a i r photographs. These include a wide range of morphometric i n d i c i e s d e p i c t i n g basin slopes, nature of the v a l l e y bottom and drainage network composition. In the present study i t i s accepted that some degree of d i s s i m i l a r i t y e x i s t s between the comparison basins. A c r i t i c a l review of several b i o p h y s i c a l c h a r a c t e r i s t i c s and an evaluation of the s i m i l a r i t y of basins to be compared i s presented i n Section 2.2, 2.3 and Appendix B. 2.1.2 Statistical Procedures In t h i s report i n f e r e n t i a l s t a t i s t i c s are used i n two s i t u a t i o n s : f i r s t l y , to determine i f a s i g n i f i c a n t d i f f e r e n c e e x i s t s between watersheds (watershed comparability) and secondly, to determine i f a s i g n i f i c a n t d i f f e r e n c e e x i s t s i n channel morphology between streams ( e f f e c t of land-use p r a c t i c e s ) . The f i r s t s i t u a t i o n i s intended to ensure that basins are comparable with repect to several b i o p h y s i c a l c o n d i t i o n s . Here one i s more w i l l i n g to accept a type 1 e r r o r , hence a confidence l i m i t of 90% appears reasonable. However, i n the second s i t u a t i o n , where conclusions r e f e r to land-use p r a c t i c e s , a type 1 error i s l e s s acceptable and a more stringent confidence l e v e l i s warranted. In t h i s case a confidence l i m i t of 99% appears appropriate and hence, i s used i n t h i s study. 2.2 Study Watersheds In accordance with the study design, the study watersheds to be compared require s i m i l a r b i o p h y s i c a l conditions. These include geology, - 23 -basin morphometry, climate, s o i l s and vegetation. In t h i s section the selected watersheds are discussed i n terms of thei r location and biophysical conditions. 2.2.1 General Description of Study Watersheds Three watersheds were selected for study. They are Government Creek, Mosquito Creek and Bonanza Creek (Figure 2.2). Two watersheds are within the Queen Charlotte Ranges physiographic unit (Figure 2.2) and the l a t t e r i s within the Skidegate Plateau unit near the boundary of the Queen Charlotte Ranges. Government Creek flows northwest into Skidegate Channel. Mosquito Creek flows northeast and jo i n s Pallant Creek, which then flows into G i l l a t t Arm. Bonanza Creek watershed i s located on Graham Island. The creek flows southwest to i t s confluence with Hangover Creek, entering from the northwest, and continues westward into Rennell Sound. 2.2.2 Geology The general geology of the Queen Charlotte Islands has been discussed thoroughly by Sutherland Brown (1968). The Quaternary geology, i n p a r t i c u l a r studies dealing with sea-level adjustments and stratigraphy, has been detailed by Clague et a l . (1982a, 1982b) Mathewes and Clague (1982). Geomorphic processes associated with s p e c i f i c geological units have been considered by A l l e y and Thompson (1979) and tectonic a c t i v i t y has been inventoried by Milne et a l . , (1978). For the purposes of the present paper, discussion of geology i s r e s t r i c t e d to - 24 -FIGURE 2.2: STUDY WATERSHEDS ON THE QUEEN CHARLOTTE ISLANDS. - 25 -those topics important i n s e l e c t i n g comparable watersheds, s p e c i f i c a l l y bedrock geology and s u r f i c i a l m a t e r i a l . Bedrock geology of the unlogged-logged watershed p a i r of Hangover and Bonanza Creeks c o n s i s t s p r i m a r i l y of the v o l c a n i c Masset Formation of Paleocene age. Dark-brown to black aphanitic basalt i s the most abundant l i t h o l o g y (Sutherland Brown, 1968). This rock material i s often deeply weathered, e a s i l y eroded and highly susceptible to mass movements ( A l l e y and Thompson, 1978; Wilford and Schwab, 1982; Schwab, 1983). The s u r f i c i a l materials of the Hangover and Bonanza watersheds have been mapped at 1:15,000 scale by P e r i l Geotechnic Services (1979). Steep side v a l l e y slopes and headwater areas are characterized by c o l l u v i a l veneers and blankets ( l e s s than 1 m and greater than 1 m thickness r e s p e c t i v e l y ) and bedrock outcrops. Mid-slope and v a l l e y side l o c a t i o n s e x h i b i t both c o l l u v i a l and morainal veneers and blankets. In the f l a t v a l l e y bottoms f l u v i a l blankets and morainal veneers are more abundant. At elevations of le s s than 15 m, estuarine muds and l i t t o r a l sands are prevalent ( A l l e y and Thompson, 1978). Sutherland Brown (1968) mapped both the Government and Mosquito Creek v a l l e y bottoms as Quaternary deposits c o n s i s t i n g of recent alluvium, Pleistocene t i l l , marine d r i f t and outwash sands. In Government Creek these deposits o v e r l i e the Kunga Formation, at lower e l e v a t i o n s , and the Karmutsen Formation, at higher e l e v a t i o n s , i n the watershed. The former i s a sedimentary u n i t of Mesozoic age and c o n s i s t s of massive grey limestone, black limestone and black - 26 -a r g i l l i t e . Quaternary deposits i n Mosquito Creek, o v e r l i e the Karmutsen Formation. This formation i s exposed at elevations above about 60 m i n both watersheds. In Mosquito Creek watershed, c o l l u v i a l veneers and exposed bedrock are abundant on steeper side slopes, c o l l u v i a l and morainal veneers and blankets are prevalent i n mid slope areas and deep f l u v i a l blankets with minor pockets of l a c u s t r i n e s i l t s c h a r a c t e r i z e v a l l e y bottom areas (Lewis, 1982). S u r f i c i a l m a t erial mapping of the Government Creek watershed has not been undertaken. 2.2.3 Hydrometeorology  Climate The Queen Charlotte Islands are characterized by a humid, temperate climate with mild winters and cool summers. Working with only ten Atmospheric Environment Service (AES) s t a t i o n s , Williams (1968) presented a r e l a t i v e l y thorough review bf climate patterns on the Queen Charlotte Islands. S p a t i a l patterns of p r e c i p i t a t i o n are considered i n the present paper; the reader i s r e f e r r e d to Williams (1968) f o r review of other climate parameters and Karanka (1984) f o r an assessment of long term temporal v a r i a b i l i t y . Because p r e c i p i t a t i o n influences runoff, which i n turn determines channel s i z e , i t i s important to compare logged and unlogged channels i n regions of homogeneous p r e c i p i t a t i o n . The AES operates eight f i r s t c l a s s weather stat i o n s i n the Islands. These s t a t i o n s are not well d i s t r i b u t e d , with only one s t a t i o n (Tasu) located on the west coast. This makes the d e l i n e a t i o n of zones with homogeneous p r e c i p i t a t i o n amounts d i f f i c u l t . AES records i n d i c a t e - 27 -that mean annual p r e c i p i t a t i o n v a r i e s from approximately 1,200 mm on the east coast of Graham Island to over 4,200 ram on the west coast. Williams (1968) considered a short record from Tasu (18 months) and long term records from other co a s t a l s t a t i o n s , assessed orographic e f f e c t s , and concluded that some lo c a t i o n s on the west coast w i l l receive 7,600 mm of p r e c i p i t a t i o n on average each year. Snowfall amounts are i n s i g n i f i c a n t when compared to average r a i n f a l l amounts, accounting for j u s t over 1 percent of the average annual p r e c i p i t a t i o n at Cape St. James and Tasu, and about 5 percent at other s t a t i o n s (Williams, 1968). To supplement the AES records, the p r o v i n c i a l M i n i s t r y of Environment, A i r Studies Branch (ASB) i n s t a l l e d 55 weather stat i o n s on the Islands i n 1978 ( M i n i s t r y of Environment, 1980). By regression a n a l y s i s , short term ASB p r e c i p i t a t i o n records were used to simulate 1951 - 1980 p r e c i p i t a t i o n normals (unpublished data, M i n i s t r y of Environment, 1983). Mean monthly records f o r 8 AES and 27 ASB s t a t i o n s were used to develop zones of homogeneous p r e c i p i t a t i o n . A d e t a i l e d d i s c u s s i o n of t h i s work i s contained i n Appendix A; r e s u l t s are summarized here. The geographical pattern of p r e c i p i t a t i o n i s shown i n Figure 2.3. The annual p r e c i p i t a t i o n ranges f o r each zone r e f e r to the 95% confidence l i m i t s . Note that the zones include st a t i o n s with mean annual t o t a l s higher than the range l i m i t s (compare Tasu value i n Appendix Figure A . l and Figure 2.3): that i s , the zones do not uniquely d e l i m i t the p r e c i p i t a t i o n at every point within them. Because the zones are based on r e l a t i v e l y few values (34 s t a t i o n s spaced unevenly over the 9,940 km^ - 28 -FIGURE 2.3: SPATIAL VARIATION OF PRECIPITATION ON THE QUEEN CHARLOTTE ISLANDS. - 29 -area comprising the Queen Charlotte I s l a n d s ) , the exact boundary of each region i s hard to determine. The delimited zones correspond well with re g i o n a l physiography ( c f . , Figures 2.2 and 2.3). In comparing Figures 2.2 and 2.3, i t appears that the Government and Mosquito Creek watersheds and Hangover and Bonanza Creek watersheds have homogeneous p r e c i p i t a t i o n regimes. To provide an a d d i t i o n a l check on p r e c i p i t a t i o n s i m i l a r i t y between watersheds, a regression model incorporating geographic l o c a t i o n (longitude and l a t i t u d e ) , e l e v a t i o n (varying from 3 m to 468 m above sea l e v e l ) and s t a t i o n aspect was developed. When a l l stat i o n s are combined (n = 35) the best r e l a t i o n i s : Y = 1342.341 X! - 1327.320 X 2 - 104449.480 where X i = longitude, i n degrees X2 = l a t i t u d e , i n degrees Y => mean annual p r e c i p i t a t i o n , i n mm. This r e l a t i o n accounts for 44% of the v a r i a t i o n i n p r e c i p i t a t i o n ( s i g n i f i c a n t at a = 0.10, df = 32). The model i n d i c a t e s that p r e c i p i t a t i o n i s s i m i l a r i n the paired watersheds and that a d i f f e r e n c e of l e s s than 100 mm per year e x i s t s between a l l paired study watersheds. I t should be noted that a major problem i n ext r a p o l a t i n g patterns of point r a i n f a l l to i n f e r homogeneity of watersheds i s evaluating the e f f e c t of r e l i e f . To minimize the e f f e c t , the compared watersheds should have s i m i l a r basin topographic c h a r a c t e r i s t i c s ( t h i s - 30 -i s considered i n Sections 2.2.5 and 2.3.1). Runoff There are only three long term runoff records (longer than ten years) a v a i l a b l e for the Queen Charlotte Islands. The s p a t i a l and temporal c h a r a c t e r i s t i c s of these records are discussed i n Appendix A.2. B r i e f l y , by comparing actual runoff with the appropriate p r e c i p i t a t i o n zone (Appendix Figure A.5) i t can be shown that a high c o r r e l a t i o n e x i s t s between p r e c i p i t a t i o n and runoff. This suggests that, i n the absence of more complete runoff records, i t i s appropriate to s e l e c t comparable watersheds based on p r e c i p i t a t i o n alone. Review of the runoff records also i n d i c a t e s the importance of drainage basin morphometry i n s e l e c t i n g comparable basins. 2.2.4 S o i l s and Vegetation A complete s o i l survey has not been conducted on the Queen Charlotte Islands. Preliminary r e s u l t s by Smith et a l . (1983) i n d i c a t e that the s o i l s i n several of the study watersheds are predominantly Orthic or Gleyed Ferro-Humic Podzols and l e s s abundantly, Orthic and Gleyed Humo-Ferric Podzols. S o i l s i n areas disturbed by mass-wastage events are characterized by Orthic D y s t r i c B r u n i s o l s , Orthic Regosols and l e s s frequently, Gleyed and Orthic Ferro-Humic Podzols. In the absence of d e t a i l e d s o i l studies i t i s not possible to comment on the pedologic s i m i l a r i t y between study watersheds. Since c h a r a c t e r i s t i c s o i l s w i l l develop on s p e c i f i c parent material types and i n response to - 31 -c l i m a t i c influence there should be no s u b s t a n t i a l d i f f e r e n c e s i n s o i l s between paired study basins. The Mosquito Creek watershed l i e s within the Coastal Western Hemlock biogeoclimatic zone (Banner et a l . , 1983). The commercial tree stands at lower elevations are composed of western hemlock (Tsuga  h e t e r o p h y l l a ) , S i t k a Spruce (Picea s i t c h e n s i s ) , western red cedar (Thuja p l i c a t a ) and Alaska yellow cedar (Chamaecyparis nootkatensis) (Carr, 1983). Mountain hemlock (Tsuga mertensiana) i s present at higher elevations (Banner et a l . , 1983). The Government and Bonanza Creek watersheds l i e within the Coastal Cedar-Pine-Hemlock zone which, i n a d d i t i o n to hemlocks and cedars, supports shore pine (Pinus contorta var contorta) (Banner et a l . , 1983). A f t e r logging, the lower slopes follow a vegetation succession trend which includes, predominantly, red alder (Alnus rubra) for the f i r s t 20 years, then a thinning of the alders followed by an increase i n spruce and hemlock u n t i l about 60 years (Smith et a l . , 1983). D e t e r i o r a t i o n of the alder overstory occurs by 70 years and then a predominance of spruce and hemlock i s maintained for several centuries (Smith et a l . , 1983). Vegetation i n areas of s i m i l a r parent m a t e r i a l , t e r r a i n , climate and logging h i s t o r y should be s i m i l a r . 2.2.5 Basin Morphometry Stream channel c h a r a c t e r i s t i c s are c o n t r o l l e d p a r t i a l l y by fa c t o r s r e l a t i n g to basin shape. For instance, r e l i e f , v a l l e y side slope angle and extent of f l a t v a l l e y bottom w i l l determine whether the - 32 -sediment mobilized at higher elevations i s d e l i v e r e d d i r e c t l y to the channel. Further, the physiography and the complexity of the drainage network both influence the amount and timing of runoff. In turn, runoff c h a r a c t e r i s t i c s w i l l i nfluence the t r a n s f e r of sediment through the stream system and subsequently, the channel morphology. Therefore, i n a comparative study of stream c h a r a c t e r i s t i c s , basin morphometry must be examined. Morphometry of the study watersheds i s presented i n two p a r t s . F i r s t , properties of the main basins (Bonanza, Mosquito and Government) w i l l be examined i n t h e i r e n t i r e t y . Second, pr o p e r t i e s of basin sub-d i v i s i o n s (areas upstream of the d e t a i l e d study reaches) w i l l be discussed. The l a t t e r are presented i n Section 2.3.1. A d e t a i l e d d e s c r i p t i o n of methods, mate r i a l s and op e r a t i o n a l rules used i n morphometric a n a l y s i s , and complete r e s u l t s , are presented i n Appendix B. A summary comparison of basin c h a r a c t e r i s t i c s i s presented i n Table 2.1. Of the three po s s i b l e combinations of p a i r s , the Government and Mosquito Creek watershed p a i r i s the most important because Bonanza i s subdivided and then comparisons are made between the sub-basins (Section 2.3.1). The three combinations are presented here for completeness. To t a l drainage basin areas, mainstream lengths and stream orders are s i m i l a r for Government and Mosquito Creeks (Table 2.1). The r e l i e f of the Mosquito Creek watershed i s approximately twice that of Government and the l o n g i t u d i n a l p r o f i l e concavity i s 50 percent greater fo r the former. This i n d i c a t e s that although there are some morphometric d i f f e r e n c e s between the Government and Mosquito Creek - 33 -table 2.1 Watershed c h a r a c t e r i s t i c s of selected Queen Charlotte Island streams, a) General watershed c h a r a c t e r i s t i c s WATERSHEDS Government Creek (Gov't) Mosquito Creek (Mosq) Bonanza Creek (Bonz) Total Area (km ) Absolute Relief (m) Stream Length (malnstem, km) Stream Order 2 Geology Longitudinal P r o f i l e Concavity Land Use 16.2 520 5.1 4 Recent Alluvium T r i a s s i c Basalt 0.6067 Unlogged 17.3 1,110 6.4 4 Recent Alluvium T r i a s s i c Basalt 0.9146 Logged 88.5 730 16.0 5 Paleocene Basalt 0.7273 Unlogged & Logged b) Comparisons of basin c h a r a c t e r i s t i c s : Ratios of selected dimensionless numbers. li n e a r scale features and Watershed Pairs Linear Scale R a t i o s 3 Dimensionless Number Ratios'* L2 D R R b • C L S h HI S1 Main Basins Bonz/Mosq 1." 12 Gov't/Bonz 0.76 Gov't/Mosq 1.18 1.05 0.88 0.92 1.53 1.38 0.56 0.61 0.44 0.84 0.80 1.31 0.83 0.39 0.66 0.51 1.35 0.67 0.86 0.79 0.85 0.79 Notes: *From Sutherland-Brown (1968) - prominent rock type Strahler ordering based on 1:15,000-1:20,000 topographic maps and a i r photographs Linear scale r a t i o s include: Dimensionless number r a t i o s include: L 2 " mean length of second order streams R D " geometric b i f u r c a t i o n r a t i o D - drainage density C L " longitudinal profile, concavity R - mean basin elevation S n • geometric shape factor HI - hypsometric i n t e g r a l S1 " Mean slope - 34 -watersheds, they are r e l a t i v e l y s i m i l a r i n many respects and, therefore constitute a matching p a i r . Table 2.1 also includes a comparison of l i n e a r scale r a t i o s and dimensionless number r a t i o s for the main basins. In Table 2.1 the r a t i o for each watershed pair i s the unlogged basin value divided by the logged basin value. Considering the Government-Mosquito r a t i o s , a l l values except mean elevation and shape are within approximately 20%. The shape r a t i o value of 0.51 indicates that Mosquito Creek i s a r e l a t i v e l y long, narrow basin i n comparison to Government. Although the mean elevation r a t i o s are considerably d i f f e r e n t , both hypsometric i n t e g r a l values are generally low (Appendix Table B . l ) . The s i m i l a r HI r a t i o s i n d i c a t e that both basins have f a i r l y large proportions of the drainage basin area at r e l a t i v e l y low elevations. The other basins are d i f f e r e n t i n several ways, p a r t i c u l a r l y i n terms of mean basin el e v a t i o n , geometric shape factor and geometric b i f u r c a t i o n r a t i o . 2.2.6 Logging Histories Logging a c t i v i t i e s i n the study watersheds were reviewed by analyses of p r o v i n c i a l Ministry of Forests Continuous History Maps and a i r photographs. The date method and extent of logging are summarized i n Table 2.2 and the locations of logged areas are shown i n Figure 2.4. Logging h i s t o r i e s and a c t i v i t i e s are discussed i n the following se c t i o n . Mosquito Main Creek Logging began i n this watershed i n the 1940s. Between 1946 and - 35 -Table 2.2 Logging histories of the study watershed. Basin Date Area Logged Road Length Logging Watershed Area (km2) Logged km2 % Basin km km/ km Method Mosquito Main 11.9 1940s 1.60 13.5 2.06 0.17 Skidded 1960s 5.17 43.4 15.47 1.30 High lead Total 6.77 56.9 17.50 1.47 Mosquito Tributary 5.4 1960s 1.76 32.6 5.06 0.94 High lead Bonanza 68.3 1975-1982 7.52 11.01 31.54 0.46 High lead - 36 -0 1.0km FIGURE 2.4: DRAINAGE PATTERNS, LOGGING HISTORIES AND LOCATION OF STUDY REACHES IN SELECTED QUEEN CHARLOTTE ISLAND WATERSHEDS. - 37 -FIGURE 2.4: continued - 38 -1949, a t o t a l a r e a of 1.6 km (13.5% of the e n t i r e b a s i n ) was l o g g e d . Timber was yarded by s k i d d e r and h a u l e d by t r u c k out of the watershed a l o n g a major road which f o l l o w e d the l e f t bank of the c r e e k . L o g g i n g o p e r a t i o n s o c c u r r e d on the streambank; c r o s s - s t r e a m f e l l i n g and y a r d i n g were e x t e n s i v e and i n - s t r e a m s k i d d i n g o c c u r r e d to a l i m i t e d e x t e n t . A second p e r i o d of l o g g i n g began i n 1962 and c o n t i n u e d u n t i l 2 1969. D u r i n g t h i s time an a r e a of a p p r o x i m a t e l y 5.2 km , or 43% of the b a s i n , was l o g g e d . Y a r d i n g was done by h i g h l e a d methods and timber was h a u l e d from the watershed by t r u c k . L o g g i n g to the streambank o c c u r r e d e x t e n s i v e l y and c r o s s - s t r e a m f e l l i n g and y a r d i n g o c c u r r e d i n f r e q u e n t l y . No i n - s t r e a m s k i d d i n g o c c u r r e d d u r i n g t h i s p e r i o d . Mosquito T r i b u t a r y L o g g i n g a c t i v i t i e s began i n the Mosquito T r i b u t a r y watershed d u r i n g 1963 (a s m a l l e r a r e a at the c o n f l u e n c e of the T r i b u t a r y and Main c r e e k s was logged d u r i n g 1947). In t o t a l , the c l e a r cut logged a r e a 2 i n c l u d e s 1.76 km , a c c o u n t i n g f o r a p p r o x i m a t e l y one t h i r d of the e n t i r e b a s i n . Cut timber was yarded by h i g h l e a d s and h a u l e d by t r u c k over a road which r a n p r e d o m i n a n t l y a l o n g the r i g h t s i d e of the v a l l e y bottom. The l o g g i n g h i s t o r y of Mosquito T r i b u t a r y Creek has been d e t a i l e d by R o b e r t s (1984); c r o s s - s t r e a m y a r d i n g o c c u r r e d e x t e n s i v e l y but c r o s s -stream f e l l i n g o c c u r r e d l e s s f r e q u e n t l y and i n - s t r e a m s k i d d i n g was not p r a c t i c e d . A f t e r l o g g i n g was completed a l l , t h r e e b r i d g e c r o s s i n g s c o l l a p s e d , c o n t r i b u t i n g l a r g e volumes of g r a v e l to the channel zone. Streamflow was d i v e r t e d a l o n g a h a u l road ( s e e F i g u r e 2.4) r e s u l t i n g i n - 39 -a shortening of the stream length by 0.4 km. and an increase i n average channel slope of approximately 0.4°. Bonanza Creek Logging a c t i v i t i e s i n the Bonanza Creek watershed began i n the 2 mid 1970s and continued u n t i l 1982. The logged area includes 7.5 km , accounting for approximately 11% of the basin. Timber was yarded by high lead methods and hauled by truck. Logging did not extend to the streambank and only minor cross-stream f e l l i n g and yarding occurred; no in-stream skidding took place. 2.3 Stream Channel and Reach Study Areas Within the main study watersheds sub-basins were selected for examination of p a r t i c u l a r channel features. Also, within each sub-basin a short reach was selected for deta i l e d study of morphological features. The general c h a r a c t e r i s t i c s of both the sub-basins and the d e t a i l e d study reaches are presented in the following sections. 2.3.1 Sub-basin Characteristics The general c h a r a c t e r i s t i c s of each sub-basin are presented i n Table 2.3. The drainage basin areas of Government sub-basins B and C are s i m i l a r , but both are about 35% smaller than the area of t h e i r comparison sub-basin (Mosquito Main). Government sub-basin D, with a 2 drainage basin area of 3.9 km , i s about 28% smaller than i t s comparison sub-basin (Mosquito T r i b u t a r y ) . The drainage basin area of Hangover i s - 40 -Table 2.3 Sub-basin c h a r a c t e r i s t i c s . BASINS PAIR PAIR Government Creek Mosquito Cr. Hangover Bonanza Cr. C r . Sub-basins' GA GB GC GD MM MT Hang A B Contributing Area (km 2) 16.2 6.9 6.8 3.9 10.5 5.V 20.2 68.3 45.2 Stream Order 2 4 3 4 3 3 3 4 5 4 Average Gradient 3 0.0080 0.0125 0.0199 .0207 .0092 .0191 0.0125 0.0034 0.0065 Geology 1 4 Uncon. Uncon. Uncon. Volcanics Uncon. Volcanics Volcanics Uncon. Volcanics Land Use Unlogged Logged Unlogged Logged " T J - T T T T Notes: lSub-basin locations are shown i n Figure 2.4. Strahler ordering, based on 1:15,100 - 1:20,000 topographic maps and a i r photographs. 3Average gradients are based on f i e l d surveys of channel sections, not the ent i r e stream length. "*From Sutherland-Brown (1968), prominent rock type of watershed; uncon. refers to unconsolidated Quaternary sediments. - 41 -l e s s than h a l f that of Bonanza. The stream orders of paired sub-basins are s i m i l a r (Table 2.3). With a few exceptions, s p e c i f i c a l l y Hangover and Bonanza and Government Reach C and Mosquito Main, the average gradient of stream sections within the paired sub-basins (not gradient of the e n t i r e stream length) i s also s i m i l a r . The geology of each sub-basin i s comparable. The morphometry of each sub-basin was analyzed. Results are summarized and compared i n Table 2.4. I t i s d i f f i c u l t to e s t a b l i s h q u a n t i t a t i v e l y the degree of s i m i l a r i t y between two sub-basins. It i s evident from Table 2.4 that d i f f e r e n c e s i n both l i n e a r scale features and dimensionless number r a t i o s can e x i s t between two sub-basins which appear,in most respects, to be s i m i l a r . For example, the r a t i o s of Government sub-basins B and C are s u b s t a n t i a l l y d i f f e r e n t than 1.0 i n several morphometric aspects. In order to determine i f these two sub-basins are s i m i l a r i n terms of morphometric parameters, i t i s necessary to consider the v a r i a b i l i t y of the parameters between several sub-basins within one major basin. Although there are only three sub-basins w i t h i n the Government Creek watershed, i t provides the only a v a i l a b l e estimate of within basin morphometric v a r i a b i l i t y . Therefore, for the purposes of s e l e c t i n g comparable sub-basins, the pa i r s are assumed to be s i m i l a r i f the morphometric r a t i o s do not d i f f e r by more than one standard d e v i a t i o n (columns i n Table 2.4). Another method of determining p a i r s i m i l a r i t y i s to c a l c u l a t e a mean value f o r a l l the r a t i o s f o r each pair (rows i n Table 2.4) and compare t h i s mean value to 1.0. This approach requires - 42 -Table 2.4 Comparison of dimensionless sub-basin numbers.1 characteristics: ratios of selected linear scale features and SUB-BASIN PAIRS LINEAR SCALE RATIOS 2 DIMENSIONLESS NUMBER RATIOS3 L2 D R CL Sh HI S l Sub-basin Comparisons GB/GC GB/GD GC/GD 1.56 1.79 1.15 1.39 1.33 0.96 0.90 0.97 1.08 1.03 1.18 1.14 1.60 1.50 0.94 1.77 0.77 0.99 1.25 0.81 0.65 X S 1.50 0.32 1.23 0.23 0.98 0.09 1.12 0.08 1.35 0.36 1.18 0.53 0.90 0.31 GB/MM GC/MM 0.83 0.87 0.87 0.82 0.40 0.44 0.73 0.71 0.95 0.62 1.26 1.63 0.61 0.49 GC/MT GD/MT 0.89 0.78 1.09 1.14 0.45 0.42 0.71 0.62 0.33 0.35 1.24 1.25 0.47 0.72 Hang/Bonz 0.84 0.80 1.0 0.72 0.85 1.33 1.18 Notes: Detailed results are Included in Appendix B. Linear scale features: L2 " mean length of second order streams; D " drainage density; R =» relative relief 3 D i m e n s i o n l e s 8 numbers: C L • longitudinal profile concavity; S n • geometric shape factor; HI - hypsometric integral; _ S\ " geometric mean basin slope X » arithmetic average S » standard deviation - 43 -the assumption that a l l basin parameters are of equal Importance. I f they are not, the s p e c i f i c basin parameter w i l l require weighting before c a l c u l a t i n g the mean. The f i r s t method i s preferred. After allowing for a departure of one standard deviation, i t i s evident (Table 2.4) that a l l pairs have s i m i l a r L2 and D r a t i o s but d i s s i m i l a r R r a t i o s . Considering the GB/MM pa i r , the sub-basins are si m i l a r with respect to Sh and HI but d i s s i m i l a r i n S±. The GC/MM pai r dimensionless number r a t i o s are d i s s i m i l a r . Considering GD and MT, a l l dimensionless number r a t i o s are s i m i l a r , with the exception of Sh» The Hang/Bonz sub-basin pair i s s i m i l a r i n a l l respects. Based s o l e l y on morphometric analyses, the most appropriate pairing of unlogged and logged sub-basins i s as follows: Unlogged Logged Government Sub-basin B Mosquito Main Government Sub-basin D Mosquito Tributary Hangover Bonanza The most appropriate within basin comparisons are Government reaches B and C. 2.3.2 Detailed Study Reach Characteristics Within each sub-basin a minimum of one reach was selected and studied i n d e t a i l . The se l e c t i o n of detail e d study reaches was based upon several c r i t e r i a . F i r s t , the reach had to be incorporated into the FFIP f i s h e r i e s program and be included i n t h e i r habitat inventories. Second, study s i t e s were to be selected within each class of the FFIP - 44 -stream types ( u n i t 3 = Channel gradients < 1°; u n i t 2 = gradients 1° -5°). Because the basins and sub-basins were f a i r l y s i m i l a r with respect to b i o p h y s i c a l p r o p e r t i e s , the d e t a i l e d study reaches could be placed anywhere within the sub-basin. Although reach s e l e c t i o n w i t h i n each sub-basin should have been random, compliance with the above c r i t e r i a and l o g i s t i c a l problems made t h i s impossible. The p h y s i c a l c h a r a c t e r i s t i c s of each study reach are summarized i n Table 2.5. The channel width and median surface sediment s i z e values d i f f e r between reaches. These values r e f l e c t d i f f e r e n c e s i n sub-basin p r o p e r t i e s , p a r t i c u l a r l y i n drainage basin areas, and are used to standardize r e s u l t s i n subsequent analyses of channel morphology. 2.4 Summary The channel morphology study design incorporates a paired watershed approach. The advantages of t h i s approach are twofold. F i r s t , because several streams are considered, d e t a i l e d r e s u l t s are a v a i l a b l e f o r a wider range of streams than i s poss i b l e i f the study i s r e s t r i c t e d to a si n g l e watershed. Second, the paired approach enables comparisons to be made over short time periods. The requirements necessary for a paired watershed study include comparison of drainage basins with s i m i l a r b i o p h y s i c a l c h a r a c t e r i s t i c s ( c l i m a t e , geology, s o i l s , vegetations and morphometry) but d i f f e r e n t land use a c t i v i t i e s . The v a l i d i t y of the paired watershed approach i s tested by examining the v a r i a b i l i t y of channel morphologic features within a si n g l e reach and between reaches contained within an i n t e r n a l l y homogeneous watershed. - 45 -Table 2.5 Detail Study Reach Characteristics. STREAM REACHES SUB-BASIN PAIR SUB-BASIN PAIR Government Creek Mosquito Cr. Hangover Bonanza Sub-basins1 GB GC GD MM MT Hang Bonz Average Reach Gradient 0.0133 0.0150 0.0244 0.0096 0.0194 0.0071 0.0095 FFIP Stream Type (unit) 3 3 2 3 2 3 3 D 5 0 (mm) 30 43 77 51 74 57 34 Mean Bankfull Width (m) 20.2 21.1 18.8 37.6 27.7 29.3 45.4 Sinuosity 2 1.10 X " 1.09 1.06 1.10 1.20 1.44 1 14 Reach Pairs Notes 1 Sub-basins are shown in Figure 2.4. ^ 5 0 " surface sediment, median b-axis. Sinuosity » thalweg length/reach length. - 46 -Drainage basins with s i m i l a r b i o p h y s i c a l conditions were selected and sub-basins were p a r t i t i o n e d within each. In turn, study reaches within each sub-basin were selected i n conjunction with the FFIP f i s h e r i e s program. The study reaches to be compared are summarized i n Table 2.6. - 47 -Table 2.6 Summary of Selected Basin, Channel and Reach Scale Study Pairs Watershed Pair 1 Studv Design FFIP Stream Unlogged Logged 2 Basin Type Type 3 Basin Scale Government Mosquito B 3,2 Studies Hangover Bonanza B 3 Channel Scale GA,GB,GC,GD - A 3,2 Studies GB MM B 3 GD MT B 2 Hang Bonz B 3 Reach Scale GB,GC,GD - A 3,2 Studies • GB MM B 3 GD MT B 2 Hang Bonz B 3 Notes: Basin study locations are shown i n Figure 2.2. Channel and reach scale study locations are shown i n Figure 2.4. (Government A includes GB, GC and GB; Mosquito M includes MM and MT; and Bonanza A includes Hang and Bonz). o Study design basin types: A = test i n t e r v a l v a r i a b i l i t y B = test between basin v a r i a b i l i t y (see Figure 2.1) FFIP stream type 3 = average channel slope < 1° FFIP stream type 2 = average channel slope 1° - 5°. - 48 -3.0 METHODS The study objectives state that channel morphology (physical f i s h habitat) Is to be compared in logged and unlogged watersheds and the va r i a b i l i t y of habitat in response to changing streamflow stage is to be assessed. The following section details f i e l d methods used in the study. The procedures used, both In selecting study locations and in f i e l d work, are summarized in Figure 3.1. With the exception of channel scale longitudinal profiles, f i e l d methods are discussed in the order presented in Figure 3.1. 3.1 Channel Scale Longitudinal Profiles To determine the general longitudinal form and characteristics of pools and r i f f l e s over a large proportion of each stream, a longitudinal profile survey was conducted. Surveys extended from low gradient (<1°), beginning at or near sea level, through moderate gradient channels (<4°). Time constraints prohibited surveys to head slopes. This does not represent a significant problem because most salmonid habitat of interest is in lower gradient areas. Survey equipment used included automatic level, stadia rod and surveyor's hip chain. Slope was calculated from f i e l d surveys as the difference in elevation over the horizontal distance. A l l surveys followed the thalweg; the water surface elevations were measured by direct reading by the rodman. The f i e l d survey methods are based on partitioning the channel into primary habitat elements, thus set - 49 -BASIN Select Comparable Basin Homogeneous Biophysical Conditions Basin A Basin B Paired Watersheds CHANNEL Select Stream Channels Characterize Channel Features 1:20,000 Mr Photos and FFIP Fisheries Studies Longitudinal Profile Field Survey REACH Select Stream Reaches for Detailed Study > 1 Reach per Major Channel Divison; Slopes of 0-2°, 2-4° Morphological Studies | Low Flow Studies - longitudinal profiles - in-channel topography - large organic debris characteristics - sediment characteristics I Habitat-Streamflow Studies - at-a-station hydraulic geometries - flow stage-water velocity, depth, area relations FIGURE 3.1: CHANNEL MORPHOLOGY STUDY PROCEDURES. - 50 -distance'intervals were not used. Pools and r i f f l e s were delineated by topographic p o s i t i o n , with pools being low areas and r i f f l e s being high areas of the channel. The standard f i e l d method, shown i n Figure 3.2, was to record thalweg elevation and distance at each r i f f l e (R) downstream-pool upstream (P) break (R/P), see Figure 3.2a, at the deepest point i n the pool (not always accessible), and at each pool downstream-riffle upstream break (P/R). Two exceptions to th i s standard technique were used i n the f i e l d . F i r s t , i n cases where large organic debris pieces crossed the channel forming a step (LOD ), intermediate survey stations were included (Figure 3.2b). In addition to surveying the conventional topographic breaks, elevations and distances were surveyed i n the downstream pool and both immediately downstream and upstream of the step (P/LOD , LOD /R, res p e c t i v e l y ) . In such cases, the operational d e f i n i t i o n required that i n order for the LOD to form a step i t had to a l t e r bed elevation and water surface elevation. The second exception involved high gradient r i f f l e s . In such cases, an additional survey sta t i o n was included at the break i n slope along the r i f f l e surface (point R i n Figure 3.2c). Areas of the channel which did not f a l l c l e a r l y into pool or r i f f l e categories were designated as glides and runs; the former more closely resembles a pool than a r i f f l e and the l a t t e r more closely resembles a r i f f l e . The survey also included notes on the influence of large organic debris on bed and bank erosion. The advantage of longitudinal p r o f i l e s conducted In th i s manner i s that the character of pools and r i f f l e s I - 51 -R/P STANDARD FIELD METHOD: 3.2.a P/R Breaks based on bed topography. EXCEPTIONS: 3.2.D LOO /R 1. LOD STEPS. P/LOD I and downstream of log. R/P FIGURE 3.2: DIAGRAM OF METHOD OF CONDUCTING LONGITUDINAL PROFILE SURVEYS. - 52 -(frequency and proportions) can be i d e n t i f i e d d i r e c t l y for long channel lengths. The c o n t r i b u t i o n of large organic debris to channel slope and sediment storage can also be assessed. One disadvantage i s that the P/R break, i s often d i f f i c u l t to d i s t i n g u i s h i n the f i e l d . The R/P break can be located quite accurately and therefore, the p o o l - r i f f l e combined length i s c a l c u l a t e d between two successive R/P l o c a t i o n s . A po s s i b l e e r r o r develops i n determining the proportion of pool and r i f f l e over the combined length. 3.2 Beach Scale Morphological Studies D e t a i l e d morphological i n v e s t i g a t i o n s were conducted wi t h i n r e l a t i v e l y short stream sections of each main channel. The lengths of these reaches ranged from approximately 200 m to 300 m. The f i e l d techniques used to study these reaches i n d e t a i l are described i n the fol l o w i n g s e c t i o n s . 3.2.1 Morphological Studies Conducted at Low Flow Studies of morphological features during low flow conditions are aimed at accomplishing study o b j e c t i v e 1. As ind i c a t e d i n Figure 3.1, l o n g i t u d i n a l gradients, planimetric form and sedimentological c h a r a c t e r i s t i c s were considered. L o n g i t u d i n a l P r o f i l e The l o n g i t u d i n a l p r o f i l e of the reach thalweg was surveyed i n the same manner as for the longer channel surveys (Section 3.1). However, i n ad d i t i o n to recording elevations and distances f o r a l l topographic breaks, several intermediate survey s t a t i o n s were obtained. - 53 -Successive survey points did not exceed a 10 m separation. This method provides a detai l e d l o n g i t u d i n a l p r o f i l e and allows evaluation of c l a s t i c sediment storage. In-Channel Topography and Bed Configuration Detailed mapping of the morphological features within each study reach was accomplished by theodolite, stadia rod with l e v e l , and f i b r e measuring tape. Surveys were conducted by e s t a b l i s h i n g bench marks i n overbank areas and a series of head-pins within the active channel zone. These were ti e d i n to bench mark elevations established during channel scale l o n g i t u d i n a l p r o f i l e surveys. The purpose of the survey was to depict channel topography. Hence, many cross-sections were oriented along s p e c i f i c features, for instance, i n l i n e with a r i f f l e that diagonally crossed the channel or following the alignment of sediment trapped behind large organic debris. Small-scale features of s p e c i f i c i n t e r e s t , such as l o c a l accumulations of sand or an i s o l a t e d back channel pool, were located and recorded for mapping. Topographic maps were drawn at scales ranging from 1:100 to 1:500 depending on t h e i r use. Surface based oblique photographs were taken at each head pin; these were used to supplement mapping. Large Organic Debris Plan form maps, based on in-channel topographic mapping and drawn at 1:500 scale, were used i n the f i e l d to map large organic debris - 54 -pieces. Mapping was based on the known position of each cross-sectional transect, bench marks and head pins; the plotting of each piece of woody material is thought to be within 1 m of its actual position and the orientation is considered to be accurate. Diameters at each end and length of each piece were measured and volumes were estimated by assuming a cylindrical log shape. The volume of root-wads (attached or free) was estimated separately. The amount of bark, branches and moss on each piece was recorded as an indication of length of time each piece had been in the channel. Trees growing on in-channel large organic debris were cored with an increment borer to determine the minimum residence time of the supporting large organic debris piece. Pieces were also described according to their influence in forming steps or banks, and directing stream flow. Sediment Characteristics The characteristics of the clastic sediment within each study reach were examined in the field. A range of techniques was used; surface (uppermost surface layer with a thickness equal to the largest stone), sub-surface (large volumes obtained from a pit) and in-channel (obtained from the riffle crest) sediments were sampled thoroughly, whereas the areal sorting of sediment was mapped with less precision. Surface and sub-surface samples were obtained from side channel bar top locations, in all cases this material was subject to reworking during high flow events. I - 55 -Surface Sediment Surface sediments were sampled within each study reach; the number of samples per reach v a r i e d . F i e l d sampling techniques are standard (see Wolman, 1954; K e l l e r h a l s and Bray 1971). B r i e f l y , at each s i t e a f i b r e tape was l a i d out p a r a l l e l to the d i r e c t i o n of steam flow and the stone d i r e c t l y beneath each 0.3 m mark was obtained and measured with respect to i t s a, b and c axes. Sampling was r e s t r i c t e d to stones with a b-axis greater than 8 mm ( f i n e gravel and sand siz e material were noted). Sample sizes ranged between 60 and 90 p a r t i c l e s . A q u a l i t a t i v e assessment was made of the angularity, l i t h o l o g y and imbrication of large c l a s t s . The b-axis measurements were arranged into half phi classes on the basis of frequency by number. Sub-Surface Sediment Sub-surface sediment was sampled at one s i t e within each reach, usually coinciding with the surface sediment sampling s i t e located at the upstream end of each reach. The f i e l d and laboratory methods used are d e t a i l e d by Roberts (1984). The general sampling procedure involved removal of the surface sediment layer, excavation of approximately 80 kg of sediment and then the use of f i e l d sieves and scale to determine the proportion, by weight, of the t o t a l sample which f a l l s into half phi i n t e r v a l s . F i e l d s i e v i n g began at 64 mm and terminated at 8 mm. A sample s p l i t was returned to the laboratory for analysis of the fin e f r a c t i o n . - 56 -In-Channel Sediments Bulk samples were obtained from the r i f f l e - p o o l break, by use of a McNeil sampler (McNeil, 1960). This technique involves the collection of both surface and sub-surface sediments. Three samples were obtained from Hangover, Bonanza, and Mosquito Tributary. It was not possible to obtain McNeil samples from the detailed study reaches i n Government or Mosquito Main Creeks. The sampling technique is detailed by Tripp and Poulin, 1985. Standard laboratory techniques were used to analyze the sediment. The material was sieved into a combination of phi and half phi intervals. Areal Sorting of Sediment The areal sorting of sediment was assessed primarily by visual inspection of the study reach. At each surveyed cross-section (usually spaced approximately 10 m apart), the channel surface was characterized as to relative proportion of sand, gravel, cobbles and boulders. A qualitative s t a b i l i t y rating was also assigned. These included unstable, moderately stable and stable; c r i t e r i a used in rating are l i s t e d in Figure 5.1. A minimum of three estimates were made per transect. Stability indices and sediment texture were mapped according to these estimates and supplemented details acquired from topographic mapping (e.g., position of local accumulations of sediment and areas of stable material). Additional detail was gained from photographs. The maps of areal sorted sediment are thought to be relatively accurate. To improve, or even evaluate their accuracy would require much more f i e l d - 57 -time. Conventional a i r photographs are of l i m i t e d assistance because, i n general, they provide i n s u f f i c i e n t r e s o l u t i o n and i n unlogged basins the channel i s l a r g e l y obscured from view by the dense tree canopy. Volume of Stored Sediments The c a l c u l a t i o n of sediment volumes stored along each reach was based on surveyed topographic maps (1:200). Determination of the depth of each deposit was often d i f f i c u l t . If the sediment was stored behind a piece of large organic debris then the deposit thickness was assumed to be equal to the distance from the deposit top to the e l e v a t i o n at the base of the debris piece (based on the diameter of the LOD, i f the base was not v i s i b l e ) . The deposit length was c a l c u l a t e d from the LOD upstream to the point where a l i n e of average reach slope would i n t e r s e c t the channel surface. In cases where no deposit base was evident, such as i n side and mid-channel gravel bars, the thickness was measured from the deposit top to the water surface e l e v a t i o n at zero discharge. Therefore, the thickness of a deposit i s determined by the e l e v a t i o n of the r i f f l e thalweg; t h i s represents a conservative (lower value) estimate. The widths and surface expressions of the deposit were taken d i r e c t l y from the topographic maps. 3.2.2 Habltat -Streamflow Studies The r e l a t i o n between s p e c i f i c habitat c h a r a c t e r i s t i c s and stream flow stage c o n s t i t u t e s the second study o b j e c t i v e . This o b j e c t i v e i s approached i n two ways. The methods used to determine the a t - a - s t a t i o n - 58 -hydraulic geometry of each reach and the changes in habitat quantities along the reach, at various flows, are described below. At-A-Station Hydraulic Geometry The relation between stream channel width and depth and flow velocity at different discharges i s described by the hydraulic geometry. At-a-station hydraulic geometry considers variation in channel morphology during temporal changes in discharge (Richards, 1977). Water surface width is important in terms of f i s h habitat because i t represents the maximum area of habitat available and is equal to water surface area per unit length of channel (Mosley, 1983). Cross-sectional area, the product of water surface width and mean flow depth, is important because i t is equivalent to water volume per unit length of channel and represents an index of available f i s h habitat (Mosley 1983). At-a-station hydraulic geometries for each stream reach were calculated. These were based on a surveyed cross-section, located in a pool section, approximately one third of the pool length upstream of the r i f f l e - p o o l break. Bench marks were established in the overbank zone on both sides of the channel. Depending on channel size, elevations at 0.3 m or 0.5 m intervals across the channel, were surveyed. A staff gauge was installed and tied-in with respect to elevation. The cross-section was re-surveyed at several stage heights and the water surface width, water depths and flow velocities were measured. Standard stream gauging techniques were used. - 59 -Discharge and hydraulic adjustment measures were made on a total of 87 occasions. Hydraulic geometries were based on approximately 10 discharge measurements; the maximum number of readings was obtained for Hangover Creek (n = 17) and the fewest readings were obtained for Government Creek (n = 5). It was not possible to develop hydraulic geometry relations for four Government Creek sites because an insufficient range of discharge was measured. Streamflow Stage-Habitat Quantity Relations Habitat can be quantified at various discharges by several different techniques. Inventories (e.g., DeLeeuw, 1981) can be repeated at a range of discharge and the results compared. Flow velocity, an important habitat parameter (Bovee 1978), is usually ignored in this approach. An alternative which does consider flow velocity, depth or width is the Instream Flow Group approach (Bovee and Milhous, 1978; Trihey and Wagner, 1981). This method is costly and is rarely, i f ever, applied in forestry and related projects. A rela t i v e l y simplistic method is applied here to consider habitat quantities at different streamflow stages and to compare habitat conditions in different streams. Series of staff gauges were installed in a l l study reaches. These were located at topographic breaks separating habitat units (pools, r i f f l e s , glides, runs etc.). A level survey was conducted to tie a l l staff gauges together with respect to elevation; a theodolite was used to locate the staff gauges accurately on the topographic map - 60 -( p l o t t e d at 1:200). The reference s t a f f gauge, associated with the hydraulic geometry r e l a t i o n s , was also l e v e l l e d into the s t a f f gauge network. Based on the r a t i n g curves f o r the reference s t a f f gauges, the discharge for the stream reach i s known at a l l stages. At d i f f e r e n t stages the water surface e l e v a t i o n at each s t a f f gauge i s known and i s drawn onto the contour map. Assuming non-varying, uniform flow conditions, i t i s possible to use the c o n t i n u i t y equation to c a l c u l a t e mean v e l o c i t y (V* = Q/Wsd* where discharge (Q) i s known and water surface width (Wg) and mean depth (d*) are obtained from the topographic map). By measuring width and depth and c a l c u l a t i n g mean v e l o c i t y at many cross-sections along the reach, and i n t e r p o l a t i n g between cross-sections an inventory of the amount (area) of channel which has s p e c i f i c depth and v e l o c i t y c h a r a c t e r i s t i c s was compiled. The same procedure was followed at d i f f e r e n t discharges allowing the amount of ha b i t a t at each streamflow stage or each reach to be c a l c u l a t e d . - 61 -4.0 CHANNEL SCALE STUDIES In t h i s c h a p t e r r e s u l t s of channel s c a l e s t u d i e s are p r e s e n t e d and d i s c u s s e d . These r e s u l t s a r e based on l o n g i t u d i n a l p r o f i l e s u r v e y s . The channels to be compared are summarized i n T a b l e 2.6. R e s u l t s p e r t a i n i n g to the s h o r t e r d e t a i l e d study reaches a r e p r e s e n t e d i n Chapters 5 and 6. L o n g i t u d i n a l p r o f i l e s , c o v e r i n g a p p r o x i m a t e l y 10.5 km i n t o t a l l e n g t h , were sur v e y e d i n the f i e l d . The ch a n n e l thalweg p r o f i l e f o r each stream i s p r e s e n t e d i n F i g u r e 4.1 through 4.3. These r e p r e s e n t r e l a t i v e l y s h o r t segments of the o v e r a l l c hannel l e n g t h , as shown i n Appendix F i g u r e s B.7 to B.9. The average g r a d i e n t s range from a low of 0.0048 and 0.0092 f o r Bonanza and Mosquito Main Creeks, r e s p e c t i v e l y , to a h i g h o f 0.0191 i n Mosquito T r i b u t a r y Creek and 0.0207 i n Government Reach D ( T a b l e ( 2 . 3 ) . A l l l o n g i t u d i n a l p r o f i l e s e x h i b i t s m a l l s c a l e v e r t i c a l i r r e g u l a r i t i e s ( p o o l s and r i f f l e s ) and l a r g e r , l e s s f r e q u e n t , convex s e c t i o n s (zones o f d e p o s i t i o n ) . These l a r g e r zones of sediment a c c u m u l a t i o n , seen f o r example i n Government Creek reaches A and D ( F i g u r e 4.1) and Mosquito Main Creek (300 m upstream of the c o n f l u e n c e i n F i g u r e 4.2), are due l a r g e l y to sediment d e p o s i t i o n behind l a r g e l o g jams. The i n f l u e n c e of l o g s on ch a n n e l g r a d i e n t and morphology i s c o n s i d e r e d i n Chapter 5.0. P o o l s and r i f f l e s a r e ch a n n e l f e a t u r e s which r e f l e c t changes i n sediment s u p p l y to the stream system; hence they p r o v i d e an i n d i r e c t measure of sediment d e l i v e r y t o the c h a n n e l . The adjustment of p o o l s FIGURE 4.1: LONGITUDINAL PROFILE OF CHANNEL THALWEG: GOVERNMENT CREEK. - 63 -18-17-19 18 E 14-> 13--I (0 5 ,,. ui 3 Uj 10-s < 9-> S 7 31 30 28-28-d " < UI <0 25-W 24-UI 23-5 < 21 ul 20-18-18-700 16-FIGURE 4. REACH C CONFLUENCE WITH RIGHT BRANCH ~ 1 (REACH 0) ' LOO I LOO) : LOO STEP, PLUNGE POOL WATER SURFACE LOOt 100 200 300 400 800 800 700 DISTANCE ABOVE MAIN CONFLUENCE (REACH A) (m) REACH D LOO • : LOO STEP, PLUNGE POOL LOO* WATER SURFACE 800 1000 1200 DISTANCE ABOVE MAIN CONFLUENCE (REACH A) (m) 1: LONGITUDINAL PROFILE OF CHANNEL THALWEG: GOVERNMENT CREEK. FIGURE 4.2: LONGITUDINAL PROFILE OF CHANNEL THALWEG: MOSQUITO CREEK. FIGURE 4.3: LONGITUDINAL PROFILE OF CHANNEL THALWEG: BONANZA AND HANGOVER CREEKS. - 66 -and r i f f l e s to an increase i n sediment supply i s complex, i n v o l v i n g changes i n l o c a l slope, sediment texture, bed e l e v a t i o n and h y d r a u l i c c h a r a c t e r i s t i c s . For the purposes of t h i s paper, and at the channel s c a l e , only the geometry of pools and r i f f l e s can be considered. The p r e v i o u s l y documented shape changes i n response to increased sediment supply included reduced pool-to-pool spacing (Kelsey, 1980) and decreased r i f f l e r e l i e f ( L i s l e , 1982). Therefore, i t i s hypothesized that i f logging and r e l a t e d a c t i v i t i e s increase the q u a n t i t i e s of sediment d e l i v e r e d to the stream channel, response w i l l include reduced p o o l - r i f f l e spacing, reduced r i f f l e height and an increased proportion of r i f f l e s compared to pools. L o n g i t u d i n a l p r o f i l e s (Figures 4.1 to 4.3) were analyzed i n order to c h a r a c t e r i z e both the spacing and r e l i e f of pools and r i f f l e s i n each stream. The methods used to determine r i f f l e spacing, amplitude, r e l a t i v e r e l i e f and magnitude are presented i n Figure 4.4. 4.1 Pool and Riffle Spacing The frequency d i s t r i b u t i o n of pool-to-pool (one p o o l - r i f f l e sequence) spacing f o r i n d i v i d u a l unlogged and logged watershed streams i s presented i n Figure 4.5. In order to compare streams of d i f f e r e n t s i z e i t i s necessary to standardize the spacing lengths. The conventional method of reporting spacing lengths i n units of b a n k f u l l width (WD) has been adopted here and i s used i n Figure 4.5. Bankfull widths were measured i n the f i e l d and were based on morphological evidence. The mean spacing f o r Government Creek reaches range between - 67 -DISTANCE ALONG CHANNEL X = POOL-RIFFLE SPACING A = RIFFLE AMPLITUDE L R = RIFFLE LENGTH L p = POOL LENGTH •p-= RIFFLE RELATIVE RELIEF RIFFLE MAGNITUDE FIGURE 4 . 4 : SCHEMATIC DIAGRAM OF POOL AND RIFFLE SEQUENCE AND METHOD OF DETERMINING RIFFLE SPACING, AMPLITUDE, RELATIVE RELIEF AND MAGNITUDE. - 68 -60-40-GA n-11 X=1-92 Wb 3 - 0 . 7 4 Wb UJ o z UI oc B a o o o > o z UI 3 o ui K U . GB n=22 %=2.79 Wb 3=1.49 Wb . n 60-40 20 n I GC | n=17 | %=2.48 Wb s=1.45 Wb i i i — i — i — i I . • MM n=18 51=1.66 Wb 3=0.64 Wb LOGGED Hang n=21 51=3.51 Wb 8=1.59 i i 60-| I i 40 20 GD n = 18 X=2.85 Wb 3=1.56 Wb 2 4 6 8 MT n=13 X=1.32 Wb 3=0.57 Wb LOGGED 60 40 20H J l Bonz n = 18 X = 2.7 Wb 3=1.9 Wb LOGGED i , n 10 | POOL-TO-POOL SPACING IN CHANNEL WIDTHS n = NUMBER OF POOL-RIFFLE SEQUENCES X = MEAN SPACING IN BANKFULL WIDTHS (Wb). 3 = SPACING STANDARD DEVIATION. FIGURE 4.5: FREQUENCY DISTRIBUTION OF POOL-TO-POOL SPACING FOR FIVE UNLOGGED WATERSHED STREAMS AND THREE LOGGED WATERSHED STREAMS. - 69 -approximately 2 WD and 3 W^ . The spacing for reaches In Mosquito Creek i s less than 2 WD. The mean spacing i n Bonanza Creek i s less than i n Hangover Creek. S t a t i s t i c a l tests of the frequency d i s t r i b u t i o n s were undertaken by the same method used by K e l l e r and Melhorn, 1978. The Kolmogorov-Smirnov goodness of f i t test determined that the frequency d i s t r i b u t i o n s (Figure 4.5) are normally d i s t r i b u t e d and hence parametric s t a t i s t i c s are v a l i d . One way analysis of variance (anova) tests were used to determine i f a s i g n i f i c a n t d i f f e r e n c e exists between morphological features i n unlogged and logged stream p a i r s . For testing purposes a l l p o o l - r i f f l e sequences were used, leading to an unequal number of sequences used i n the anova. To ensure that the d i f f e r e n t sample sizes (number of sequences per stream) did not influence the s t a t i s t i c a l t e s t s , the complete sequence for each stream was par t i t i o n e d into smaller groups (separated into two or three groups) and the mean for each was compared. There was no s i g n i f i c a n t difference (at a= 0.01) between the means for the smaller groups and the t o t a l groups. The anova r e s u l t s are summarized i n Table 4.1. As outlined i n Figure 2.1, the i n i t i a l step i s to evaluate the v a r i a b i l i t y within one watershed characterized by homogeneous biop h y s i c a l conditions. The anova test r e s u l t s (Table 4.1) indicate that there i s no s i g n i f i c a n t difference ( a = 0.01) i n pool-to-pool spacing for the four reaches within Government Creek. Thus, the within-basin variance i s i n s i g n i f i c a n t , hence between basin comparisons can be considered. Table 4.1 Summary of analysis of variance results for pool-to-pool spacing. Stream Channels Degrees of Freedom F Fc(0.01) Decision Compared Between Streams Within Streams Within Basin Comparison: GA, GB, GC, GD 3 64 1.21 4.12 Accept H o MM, MT 1 30 2.52 7.56 Accept H o Between Basin Comparisons: GB, MM 1 38 8.85 7.31 Reject H 0 GD, MT 1 29 11.51 7.60 Reject H 0 Hang, Bonz 1 38 1.98 7.31 Accept H o Unlogged, logged 1 136 10.59 6.84 Reject H 0 Adjusted Width: GB, MM 1 38 0.01 7.31 Accept H o GD, MT • 1 29 2.83 7.60 Accept H o Influence of LOD: GA, GB, GC, Hang, Sachs 4 88 11.57 3.58 Reject H o GB, Sachs 1 42 16.05 7.31 Reject H o Hang, Sachs . 1 41 10.20 7.31 Reject H o Notes: Ho ~ there is no significant difference, at o - 0.01, in mean spacing of pools. F c - c r i t i c a l F-test value for a probability level of 99Z. - 71 -Between basin s t a t i s t i c a l comparisons show that there i s a s i g n i f i c a n t d i f f e r e n c e between spacings i n two of the three unlogged-logged basin pairs (Table 4.1). In both the Government Creek Reach B-Mosquito Creek Main and Government Creek Reach D-Mosquito Creek Tr i b u t a r y p a i r s the logged basin channels have shorter spacings than t h e i r corresponding unlogged basin channels. There i s no s i g n i f i c a n t d i f f e r e n c e i n spacing lengths between Hangover and Bonanza Creeks. When a l l f i v e unlogged streams are grouped there i s no s i g n i f i c a n t d i f f e r e n c e i n spacing. There i s no s i g n i f i c a n t d i f f e r e n c e i n spacing between the two logged Mosquito Creeks (Main and Tributary) but spacing i n Bonanza Creek does d i f f e r s i g n i f i c a n t l y from that i n Mosquito Creek. Spacing i n Bonanza Creek i s not d i f f e r e n t from Government Reaches B, C, or D. Comparison of the combined unlogged and logged stream types i n d i c a t e s that pool-to-pool spacing i s s i g n i f i c a n t l y shorter i n the l a t t e r type; the mean spacing i n unlogged channels i s 2.8 W^, and 2.0 W^  i n logged basin channels. Before i t i s possible to conclude that p o o l - r i f f l e spacings are reduced through the i n f i l l i n g of pools due to an increase i n sediment, i t i s necessary to discount the influence of large organic debris and other f a c t o r s not r e l a t e d to sediment discharge. To consider the importance of LOD on p o o l - r i f f l e spacing a nin t h stream reach was surveyed. Sachs Creek, located i n northeastern Moresby Island (Figure 2.2) i s unique because a l l in-stream LOD was removed from the lower 2 km of channel during the 1950s (H. Klassen pers. comm., 1982). A l l other streams considered were characterized by in-stream LOD (considered In 44-30- I I 25-20-15-10-^ 5-UJ O o -UJ oc OC 3 o o o IL o > u z 111 3 o Ul oc I „ a) Influence of LOD. SACHS (N=22 X = 6.9 W b S=4.6 W b ) GB MM 30-25-20-15-10-4—, r- T r-' 1 I I SACHS HANG BONZ T r 0 1 2 3 4 5 6 7 8 8 10 11 12 13 14 15 16 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 60 50 40 30 20 10-b) Adjusted width. MM adjusted width GB I I I I 60-50-40 30-20 i 1 1 1 1 r 0 1 2 3 4 5 6 7 to MT adjusted width GD 10-| | 1 I I I—n I > 1 - ! 1 1 h 0 1 2 3 4 5 6 7 8 POOL-TO-POOL SPACING IN CHANNEL WIDTHS FIGURE 4.6: FREQUENCY DISTRIBUTION OF POOL-TO-POOL SPACING FOR STREAMS WITH IIMAL L O D AND A D J U S T E D C H A N N E L W IDTHS . - 73 -d e t a i l i n Chapter 5). About 40% of Sachs Creek has been logged since the early 1960s (Klassen, 1983), logs were trucked from the watershed and logging extended to the stream channel. The Sachs Creek drainage basin area i s 19 km and the channel gradients ranged from less than 0.0100 to 0.030 over the surveyed l o n g i t u d i n a l p r o f i l e . The frequency d i s t r i b u t i o n of pool-to-pool spacing i n both logged and unlogged basin pairs with the i n c l u s i o n of Sachs Creek spacing data i s shown i n Figure 4.6a. There are several very long pool and r i f f l e sequences i n Sachs Creek, including one that i s 15 to 16 widths i n length; the average spacing for Sachs alone i s 6.94 WD. Anova tests (Table 4.1) show that pool-to-pool spacing lengths are s i g n i f i c a n t l y longer i n Sachs Creek than i n other logged and unlogged streams with s i m i l a r stream gradients. The mean spacing for a l l logged basin streams i s increased to 3.16 widths. Although Sachs Creek has been subjected to increased sediment loads due to d i r e c t influence of mass wastage events on the channel, there are long spacing lengths i n areas both influenced and unaffected by material from the h i l l s l o p e s . In Sachs Creek the p o o l - r i f f l e spacing lengths increased with a decrease i n LOD quantity. Because logging tends to reduce the volume of LOD i n a channel, spacing should increase rather than decrease, as evidenced by the analyses which exclude Sachs Creek. It appears that a s u b s t a n t i a l increase i n sediment input must occur for spacings to shorten i n conjunction with a decrease i n LOD volumes. Another factor which may lead to an apparent change i n p o o l - r i f f l e spacing i s the use of channel bankfull width to standardize - 74 -spacing distances so that streams of various sizes can be compared. Channel widening due to bank erosion and bed aggradation has been identified in many logged watersheds and is documented in Mosquito Tributary Creek by Roberts (1984). If channel width increases, standardized spacing lengths w i l l appear shorter even without an actual change in p o o l - r i f f l e proportions. The channel width for Mosquito Main and Tributary Creeks were adjusted to account for recent channel widening. This was accomplished by assuming that those gravel deposits that have been stable for several years, as determined by alder re-colonization (e.g., see Figure 5.4 and 5.5) delineate the approximate channel width before logging. The reduction in width averaged approximately 35%. The distribution of pool-to-pool spacing, with adjusted widths used for the logged basin streams i s presented i n Figure 4.6b. There i s no significant difference between either the logged and unlogged basin pairs or the combined set of streams. It appears from the above results that p o o l - r i f f l e spacing is significantly shorter in some logged channels than their corresponding unlogged pair. However, i t is not clear whether this difference is due simply to an artifact of the analytical procedure. It is also possible that basin morphometric differences confuse the Interpretation of results. Therefore, spacing results are inconclusive. To determine the relative importance of increased sediment supply to pools and r i f f l e s i t is necessary to consider the proportion and shape of each, rather than the spacing of pools and r i f f l e s combined, and avoid using width to standardize results for streams of different sizes. - 75 -4.2 Riffle Amplitude, Magnitude and Relative Relief The v e r t i c a l components of the longitudinal p r o f i l e were examined by considering r i f f l e amplitude, r e l a t i v e r e l i e f and magnitude. Amplitude i s the r i f f l e height after accounting for channel gradient, r e l a t i v e r e l i e f i s the r i f f l e height divided by r i f f l e length and magnitude i s the amplitude divided by the p o o l - r i f f l e spacing length (Figure 4.4). Magnitude i s used to provide a scaled measure of the i n f i l l i n g of pools; smaller magnitude values indicate shallower pools. The r e l a t i v e r e l i e f measure i s actually the channel gradient over the r i f f l e f ront. Larger average r e l a t i v e r e l i e f values indicate that r i f f l e s are r e l a t i v e l y steep and suggest that they are building into the downstream pool. The channel averaged results are summarized i n Table 4.2 and are compared i n Table 4.3. The within basin comparison indicates that between basin comparisons are v a l i d . Amplitude i s scale dependent so that only streams of si m i l a r size should be compared. There i s a s i g n i f i c a n t difference ( a = 0.01) i n amplitude between Government Reach B and Mosquito Main and between Government Reach D and Mosquito Tributary. In both cases the average values are lower i n the Government Creek pairs (Table 4.2). This indicates that bar r e l i e f i s increased i n the logged channels and suggests that r i f f l e s are building but pools are not being f i l l e d . The differences i n basin morphometry between Government and Mosquito Creeks may contribute p a r t i a l l y to thi s difference. There i s no difference i n the average r i f f l e amplitude between Hangover and Bonanza Creeks. - 76 -Table 4.2 Summary, of channel averaged r i f f l e amplitude, magnitude and relative r e l i e f . Channel GA GB GC GD MM MT Hang Bonz Amplitude (m) Average Standard deviation 0.351 0.205 0.305 0.181 0.390 0.249 0.324 0.231 0.667 0.371 0.662 0.273 0.618 0.283 0.681 0.302 Magnitude (m/m) Average Standard deviation 0.0095 0.0163 0.0114 0.0101 0.0128 0.0200 0.0113 0.0112 0.0059 0.0106 0.0074 0.0053 0.0065 0.0119 0.0098 0.0109 Relative Relief (m/m) Average Standard deviation 0.0264 0.0214 0.0229 0.0315 0.0211 0.0295 0.0225 0.0262 0.0257 0.0204 0.0161 0.0259 0.0116 0.0160 0.0229 0.0294 Average channel gradient 0.0090 0.0125 0.0199 0.0207 0.0092 0.0191 0.0125 0.0048 Table 4 . 3 Summary of analysis of variance for r i f f l e amplitude, magnitude and relative r e l i e f . Stream Channels Degrees of Freedom F F C ( 0 . 0 1 ) Decision Compared Between Within Within Basin Comparison: GA, GB, GC, GD Amplitude 3 60 0 . 5 2 4 . 1 3 Accept H 0 Magnitude 3 60 0 . 3 2 4 . 1 3 Accept H 0 Relative Relief 3 60 0 . 7 2 4 . 1 3 Accept H 0 Between Basin Comparison: GB, MM Amplitude Magnitude Relative Relief 42 42 42 1 5 . 9 4 8 . 3 6 0 . 0 0 4 7 .31 7 .31 7 .31 Reject H 0 Reject H 0 Accept H g GD, MT Amplitude Magnitude Relative Relief 24 24 24 1 1 . 6 8 8 . 1 8 0 . 0 4 7 . 8 2 7 . 8 2 7 . 8 2 Reject H 0 Reject H 0 Accept H o Hang, Bonz Amplitude Magnitude Relative Relief 39 39 39 0 . 4 8 0 . 2 7 0 . 2 1 7 . 3 2 7 . 3 2 7 . 3 2 Accept H o Accept H o Accept HQ Note: HQ " there is no significant difference (a = 0 . 0 1 ) in mean amplitude, magnitude and relative relief. - 78 -There i s a s i g n i f i c a n t difference i n r i f f l e magnitude between the Government and Mosquito Creek pairs (Table 4.3). However, the pattern i s reversed In each; the magnitude i s greater i n Government Reach B than Mosquito Tributary, and greater i n Mosquito Tributary than i n Government Reach D (Table 4.2). This indicates that pools i n Mosquito Main Creek have undergone some i n f i l l i n g but this i s not evident i n Mosquito Tributary. The apparent deepening of pools i n Mosquito Tributary i s due to pools associated with deep scour holes around large organic debris pieces. Pool and r i f f l e c h a r a c t e r i s t i c s related to LOD are discussed i n Section 5.2. There i s no s i g n i f i c a n t difference i n r e l a t i v e r e l i e f between any of the unlogged channel p a i r s . This indicates that r i f f l e surface gradients are s i m i l a r i n a l l p a i r s . Based on the l o n g i t u d i n a l p r o f i l e of the eight stream sections, i t appears that a s i g n i f i c a n t difference exists i n r i f f l e amplitude and magnitude between older logged and unlogged basin channels. Although the higher r i f f l e amplitude i n the older logged areas indicates that r i f f l e r e l i e f i s increased, this generalization i s not supported by the scaled measures. There i s an i n d i c a t i o n that pools have been i n f i l l e d i n Mosquito Main but this tendency i s masked i n Mosquito Tributary because of the influence of large organic debris. In addition to spacing and v e r t i c a l dimensions i t i s necessary to consider the proportion of each sequence that consists of pool and r i f f l e morphology. - 79 -4.3 Pool-Riffle Proportions In addition to pools and r i f f l e s , the longitudinal profiles were partitioned into glides and runs (see Section 3.1 for the distinction between each). The length of each type was totalled and expressed as a percentage of the total surveyed length (Table 4.4a). Pools are the most prevalent morphologic unit in Government Creek, with the largest proportion in Government Reach A (60%) and between 47% and 50% pools in Government Reaches B, C and D. Ri f f l e s are proportionally longer than pools in Mosquito Creek. Hangover Creek has more r i f f l e s than pools, but glides and runs which represent intermediate morphologies between pools and r i f f l e s are also important. Combining pools with glides and r i f f l e s with runs, and grouping reaches into pairs (Table 4.4a), i t is evident that pool type morphologies cover approximately 62% of the surveyed reaches in Government Creek compared to only about 40% in Mosquito Creek. Approximately 46% of the stream length surveyed in Hangover Creek is characterized by pools compared to 59% pool length in Bonanza. This reversal in form (more pool length in the logged stream) implicates further the importance of basin morphometry. In both cases the steeper watersheds (Mosquito and Hangover) have longer lengths of r i f f l e . Pool and r i f f l e proportions calculated as a percentage of the total survey length are conventionally reported in f i s h habitat studies. To determine i f significant differences in proportions exist between stream channels i t is necessary to assess the v a r i a b i l i t y in a l l n individual p o o l / r i f f l e ratios (assess E L p /L„ as opposed to - 80 -Table 4.4 Summary of pool and r i f f l e proportions for Individual study channels. 4.4a Individual Channels Stream Channels GA GB GC GD MM MT Hang Bonz Survey length (m) 476 981 697 575 1251 479 1844 2143 Average channel gradient 0.0090 0.0125 0.0199 0.0207 0.0092 0.0191 0.0125 0.0048 Pool (Z) 60.2 47.2 50.2 47.8 28.3 32.5 21.8 51.8 R i f f l e (Z) 39.9 24.1 25.4 37.4 52.1 56.9 37.4 35.2 Glide (Z) 0 14.8 15.0 11.4 13.7 6.3 23.9 6.7 Run (Z) 0 14.0 9.5 3.4 6.0 4.3 16.9 9.7 Pool + Guide (Z) 60.2 62.0 65.2 59.2 41.9 38.8 45.7 58.5 R i f f l e + Run (Z) 39.9 38.1 34.9 40.8 58.1 61.2 54.3 44.9 4.4b P o o l / R i f f l e Ratios by Stream Channel Channel GA GB GC GD MM MT Hang Bonz n 1 S i i-1 n 1.51 1.63 .1.87 1.45 0.72 0.63 0.84 1.30 E L R i i-1 R 1 Z ( r ^ i ) / n 1.16 3.01 3.01 4.43 1.33 0.94 1.52 2.17 i-1 LR - 81 -n n E L / E L (Figure 4.4)). The mean p o o l / r i f f l e ratios are i-1 P i i-1 R i presented in Table 4.4b and are summarized in Table 4.5. It is apparent that no significant difference exists between p o o l / r i f f l e ratios in any of the unlogged or logged channels considered (Table 4.5). The relatively high ratio values for Government Reaches B and C are due to the influence of accumulations of in-channel logs which pond relatively long lengths of water upstream and produce short steep r i f f l e s downstream. These characteristics are considered in Chapter 5.0. 4.4 Summary Pools and r i f f l e s are important components of fis h habitat. They are also channel features which reflect changes in sediment supply to the stream. Therefore, pools and r i f f l e s provide both a useful measure of habitat character and an indirect indicator of the influence of land-use practices on channel conditions. Longitudinal profiles are used to determine i f p o o l - r i f f l e spacing, amplitude and proportions are significantly different in selected paired unlogged and logged stream channels. Although a s t a t i s t i c a l l y significant difference exists in mean pool-riffle, spacings between unlogged and older logged areas, i t i s not possible to infer that the difference Is due to altered sediment supply. Scaled measures of r i f f l e amplitude suggest that r i f f l e s are becoming larger in older logged areas and that i n f i l l i n g of pool zones is Insignificant. No significant difference was detected in p o o l - r i f f l e proportions between logged and unlogged channels. - 82 -Table 4 . 5 Summary of analysis of variance results for p o o l / r i f f l e r a t i o s . Stream Channels Degrees of Freedom F F ( o»0 0 1 ) Decision Compared Between Within Within Basin Comparison: GA, GB, GC, GD 3 60 1.49 4 . 1 3 Accept Ho Between Basin Comparison: GB, MM GD, MT Hang, Bonz 38 31 37 4 . 5 2 3 . 6 0 1 .22 33 55 34 Accept Ho Accept Ho Accept Ho Note: HQ » there i a no s i g n i f i c a n t difference ( a - 0 . 0 1 ) i n mean p o o l - r i f f l e proportions. - 83 -Therefore, i t appears from evaluation of channel scale features that land-use p r a c t i c e s have had minimal influence on morphological c h a r a c t e r i s t i c s important to f i s h use. However, there are a d d i t i o n a l points which must be considered. The low p o o l - r i f f l e spacing values i n d i c a t e that f a c t o r s other than hydraulic s o r t i n g of sediment are important. The i n f l u e n c e of large organic debris has been c i t e d i n a l l aspects of the above a n a l y s i s . Also, i t i s possible that at the channel scale (>20 W^) any change i n pools and r i f f l e s may be damped, or hidden, by averaging. In both cases (LOD and scale considerations) i t i s necessary to conduct studies at a more d e t a i l e d s c a l e . The morphological character of d e t a i l e d study reaches i s addressed i n the next chapter. - 84 -5.0 REACH SCALE MORPHOLOGICAL STUDIES R e l a t i v e l y long lengths of channel were considered i n the previous chapter. In the following sections the morphological character of r e l a t i v e l y short study reaches (less than or equal to 12 channel widths i n length) i s presented and discussed. 5.1 Large Organic Debr is C h a r a c t e r i s t i c s The primary focus of the reach scale studies conducted during low flow conditions i s the influence of large organic debris on channel morphology. Maps of large organic debris placement are presented i n Figures 5.1 through 5.7, i n c l u s i v e . Debris c h a r a c t e r i s t i c s are considered i n Section 5.1. The morphological character of .the detailed study reaches i s discussed i n Section 5.2. 5.1.1 Large Organic Debr i s Quan t i t i e s The t o t a l number of large organic debris pieces i n each reach i s presented i n Table 5.1. The area of the study channel i s used to standardize the data for comparison between reaches. In terms of the number of pieces per unit channel area, the paired reaches reveal no consistent pattern. There are fewer pieces i n Government Reach D than i n Mosquito Tributary, but the opposite pattern occurs between Mosquito Main and the other Goverment Creek reaches. When the streams are combined into logged and unlogged groups, the number of pieces per unit channel area i n logged reaches i s 71 percent of that i n unlogged HORIZONTAL DISTANCE metres - 85 -TOP OF CHANNEL BANK BOTTOM OF CHANNEL BANK STREAM J BACKWATER J ^ ^ P^ T r ; POOL AND RIFFLE DIVISIONS -» THALWEG AND FLOW DIRECTION tnuuuwiw. UNDERCUT BANK • DEPOSITION BOUNDARY LOD BURIED LOD ~~tD)xx»ri DATED DEBRIS. MINIMUM TIME IN CHANNEL LOD CLUSTER NUMBER OF PIECES IN CLUSTER STUMP DISTANCE FROM BOTTOM OF LOD TO WATER SURFACE MEDIAN SEDIMENT SIZE (b-axls, mm) LENGTH AND LOCATION OF SURFACE LINE TRANSECT MEDIAN SEDIMENT SIZE (b-axls. mm) by McNeil Sampler POOLS P i : TRENCH POOL P2: PLUNGE POOL (LOD) P3: LATERAL SCOUR POOL (LOD) P4: LATERAL SCOUR POOL (ROOTWADS) PS: BACKWATER POOL (ROOTWADS) P6: LOD DAMMED POOL P7: UNDERSCOUR POOL (LOD) GLIDE G: GLIDE RIFFLES Ri: LOW GRADIENT RIFFLE (s<0.04) R2: RAPIDS (s > 0.04) R3: CASCADE RIFFLE (Series of boulder steps and small ponds.) STORED SEDIMENT Ola: STORED CLASTIC SEDIMENT (LOD) Cas: STORED CLASTIC SEDIMENT ALONG CHANNEL ZONE. MINOR INFLUENCE OF LOD. STABILITY 1: LOW - not vegetated, sediment moved during annual floods. 2: MODERATE - young alder and grass present, moved during large storms. 3: HIGH - old, well-established moss and trees (deciduous and conifers). TEXTURE b: BOULDER b-axla >256mm-c: COBBLE b-axla 84-266mm g: GRAVEL (PEBBLE) b-axis 2-64mm a: SAND b-axls< 2mm F I G U R E 5 .1: L A R G E O R G A N I C D E B R I S , M O R P H O L O G Y A N D L O N G I T U D I N A L P R O F I L E O F G O V E R N M E N T R E A C H B. - 86 -L A R G E ORGANIC DEBRIS HORIZONTAL DISTANCE met res TOP OF CHANNEL BANK ' BOTTOM OF CHANNEL BANK STREAM - - 7 3 BACKWATER ^ ^ T ^JR ^ POOL AND RIFFLE DIVISIONS THALWEG AND FLOW DIRECTION <to„,iiuiw, UNDERCUT BANK DEPOSITION BOUNDARY LOD BURIED LOD " t6)xx»r. DATED DEBRIS, MINIMUM TIME IN CHANNEL LOD CLUSTER NUMBER OF PIECES IN CLUSTER STUMP nm— DISTANCE FROM BOTTOM OF LOD TO WATER SURFACE e 1 MEDIAN SEDIMENT SIZE (b - ax i s , mm) x x LENGTH AND LOCATION OF SURFACE LINE TRANSECT xx _o MEDIAN SEDIMENT SIZE (b-axis, mm) by McNeil Sampler POOLS P1: TRENCH POOL P2: PLUNGE POOL (LOD) P3: LATERAL SCOUR POOL (LOD) P4: LATERAL SCOUR POOL (ROOTWADS) P5: BACKWATER POOL (ROOTWADS) P6: LOD DAMMED POOL P7: UNDERSCOUR POOL (LOD) GLIDE G: GLIDE RIFFLES R1: LOW GRADIENT RIFFLE (a < 0.04) R2: RAPIDS (a > 0.04) R3: CASCADE RIFFLE (Ser ies of boulder steps and small ponds.) STORED SEDIMENT Das: STORED CLASTIC SEDIMENT (LOD) Caa: STORED CLASTIC SEDIMENT ALONG CHANNEL ZONE, MINOR INFLUENCE O F L O D . STABILITY 1: LOW - not vegetated, aadimant moved during annual f looda. 2: MODERATE - young alder and grass preaent, moved during large atorma. 3: HIGH - o ld, woll- es tab l i shed moaa and treea (daciduoua and coni fers ) . TEXTURE b: BOULDER b - ax i s>256mm c: COBBLE b - a x i s 6 4 - 2 5 6 m m g: GRAVEL (PEBBLE) b-axla 2-64mm a: SAND b -ax is< 2mm F I G U R E 5.2: L A R G E O R G A N I C DEBRIS, M O R P H O L O G Y AND L O N G I T U D I N A L P R O F I L E O F G O V E R N M E N T R E A C H C. L A R G E ORGAN IC DEBRIS HORIZONTAL DISTANCE m e t r e s - 87 -TOP OF CHANNEL BANK BOTTOM OF CHANNEL BANK STREAM BACKWATER J^^T^JR^ POOL AND RIFFLE DIVISIONS THALWEG AND FLOW DIRECTION t t o i i o u i i ^ . UNDERCUT BANK DEPOSITION BOUNDARY LOD BURIED LOD ~ ^ @ X X Y T , DATED DEBRIS. MINIMUM TIME IN CHANNEL LOD CLUSTER NUMBER OF PIECES IN CLUSTER STUMP DISTANCE FROM BOTTOM OF LOD TO WATER SURFACE MEDIAN SEDIMENT SIZE ( b - a x i s . mm) LENGTH AND LOCATION OF SURFACE LINE TRANSECT MEDIAN SEDIMENT 8IZE ( b - a x i s . mm) xx by McNeil Sampler POOLS P i : TRENCH POOL P2: PLUNGE POOL (LOD) P3: LATERAL SCOUR POOL (LOD) P4: LATERAL SCOUR POOL (ROOTWADS) P5: BACKWATER POOL (ROOTWADS) P6: LOD DAMMED POOL P7: UNDERSCOUR POOL (LOD) GLIDE G: GLIDE RIFFLES R1: LOW GRADIENT RIFFLE ( a < 0 . 0 4 ) R2: RAPIDS (a >0.04) R3: C A S C A D E RIFFLE (Ser ies of boulder s teps and small ponds.) STORED SEDIMENT Dsa: STORED CLASTIC SEDIMENT (LOD) C s s : STORED CLASTIC SEDIMENT ALONG CHANNEL ZONE. MINOR I N F L U E N C E O F L O D . STABILITY 1: LOW - not vegetated, sediment moved during annual f loods. 2: MODERATE - young alder and g r a s s present, moved during large storms. 3: HIGH - o ld , w e l l - e s t a b l i s h e d moaa and treea (dec iduous and coni fera) . TEXTURE b: BOULDER b - a x i s >256mm c: C O B B L E b - a x i s 6 4 - 2 5 6 m m g: G R A V E L (PEBBLE) b - a x l a 2-64mm a: SAND b - a x i s < 2mm FIGURE 5.3: LARGE ORGANIC DEBRIS, MORPHOLOGY AND LONGITUDINAL PROFILE OF GOVERNMENT REACH D. - 88 -L A R G E ORGANIC DEBRIS M O R P H O L O G Y R E A C H PROFILE HORIZONTAL DISTANCE met res T O P O F C H A N N E L B A N K B O T T O M O F C H A N N E L B A N K S T R E A M J B A C K W A T E R P O O L A N D . R I F F L E D I V I S I O N S . - — T H A L W E G A N D F L O W D I R E C T I O N ^ I M U L U W . U N D E R C U T B A N K ; D E P O S I T I O N B O U N D A R Y L O D B U R I E D L O D ~X§)xxyri D A T E D D E B R I S , M I N I M U M T I M E I N C H A N N E L L O D C L U S T E R N U M B E R O F P I E C E S I N C L U S T E R S T U M P D I S T A N C E F R O M B O T T O M O F L O D T O W A T E R S U R F A C E e 1 M E D I A N S E D I M E N T S I Z E ( b - a x i s . mm) X X L E N G T H A N D L O C A T I O N O F S U R F A C E L I N E T R A N S E C T xx o M E D I A N S E D I M E N T S I Z E (b-axis. mm) by McNeil Sampler POOLS P I : T R E N C H P O O L P2: P L U N G E P O O L ( L O D ) P3: L A T E R A L S C O U R P O O L ( L O D ) P4: L A T E R A L S C O U R P O O L ( R O O T W A D S ) P5: B A C K W A T E R P O O L ( R O O T W A D S ) P6: L O D D A M M E D P O O L P7: U N D E R S C O U R P O O L ( L O D ) GLIDE G : G L I D E RIFFLES R I : L O W G R A D I E N T R I F F L E (a< 0.04) R2: R A P I D S (a > 0.04) R3: C A S C A D E R I F F L E (Series of boulder steps and amall ponds.) STORED SEDIMENT Dss: S T O R E D C L A S T I C S E D I M E N T ( L O D ) Css: S T O R E D C L A S T I C S E D I M E N T A L O N G C H A N N E L Z O N E . M I N O R I N F L U E N C E O F L O D . STABILITY 1: L O W - not vegetated, sediment moved during annual floods. 2: M O D E R A T E - young alder and grass present, moved during large storms. 3: H I G H - old, well-established moss and treea (daciduoua and conifers). TEXTURE b: B O U L D E R b-axis >266mm c: C O B B L E b-axis 64-256min g: G R A V E L ( P E B B L E ) b-axla 2-64mm a: S A N D b-axia< 2mm FIGURE 5.4: LARGE ORGANIC DEBRIS, MORPHOLOGY AND LONGITUDINAL PROFILE OF MOSQUITO MAIN. - 89 -L A R G E ORGAN IC DEBRIS M O R P H O L O G Y O 5 10 2 0 3 0 m e t r e s 50 Cssl(gcb) Css2[gcb) DIC)ssZ(cs) 76 I W&f Dssllcgb] D(C)ss2(cg) R E A C H PROF ILE o I-< > -1 S >- e S E c i -1 0 3 . 0 1 0 2 . 0 r-101.0 100.0 40 I 60 I 80 I 100 1 2 0 1 4 0 1 6 0 1 8 0 l 2 0 0 I 2 2 0 I 2 4 0 I HORIZONTAL DISTANCE met res TOP OF CHANNEL'BANK BOTTOM OF CHANNEL BANK STREAM ^ BACKWATER POOL AND RIFFLE DIVISIONS • THALWEG AND FLOW DIRECTION < « i i u U i U U U . UNDERCUT BANK DEPOSITION BOUNDARY LOD BURIED LOD ~t§)xx»ri DATED DEBRIS. MINIMUM TIME IN CHANNEL LOD CLUSTER NUMBER OF PIECES IN CLUSTER STUMP DISTANCE FROM BOTTOM OF LOD TO WATER SURFACE MEDIAN SEDIMENT SIZE (b-axis, mm) XX LENGTH AND LOCATION OF SURFACE LINE TRANSECT xx 0 MEDIAN SEDIMENT SIZE (b-axis. mm) by McNeil Sampler POOLS PI: TRENCH POOL P2: PLUNGE POOL (LOD) P3: LATERAL SCOUR POOL (LOD) P4: LATERAL SCOUR POOL (ROOTWADS) P5: BACKWATER POOL (ROOTWADS) P6: LOD DAMMED POOL P7: UNDERSCOUR POOL (LOD) GLIDE G: GLIDE RIFFLES R1: LOW GRADIENT RIFFLE (a < 0.04) R2: RAPIDS (s > 0.04) R3: CASCADE RIFFLE (Series of boulder steps and small ponds.) STORED SEDIMENT Das: STORED CLASTIC SEDIMENT (LOD) Cas: STORED CLASTIC SEDIMENT ALONG CHANNEL ZONE, MINOR INFLUENCE OF LOD. STABILITY 1: LOW - not vegetated, aediment moved during annual flooda. 2: MODERATE - young alder and grass present, moved during large atorma. 3: HIGH - old, well-established moaa and trees (deciduous and conifers). TEXTURE b: BOULDER b-axis >256mm c: COBBLE b-axis 64-256mm g: GRAVEL (PEBBLE) b-axla 2-64mm a: SAND b-axis< 2mm FIGURE 5.5: LARGE ORGANIC DEBRIS, MORPHOLOGY AND LONGITUDINAL PROFILE OF MOSQUITO TRIBUTARY. - 90 -L A R G E ORGANIC DEBRIS P P E D O 5 10 20 30 M O R P H O L O G Y Dss l ( g c ) D s s l ( g c ) R E A C H PROFILE 380 HORIZONTAL DISTANCE metres T O P O F C H A N N E L B A N K * B O T T O M O F C H A N N E L B A N K • ^-p^Z S T R E A M ~ - 7 3 B A C K W A T E R I X ^ P ^ JR ^ P O O L A N D R , F F L E D I V I S I O N S - » . T H A L W E G A N D F L O W D I R E C T I O N iUuttxuHUM. U N D E R C U T B A N K D E P O S I T I O N B O U N D A R Y L O D B U R I E D L O O "X2)xx»r» D A T E D D E B R I S , M I N I M U M T I M E IN C H A N N E L L O D C L U S T E R N U M B E R O F P I E C E S IN C L U S T E R xx STUMP DISTANCE FROM BOTTOM OF LOD TO WATER SURFACE -i MEDIAN SEDIMENT SIZE (b-axls, mm) LENGTH AND LOCATION OF SURFACE LINE TRANSECT xx 0 MEDIAN SEDIMENT SIZE (b-axis. mm) by McNeil Sampler POOLS PI: TRENCH POOL P2: PLUNGE POOL (LOD) P3: LATERAL SCOUR POOL (LOD) P4: LATERAL SCOUR POOL (ROOTWADS) PS: BACKWATER POOL (ROOTWADS) P6: LOD DAMMED POOL P7: UNDERSCOUR POOL (LOD) GLIDE G: GLIDE RIFFLES Hi: LOW GRADIENT RIFFLE (s<0.04) R2: RAPIDS (a >0.04) R3: CASCADE RIFFLE (Series of boulder steps and small ponda.) STORED SEDIMENT Das: STORED CLASTIC SEDIMENT (LOD) Css: STORED CLASTIC SEDIMENT ALONG CHANNEL ZONE. MINOR INFLUENCE OF LOD. STABILITY 1: LOW - not vegetated, sediment moved during annual floods. 2: MODERATE - young alder and grass present, moved during large storms. 3: HIGH - old, well-established moss and trees (deciduoua and conifers). TEXTURE b: BOULDER b-axi8>2S6mm c: COBBLE b-axis 64-256mm g: GRAVEL (PEBBLE) b-axla 2-64mm a: SAND b-axis< 2mm FIGURE 5.6: LARGE ORGANIC DEBRIS, MORPHOLOGY AND LONGITUDINAL PROFILE OF HANGOVER CREEK. - 91 -L A R G E ORGANIC DEBRIS TOP OF CHANNEL BANK BOTTOM OF CHANNEL BANK STREAM j BACKWATER POOL AND RIFFLE DIVISIONS THALWEG AND FLOW DIRECTION « i L L L O i i J A U A < . UNDERCUT BANK DEPOSITION BOUNDARY LOD BURIED LOD ~XS)XX»" DATED DEBRIS, MINIMUM TIME IN CHANNEL LOD CLUSTER NUMBER OF PIECES IN CLUSTER STUMP DISTANCE FROM BOTTOM OF LOD TO WATER SURFACE I o 1 MEDIAN SEDIMENT SIZE (b-axis, mm) x x LENGTH AND LOCATION OF SURFACE LINE TRANSECT xx • MEDIAN SEDIMENT SIZE (b-axla. mm) by McNeil Sampler POOLS P i : TRENCH POOL P2: PLUNGE POOL (LOD) P3: LATERAL SCOUR POOL (LOD) P4: LATERAL SCOUR POOL (ROOTWADS) P5: BACKWATER POOL (ROOTWADS) P6: LOD DAMMED POOL P7: UNDERSCOUR POOL (LOD) GLIDE G: GLIDE RIFFLES R1: LOW GRADIENT RIFFLE (a < 0.04) R2: RAPIDS (a > 0.04) R3: CASCADE RIFFLE (Series of boulder steps and small ponds.) STORED SEDIMENT Das: STORED CLASTIC SEDIMENT (LOD) Css: STORED CLASTIC SEDIMENT ALONG CHANNEL ZONE, MINOR INFLUENCE OF LOD. STABILITY 1: LOW - not vegetated, sediment moved during annual floods. 2: MODERATE - young alder and grass present, moved during large storms. 3: HIGH - old, well-established moss and trees (deciduous and conifers). TEXTURE b: BOULDER b-axia>256mm c: COBBLE b-axis 64-256mm g: GRAVEL (PEBBLE) b-axis 2-64mm s: SAND b-axis< 2mm H O R I Z O N T A L D I S T A N C E m e t r « « FIGURE 5.7: LARGE ORGANIC DEBRIS, MORPHOLOGY AND LONGITUDINAL PROFILE OF BONANZA CREEK. Table 5.1 Number of pieces and volume of large organic debris. Stream Pairs Number of Pieces Total Volume (m ) Study Channel Area (m2) No. per Unit Channel Area Volume per Unit Channel area (m /m ) Mean Volume (m3) Standard Deviation Vol. (m3) Stability Index GB 236 280.04 4,937.5 0.048 0.057 1.19 2.83 high GC 204 306.89 5,268.2 0.039 0.058 1.50 4.82 high GD 186 192.90 4,320.3 0.043 0.045 1.04 2.98 high MM 209 286.46 10,153.7 0.021 0i028 1.37 4.52 low MT 290 234.05 6,169.3 0.047 0.038 0.69 2.33 low Hang 182 395.56 7,653.7 0.024 0.052 2.17 5.22 high ' Bonz 186 537.85 13,653.7 0.014 0.039 3.09 7.08 medium Unlogged Mean 202 293.85 5,544.93 0.038 0.053 1.46 3.93 high Logged Mean 228 352.79 9,992 0.027 0.035 1.55 4.64 low-medium Stability Index: high > 502 LOD covered by Moss medium 20-50% LOD covered by Moss low < 20% LOD covered by Moss - 93 -reaches. The range in large organic debris volumes per unit area of channel i s given Table 5.1. The pattern is similar to that exhibited by the number of pieces. The mean debris loading by volume in logged reaches is 66 percent of that in unlogged reaches. The mean volume of debris pieces for each reach i s presented in Table 5.1. The large standard deviations indicate that the woody material consists of a wide range of sizes. If logging alters the character of woody material, through both removal of large material and break-up of material into smaller pieces (Toews and Moore, 1982), there should be a difference in the size distribution between stream types. Frequency histograms of large organic debris volumes for individual .logged and unlogged reaches are presented in Figure 5.8. Analysis of variance tests (Table 5.2) indicate that the mean large organic debris volume i s significantly (a = 0.01) smaller in Mosquito Tributary than in Government Reach D. Although the same trend i s evident for the other reach pairs the difference i s not significant at the 99 percent confidence l i m i t . There appears to be a higher frequency of very small material in logged channels and more intermediate sized material (0.13 to 3.0 m ) in unlogged streams. There are relatively few very large pieces in either stream type. The intermediate and larger sized material w i l l have the greatest influence on the channel character. This w i l l however depend on the position of the debris with respect to the stream flow. LOD VOLUMES (m 3 ) FIGURE 5.8: FREQUENCY DISTRIBUTION OF LARGE ORGANIC DEBRIS BY VOLUMES. - 95 -Table 5.2 Summary of analysis of variance results for large organic debris volumes. Degrees of Freedom Between Reached Within Reach c(0.01) Decision Within Basin Comparison: GB, GC, GD 631 0.33 4.61 Accept HQ Between Reach Comparison: GB, MM GD, MT Hang, Bonz 442 470 335 4.22 7.58 1.96 6.63 6.63 6.63 Accept HQ Reject H o Accept H o Note: H o ~ There is no significant difference, at a » 0.01 in the mean volume of large organic debris. - 96 -5.1.2 Large Organic Debr i s Arrangement Wi th in the Channel Zone A commonly held opinion in fis h habitat rehabilitation i s that " . . . management plans dealing with large organic debris should strive to duplicate natural processes found in undisturbed basins" (Keller et a l . , 1981, p. 175). Although several previous studies have provided inventories of large organic debris quantities and noted the influence of specific debris pieces on channel morphology (see Section 1.2), there has been relatively l i t t l e work done on the actual placement, or arrangement, of the material within the channel zone. The orientation of material is an important consideration because specific channel features, such as pools, r i f f l e s and gravel bars w i l l depend pa r t i a l l y on the way in which woody material influences stream flow direction. Specific orientations may produce particular features; some may be preferred f i s h habitat. Also, documentation of debris arrangement patterns provides a basis upon which to "duplicate" undisturbed channel conditions. Field investigations indicated that much of the stable large woody material, which influences pool and r i f f l e configuration and stored c l a s t i c sediment, crosses the channel diagonally with the logs pointing either up or down stream. Cross-channel debris appears to be more prevalent in unlogged basins (Figures 5.1 and 5.2) and material oriented parallel to the channel banks appears more frequently in logged basin streams (Figures 5.4 and 5.5). This pattern is thought to be due to the generally smaller nature and greater mobility of debris in logged basin streams. - 97 -To determine whether or not a preferred orientation exists in each stream type, the orientation of each debris piece was measured on the large organic debris maps (Figure 5.1 to 5.7). A l l measurements were made with respect to a center line drawn parallel to the trend of the channel banks; a definition sketch is provided in Figure 5.9. Log direction (pointing up or down stream) was based on log diameter or position of the root wad. The long axis of debris clusters were measured i f i t was not possible to account for individual pieces. I n i t i a l l y , debris arrangement w i l l depend on the mechanism of input from the overbank zone to the stream channel. The main debris input mechanisms are mass-wastage from adjacent hillslopes, tree blow down, near channel debris Input by bank erosion and flotation of woody material from upstream (Keller and Swanson, 1979). A l l appear to be important in the streams studied, although direct mass-wastage was evident in Government Reach D only. The orientation of material entering the stream system by a l l mechanisms other than flotation is determined by considering only material which is more than 1 m above the channel surface. The number of pieces and volume of large organic debris contained within 40° sectors (20° on either side of 0-180° axis) for a l l material more than 1 m above the channel is presented in Figure 5.10. It is evident in Figure 5.10 that the most prevalent orientation of material prior to rearrangement by streamflow is diagonally crossing the channel (between 41° to 140° and 221* to 320°). The most frequent orientation sector is between 100° to 120° and 241° to 261°. However, once the material has entered the stream system and is moved during high - 98 -* * N A ROOTWAD AND LARGE 2 3»227° 3 3 S I 8 0 8 U ORGANIC DEBRIS ORIENTATION REFERENCE LINE — SUB-REACH DIVISION FIGURE 5.9: DEFINITION DIAGRAM FOR LARGE ORGANIC DEBRIS ORIENTATION. - 99 -(0 UJ o LU E u. o oc LU ffi 5 3 Z 3 0 -2 0 -1 0 -n = 22 20 40 I 60 I 80 — I 1 1 1 — 100 120 140 160 360 340 320 300 280 260 240 220 2 0 0 180 ORIENTATION OF LOD (°) 6 0 -4 0 -Ct O -1 Lk O LU 5 Z) _ l O 20-> n = 22 20 40 - r — 60 I 80 I 1 1 1 — 100 120 140 160 360 340 320 300 280 260 240 220 200 180 ORIENTATION OF LOD (°) FIGURE 5.10: ORIENTATION OF LOD BY VOLUME PRIOR TO REARRANGEMENT BY STREAMFLOW. (ONLY LOD>1m ABOVE WATER S U R F A C E ) - 100 -flow events there may be a preferred arrangement along the channel. To determine If a preferred orientation exists, and whether this orientation differs between logged and unlogged basin streams, the orientation of LOD 1 m or less above the channel surface is considered. The volume of large organic debris (excluding material greater than 1 m above the water surface) contained within 40° sectors for each reach is presented in Figure 5.11. It is evident that no strongly consistent pattern emerges when considering only unlogged channels in Government Creek (Figure 5.11a). In general, however, the distribution indicates that maximum volumes occur in sectors between 80° to 160° and 221° to 281°. The preferred orientation is debris placed diagonally across the channel, from either right or l e f t bank, with the large end of the tree on the downstream end and close to the bank. In the logged and unlogged pairs (Figure 5.11b and c), there appears to be a definite shift in preferred orientation from the diagonal in the unlogged towards parallel in the logged streams. The relatively high volumes (approximately 45% of the total material) arranged between 320° and 40° in Mosquito Main and Tributary Creeks indicate that much of the material i s oriented with the large end upstream. The large value (24%) for the 80° to 100° sector in Mosquito Tributary is associated with one major log jam. The debris distributions by orientation sector for Hangover and Bonanza are similar (Figure 5 . l i d ) . The main departure in orientation is an increased amount lying parallel to the channel with the large end downstream in Bonanza. Generally, both streams have a pattern similar * o o _l u. o UJ £ a O > 6 0 -40-2 0 -a) QB QC GD I 20 40 60 - 1 -80 —I 1 1 1— 100 120 140 160 360 340 320 300 280 260 240 2 2 0 2 0 0 180 4 0 -20-C) GD MT I 20 I 0 20 40 60 360 340 320 300 280 260 240 220 200 I 8 0 I 1 1 1— 100 120 140 160 180 6 0 -4 0 -2 0 -b) GB GC — — M M r 20 40 60 - r ~ 80 —I 1 1 1— 100 120 140 160 360 340 320 300 280 260 240 2 2 0 2 0 0 180 4 0 -2 0 -d) HANG BONZ I 1 I I r = j — r ~T-~ 20 —T-40 60 I 80 —I 1 1 1— 100 120 140 160 360 340 320 300 2 8 0 260 240 2 2 0 2 0 0 180 I o I ORIENTATION OF LOD (°) FIGURE 5.11: ORIENTATION OF IN-STREAM LOD BY VOLUME. (DOES NOT INCLUDE LOD>1rn ABOVE WATER S U R F A C E ) - 102 -to that of Government Creek. The similarity in LOD orientation of the logged Bonanza reach is probably due to the abundant large material remaining In the system. Results of Chi Square tests on the number of LOD pieces in each sector show that a significant difference exists in the distribution between each unlogged pair. Anova tests were conducted on the distributions of large organic debris orientation by standardized volume; these are summarized i n Table 5.3. Within basin comparisons indicate that there is no significant difference in the volume of LOD oriented either parallel or perpendicular to the channel between the three reaches in Government Creek (parallel and perpendicular orientations were treated separately in each test; for example, parallel material in Reach B was compared to parallel material in Reaches C and D). Between reach comparisons show that there is significantly more material lying parallel to the channel in Mosquito Main than in Government Reach B. Although there is more material oriented perpendicular to the channel in Government Reach B, the difference i s not significant. The differences in orientation between the other reach pairs is not significant at the 99 percent confidence level. This discussion has considered the volume of material contained in each orientation sector. The distributions based on the number of pieces are similar except that a disproportionately few pieces comprise a large volume in some sectors, particularly 340° to 360°, in the logged stream type. Another feature of large organic debris arrangement is the - 103 -Table 5 .3 Summary of analysis of variance organic debris by volume. results for orientation or in-stream large Degrees of Freedom F F c ( 0 . 0 1 ) Decision Between Reached Within Reach Within Basin Comparison: GB, GC, GD J. 2 / / 2 203 102 1.02 0 . 1 0 4 . 7 1 4 . 8 4 Accept H g Accept H o Between Reach Comparison: GB, MM J. 1 / / 1 85 132 0 . 2 5 9 . 3 9 6 . 9 8 6 . 8 4 Accept HQ Reject H 0 GD, MT J. 1 II 1 93 118 0 . 7 0 1.20 6 . 9 5 6 . 8 5 Accept H g Accept H g Hang, Bonz 1 1 / / 1 58 136 0 . 5 5 1.56 7 . 1 0 6 . 8 3 Accept H g Accept H g Notes: Hg - There is no significant difference (a = 0 . 0 1 ) exists in low orientation between reaches. _/_ - LOD oriented perpendicular to the channel ( 9 0 ° ± 2 0 ° , 2 7 0 ° ± 2 0 ° ) // - LOD oriented parallel to the channel ( 0 ° ± 2 0 " , 180° ± 2 0 ° ) - 104 -tendency for m a t e r i a l to accumulate i n t o large c l u s t e r s . To i n v e s t i g a t e t h i s , the study reaches were p a r t i t i o n e d i n t o zones with length equal to one b a n k f u l l width (the actual width, rather than the modified width, was used i n a l l cases). The volume of material within each zone was c a l c u l a t e d and the standardized d i f f e r e n c e s were plotted (Figure 5.12). Caution must be exercised when i n t e r p r e t i n g these r e s u l t s because the stream lengths are r e l a t i v e l y short ( l e s s than twelve bankful widths). The c l u s t e r spacing f o r the three Government Reaches (Figure 5.12a and b) are s i m i l a r ; spacings of 3.0 to 3.7 widths are longer than pool and r i f f l e spacings of 1.9 to 2.8 widths (Figure 4.5). The width of each c l u s t e r i s l e s s than 1.5 channel widths for a l l reaches. Both the c l u s t e r and pool to r i f f l e spacing f o r Mosquito Main (Figure 5.12a and Figure 4.5) are l e s s than the values observed for the unlogged p a i r . Mosquito T r i b u t a r y (Figure 5.12b) i s characterized by only 1 c l u s t e r i n 8 widths compared to a spacing of 3.7 widths for Government Reach D. Although the Mosquito T r i b u t a r y reach i s r e l a t i v e l y short, the large c l u s t e r spacing value i s s i m i l a r to that observed during l o n g i t u d i n a l p r o f i l e surveys over greater d i s t a n c e s . 5.1.3 Summary of LOD Input, s torage and output c h a r a c t e r i s t i c s A complete summary of large organic debris would provide q u a n t i t a t i v e statements regarding the t r a n s f e r of debris within the study basin. Only a q u a l i t a t i v e comparison of debris input, storage and output components of the LOD budget f o r each stream type i s p o s s i b l e here. - 105 ui S 3 -I O > o o a) A A G O V E R N M E N T R E A C H C: \=3.7 w b a a M O S Q U I T O MAIN : x= 2.7 w b O .© G O V E R N M E N T R E A C H B: X=3.0 w D v / \/ \ • A/ R E A C H M E A N V O L U M E O 30-• (0 0 i_ • 23+ b) /\ / I /. -I / \ A A G O V E R N M E N T R E A C H D: X = 3.7 w D (3 E M O S Q U I T O T R I B U T A R Y : X = 6 . 0 w b R E A C H M E A N V O L U M E 3 -10+ > 30+ e 0 29 + 20- • e. • a co *• e • u mm 0. c) A — - A H A N G O V E R : T = 4 . 5 w b a H B O N A N Z A : X = 2.0 w b " X = M E A N C L U S T E R S P A C I N G IN B A N K F U L L WIDTHS ( w b ) . R E A C H M E A N V O L U M E —S DISTANCE ALONG REACH IN BANKFULL WIDTHS (wb) FIGURE 5.12: CLUSTERING OF LARGE ORGANIC DEBRIS. - 106 -The Input mechanisms are grouped into two types; external input, which includes material delivered to the stream by landslides, windthrow and bank collapse; and internal input, which consists of material floated from upstream. The change in large organic debris input characteristics between logged and unlogged basins can be inferred from the ve r t i c a l distribution of debris (Figure 5.13). It is probable that a l l material located more than 0.5 m. above the channel bed is due to external input mechanisms (this material is supported above the streambed by channel bank, riparian vegetation or other in-stream debris). It is assumed that a l l material on the channel bed has been influenced by streamflow and i s , therefore, an internal input. Although an unknown amount of large organic debris from external input sources may be Included in the internal input category, i t does seem evident that much more external input material is staged to enter the unlogged channels than the logged. In Government Reaches B and C approximately 20% of the total volume of debris is located more than 0.5 m above the channel compared with less than 3% in Mosquito Main (Figure 5.13). The v e r t i c a l distribution is similar for Hangover and Bonanza. When logged and unlogged reaches are combined there is 12% more internal source material in logged channels and a corresponding d e f i c i t in external material. This difference implies that logging and related a c t i v i t i e s influence material input characteristics by decreas-ing the number of large (high volume) pieces of debris entering from overbank areas and increasing the relative quantities of floated material. - 107 -100H GOVERNMENT REACH B 100-1 GOVERNMENT REACH C 100-1 GOVERNMENT REACH D 75 50' 25-<.1 .1-.5 .5-1 <1 75 50 25 <.1 .1-.5 .5-1 >1 75 50-25-<.1 .1-.5 .5-1 >1 100-75 50-* 25-UJ s 3 o > a O 100 75' MOSQUITO MAIN 50 25-<.1 .1-.5 .5-1 >1 HANGOVER CREEK 80 60 40 20 100 75-50-25-MOSQUITO TRIBUTARY 100 75-50 25-I <.1 .1-.5 " .5-1 " >1 BONANZA CREEK <.1 .1-.5 .5-.1 >1 - UNLOGGED LOGGED <.1 .1-.5 .5-1 >1 DISTANCE OF LOD ABOVE CHANNEL SURFACE (m) FIGURE 5.13: VERTICAL DISTRIBUTION OF LARGE ORGANIC DEBRIS. - 108 -The difference i n stored large organic debris between unlogged and logged basin channels has been presented previously (Figures 5.8 and 5.11). There appears to be a small d i f f e r e n c e i n the number of pieces and a s i g n i f i c a n t l y larger proportion of small material i n the logged channels. This i s expected because there i s less large material input from external areas and more small f l o t a b l e debris. The o r i e n t a t i o n of stored material i s also d i f f e r e n t between the two stream types. The increased frequency of debris oriented p a r a l l e l to the logged channel i s a further consequence of altered input mechanisms. The greater mobility of debris i n logged channels appears to lead to c l u s t e r i n g of small debris pieces. The output of large organic debris i s influenced by the change i n both input mechanisms and storage c h a r a c t e r i s t i c s . The material i s less stable i n logged channels, as witnessed by the lower s t a b i l i t y index values (Table 5.1). Increment cores obtained from trees growing on In-channel debris indicate that c e r t a i n pieces have residence times i n excess of 90 years (Figure 5.1, 5.2 and 5.3) and that a l l unlogged channels have material with residence times of more than 40 years. Bonanza Creek has debris with residence times varying between 37 and 68 years (Figure 5.7), but no large organic debris i n either Mosquito Creek reach supports l i v i n g trees. An altered debris budget has several implications for f i s h e r i e s . These include a reduction i n overhead coverage i n logged channels because of less external source material, possible changes i n rearing habitat due to the influence of log o r i e n t a t i o n i n pool shape, and - 109 -possible losses in stable spawning areas because of the increased mobility and reduced sediment trapping efficiency of in-stream debris. The influence of large organic debris on channel morphology, and the consequences of altered debris budget characteristics are examined in the following section. 5.2 The Influence of Large Organic Debris on Channel Morphology Large organic debris can be shown to influence several channel features. Its effect on channel depth, width, gradient, sediment texture and stored volumes, and p o o l - r i f f l e characteristics are considered here. 5.2.1 Channel Depth and Width Keller and Tally (1978) suggested that one role of large organic debris i s to increase the v a r i a b i l i t y in channel depths and widths. The variation of both in each study reach is shown in Figures 5.1 to 5.7. The influence of LOD on depth is assessed by comparing the longitudinal profiles and LOD maps and on width by comparing the morphology and LOD maps. Hangover Creek (Figure 5.6) provides a clear i l l u s t r a t i o n of the influence of LOD because i t has two distinct sections; the downstream half of the reach has below normal debris loading while the upstream half has above average quantities (Figure 5.6c). The longitudinal profile (Figure 5.6) shows the downstream section as one long deep pool (2.5 widths in length), whereas the upstream section alternates between - 110 -short pools and r i f f l e s (combined total equalling less than 1 width). While the channel width i s relatively constant in the downstream section, the mean width varies by almost 30 percent in the upstream zone. The width doubles in certain areas with large amounts of material. The same general pattern of low v a r i a b i l i t y in zones characterized by low volumes of debris is evident in a l l three unlogged study reaches in Government Creek. In the two logged reaches of Mosquito Creek the longitudinal profiles and morphologic maps (Figure 5.4 and 5.5) show much less depth and width v a r i a b i l i t y . The maps and longitudinal profiles show the change in bed topography and channel width associated with large organic debris. In order to assess the v a r i a b i l i t y of depth, the standard deviation of the difference between the actual and average thalweg elevation for each pa r t i a l length of channel was calculated (see definition diagram Figure 5.14). The average elevation was calculated by regression analysis (average elevation is a function of the channel slope and distance upstream). The results are plotted with LOD relative abundance values in Figure 5.15 (actual bankfull widths are used in a l l cases). The positive depth v a r i a b i l i t y values indicate that the channel bed is more irregular than the average and the minus values indicate smooth surfaces (either r i f f l e or pool). Therefore, a stream bed with numerous pools and r i f f l e s per unit length of channel would have a larger positive value than a similar length consisting of one pool and r i f f l e sequence. Much longer reaches are required for a measure of channel width variance - I l l -a) LARGE ORGANIC DEBRIS VARIABILITY: BANKFULL WIDTHS (Wj) X VOL X-AXIS = CHANNEL LENGTH IN BANKFULL WIDTHS. Y-AXIS = DIFFERENCE (%) BETWEEN LOD VOLUME FOR A GIVEN CHANNEL LENGTH AND THE REACH AVERAGED LOD VOLUME. b) WIDTH VARIABILITY: -BANKFULL WIDTHS -CROSS-SECTION TRANSECTS X-AXIS = CHANNEL LENGTH. Y-AXIS = DIFFERENCE (%) BETWEEN CHANNEL WIDTH FOR A GIVEN CHANNEL LENGTH AND THE REACH AVERAGED WIDTH. c) DEPTH VARIABILITY: z o < > UJ -J 111 -I UJ z z < X o II > -REGRESSION LINE BETWEEN DISTANCE AND CHANNEL ELEVATION X = HORIZONTAL DISTANCE IN BANKFULL WIDTHS V A / \ A / \ * l - V - t -\ V X-AXIS= CHANNEL LENGTH Y-AXIS = DIFFERENCE (%) BETWEEN STANDARD DEVIATION FOR GIVEN CHANNEL LENGTH AND REACH AVERAGED STANDARD DEVIATION. FIGURE 5.14: DEFINITION DIAGRAMS FOR VARIABILITY OF LARGE ORGANIC DEBRIS VOLUMES, CHANNEL WIDTHS AND DEPTHS. FIGURE 5.15: VARIABILITY OF CHANNEL DEPTH, WIDTH AND LARGE ORGANIC DEBRIS. FIGURE 5.15: (cont'd) - 114 -FIGURE 5.15: (cont'd) - 115. -to be c a l c u l a t e d . The estimate of width v a r i a b i l i t y used i s the diff e r e n c e between the mean width for each unit length of reach (equal to one bankfull width) and reach averaged width (Figure 5.14). The reach averaged width i s the area of the channel divided by reach length. Width and LOD v a r i a b i l i t y are plotted together i n Figure 5.15. The general pattern evident i n Figure 5.15 i s for both depth and width v a r i a b i l i t y to increase with an increase i n LOD abundance. Although the pattern i s f a i r l y consistent i n Government Reaches B and D and Hangover, the r e l a t i o n i s s i g n i f i c a n t at the 99 percent confidence l i m i t for the former reach only (Table 5.4a). The lack of high p o s i t i v e c o r r e l a t i o n c o e f f i c i e n t s for Government Reach C and Mosquito Main and Tributary suggests that other factors besides LOD abundance exert an important influence over depth and width v a r i a b i l i t y . Comparison of Figures 5.1 through 5.7 and 5.15 shows that much of the departure between LOD abundance and channel width and depth trends appears due to LOD o r i e n t a t i o n . The large separation between depth v a r i a b i l i t y and LOD abundance at a distance of s i x widths i n Goverment Reach C (Figure 5.15a) i s due to a very deep, but short scour pool beneath one piece of debris which diagonally crosses the channel and i s securely imbedded i n both banks (Figure 5.2). Several other examples which exhibit t h i s pattern of high depth and width v a r i a b i l i t y values associated with normal or below average LOD amounts appears related to diagonally oriented material (e.g., Mosquito Main and Tributary; Figures 5.4, 5.5 and 5.15b). In the opposite s i t u a t i o n , where low depth and width v a r i a b i l i t y - 116 -values correspond to high values of LOD abundance, the channel zones are characterized by debris oriented predominantly parallel to the channel (e.g., Bonanza, Mosquito Main and Tributary; Figures 5.7, 5.4, 5.5 and 5.15). In order to evaluate the influence of LOD orientation on channel character, the volume of Individual debris pieces in each unit length of channel was adjusted by i t s angle to the flow di rection (see Table 5.4 for d e t a i l s ) . Correlation coefficients relating LOD orientation to channel depth and width v a r i a b i l i t y are summarized in Table 5.4b. Although the relations are better overall they remain, with the exception of Government Reach B, insignificant at the 99 percent confidence lev e l . Because the study lengths are relatively short, the placement of unit lengths may influence the results. Therefore, i t appears that LOD quantities and orientation influence channel shape. In situations with abundant LOD and diagonally crossing material there is increased local bank erosion and l a t e r a l scour of the bed. In the logged channel where debris is oriented predominantly parallel to the channel, both width and depth are more consistent. Large pieces of debris lying parallel to the channel often protect the channel walls and are occasionally incorporated into the bank (e.g., upstream end of Mosquito Tributary, Figure 5.5). It Is also evident that more work, particularly over longer lengths of channel, is required to determine conclusively the level of importance to be attributed to large organic debris. As indicated in Section 4.1, both study reaches in Mosquito Creek - 117 -Table 5.4 Summary of the relation between large organic debris characteristics and channel width and depth variability. A. LOD Abundance Related to Channel Width and Depth Study Reach Pairs Correlation Coefficients (r) N rc(0.01) Significance of relation Relating LOD Abundance and: Depth Variability Width Variability GB 0.80 0.88 12 0.71 S GC -0.18 -0.11 12 0.71 NS GD 0.51 0.50 11 0.74 NS MM 0.16 0.11 7 0.86 NS MT 0.0 0.42 8 0.83 NS Hang 0.76 0.47 9 0.80 NS Bonz 0.74 -0.42 7 0.86 NS B. LOD 2 Orientation Related to Channel Width and Depth GB 0.85 0.78 12 0.71 S GC 0.22 - .05 12 0.71 NS GD 0.43 .45 11 0.74 NS MM 0.16 0.11 7 0.86 NS MT 0.0 0.66 8 0.83 NS Hang 0.76 0.55 9 0.80 NS Bonz 0.73 -0.19 7 0.86 NS Notes: 1. Tests i f a significant relation exists between the independent variable (LOD abundance or orientation) and the dependent variables (channel depth and width); S - significant relation (a - 0.01); NS - not significant relation ( a « .01). 2. LOD orientation refers to the angle of LOD pieces with respect to stream flow direction and is n calculated as ^Ej VsinS; where V - volume of each LOD piece, 8 = angle of LOD piece, n » number of pieces In each unit length. N » Number of unit lengths (bankfull widths) used tn correlation analysis. r c • c r i t i a l values of r at probability level of 99 percent. - 118 -have experienced o v e r a l l channel widening since logging. Presently channel widths appear to be narrowing as evidenced from vegetated gravel deposits (Figures 5.4 and 5.5). A consequence of the altered channel width i n terms of f i s h habitat i s the loss of undercut bank areas. A summary of cutbank areas for a l l study reaches i s given i n Table 5.5. It appears that as channel widening progressed the amount of area characterized by undercut banks has diminished. Both the area and volume of cutbanks i s much less (<5%) i n Mosquito Main compared to Government Reach B. The area of overhang i n Mosquito Tributary i s 85 percent that of Government Reach D. The pattern i s reversed i n the Hangover and Bonanza pair where the former has only 80 percent of the area of undercut compared to the l a t t e r reach. S t a t i s t i c a l testing i s not possible because there are i n s u f f i c i e n t data to*1 c a l c u l a t e the within reach variance i n the Mosquito Creek streams. 5.2.2 Pool and R i f f l e Characteristics The types and configuration of pools and r i f f l e s are presented i n Figures 5.1 to 5.7. The c l a s s i f i c a t i o n of pool and r i f f l e types i s based on the scheme developed for f i s h e r i e s studies by Bisson et a l . (1982). S l i g h t modifications were adopted; for instance, a pool formed by scour under a debris piece (P7) was added. Although the general pool and r i f f l e breaks were accurately surveyed i n the f i e l d , the deline a t i o n of s p e c i f i c pool and r i f f l e types (e.g., back channel pool) was i n part made afterwards with the aid of photographs and f i e l d notes. Therefore, the boundaries are not exactly placed but the general morphological character of each reach has been preserved. - 119 -Table 5.5 Summary of channel cutbanks. Stream Reach Pairs Area of Overhang 1(Area/30 m channel; m2/30 m) Volume of Overhang and Undercut2 (Volume/30 m channel; m3/30 m) Length of Study Reach (m) GB 6.23 3.20 255 GC 3.51 1.63 261 GD 5.40 2.88 216 MM 0.26 0.13 291 MT 4.60 1.42 209 Hang 8.16 5.10 315 Bonz 10.37 5.44 324 Unlogged 5.83 3.20 Logged 5.08 2.33 Notes: 1. Area of overhang Is calculated as the product of the overhang width and the longitudinal length of undercut. 2. Volume of overhang and undercut is calculated as the product of overhang width, undercut height (i.e., distance from overhang lip to the channel bed) and the longitudinal length of undercut. - 120 -The proportion of the t o t a l channel area of each morphological type i s included i n Table 5.6. These area values are streamflow stage dependent, hence i t i s d i f f i c u l t to compare reaches. However, the comparison of the type of feature most prevalent i n each reach i s appropriate. The unlogged channels are characterized by r e l a t i v e l y more l a t e r a l scour pools and low gradient diagonal r i f f l e s . Generally, i n the logged channels there i s an increase i n the r e l a t i v e importance of scour pools associated with root wads (P4). Also, there are more trench pools (PI) i n Mosquito Main and side channel pools (P5) i n Bonanza Creek. The s h i f t towards pools associated with root wads i s due to debris oriented p a r a l l e l to the channel with the attached root wad oriented perpendicular to the flow d i r e c t i o n , (see, f o r example Mosquito Main, Figure 5.4). This d e b r i s , which i s t y p i c a l l y a large root wad attached to a short stump (cut during logging), entered the channel zone as a r e s u l t of bank erosion and channel widening. The pool i s a scour hole around the wad and c o n s t i t u t e s a small break i n the r i f f l e (small pool surrounded by long r i f f l e ) . This type of pool i s the most frequently occurring i n Mosquito T r i b u t a r y (Figure 5.5) and provides the only deep zones i n the thalweg p r o f i l e . Trench pools are more abundant i n areas with minimal large organic debris (Figure 5.3 and 5.4). Low gradient r i f f l e s (Rl) predominate i n the logged channels. The proportion of combined pools, g l i d e s and r i f f l e s i s presented i n Table 5.6. Ignoring the problem of comparable flow-stage, and assuming that a l l mapping was done at "low-flow" conditions, i t appears that pool type morphology i s s l i g h t l y more common i n unlogged reaches - 121 -Table 5.6 Area and shape of pools and r i f f l e s , Stream Pair GB GC GD MM MT Hang Bonz Total Area of Morphological Type (%) Morphology 2 PI 6.3 12.6 P2 0.8 0.5 P3 61.9 72.8 29.3 21.7 4.5 39.5 23.2 P4 1.1 14.5 15.9 2.9 P5 ' 1.3 0.5 0.5 16.7 P6 1.0 • 1.2 0.4 P7 2.5 1.2 0.4 G 6.0 4.5 13.3 9.4 9.8 16.0 RI 30.2 22.1 47.3 29.4 63.8 37.7 32.3 R2 0.8 12.6 4.9 5.5 2.2 1.8 Summary Pool 63.1 77.9 35.6 52.4 21.4 53.0 49.9 Glide 6.0 0 4.5 13.3 9.4 9.8 16.0 Riffle 30.9 22.1 60.0 34.3 69.3 37.0 34.1 Mean Shape Index1 PI 0.25 0.29 P2 1.75 3.22 P3 0.45 0.46 0.58 0.42 0.42 0.89 1.12 P4 0.37 0.77 0.70 0.70 P5 0.44 0.39 0.30 0.72 P6 5.39 0.14 0.15 0.52 1.60 P7 3.14 ' 5.45 0.79 G 0.41 0.10 0.50 1.59 0.22 0.47 RI 0.52 0.33 0.38 1.42 0.27 0.39 0.33 R2 0.84 0.52 0.73 0.34 0.50 0.76 Notes: 1. Shape Index area of morphological feature A maximum length of feature (in downstream direction) 2 L if shape index » 1; feature with equilateral sides i f shape index » <1; feature is long and narrow If shape index • >1; feature is short and wide 2. Pools, r i f f l e s and glides are described in Figures 5.1 to 5.7. - 122 -and g l i d e and r i f f l e morphology i s more prevalent i n logged basin channels. To consider the shape of each morphological feature, a shape index was calculated and tabulated (Table 5.6). Several of the mean shape index values l i s t e d i n Table 5.6 are not good averages because an i n s u f f i c i e n t number of features was measured. The features with low area values are not properly represented by the mean shape index. In general, the range of shape index values for the l a t e r a l scour pools (0.42 to 0.58) i s r e l a t i v e l y low for a l l Government and Mosquito Creek reaches. The morphological maps show that the pool type i s pr o p o r t i o n a l l y longer than wide. The l a t e r a l scour pools are r e l a t i v e l y short i n both Hangover and Bonanza. This i s due to several small, wide pools associated with debris diagonally crossing the channel. The pools i n Mosquito Main and Tributary associated with scour around root wads, are wide and short (Figures 5.4 and 5.5) with shape index values of 0.77 and 0.70, r e s p e c t i v e l y . Trench pools, which are not influenced by large organic debris, are considerably longer than wide, as seen i n Government Reach D (shape index of 0.25) and Mosquito Main (shape index of 0.29). The shape of the low gradient r i f f l e s i s v a r i a b l e (Table 5.6). Mosquito Tributary has the longest r i f f l e s (with a mean shape index equal to 0.27 and a range of 0.10' to 0.57) and Mosquito Main has the shortest r i f f l e s (with a mean index equal to 1.42 and a range of 0.17 to 3.77). There i s a tendency f o r r i f f l e s to be located i n areas characterized by low volumes of large organic debris. This suggests that much of the organic debris i s transported over the r i f f l e during - 123 -high flow events and deposited downstream. Scour beneath and around the debris occurs producing pools at both high and moderate flows. R i f f l e s , therefore, are located on both the upstream and downstream end of zones characterized by abundant large organic debris volumes. Examples of t h i s are seen i n a l l of the reach morphology maps. 5.2.3 Sediment Texture The texture of c l a s t i c sediment i n proximity to large organic debris was not r i g o r o u s l y measured. A q u a l i t a t i v e assessment based on the morphology maps (Figures 5.1 to 5.7) i s presented here. Results from t e x t u r a l a n a l y s i s of surface, subsurface and McNeil samples, summarized on the morphologic maps, are d e t a i l e d i n Appendix C. The s i z e d i s t r i b u t i o n s i n d i c a t e _that the sediments are well sorted. The c l a s t s are sub-angular to rounded. The general pattern of sediment texture i s characterized by r e l a t i v e l y coarse material immediately upstream of large accumulations of debris with a t a i l of f i n e textured material extending downstream. Government Creek Reach C provides an example of t h i s pattern. At the upstream end of t h i s reach, and upstream of the large d i a g o n a l l y c r o s s i n g d e b r i s , cobble s i z e sediment (median b-axis length equal to 72 mm) predominates. Downstream of the d e b r i s , the sediment texture i s f i n e r c o n s i s t i n g p r i m a r i l y of g r a v e l . Also i n Government Reach C, the large debris step (approximately 1 m high, see Figure 4.1) appears to i n f l u e n c e sediment texture. The cobble and gravel textured material deposited i n mid-channel upstream of the LOD step i s considerably - 124 -coarser than the sediment found fur t h e r upstream (40 mm opposed to 24 mm upstream). A d d i t i o n a l examples of t h i s general pattern are seen i n Government Reach D at 40 m upstream from the reach beginning. In t h i s case r e l a t i v e l y stable cobbles, gravel and boulders p r e v a i l upstream of the debris while only cobbles and gravel occur downstream. Hangover has several s i m i l a r examples; at the f i r s t major debris accumulation (200 m upstream, Figure 5.6) gravel and cobble sized sediment are most abundant upstream while g r a v e l , sand and cobble textures extend downstream. A s i m i l a r pattern e x i s t s i n the logged study reaches whenever LOD i s oriented across the channel such that stream flow d i r e c t i o n i s a l t e r e d . However, debris i n t h i s arrangement occurs l e s s frequently i n logged channels, hence, the sediment texture pattern i s l e s s v a r i a b l e . 5.2.4 Channel Gradient and Stored Sediment Volumes Before considering the sediment stored i n each d e t a i l e d study reach, i t i s necessary to re-examine the channel scale l o n g i t u d i n a l p r o f i l e s presented i n Chapter 4. From these p r o f i l e s i t i s evident that debris steps (defined as a LOD piece which crosses the channel and a l t e r s both the water surface and bed e l e v a t i o n ; see Section 3.1) exert a considerable influence on channel gradient l o c a l l y . In Government Creek, LOD steps account for between 6.7 and 13.4 percent of the t o t a l drop In bed e l e v a t i o n (Table 5.7). Large organic debris steps are not present i n e i t h e r of the surveyed channels i n Mosquito Creek. The l o n g i t u d i n a l p r o f i l e s (Figures 4.1 to 4.3) i n d i c a t e that q u a n t i t i e s of stored sediment occur immediately upstream of the debris step. In - 125 -Table 5.7 Percentage change In channel elevation due to large organic debris steps (channel scale studies). Government Watersheds Mosquito Hangover Bonanza 2 Reach A B C D Main Tributary A B Contributing Area (km2) 16.2 6.9 6.8 3.9 10.5 5.4 20.2 65.4 45.2 Stream Order1 4 3 4 3 3 3 4 5 4 Average Gradient 0.0090 0.0125 0.0199 0.0207 0.0092 0.0191 0.0125 0.0034 0.0065 Total Length of Survey (m) 476 981 696 575 1251 479 1852 1752 391 No. of LOD Steps 3 4 7 3 0 0' 5 0 4 Z Change In Bed Elevation due to LOD Steps 6.7 7.7 13.4 • 8.7 0 0 9.3 0 14.5 Notes: Strahler ordering based an 1:15,000 topographic maps and air photographs. 2 Bonanza A is below the Bonanza-Hangover confluence Bonanza B is above the Bonanza-Hangover confluence. - 126 -Mosquito Main and Tr i b u t a r y (Figure 4.2) very large amounts of sediment are stored upstream of major, but less frequently occurring log jams. In both unlogged and logged streams, l a r g e organic debris exerts considerable c o n t r o l over the l o n g i t u d i n a l p r o f i l e , i n f l u e n c i n g morphology by s t o r i n g sediment which reduces channel gradients upstream of the debris and promotes channel widening. In unlogged streams slope appears to be adjusted l o c a l l y to a combination of log jams and d i s c r e t e debris steps while i n logged channels, l o c a l slope i s influenced p r i m a r i l y by log jams. The s t a b i l i t y of the unlogged channel should,therefore, be greater because sediment i s stored more evenly along the channel with the many log steps and minor log jams b u f f e r i n g the e f f e c t s of large f l o o d flows and f a i l u r e of i n d i v i d u a l b a r r i e r s . On the other hand, large floods i n logged channels may dis p l a c e infrequent debris obstructions r e s u l t i n g i n major r e d i s t r i b u t i o n of sediment. The d e t a i l e d study reaches were examined i n order to quantify the volumes of sediment stored i n r e l a t i o n to large organic d e b r i s . The LOD maps (Figures 5.1 to 5.7) and large scale topographic maps (1:200) were used to c a l c u l a t e the volume and p o s i t i o n of stored sediment. These r e s u l t s are presented i n Table 5.8. Both the b a n k f u l l width and channel length have been used to standardize the reaches f o r comparison. The use of the l a t t e r method i s consistent with most other published r e s u l t s but i t can be used f o r comparison purposes only when channel gradients and widths are s i m i l a r . Review of Table 5.8 i n d i c a t e s that there i s approximately one h a l f as many storage s i t e s per channel length i n the Mosquito Creek Table 5.8 Volumes of sediment related to large organic debris. Stream Reach Bankfull Reach Total Sediment Storage Sediment Storage Position 1 Reach Length . Width, Pairs W Wb Total per Reach Total per W^  Total/30 ra Channel Mid-Channel Side Channel No. of Vol. No. of Vol. No. of Vol. Downstream Upstream Downstream Upstream Storage Storage Storage Sites Sites Sites (m) (m) (m2) (m3) (No/W.) b (m3/Wb) (No/30 m) . (m3/30 m ) (*) « ) <Z) « ) GB 244 20.2 4,938 8 148.6 0.40 7.36 0.98 17.48 46.5 23.0 30.5 GC 250 21.1 5,268 8 363.9 0.38 12.25 0.96 41.82 5.0 20.0 36.3 38.7 CD 230 18.8 4,320 5 138.8 0.27 7.38 0.65 19.28 36.6 63.4 MM 270 37.8 10,154 4 291.1 0.11 7.70 0.44 30.01 35.5 64.6 MT 223 27.7 6,169 2 240.2 0.07 8.67 0.27 34.47 100.0 Hang 261 29.3 7,654 9 430.3 0.31 14.69 1.03 40.98 56.0 13.3 30.6 Bonz 300 45.4 13,654 6 1,074.6 0.20 23.67 0.60 99.50 30.3 22.2 47.6 Note: 'sediment storage position refers to the location of sediment accumulation; downstream and upstream are with respect to the controlling LOD. - 128 -reaches as i n those of Government Creek. Bonanza Creek has approximately one t h i r d the number of storage s i t e s compared to Hangover. There i s no apparent d i f f e r e n c e i n the volume of stored sediment between Government and Mosquito Creek when considering q u a n t i t i e s standardized by channel width; Bonanza has almost 40% more than Hangover. When volumes are standardized by channel lengths of 30 metres there appears to be more sediment stored along logged reaches. Also, i n logged channels there i s more sediment stored upstream of debris c l u s t e r s and r e l a t i v e l y l i t t l e m a t e r i a l stored on the downstream s i d e . In contrast, i n the unlogged reaches there are considerable amounts of sediment stored on the downstream side of debris pieces. Debris producing a step u s u a l l y c o n s i s t s of pieces greater than 2 m^  i n volume oriented predominantly between 80° to 130° and 230° to 280°. As the stream flow follows the debris and crosses the channel, sediment accumulates on both sides of the d e b r i s . Both channel and reach scale studies suggest that logged streams are characterized by l a r g e r volumes of sediment stored i n fewer zones along the channel. The suggestion that t h i s leads to les s stable channels i s supported by the gene r a l l y low s t a b i l i t y index r a t i n g f o r logged channels and high r a t i n g s f o r uniogged channels (Table 5.1). The l a r g e r volumes of sediment upstream of debris jams, with the associated lower channel gradients, leads to an increased prevalence of de-watering during low flows i n logged channels. For example, during low flow conditions i n Mosquito T r i b u t a r y , surface water i s often found only i n pools associated with stumps. S i m i l a r s i t u a t i o n s occur i n Bonanza Creek. - 129 -5.2.5 Summary In t h i s s ection the influence of large organic debris on channel morphology has been considered. I t i s concluded that both the abundance and o r i e n t a t i o n of the debris are important f a c t o r s i n f l u e n c i n g morphology. Section 5.1 in d i c a t e d that both f a c t o r s are, i n turn, a f f e c t e d by some logging a c t i v i t i e s . In zones characterized by abundant debris which d i a g o n a l l y crosses the channel, both the width and depth v a r i a b i l i t y are increased. Also, sediment i s stored both upstream and downstream of the debris; q u a l i t a t i v e evidence i n d i c a t e s that the downstream sediment i s f i n e r i n texture. The unlogged streams have more frequent LOD steps and sediment storage zones which tends to increase channel s t a b i l i t y . This suggests that f i s h habitat i s more favourable i n unlogged channels. In streams with more LOD oriented p a r a l l e l to the channel, u s u a l l y the logged streams, width and depth are l e s s v a r i a b l e . Pools are more frequently associated with root wads and stumps. In some cases LOD becomes incorporated into the channel bank and appears to lead to narrowing of the channels. Sediment textures are l e s s v a r i a b l e and f i s h h a bitat seems l e s s favourable because of the gene r a l l y lower d i v e r s i t y of features, the Increased chance of large volumes of sediment p e r i o d i c a l l y moving through the channel and the increased occurrence of channel de-watering. - 130 -6.0 HABITAT-STREAMFLOW STUDIES In the previous chapters the channel form was evaluated. In the following sections the flow conditions associated with s p e c i f i c habitat features i n each study reach are considered. The physical parameters relevant to salmonid habitats are flow v e l o c i t y , channel width and depth, substrate composition and water temperature (Bovee, 1978). Only the f i r s t three parameters are considered e x p l i c i t l y here. Habitat i s characterized by flow and channel conditions, therefore i t i s appropriate to investigate t h e i r i n t e r r e l a t i o n s , commonly referred to by the term hydraulic geometry; this i s considered i n Section 6.1. In section 6.2 an alterna t i v e approach which, unlike hydraulic geometry r e l a t i o n s , does not r e l y on average conditions, i s presented. 6.1 Hydrau l i c Geometry The hydraulic geometry of a stream channel expresses the change i n water surface width, mean depth and mean v e l o c i t y (Figure 6.1) i n response to changing discharge at either a single cross-section (at-a-station hydraulic geometry) or associated with downstream increases i n drainage basin areas (downstream hydraulic geometry). Mosley (1983) has considered such relations i n terms of f i s h habitat. Water surface width i s important because i t represents the maximum area of substrate available and i s equal to water surface area per unit length of channel. Cross-sectional area, the product of water surface width and mean flow depth, i s important because i t i s equivalent to - 131 -FIGURE 6.1: DEFINITION DIAGRAM OF CHANNEL GEOMETRY. - 132 -water volume per unit length of channel and represents an index of av a i l a b l e f i s h h a b i t a t . Hydraulic geometries are generally expressed as simple power functions as follows: W = aQ b s x d* = cQ f V* = kQ m A = AQP = ( a x c ) Q b + f where: W = water suface width s d* = mean depth = A/Ws V* = mean v e l o c i t y = Q/A A = channel c r o s s - s e c t i o n a l area Q = discharge The exponents (b,f,m) and the c o e f f i c i e n t s (a,c,k) are derived s t a t i s t i c a l l y . From the c o n t i n u i t y equation (Q = Wsd*V*) i t i s evident that the exponents w i l l sum to unity and the c o e f f i c i e n t s w i l l have a product of unity, hence there are only two independent r e l a t i o n s . A t - a - s t a t i o n r e l a t i o n s r e l a t e Ws,d* and V* to changing discharge over time. In contrast, downstream hydraulic geometry r e l a t i o n s r e l a t e these v a r i a b l e s to a reference discharge at s i t e s located p r o g r e s s i v e l y downstream. As i n d i c a t e d i n Section 3.2.2, the stream gauging cross-sections upon which the a t - a - s t a t i o n r e l a t i o n s are based, are located i n the downstream t h i r d of a pool i n each study reach. The a t - a - s t a t i o n - 133 -relations, determined for a l l study sites with the exception of Government Reach B, C and D (due to insufficient data), are presented in Appendix D - Figures D.l through D.5. The exponents and coefficients are summarized i n Table 6.1. The exponents l i s t e d in Table 6.1 indicate that as discharge increases, the largest corresponding adjustment occurs in velocity. Width and depth increase at slower rates. Although these relations provide specific hydraulic information important to habitat characterization, they represent average conditions for one location within a single habitat type. That i s , width, depth and velocity can be estimated for the downstream end of trench pools at different discharges but extrapolation to other areas, particularly to non-trench pool habitats, is not appropriate. Therefore, at-a-station relations enable estimates to be made regarding hydraulic conditions but the relations are too specific to represent the reach or entire stream. At-a-station relations are often the only flow data available for fisheries studies (eg. Shirvell, 1981). Downstream hydraulic geometries provide a basis upon which to estimate the average hydraulic conditions at various locations within the stream system. The development of downstream relations required more time than was available for the present study but previous work has shown that certain relations are relatively consistent. It is possible to use published relations to estimate channel widths, mean depth and mean velocity at different locations but this approach does not provide details within particular reaches. Thus, at-a-station relations provide Table 6.1 At-a-station hydraulic geometry exponents and c o e f f i c i e n t s . W s a b e f k m o P Government 18.06 0.28 0.15 0.05 0.37 0.67 2.70 0.33 MM 9.05 0.14 0.30 0.20 0.38 0.66 2.67 0.34 MT 9.32 0.22 0.19 0.17 0.58 0.61 1.74 0.40 Hang 11.77 0.13 0.42 0.17 0.20 0.70 4.90 0.30 Bonz 9.66 0.19 0.56 0.08 0.19 0.73 5.36 0.27 South B.C. Coast 2 .11 .39 .49 3 Central Rocky Mountains .05 0.43 0.52 W = aQ b s d * = eQ f A = oQ P Notes: metric units from Ponton (1972) 3 from Heede (1972) - 135 -data for a range of discharges at one s i t e and downstream hy d r a u l i c geometries provide information f o r d i f f e r e n t l o c a t i o n s at one discharge. Another approach which combines aspects of both the above methods i s the use of a s e r i e s of cross-sections within one reach. The h y d r a u l i c adjustments for a l l cross-sections at each discharge are averaged. These reach averaged h y d r a u l i c geometries include both temporal and s p a t i a l aspects of the flow conditions along the channel. This method has been used i n the Hangover and Bonanza Creek reaches but not for Mosquito Creek because i t i s not possible to c a l c u l a t e the corresponding r e l a t i o n s f o r Government Creek. Stream surveys of flow v e l o c i t y were not conducted at a l l cross-sections f or a range of discharges. Instead, the reach averaged h y d r a u l i c geometries were based on d e t a i l e d topographic maps (1:200) with water surface elevations f or each discharge superimposed. Cross-sections were spaced evenly along each reach (53 and 62 cro s s - s e c t i o n s i n Hangover and Bonanza Creeks r e s p e c t i v e l y ) and width and depth were measured. This work forms the basis of section 6.2 and w i l l be discussed therein; the method i s d e t a i l e d i n s e c t i o n 3.2.2. The v e l o c i t y r e l a t i o n i s c a l c u l a t e d based on width and depth. The reach averaged hydraulic geometries for the Hangover and Bonanza Creek study reaches are given i n Figures 6.2 and 6.3. There appear to be only minimal d i f f e r e n c e s between the two reaches. In both, as discharge increases the v e l o c i t y increases at a greater rate r e l a t i v e to width and depth, i n a l l sections of the reach. These r e l a t i o n s i n d i c a t e that f or t h i s unlogged-logged stream p a i r there i s - 136 DISCHARGE (*>«-') FIGURE 6.2: REACH AVERAGED HYDRAULIC GEOMETRY: HANGOVER CREEK. QISCHAROC (m>.H) FIGURE 6.3: REACH AVERAGED HYDRAULIC GEOMETRY: BONANZA CREEK. - 137. -very l i t t l e difference in averaged hydraulic conditions. The reach averaged hydraulic relations provide mean conditions for the reach and therefore, mask much within reach v a r i a b i l i t y . Figure 6.4 gives an example of the hydraulic conditions in an adjacent trench-pool and low gradient r i f f l e in Hangover Creek. As discharge increases both velocity and width increase more quickly in pools than in r i f f l e s . The opposite trend is evident for depth. Flow conditions become more uniformly r i f f l e - l i k e through the system as discharge increases. Information contained in Figure 6.4 is more useful in terms of f i s h habitat evaluation and can be used directly in conjunction with habitat probability of use curves (Bovee, 1978). This approach i s considered in the following section. Another point worth noting from Figure 6.4 regards habitat inventory schemes. If habitat, units are delineated on a hydraulic basis (often the case at higher streamflow stages when the substrate is not visible) then the same discharge frequency must be used in any comparison of two streams. If the discharge changes during the time that the two inventories are being compiled i t is not possible to compare the percentage of each habitat unit in both streams; as discharge increases a larger proportion of the channel w i l l be inventoried as r i f f l e . In such a case the apparently larger area of r i f f l e between streams is simply an ar t i f a c t of the sampling procedure. In summary, although hydraulic geometries provide information relevant to flow conditions for the entire stream, specific reach and individual cross-section their usefulness In terms of habitat evaluation - 138 -DISCHARGE ( m 3 s H ) FIGURE 6.4: HABITAT AVERAGED HYDRAULIC GEOMETRY: HANGOVER CREEK. - 139 -i s l i m i t e d because they express average hydraulic conditions only. However, the averaged conditions can be used to determine whether two streams respond d i f f e r e n t l y to an increase i n discharge. There appears to be very l i t t l e difference i n hydraulic conditions between Hangover and Bonanza Creeks i n d i c a t i n g that there are s i m i l a r i t i e s i n channel form and flow character. The logged channel has not become more r i f f l e - l i k e , thus suggesting that there has not been a change i n rearing habitat. The next section considers s p e c i f i c habitats i n more d e t a i l . 6.2 Stream Flow Stage and Velocity-Depth Relations F i s h require s p e c i f i c flow conditions during d i f f e r e n t phases of t h e i r l i f e c y c l e . Therefore, the actual combination of depth and v e l o c i t y at a l l locations within the study reach i s important. The combination preferred by Coho salmon for t h e i r spawning, fr y rearing and egg incubation stages has been estimated by using Bovee's (1978) p r o b a b i l i t y of use curves. The l i n e s of equal probabality of use by Coho salmon (Figure 6.5) delineate the preferred combination of depth and v e l o c i t y . Favorable spawning areas are r e l a t i v e l y shallow with v e l o c i t i e s ranging from 0.2 ms - 1 to 0.6 ms - 1. Preferred rearing areas are characterized by r e l a t i v e l y deep and slow moving water. Egg incubation i s possible over a wider range of flow depths and v e l o c i t i e s . Complete inventories of depth and v e l o c i t y combinations for Hangover and Bonanza Creeks are given i n Figures 6.6 and 6.7. The water surface areas i n square metres, i n increments of 0.1 m depth and 0.1 ms - 1 v e l o c i t y , were calculated (see section 3.2.2) for a range of - 140 -VELOCITY (ms _ 1 ) 0.0 £ - M £-2| £ . 3| <.4| £ . S £ . 9 | £.7| £ .«| £ .8|£1.0 < 1 . 1 | £ 1 . 2 l £ 1 . 3|£l . 4 | < 1 . a <1.6|<1.7|<1.8)S1.»|52.0 < 2.1|<2.2|<2.3|<2.4|<2.5 <2.6|S2.7|<2.8| £.1 £.2 £.3 £.4 „ £.s c — • i " 1 c — £ . 9 I -£ UI -Q < 8 £ • » £ 1 . 0 S A| ' I a 1 / o -< 1.1 £ 1 . 2 £ 1 . 3 J S60: SPAWNING HABITAT AT 60% OF THE OPTIMAL DEPTH - VELOCITY LEVEL. R60: REARING HABITAT (FRY) VELOCITY (ms- 1) 0.0 £ . l | £.21 £.31 £.41 £ .« £•«! £•'! £.a| £.» J1 . 0 £ l . l |£ t .2|£t .3|<1 .4|<1 .8 <t.ei<i.7|<i.ai£i.oi£2.o < 2.1|<2.2|<2.3|<2.4|<2.S <2 .«f£2-7|£2.8| £.2 £ 3 £.4 £.s ^"s—lao ^ 1 4 0 - ^ E — ' £.» I " ui -O £-8 £•» £ 1 . 0 1 2 0 — — ^ ^ £ i'< £1 .2 £1 . 3 160: INCUBATION HABITAT (CLEAR WATER 3=0.004) FIGURE 6.5: LINES OF EQUAL PROBABILITY OF USE BY C O H O SALMON FOR SPAWNING, FRY REARING AND EGG INCUBATION. (After Bovee, 1978) - 141 -6.6a: VELOCITY (ms - 1 ) 0.0 £ - l | £.21 £-31 £.4| £.5 s.'i s.ai S . 9 I S I . 0 < 1 . l | S 1 . 2 | < t . 3 l < l . < l < 1 . 5 < 1 . 9 | < 1 . 7 | i 1 . « | S 1 . » | £ 2 . 0 < 2.1|< 2 .2 |<2 .3K2.4i<2 . s | <2 .«1S2.7 |<2 .a : < . 1 £.2 S 3 S « S i • • • £ • • • • • • • | E w s .e I -UJ Q S » S.» SI.O • Q = 0 . 3 2 m 3 3 _ l SURFACE AREA: + < 10 m 2 • 1 0 - 4 0 m 2 . At-an m 2 S ' l St.2 i l l • 9 1 - 1 6 0 m 2 # 1 6 1 - 2 5 0 m 2 A > 2 5 0 m 2 1 6.6b: VELOCITY (ms" 1) 0.0 S.I < 2 1.3 £.4 < 5 E w j . a X UJ Q < a £ . » S 1.0 £ i i S I . 2 < 1.3 S.ll S.2I £.3| £.4| S.» S .a i S-f I S.ai £•» 111.0 £ l . l | S1 .2 |S1 .3 t<1.4 | <1 .» < l .e|<1 . r|<1.»|i1 .» |S».0 < 2.1|<2.2|<2.3|<2.4 |<2.5 <2 .a iS2 .7 |<2 .a i • • • • Q = 0 . 5 7 m 3 3 H SURFACE AREA: + < 10 m 2 • 1 0 - 4 0 m 2 • 4 1 - 9 0 m 2 • 9 1 - 1 6 0 m 2 % 1 6 1 - 2 5 0 m 2 A > 2 5 0 m 2 FIGURE 6.6: DISTRIBUTION OF WATER SURFACE AREA BY DEPTH-VELOCITY CLASS : HANGOVER CREEK. - 142 -6.6c: VELOCITY (ms - 1) 0.0 £ . 1 £ . 2 i £.31 <.4i i.t £ « l £ . 7 | £.81 £.9 |< 1.0 <1.1!S1.2l<1.3|<l.4|<t.5 <1.0|<l.7|<1.a|<1.9|{2.0 < 2.1|<2.2!<2.3l<2.4[<2.5K2.«!<; 2.7i< 2.a £ . 1 £ . 2 £.3 £.4 £.s • • • • • • • • • • • • • • • • • i -t- £-r a. UJ _ o <» £ . » S 1 . 0 • • • • • Q=0.79m3sH SURFACE AREA: + < 10 m 2 • 10-40 m 2 • A1-on m 2 £ <•' £1 .2 £1.3 • 9 1 - 1 6 0 m 2 # 161-250 m 2 0 >250 m 2 i 6.6d: VELOCITY (ma"1) 0.0 £ . 1 | £.21 £ .3 ! <.4| £.8 £•91 £ . 7 | S.8I £.9151.0 £1.1|S1.2|£1.3!<1.4|<1.8 <1.0 I<1.7|<1.S IS1.»K2.0 < 2.l|<2.2|<2.3K2.4l<2.sj<2.8|£2.7iS2.8 £.1 £.2 £.3 £.4 £.3 • • • • • • • • • • i • 3 S.I I " t- £ . 7 a. Ul Q <9 £ 9 £ 1.0 • • • » * Q=1.48m3sH • — SURFACE AREA: + < 10 m 2 • 10-40 m 2 m A 1 —Qfl rr>2 i ' I £ 1 2 £ 1 -3 • 4 1 c f v l ••• • 9 1 - 1 6 0 m 2 # 161-250 i n 2 0 >250 m 2 FIGURE 6.6: cont'd. - 143 -6.6e: VELOCITY (ms-1) 0 .0 5 .1 £ . 2 1 £ . 3 ! £ . 4 , £ . 5 | £ . 8 | £ . 7 j £ . 8 1 M K I . O ! ' -1 | £ 1 - 2 | < 1 - 3 | £ 1 . 4 | < 1 . 8 |< 1 .8 |<1.7 |< 1.8|< 1 . 9 | £ 2 . 0 < 2 . 1 K 2 . 2 | < 2 . 3 | < 2 . 4 , < 2 . 5 | < 2 . 8 ;<2.7<< 2.8 <. 1 £ 2 < 3 £ . 4 <s Q=5.00m 38 _ 1 • • j • E »» !• I " K < 7 0. UJ -Q £ •» £•» < i.O • • • • • • • SURFACE AREA: + < 10 m 2 • 10-40 m 2 m A1 -flft m 2 < i . 1 £ 1 . 2 £ 1 . 3 • 9 1 - 1 6 0 m 2 # 161-250 m 2 - 0 >250 m 2 6.6f: VELOCITY (ms H ) E 0 . 0 £ • 1 £ . 2 l £ - 3 1 £ . 4 | £ . 3 | £ . 8 | £ . 7 | £ . » | £ . » | £ 1 . 0 £ ' . 1 | S 1 . 2 | £ I . 3 | £ 1 . 4 | < 1 . 8 < 1.8|< 1 . 7 K I.S|< 1 » l £ 2 . 0 < 2.1l< 2 . 2 | < 2 . 3 K 2 . 4 I < 2 . 5 | < 2 . « I S 2 . 7 ' < 2.8 £ . 1 £ . 2 £ . 3 < .4 £ . 5 Q=24.13m 3 s _ l i < 8 < .7 < 8 £ • » 1.0 • • • • * • • • • • • • • • SURFACE AREA: + < 10 m 2 • 10-40 m 2 _ i i - a n m2 1.1 1.2 1.3 • • • • • • 9 1 - 1 6 0 m z 0 161-250 m z 0 >250 m 2 i FIGURE 6.6: cont'd. - 144 -6.7 a: 0 . 0 VELOCITY (ms" 1) <.3i « . 4 | £ .8| <.»i J.T\ a.ai £.»i£i.o <i.iisi.ai£i.3i<i.*i<i.g|<i.ai<t.ri<i.a)si.ai^ a.ol<2.ii<a.ai<a.3i<z.4;<a>,sl<a.aisa-^ i<a a; £.2 £.3 £ . 4 £ . 8 I -LU -Q < 8 £•» S 1 . 0 £'•' £ 1 . 2 <1.3 Q=0.33m3 s _ l SURFACE AREA: + < 10 m 2 • 10-40 m 2 • 4 1 - 9 0 m 2 _ • 9 1 - 1 6 0 m 2 • 161-250 m2 0 >250 m 2 1 6.7b: 0 . 0 S i £ • ' 1 £ . 2 1 < . 3 | £ . 4 | £ . 5 VELOCITY (ms H ) £•«! S -7 | £.81 £ . 8 | £ 1 . 0 < 1 - l | S I . 2 l £ 1 . 3 l < 1 . 4 | < 1 . 8 | < 1 . 9 | ; i . 7 | < l . 8 | S 1 . » K 2 . 0 | < 2.1|<2.2|<2.8|S2.4|<2.8|<2.61£2.71<2.8| £.2 £.3 £ . 4 £.8 3 S . . Ul Q < a £.» St.O £ ' • ' £ 1 . 2 £ 1 - 3 Q=0.53 m3s_i SURFACE AREA: + < 10 m 2 • 10-40 m 2 - • 4 1 - 9 0 m 2 . • 9 1 - 1 6 0 m 2 • 161-250 m2 Q >250 m 2 i FIGURE 6.7: DISTRIBUTION OF WATER SURFACE AREA BY DEPTH-VELOCITY CLASS : BONANZA CREEK. - 145 -6.7c: VELOCITY (ma"1) 0 0 | £ - 1 | 1.31 £ - 3 | £ - 4 | £ • » [ £ • « ! £ - T | £ , B | £ . » l £ 1 . 0 < £1 .81 1 1.3I< 1 • « ! < 1.61< 1 . « ! < 1.7| < 1 , » | j 1 . » | £ 2 . o l £ 2. I|< 2.2| < 2.3| <2 .4 |< 2 .t\<2.tl j 2 .T\<2.t: £ . 2 S 3 £ . 4 s» — £•» i i •- i' a. UJ -Q <•» £•» £ 1 . 0 Q=0.94m3 s"1 < 1.1 i t . 2 < 1.3 SURFACE AREA: + < 10 m 2 • 10-40 m 2 . • 4 1 - 9 0 m 2 • 9 1 - 1 6 0 m 2 • 161 -250 m 2 ^ >250 m 2 1 6.7d: VELOCITY (ma"*) 0 . 0 <.11 S . 2 | £ . 3 1 < .4 | i.s S . « l £ . 7 | £ . » l £ . » l £ l . O £ 1 . 1 | £ 1 . 2 I £ 1 . 3 I < 1 . 4 | < 1 . « < 1 . « I < 1 . 7 | < 1 . 8 I S 1 . 9 ! S 2 . 0 < 2 . 1 | < 2 . 2 | < 2 . 3 | < 2 . 4 | < 2 . 5 £ 2 . e t £ 2 . 7 | £ 2 . « ( £ . 1 £ . 2 £ 3 £ • 4 S » o • ••• • • • • • • • • • • • • • • • • E »» s « x -UJ -Q <a £ • » S i . o • • • • Q=2.39m3 s*1 SURFAC + < 1( • 10 -• 4 1 -E AREA: ) m 2 40 m 2 90 m 2 < 1.1 S I . 2 S I - 3 • 9 1 - 1 6 0 m 2 # 161-250 m 2 ^ >250 m 2 i FIGURE 6.7: cont'd. - 146 -6 7e: 0 . 0 £ . I £ . 2 £ . 3 £ 4 £ 8 £ • ' 1 £ . 2 1 £ - 3 | £ . 4 | £ . 8 VELOCITY (msH) £ . 8 | £ - 7 | £ . 3 1 £ • » l £ 1 . 0 <1.1 | £ 1 . 2 | £ 1 . 3 | £ 1 . 4 | £ 1 . 3 [ < 1 , 8 | < 1 , 7 | < 1 . 8 | £ 1 . » | £ 2 . 0 | < 2.1]< 2.21 < 2 . 3 I £ 2 . 4 | < 2 . s | < 2 . « l £ 2 . 7 | < 2.8, Q=10.06m3 s - 1 x -i- . O. ' UJ Q £ . 8 £ • • £ 1 . 0 £ 1 1 £ 1 . 2 £ 1 . 3 • • • SURFACE AREA: + < 10 m 2 • 10-40 m 2 • 4 1 - 9 0 m 2 • 9 1 - 1 6 0 m 2 • 161 -250 m 2 A >250 m 2 6.7f: VELOCITY (ms~') £ . 2 1 £ - 3 | £ . 4 | £ . 8 £ - 8 | £ . ? ! S . 8 | £ . 8 | £ 1 . 0 £ 1 . 1 | £ 1 . 2 | £ 1 . 3 I £ 1 . 4 | £ I . 8 , 1 . 8 | £ 1 . 7 | < 1 . 8 | S 1 . » | £ 2 . 0 < 2 . 1 | < 2 . 2 | £ 2 . 3 t < 2 . 4 | £ 2 . 8 < 2 . 8 | £ 2 . 7 | £ 2 . 8 I £ . 1 £ . 2 £ . 3 £ 4 £ 8 E w j . e I UI Q < 8 £•» £ 1 . 0 Q=20.11m3s"' £ 1 . 1 £ 1 . 2 £ 1 . 3 • • • .| SURFACE AREA: + < 10 m 2 • 10-40 m 2 • 4 1 - 9 0 m 2 • 9 1 - 1 6 0 m 2 • 161-250 m 2 t £ >250 m 2 1 FIGURE 6.7: cont'd. - 147 -6.7g: VELOCITY (msT1) < 1 . 1 | £ 1 . 2 | <1.»|£1.«| £ 1 . 8 £ 1 . « | < 1 . 7 I < 1 . H £ 1 . » | S 2 . 0 S2.1|£».2|£2 .3|S2 .4j<2.a|<2.a|<2.T|<2 .H£I .9|S3 .0| <3.i|<».2|<3.3|<a . « i<a.5lj;3 . » i < a.7|ia j | £.e £ . 7 s.» s.» £ 1 . 0 £ 1 . 1 £ 1 . 1 £ 1 . 3 £ 1 . « £ 1 J Si.a £ 1 . 7 < 1 - » HQ=96.58mV SURFACE AREA: + < 10 m 2 • 10-40 m z . • 4 1 - 9 0 m 2 • 9 1 - 1 6 0 m 2 • 161-250 m 2 0 >250 m 2 i NOTE CHANGE IN DEPTH-VELOC ITY ORIGIN FIGURE 6.7: cont'd. - 148 -discharges. The e n t i r e study reach was used i n both cases; this included 260 m (or 8.8 bankfull channel widths) i n Hangover and 300 m (or 6.6 channel widths) i n Bonanza. The discharges cover a range from the lowest recorded during the 1983 summer to the estimated bankfull discharge (extrapolated from morphological evidence and stage-discharge r a t i n g curves). The c i r c l e s i n each subclass are drawn proportional to the water surface area for that subclass. This procedure, introduced by Mosley (1982), provides a graphic demonstration of both the o v e r a l l change i n water surface area with increasing discharge and the changing flow character. At low flow conditions (Q = 0.32 m s~ i n Hangover and Q = 0.33 3 1 m s~ i n Bonanza; Figures 6.6a and 6.7a) both channels are composed pr i m a r i l y of r e l a t i v e l y deep, slow moving water which i s well suited to fry r earing. Only a small proportion of either channel i s well suited for spawning. As discharges increase (Figures 6.6b and c and 6.7b and c) there i s a corresponding increase i n o v e r a l l water surface area and an increase i n s u i t a b l e spawning habitat. The r e l a t i v e area of rearing habitat begins to decline at Q = 0.79 m 3 s - 1 i n Hangover and 0.96 mV'1 i n Bonanza, i n d i c a t i n g that as discharge increases v e l o c i t y increases at a f a s t e r rate than depth. As flow increases i n both channels (Figures 6.6e and f and 6.7e, f and g) there i s a progressive s h i f t towards predominantly fast flowing, r e l a t i v e l y deep water which i s well suited f o r neither spawning nor rearing of f i s h . The rate of increase i n depth and v e l o c i t y with increased discharge i s given i n Figures 6.8 and 6.9. The patterns displayed i n - 149 -a) MEAN VELOCITY: ro O FIGURE 6.8: CUMULATIVE PLOTS OF CHANGES IN MEAN DEPTH - 150 -b) MEAN DEPTH: O t F e M r DISCHARGE (rr^s-1) FIGURE 6.8: cont'd. - 151 -a) MEAN VELOCITY 10 O DISCHARGE (m33-') FIGURE 6.9: CUMULATIVE PLOTS OF CHANGES IN MEAN DEPTH AND MEAN VELOCITY WITH CHANGING DISCHARGE: BONANZA CREEK. - 152 -FIGURE 6.9: cont'd. - 153 -Hangover and Bonanza are s i m i l a r . It i s evident that as discharge increases i n both channels v e l o c i t y increases at a greater rate than depth. This observation i s i n general agreement with the a t - a - s t a t i o n 3 1 r e l a t i o n s . However, at a discharge of approximately 1.5 to 2.0 m s~ i n 3 _ 1 Hangover Creek and 1.0 to 2.0 m s i n Bonanza Creek, the rate of change of both depth and v e l o c i t y became approximately equal. This trend i s probably a r e s u l t of the i n c l u s i o n of back and side channels, which are r e l a t i v e l y deep with slow moving water i n comparison to the adjacent channel. As discharge continues to r i s e , and a f t e r a l l back and side channels are f i l l e d , the depth and v e l o c i t y continue to increase at a s i m i l a r r ate. To summarize the .probability of use of both Hangover and Bonanza Creeks by Coho salmon, the weighted useable area has been computed. This was achieved by assessing the water surface areas i n each depth-velocity c'lass and multiplying each by i t s appropriate weighting factor (Bovee's (1978) p r o b a b i l i t y of use curves were used). Summations of the weighted areas provide the t o t a l weighted useable area and are presented i n Figures 6.10 and 6.11. For Hangover Creek, as the t o t a l water surface area increases with discharge, the spawning habitat 3 1 3 1 increases r a p i d l y between 0.32 m s and 0.79 m s ; rearing habitat increases s l i g h t l y then decreases. Discharges i n excess of 3 1 approximately 0.8 m s~ are characterized by decreasing spawning and rearing habitat. Incubation conditions follow a pattern s i m i l a r to r e a r i n g . In Bonanza Creek (Figure 6.11), the trend i n weighted useable areas i s s i m i l a r to that of Hangover Creek except that absolute areas - 154 -TO o X DISCHARGE On's"1) FIGURE 6.10: WEIGHTED USEABLE AREAS FOR COHO SALMON ( m 2 PER 200m OF CHANNEL): HANGOVER CREEK. - 155 -DISCHARGE (m3 3 H ) FIGURE 6.11: WEIGHTED USEABLE AREAS FOR COHO SALMON ( m 2 PER 200m OF CHANNEL): BONANZA CREEK. - 156 -f o r 200 m of channel are l a r g e r . There i s however, an i n d i c a t i o n that l e s s useable rearing h a b i t a t , compared to that f o r spawning, i s a v a i l a b l e at higher discharge. 6.3 Summary An attempt has been made i n t h i s chapter to l i n k channel form and flow c o n d i t i o n s . Hydraulic geometries, which r e l a t e channel width, depth and flow v e l o c i t y were developed f o r a l l study reaches except those i n Government Creek; thus, comparison of the hyd r a u l i c conditions i n Mosquito and Government Creek was not p o s s i b l e . Although the hyd r a u l i c geometry r e l a t i o n s provide flow information d i r e c t l y relevant to salmonid habitats they are l i m i t e d i n a p p l i c a b i l i t y because they express average flow conditions only. Hence, hydraulic geometries provide a poor basis both for quantifying f i s h habitat and for comparison purposes. A d e t a i l e d study of the actu a l combination of depth and v e l o c i t y at a l l l o c a t i o n s within the study reach and at various discharges was completed for Hangover and Bonanza Creeks. The r e s u l t s i n d i c a t e that both stream reaches respond i n a s i m i l a r fashion with a change i n discharge. The only d i f f e r e n c e i s a minor decrease i n useable rearing habitat at higher discharges i n Bonanza, compared to Hangover Creek. I t appears, therefore, that there are minimal, but detectable, d i f f e r e n c e s i n h y d r a u l i c conditions between t h i s unlogged-logged watershed p a i r . - 157 -7.0 CONCLUSIONS This study i n v e s t i g a t e s and compares the morphological character of stream channels In logged and unlogged watersheds i n the Queen Charlotte Islands. This enables q u a n t i f i c a t i o n of the infl u e n c e of logging and r e l a t e d a c t i v i t i e s on channel morphology and provides information concerning appropriate channel s t a b i l i z a t i o n and f i s h h a bitat r e h a b i l i t a t i o n c r i t e r i a . The morphological character of a stream channel depends upon the amount, timing and nature of sediment and water moving through the f l u v i a l system. In turn, the ph y s i c a l components of f i s h h a b i t a t s depend l a r g e l y upon channel morphology. A l t e r e d land-use p r a c t i c e s , s p e c i f i c a l l y logging and r e l a t e d a c t i v i t i e s , can influence both sediment and water discharge c h a r a c t e r i s t i c s . Therefore, logging and re l a t e d a c t i v i t i e s have been associated with changed channel morphology and f i s h h a bitat c o n d i t i o n s . Because documentation of changes i n water discharges and sediment loads i s very d i f f i c u l t to achieve over both time and space, the present study has focussed on the consideration of the r e s u l t a n t morphological character of logged and unlogged watersheds. Rather than evaluating an i n d i v i d u a l channel dimension, such as width, which often has l i t t l e relevance to f i s h h a b i t a t , t h i s study has concentrated on pool and r i f f l e c h a r a c t e r i s t i c s . Pools and r i f f l e s provide both a us e f u l measure of f i s h habitat and, because they r e f l e c t changes i n sediment supply to the streams, they provide an i n d i r e c t i n d i c a t o r of the Influence of land-use p r a c t i c e s on channel - 158 -morphology. In forested watersheds, large organic debris i s another independent v a r i a b l e i n f l u e n c i n g channel shape. This large woody ma t e r i a l c o n s t i t u t e s a s p e c i a l type of sediment load, with i t s own input, storage and output c h a r a c t e r i s t i c s . It i s a f a c t o r which i s d i r e c t l y influenced by logging; hence, i t i s considered i n d e t a i l i n t h i s study. The study i s based on a paired basin design, a preferred approach because i t allows evaluation of a range of areas with d i f f e r e n t timber harvesting techniques. The study basins compared have s i m i l a r geology, climate, s o i l s and vegetation but d i f f e r e n t logging h i s t o r i e s . Because no two basins are exact r e p l i c a s i t has been necessary to accept c e r t a i n d i f f e r e n c e s i n basin shape as unavoidable. Although basin morphometry i s s i m i l a r i n many respects there are d i f f e r e n c e s which appear to complicate the i n t e r p r e t a t i o n of study r e s u l t s . However, with t h i s caution, i t has been assumed that any morphological d i f f e r e n c e s between channels within logged and unlogged paired watersheds are due to logging and r e l a t e d a c t i v i t i e s . This assumption was evaluated p a r t i a l l y by s t a t i s t i c a l l y t e s t i n g the d i f f e r e n c e s i n morphological features within one i n t e r n a l l y homogeneous unlogged watershed. The importance of d i s s i m i l a r basin morphometries i s considered below (Table 7.2). The study conclusions r e l y on f i e l d data obtained over r e l a t i v e l y long lengths of channel (channel scale studies) and from f a i r l y short d e t a i l e d study reaches (reach scale studies) located within the longer channel segments. Results from the comparative studies are summarized i n Table 7.1. The major conclusions are presented i n the following paragraphs. - 159 -Table 7.1 Summary of channel changes associated with logging and related a c t i v i t i e s Channel Comparisons General Logging Status Not Logged Contemporary Old Logging Techniques Logging Techniques Comparison Streams GA, GB, GC, GD Hang, Bonz GD, MT GB, MM Time Since Logging (yrs) 0 < 7 < 20 > 20 FFIP Stream Type 3, 2 3 2 3 Channel Changes 1 Channel Scale Studies: 3 Pool-to-Pool Spacing 0 0 1 1 R i f f l e Amplitude 0 0 1 1 R i f f l e Magnitude 0 0 1 0 R i f f l e Relative Relief 0 0 0 0 P o o l / R i f f l e Ratios 0 0 + + LOD Steps 0 0 + + Reach Scale Studies: 1* LOD, Number of Pieces 0 + 0 + LOD, Volume 0 0 + + LOD, Orientation: P a r a l l e l Material 0 0 0 1 Perpendicular Material 0 0 0 0 LOD, Influence on Morphology: Depth V a r i a b i l i t y 0 0 + + Width V a r i a b i l i t y 0 0 + + Sediment Texture V a r i a b i l i t y 0 0 0 + Cut banks 0 0 0 + Prevalent Pool Type 0 0 + 0 P o o l / R i f f l e Proportions + 0 + 0 Stored Sediment Volume 0 + + + Stored Sediment S t a b i l i t y 0 0 + -t-Fish Habitat as a Function of Hydraulic Conditions: Spawning 0 Fry Rearing + Egg Incubation 0 Total Quantitative Differences 0 0 3 3 Qua l i t a t i v e Differences 1 3 9 10 Notes: 'changes are denoted as follows: 0 - No s i g n i f i c a n t difference (at a - 0.01) 1 » S i g n i f i c a n t difference (at a - 0.01) + - Indication of change but either not s i g n i f i c a n t at a - 0.01 or not tested s t a t i s t i c a l l y . FFIP stream type 3 » average channel slope < 1° FFIP stream type 2 - average channel slope 1° - 5° 3Channel Scale Studies are based on lon g i t u d i n a l surveys conducted over channel lengths i n excess of 12 bankfull widths. Reach Scale Studies are based on detailed study reaches less than 12 bankful widths in length. - 160 -In a l l channel and reach scale studies there i s no s i g n i f i c i a n t d i f f e r e n c e , i n the morphological features considered, between stream segments within the unlogged watershed with i n t e r n a l l y homogeneous b i o p h y s i c a l conditions (Government Creek). This lends c r e d i b i l i t y to the extensive post-treatment study design and i n d i c a t e s that i t i s v a l i d to compare channels with d i f f e r e n t land-use p r a c t i c e s given that other important b i o p h y s i c a l conditions are s i m i l a r . There are minimal d i f f e r e n c e s i n channels and reach scale morphological r e s u l t s between the unlogged and r e c e n t l y logged study areas (Hangover and Bonanza). This suggests that contemporary logging p r a c t i c e s have r e s u l t e d i n few changes to morphology and h a b i t a t . The influence of in-stream large organic debris which was not disturbed during logging appears responsible for preserving pre-logging c o n d i t i o n s . Also, because a leave s t r i p was provided a continued source of LOD i s a v a i l a b l e . This should ensure that minimal changes w i l l occur i n the f u t u r e . I t should be noted, however, that several other f a c t o r s besides logging h i s t o r y may have contributed to the minor d i f f e r e n c e s between Hangover and Bonanza Creeks. F i r s t , i t i s p o s s i b l e that i n s u f f i c i e n t time has passed since logging f o r channel changes to.occur (logging i n the Bonanza watershed had not ceased at the time that f i e l d work for t h i s report was conducted). Second, Bonanza's wide v a l l e y f l a t may slow the timing and reduce the amount of slope material entering the channel ( c f . Table 7.2). T h i r d , logging extent may be a f a c t o r because only 11% of the Bonanza Creek watershed was logged. In both the unlogged and r e c e n t l y logged watershed channels, the - 161 -p o o l - r i f f l e sequence spacing lengths d i f f e r s i g n i f i c a n t l y from most previously published values. This renders the use of past r e s u l t s to ch a r a c t e r i z e unlogged conditions of minimal use. The influence of large organic debris appears to be the f a c t o r c o n t r i b u t i n g to a t y p i c a l values. The LOD a l s o influences sediment ar e a l s o r t i n g patterns. Flow conditions over a wide range of discharges i n d i c a t e that h y d r a u l i c adjustments within the unlogged and r e c e n t l y logged reaches are very s i m i l a r . As discharge increases the v e l o c i t y i n each reach increases q u i c k l y while the depth responds more slowly u n t i l side and back channels are f i l l e d . A f t e r t h i s point the v e l o c i t y and depth increase more evenly. Although not evident i n the morphological data, there i s s l i g h t l y more rearin g area evident i n the unlogged channel. The conventional h y d r a u l i c geometry r e l a t i o n s are of l i t t l e use to habitat studies because they represent average conditions; optimal f i s h h a bitats are often s p e c i f i c channel l o c a t i o n s which do not correspond to the average. There appear to be more s u b s t a n t i a l d i f f e r e n c e s i n channel morphology and f i s h habitats associated with older logged channels, as in d i c a t e d by the r e l a t i v e l y high t o t a l s corresponding to q u a l i t a t i v e and q u a n t i t a t i v e changes l i s t e d i n Table 7.1. The morphological changes i n both watersheds logged 20 or more years ago (Mosquito Main and T r i b u t a r y Creeks) appear to be due to o l d , discontinued logging techniques which included logging to the channel banks and d i r e c t disturbance of the channel bed by cross-channel f e l l i n g and removal of instream LOD. Both older logged channels are c u r r e n t l y experiencing regrowth of r i p a r i a n - 162 -vegetation and a reduction i n channel widths. Based on the channel scale studies, i t i s concluded t e n t a t i v e l y that the channels i n watersheds logged by old techniques appear to have reduced pool-to-pool spacings and increased r i f f l e amplitudes and magnitudes. This i n d i c a t e s that more sediment i s de l i v e r e d to the channel than can be moved out of i t and, therefore, the material i s stored i n the r i f f l e zone. This increase i n stored sediment r e s u l t s i n p r o p o r t i o n a l l y l a r g e r r i f f l e s and smaller pools, and represents a reduction i n a v a i l a b l e rearing h a b i t a t . Also, these logged channels have fewer LOD steps leading to a s h i f t i n the d i s t r i b u t i o n of sediment along the channel and a p o t e n t i a l reduction i n channel s t a b i l i t y . Considering the reach scale r e s u l t s , i t i s concluded that LOD c h a r a c t e r i s t i c s are a l t e r e d i n the older logged channels. This includes a s h i f t i n the size d i s t r i b u t i o n , with smaller material being more prevalent. Also, there appears to be a change i n LOD o r i e n t a t i o n ; more material i s l y i n g p a r a l l e l to the channel and flow d i r e c t i o n , as opposed to the more common diagonal o r i e n t a t i o n found i n unlogged channels. Several morphological changes appear to have res u l t e d from the a l t e r e d LOD character. These are l i s t e d below: 1. The v a r i a b i l i t y i n channel width and depth and sediment texture i s reduced and there are fewer cut banks. This appears due p r i m a r i l y to LOD o r i e n t a t i o n rather than volume. Ma t e r i a l l y i n g d i agonally across the channel promotes greater v a r i a b i l i t y due to l a t e r a l scour across the channel and more e f f i c i e n t trapping of sediment. M a t e r i a l that i s oriented - 163 .-p a r a l l e l to the channel produces l o n g i t u d i n a l scour, poor sediment trapping e f f i c i e n c y and hence, l e s s v a r i a b i l i t y . 2. The pool area i s reduced and pool shape i s changed from long and narrow to short and wide. This i s because pools are associated p r i m a r i l y with LOD oriented p a r a l l e l to the channel. The pool i s produced frequently by scour around the attached root wad. 3. There are l a r g e r volumes of sediment, located i n r e l a t i v e l y few l o c a t i o n s , stored along the older logged channels. In contrast with unlogged channels, where slope i s adjusted l o c a l l y to a combination of minor log jams and d i s c r e t e debris steps, i n older logged channels, l o c a l slope i s influenced p r i m a r i l y by l e s s frequently occuring major log jams. The s t a b i l i t y of these logged channels i s le s s than that of unlogged streams because the displacement of any i n d i v i d u a l debris o b s t r u c t i o n may r e s u l t i n major r e d i s t r i b u t i o n of sediments. 4. F i s h habitats i n the older logged channels have reduced d i v e r s i t y i n flow depths, fewer rearing areas and l e s s near-bank hiding and r e s t i n g zones. The channel substrate i s l e s s stable which may influence egg incubation s u i t a b i l i t y . The l a r g e r volumes of sediment lead to increased occurrence of de-watering during low flow condit i o n s . As i n d i c a t e d throughout t h i s t h e s i s , an i n a b i l i t y to f u l l y account for a l l independent v a r i a b l e s has led to the p o s s i b i l i t y that - 164 -ce r t a i n documented morphological differences between unlogged and logged channels are due, to some extent, to factors other than land-use practices. For th i s reason, Table 7.2 i s included as a summary of the uncontrolled basin differences and a q u a l i f i e r to Table 7.1. I t i s clear from Table 7.2 that only basin morphometric variables d i f f e r between comparison channels. The Importance of a larger drainage basin and f l a t v a l l e y bottom i n Bonanza, compared to Hangover, i s that the influence of logging and related a c t i v i t i e s on channel morphology may be delayed. In t h i s case basin size influences the timing of channel changes and suggests that a longer study duration i s advisable. The differences i n basin r e l i e f , shape, slope and v a l l e y bottom extent evident i n the older logged basins indicate that these factors require more attention before d e f i n i t i v e conclusions can be presented. The importance of these variables to the present study i s that the steeper basin slopes i n Mosquito Creek may increase the transfer rates of sediment from the slopes to the channel thus influencing channel morphology. The importance of these variables as complicating factors can not be quantified i n the present study. Quantification of the r e l a t i v e importance of d i f f e r e n t morphometric properties and the development of a scheme to systematically determine i f basins are suit a b l y matched could be the focus of future studies. Based on the natural channel morphology i n the unlogged and recently logged channels (Government, Hangover and Bonanza Creeks), i t i s possible to outline the conditions which may be 'duplicated' i n attempts to r e h a b i l i t a t e disturbed t h i r d and fourth order coastal stream channels. These conditions are not influenced by problems associated - 165 -Table 7.2 Factors Not Related to Logging A c t i v i t i e s Which May Contribute to Documented Channel Differences (a Caveat to Table 7.1). Channel Comparison General Logging Status Comparison Streams Contemporary Logging Techniques Hang, Bonz Old Logging Techniques GD.MT GB.MM Channel Scale Studies Channel Gradients Reach Scale Studies Channel Gradients Sub-basin Climate P r e c i p i t a t i o n Sub-basin Biophysical Conditions bedrock geology s u r f i c l a l geology s o i l s vegetation 2 Sub-basin Morphometries Ad (basin size) L (channel network) R (basin r e l i e f ) Sh (basin shape) Si Ci (index of va l l e y bottom extent) HI Total Q u a l i t a t i v e Differences Notes: ^Differences are denoted as follows: 0 - no apparent difference 1 - apparent difference 2A cj • drainage basin area L » length of channel segments R « r e l a t i v e r e l i e f Sh " basin shape Si » basin slope C\ - basin concavity HI - hypsometric i n t e g r a l - 166 -with basin morphometry and include the f o l l o w i n g : 1. Pool and r i f f l e sequences should be spaced such that t h e i r average length i s equal to 2 to 3 channel widths. 2. R i f f l e magnitudes should average approximately 0.010 m/m to 0.015 m/m and t h e i r r e l a t i v e r e l i e f values should be between 0.021 m/m to 0.26 m/m. 3. Large organic debris should play a major r o l e i n r e h a b i l i t a t i o n ; only large pieces (lengths equal to the channel width, and/or volumes greater than 3 m ) should be used. Long pieces of debris should be placed diagonally across the channel, with the root wad close to the bank and on the downstream end, i n order to increase depth v a r i a b i l i t y and to store sediment on both the upstream and downstream si d e . LOD should be placed p a r a l l e l to the flow i f channel widths are to be reduced and r i p a r i a n vegetation regrowth i s to be encouraged. Large root wads should be placed between the diagonally crossing material to produce smaller scour holes (as opposed to scour p o o l s ) . 4. If large organic debris steps are to be placed i n the channel, they should consist of several small steps accounting for only about 10 percent of the o v e r a l l change i n e l e v a t i o n . 5. Large c l u s t e r s of organic debris should not be placed c l o s e r than approximately 3.5 channel widths apart. - 167 -In summary, t h i s thesis documents the channel conditions of several small c o a s t a l streams. The use of published geomorphic r e s u l t s to c h a r a c t e r i z e unlogged watershed channels i s not v i a b l e because the influence of large organic debris has not been thoroughly considered i n previous s t u d i e s . A l l hydraulic geometry r e l a t i o n s express averaged conditions which are of l i t t l e relevance to habitat requirements. 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A research approach to solving f i s h - f o r e s t r y i n t e r a c t i o n s i n r e l a t i o n to mass wasting on the Queen Charlotte Islands. Working Paper 1/83, Fish-Forestry Interaction Program, Vancouver, B r i t i s h Columbia, 20 pp. Reid, L.M. 1981. Sediment production from gravel-surfaced forest roads, Clearwater Basin, Washington. U n i v e r s i t y of Washington, F i s h e r i e s Research I n s t i t u t e , College of F i s h e r i e s , Seattle, F i n a l Report FRI-UW-8108, 247 pp. Reid, L.M. and T. Dunne. 1984. Sediment production from forest road surfaces. Water Resources Research, v.20, p. 1753-1761. Reid, L.M., T. Dunne and C.J. Cederholm. 1981. App l i c a t i o n of sediment budget studies to the evaluation of logging road impacts. Journal of Hydrology (New Zealand), v.20, p. 49-62. Rice, R.M. 1981. A perspective on the cumulative e f f e c t s of logging on streamflow and sedimentation. In Cumulative E f f e c t s of Forest Management on C a l i f o r n i a Watersheds: An Assessment of Status and Need for Information, Proceedings of the Edgebrook Conference, R.B. Standiford and S.I. Ramacher (Eds.), U.S.D.A. Forest Service, General Technical Report PNW-141, p. 39-49. Richards, R.S. 1977. Channel and flow, geometry: a geomorphological perspective. Progress i n Physical Geography, v . l , p. 65-102. Richards, K. 1982. Rivers: Form and Process i n A l l u v i a l Channels. Methuen and Co. Ltd., London, 357 pp. Roberts, R.G. 1984. Major f l u v i a l disturbances in logged watersheds i n the Queen Charlotte Islands, B r i t i s h Columbia. Working Paper 17/84, Fish-Forestry Interaction Program, Vancouver, B r i t i s h Columbia ( i n pre s s ) . Rodda, J.C. 1976. Basin Studies. In Facets of Hydrology, J.C. Rodda (Ed.), Wiley, New York 368 pp. Rothacher, J . 1970. Increases i n water y i e l d following clear-cut logging i n the P a c i f i c Northwest. Water Resources Research, v.6, p. 653-658. - 175 -Rothacher, J . 1971. Regimes of streamflow and t h e i r modification by logging. In Forest Land Uses and Stream Environment, J.T. Krygier and J.D. H a l l (Eds.), Symposium Proceedings, Oregon State U n i v e r s i t y , C o r v a l l i s , p. 40-54. Schaefer, D.G. 1979. The multi-day rainstorm of October-November, 1978, on the Queen Charlotte Islands. Canada Department of Environment, Atmospheric Environment Service, S c i e n t i f i c Services, Vancouver, 7 pp. Schumm, S.A. 1969. River metamorphosis. Journal of the Hydraulics D i v i s i o n , American Society of C i v i l Engineers, v.95, p. 255-273. Schumm, S.A. 1977. The F l u v i a l System. J . Wiley and Sons, New York, 338 pp. Schumm, S.A. and R.W. L i c h t y . 1963. Channel widening and f l o o d - p l a i n construction along Cimarron River i n southwestern Kansas. U.S. Geological Survey, Pr o f e s s i o n a l Paper 352-D, p. 71-88. S h i r v e l l , C.S. 1981. Computer analysis of f i s h populations i n f l u c t u a t i n g streams. F i s h e r i e s Management, v.12, p. 32-36. Slaney, P.A., H.A. Smith, and T.G. Halsey. 1977. Physical a l t e r a t i o n s to small stream channels associated with streamside logging practices i n the ce n t r a l I n t e r i o r of B r i t i s h Columbia. B r i t i s h Columbia M i n i s t r y of Recreation and Conservation, F i s h e r i e s Technical C i r c u l a r No.31, V i c t o r i a , B r i t i s h Columbia, 22 pp. Smart, J.S. 1976. The analysis of drainage network composition. Earth Surface Processes, v.3 p. 129-170. Smith, R.B., P.R. Commandeur, and M.W. Ryan. 1983. Natural revegetation s o i l development and forest growth on the Queen Charlotte Islands-Progress Report. Working Paper 7/83, Fish-Forestry I n t e r a c t i o n Program, Vancouver, B r i t i s h Columbia, 46 pp. Stra h l e r , A.N. 1952. Hypsometric (area-altitude) analysis of erosional topography. U.S. Geological Society of America B u l l e t i n , v.63, p. 1117-1142. Stra h l e r , A.N. 1958. Dimensional analysis applied to f l u v i a l l y eroded landforms. U.S. Geological Society of America B u l l e t i n , v.69, p. 279-300. Stra h l e r , A.N. 1964. Quantitative geomoephology of drainage basins, i n Handbook of Applied Hydrology V.T. Chow (Ed.), McGraw-Hill, New York, p. 4.39-4.76. - 176 -Sutherland Brown, A. 1968. Geology of the Queen Charlotte Islands, B r i t i s h Columbia. Province of B r i t i s h Columbia, Department of Mines and Petroleum Resources B u l l e t i n No.54, V i c t o r i a , B r i t i s h Columbia, 226 pp. Swanson, F.J., S.V. Gregory, J.R. Sedell, and A.G. Campbell. 1982. Land-water i n t e r a c t i o n s : the r i p a r i a n zone, i n Analysis of Coniferous Forest Ecosystems i n the Western United States, R.L. Edmonds (Ed.), Hutchinson Ross, Stroudsbourg, Pennsylvania, p. 267-291. Swanson, F.J. and G.W. Lienkaemper. 1978. Physical consequences of large organic debris i n P a c i f i c Northwest streams. U.S.D.A. Forest Service, General Technical Report PNW-69, 12 pp. Swanson, F.J., G.W. Lienkaemper, and J.R. S e d e l l . 1976. History, physical e f f e c t s and management implications of large organic debris i n western Oregon streams. U.S.D.A. Forest Service, General Technical Report PNW-56, 15pp. Swanson, F.J., M.M. Swanson, M.M., and C. Woods. 1981. Analysis of debris-avalanche erosion i n steep forest lands: an example from Mapleton, Oregon, U.S.A.. in_ Erosion and Sediment Transport i n P a c i f i c Rim Steeplands, T.R.H. Davies and A.J. Pearce (Eds.), IAHS Pu b l i c a t i o n No.132, p. 67-75. Swanston, D.N., and F.J. Swanson. 1976. Timber harvesting, mass erosion and steepland forest geomorphology i n the P a c i f i c Northwest. i n Geomorphology and Engineering, D.R. Coates (Ed.), Dowden, Hutchinson and Ross, Shroudsburg, Pennsylvania, p. 199-221. Thomson, T.M. and Associates. 1982. Continuous management considerations for operational planning on T.F.L. #39(BLK.6A), Graham Island. F i s h e r i e s and Environment Canada, F i s h e r i e s and Marine Service, Manuscript Report 1473, Ottawa, 32 pp. Toews, D.A.A., and M.J. Brownlee. 1981. A handbook for f i s h habitat protection on forest lands i n B r i t i s h Columbia. Canada Department of F i s h e r i e s and Oceans, Land Use Unit, Habitat Protection D i v i s i o n , F i e l d Services Branch. Vancouver, 165 pp. Toews, D.A.A. and M.K. Moore. 1982a. The e f f e c t s of three streamside logging treatments on organic debris and channel morphology of Carnation Creek, i n Proceedings of the Carnation Creek Workshop: A Ten-Year Review, G.F. Hartman (Ed.), Nanaimo, Briti'sh Columbia, p. 129-153. Toews, D.A.A. and M.K. Moore. 1982b. The e f f e c t s of streamside logging on large organic debris i n Carnation Creek. Province of B r i t i s h Columbia, Mini s t r y of Forests, Land Management Report, No.11, 29 pp. - 177 -Trihey, E.W. and D.L. Wegner. 1981. F i e l d data c o l l e c t i o n procedures for use with the physical habitat simulation system of the Instream Flow Group. U.S.D.I., Fi s h and W i l d l i f e Service, O f f i c e of B i o l o g i c a l Services, Co-operative Instream Flow Service Group, Fort C o l l i n s , Colorado, 151 pp. T r i p p , D. and V.A. Poulin. 1985. E f f e c t s of mass wasting on f i s h rearing habitat i n Queen Charlotte Islands streams. B r i t i s h Columbia M i n i s t r y of Forests, Land Management Report ( i n prep). Wilford, D.J. and J.W. Schwab. 1982. S o i l mass movements i n the Rennell Sound area, Queen Charlotte Islands, B r i t i s h Columbia, i n Hydrological Processes of Forested Areas, Proceedings of the Canadian Hydrology Symposium 1982, Fredericton, New Brunswick, p. 521-541. Williams, G.D.V. 1968. Climate of the Queen Charlotte Islands, i n F l o r a of the Queen Charlotte Islands, J.A. Calder and R.L. Taylor (Eds.), Canada Department of A g r i c u l t u r e , Plant Research I n s t i t u t e , Ottawa, p. 16-49. Wolman, M.G. 1954. A method of sampling coarse river-bed material. Transaction of the American Geophysical Union, v.35, p. 951-956. - 178 -APPENDIX A ASSESSMENT OF PRECIPITATION AND RUNOFF VARIABILITY IN THE QUEEN CHARLOTTE ISLANDS - 179 -A . l Precipitation A . l . l Introduction P r e c i p i t a t i o n i s a d i f f i c u l t factor to assess because i t i s highly variable over short distances, p a r t i c u l a r l y i n areas of diverse topography such as the Queen Charlotte Islands. The variable s p a t i a l nature and the seasonal d i s t r i b u t i o n are shown i n Appendix Figure A . l , which i s a plot of cumulative mean monthly p r e c i p i t a t i o n values for several Atmospheric Environment Service and A i r Studies Branch Stations. The highest preciptation areas are on the west and north coast of Moresby Island. The areas with more modest amounts (approximately 2,400-3,000 mm per year) are on the west coast of Graham Island and the areas with minimal amounts (less than 2,000 mm per year) are on the north and east coast of Graham Island. The shape of curves i n Appendix Figure A.l indicates that a low proportion of the t o t a l annual p r e c i p i t a t i o n f a l l s between May and August while a large proportion i s received from October through A p r i l . I f a dense network of precipitation.sampling records i s ava i l a b l e , i t should be possible to base r e g i o n a l i z a t i o n on a consideration of s p a t i a l v a r i a b i l i t y . The Queen Charlotte Islands have a dense short term p r e c i p i t a t i o n measuring network i n comparison with other areas of B r i t i s h Columbia. This appendix deals with two objectives: 1. to develop hydrologically homogeneous regions i n the Queen Charlotte Islands. -180 -2. to investigate the factors contributing to precipitation v a r i a b i l i t y and determine i f a significant regression model can be developed for each region. A.l.2 Methods Data Requirements: Data required for this generalization include precipitation records (monthly totals for year of record), sampling site elevation, location (longitude and latitude) and aspect. The site characteristics influence precipitation amounts, hence they influence the regional varability of precipitation. Data Sources: Data are available from two sources. F i r s t , the Atmospheric Environment Service (AES) operates eight weather stations on the Islands. AES data quality is carefully controlled; no problems were encountered with these data. Second, the provincial Ministry of Environment's Air Studies Branch (ASB) operates 55 short term (< 5 years record) stations on the Islands (Ministry of Environment, 1980). Data quality problems were encountered with records from some of these stations (many stations had only "simulated" records and no significant test results were available for the regression model used). Of the original 55 station records only 41 station records could be obtained. These were subjected to the following selection c r i t e r i a : - 181 -1. No more than 2 days could be missing from any one month (important i n high i n t e n s i t y r a i n f a l l areas). 2. Records had to be four years 1976-1980 i n length. The o v e r a l l data set consists of monthly values of t o t a l p r e c i p i t a t i o n for 35 stations covering 4 years of record. This data set i s considerably less extensive than was anticipated. The s t a t i o n locations and data records are given i n Appendix Figure A.l and Appendix Table A . l , respectively. Note that the stations are concentrated on the northeast side of Graham Island. Again, t h i s renders the data less appropriate for s t a t i s t i c a l analysis and must be considered i n conjunction with study r e s u l t s . Data Grouping: The grouping procedure followed i s outlined i n the following: Monthly p r e c i p i t a t i o n H i e r a r c h i c a l grouping F-Test of within group variance F-test of between group variance Duncan's new multiple range test check of h i e r a r c h i c a l groups Multiple regression of expected c o n t r o l l i n g factors within each group Elevation, l a t i t u d e , longitude, aspect - 182 -4000-AES 30 YEAR NORMALS ASB 30 YEAR SIMULATED NORMALS 3000-E E < o UJ tr _j 2000 < UI > 3 3 O 1000-TASU SOUND SEWELL INLET CAMILLA DAWSON INLET DEENA RENNELL SOUND PENTHOUSE GOSPEL POINT SJUSKATLA E. MARIE LAKE LANGARA GRAY BAY PORT CLEMENTS CAPE ST. JAMES MASSETT SEWALL MASSETT SANDSPIT A. TLELL STATION LOCATIONS ARE GIVEN IN TABLE A.1 M A 1^  O i N -r-D FIGURE A.1: CUMULATIVE PRECIPITATION PLOTS FOR S E L E C T E D AES AND ASB CLIMATE STATIONS. - 183 -Table A.l Location of selected climate stations i n the Queen Charlotte Island . Location Station Name No. Lat. Long. Elevation Aspect (deg min sec) (deg min sec) (m) (deg) Black Bear 1 53 30 55 132 08 30 21 20 Dawson Inlet 2 53 12 55 132 29 10 . 9 140 Denna Creek 3 53 07 30 132 14 29 75 190 Eden Lk. ASB 4 53 54 28 132 40 00 41 170 Ferguson Pt. 5 53 39 22 132 18 31 64 220 Gospel Pt. 6 53 24 00 132 30 50 34 220 Gray Bay 7 53 07 05 131 42 38 20 340 Juskatla E l 8 53 34 27 132 22 43 128 140 Kagen Bay 9 53 14 56 132 10 19 91 150 K l i k l 10 54 02 51 131 52 50 11 160 Mamin River 11 53 34 35 132 20 00 61 150 Marie Lk. N. 12 53 33 10 132 17 15 226 0 Marie Lk. Rid. 13 53 32 00 132 17 43 398 270 Marie Lk. Low 14 53 32 02 132 1? 27 64 0 Marie Lk. S. 15 53 32 15 132 18 25 207 240 Mayer Lk. 16 53 38 18 132 03 30 35 100 Naden Pt. 17 53. 58 14 132 37 08 20 3'50 Survey Ck. 18 53 19 48 132 10 33 133 240 Tatzun Lk. 19 53 42 13 132 36 15 101 90 T l e l l R. 20 53 34 37 131 56 16 9 120 Twin 21 53 48 52 131 49 55 201 200 Watun Ck. 22 53 54 50 132 05 10 66 270 Yakoun R 23 53 31 05 132 12 40 35 350 Marie Lk. HI. 24 53 32 15 131 17 46 468 90 Penthouse 25 53 21 48 132 26 15 378 160 Cape St. James 26 51 56 00 131 01 00 89 -Langara 27 54 15 00 133 03 00 41 -Masset 28 54 02 00 132 04 00 12 -Sandspit A 29 53 15 00 131 49 00 5 -Sewell Inlet 30 52 53 00 132 00 00 12 -Sewall Masset Inlet 31 53 46 00 132 18 00 3 -Tasu Sound 32 52 46 00 132 03 00 15 -T l e l l 33 53 29 00 131 56 00 5 -Camilla 34 53 21 00 132 19 30 251 220 Rennell Sound 35 53 20 33 132 25 .3° 12 220 - 184 -A l l procedures are standard with the possible exception of Step 2 of the flow diagram. U.B.C. Computer L i b r a r y Program "C GROUP" ( L a i , 1982) was used for i n i t i a l grouping of data. B r i e f l y , i n t h i s procedure a set of a t t r i b u t e s (monthly p r e c i p i t a t i o n ) i s ascribed to each s t a t i o n and s t a t i o n s are then s e q u e n t i a l l y agglomerated i n t o groups using the c r i t e r i o n that at each step a new group i s formed from the two s t a t i o n s (groups) whose t o t a l set of a t t r i b u t e s i s most s i m i l a r . Therefore, at any point i n the grouping procedure there w i l l be minimum variance amongst the a t t r i b u t e s within the groups. The program provides an e r r o r index (I) to i n d i c a t e the within group variance acquired on j o i n i n g two s t a t i o n s . j , ( x u " xik> 2 I = n. + n, J k where: X = a t t r i b u t e from 1 to m j,k = i n d i v i d u a l s t a t i o n s to be grouped n = number of a t t r i b u t e s per record. By r e p e t i t i o n of the process, grouping proceeds from N groups ( s t a t i o n s ) to 1 group ( a l l s t a t i o n s together). M u l t i p l e repression f i t t i n g was conducted by the U.B.C. Computer L i b r a r y Package U.B.C. TRP (Le and T e n i s c i , 1978). - 185 -A.1.3 Results and Discussion H i e r a r c h i c a l grouping was conducted using the 35 s t a t i o n s ; r e s u l t s are summarized as a dendrogram i n Appendix Figure A.2. The error index terms (Appendix Figure A.2) are plotted as cumulative t o t a l s i n Appendix Figure A.3. This figure shows a major break i n the slope of the l i n e at 3 groups. For t e s t i n g the within group variances, four groups were selected. These are indicated i n Appendix Figure A.2. F-tests i n d i c a t e that there i s no s i g n i f i c a n t d i f f e r e n c e ( a = 0.10) amongst stations within each of the four groups. Also, there i s a s i g n i f i c a n t difference (at a = 0.10) between groups and Duncan's multiple range test shows that a l l groups are s i g n i f i c a n t l y d i f f e r e n t . This procedure r e s u l t s i n four major groups, or zones, of s i m i l a r p r e c i p i t a t i o n on the Queen Charlotte Islands; the geographical pattern i s shown i n Figure 2.3. The annual p r e c i p i t a t i o n range for each refers to the 95% confidence l i m i t s . The four zones presented suggest strongly that physiography i s a major Influence c o n t r o l l i n g the s p a t i a l d i s t r i b u t i o n of p r e c i p i t a t i o n over the Queen Charlotte Islands. The areas of low p r e c i p i t a t i o n are associated with the low plateau i n northeastern Graham Island. P r e c i p i t a t i o n gradually increases towards the west where Queen Charlotte Range extends along the entire length of Moresby Island. The r e s u l t s suggest that i t should be possible to develop a regression model to r e l a t e p r e c i p i t a t i o n with elevation and l o c a t i o n . Before developing regression models i t i s necessary however, to consider the r e s u l t s to this point more thoroughly. The usefulness of 186 -GROUP 2 I 22 13 24 23 2 7' 26 29 10 7 GROUP 1 I6 20 28 33 S 21 17 31 U u GROUP 3 14 18 25 8 9 4 IS 19 12 6 II u L i GROUP 4 34 2 3 30 35 32 FIGURE A.2: DENDROGRAM DIAGRAM OF PRECIPITATION STATION GROUPINGS. 100.0 10.0 1.0 0.1 20 15 GROUPS FIGURE A.3: CUMULATIVE PLOT OF ERROR INDICES AS A RESULT OF GROUPING PRECIPITATION RECORDS (C-GROUP). - 187 -the groups shown i n Figure A.2 i s questionable. Because of the r e l a t i v e l y small sample siz e (N = 35 s t a t i o n s ) , the uneven and non-random d i s t r i b u t i o n of sampling stations render this grouping approach rather uns a t i s f a c t o r y . In f a c t , sampling i s s u f f i c i e n t l y sparse that d e l i n e a t i o n between groups over large areas i s l i t t l e better than standard extrapolation techniques. This i s discouraging because the sampling network i s superior to most. If records for the other 30 stations on the Islands had been more r e l i a b l e the problem would not have been as serious. The sample size problem undermines attempts to determine r e l a t i o n s between p r e c i p i t a t i o n and c o n t r o l l i n g f a c t o r s . The o r i g i n a l approach of developing r e l a t i o n s for each group i s not f e a s i b l e because the largest group (1) consists of only ten s t a t i o n s . Thus, the degrees of freedom associated with the r e s i d u a l become i n t o l e r a b l y low. When a l l stations were combined (N = 35, Appendix Table Al) the best r e l a t i o n i s : Y = -104449.480 + 1342.341 X i - 1327.320 X 2 where X^ = longitude (degrees) X2 = l a t i t u d e (degrees) Y = mean annual p r e c i p i t a t i o n (mm) This r e l a t i o n accounts for 44% of the v a r i a t i o n i n p r e c i p i t a t i o n ( S i g n i f i c a n t at a = 0.10, df = 32) and indicates that geographic l o c a t i o n i s of greater importance than el e v a t i o n . - 188 -A . 2 Runoff The Water Survey of Canada (WSC) has i n s t a l l e d s i x streamflow recording stations i n the Queen Charlotte Islands. Of these, only three have been operating for more than ten years. These stations are located on the Yakoun River near Port Clements, on Pallant Creek downstream of i t s confluence with Mosquito Creek, and on Premier Creek. The Yakoun watershed has a drainage basin of 477 km and includes Yakoun Lake which covers approximately 2% of the drainage basin. This drainage basin l i e s within the Skidegate Plateau physiographic zone. The Pallant Creek watershed, l y i n g within the Queen Charlotte Ranges physiographic unit, covers an area of 76.7 km and includes a lake which accounts for approximately 7% of i t s area. The Premier Creek basin i s very small (drainage area has not been calculated by WSC), and l i e s between Yakoun River and P a l l a n t Creek within the Skidegate Plateau physiographic u n i t . It does not contain a lake. The runoff c h a r a c t e r i s t i c s of watersheds containing lakes are d i f f e r e n t than those without lakes because streamflow timing i s I a l t e r e d . Most drainage basins i n the Queen Charlotte Islands are small and do not contain lake systems. Therefore, two of the three W.S.C. station s are considered a t y p i c a l for characterizing runoff over most of the Islands. Because none of the study watersheds contain lakes and since the drainage basin area of Premier Creek i s unknown, runoff patterns are presented here only to provide a general overview of the amount and timing of streamflow and to c l a r i f y the r e l a t i o n between p r e c i p i t a t i o n and runoff. - 189 -The mean monthly discharge hydrographs for the three basins are presented i n Appendix Figure A.4. These indicate that the greatest discharges occur between October and January with maximum mean values of 3 1 61.8, 14.2 and 0.039 mJ s~ for Yakoun, Pallant and Premier Creeks, r e s p e c t i v e l y . These high autumn and early winter flows are due to r a i n and r a i n on snow events. The Pallant Creek hydrograph exhibits a secondary peak i n A p r i l and May which i s probably due to snowmelt i n mountainous headwater areas (e.g., Mount Mosquito). Mean monthly unit discharges (Appendix Figure A.4) indic a t e that Pallant Creek has greater discharge per unit area drainage basin than the Yakoun watershed; this i s i n general agreement with the p r e c i p i t a t i o n patterns discussed above. Mean monthly runoff quantities for the Yakoun and Pallant Creek watersheds and the regional p r e c i p i t a t i o n amounts, as delineated i n Figure 2.3, are compared i n Appendix Figure A.5. L e i t h (1980), working with f i v e AES s t a t i o n s , concluded that more meteorological stations are necessary to improve parametric modelling r e s u l t s of Yakoun River monthly flows. Average monthly p r e c i p i t a t i o n values for zone 3 (2,035-2,325 mm/yr) and zone 4 (3,665-3,775 mm/yr) were regressed against mean monthly runoff values for Yakoun and Pallant Creeks, r e s p e c t i v e l y . Regional p r e c i p i t a t i o n accounts for 88% of the v a r i a b i l i t y i n Yakoun mean runoff and 80% of the seasonal v a r i a b i l i t y i n Pall a n t mean runoff; both are s i g n i f i c a n t at a = 0.10. No s i g n i f i c a n t r e l a t i o n s (at a = 0.10) could be found between i n d i v i d u a l AES stations and runoff. It appears that the s e l e c t i o n of comparable watersheds based on p r e c i p i t a t i o n region i s j u s t i f i e d . - 190 -i i i i 1 i i 1 1 i 1 r J F M A M J J A S O N D FIGURE A.4: ANNUAL MEAN MONTHLY DISCHARGE AND UNIT DISCHARGE FOR S E L E C T E D QUEEN CHARLOTTE ISLANDS STREAMS. - 191 -° 0 SO 100 150 200 250 300 350 400 450 ° 0 50 100 150 200 250 300 350 400 450 500 550 600 ZONE 4 PRECIPITATION (mm). (See Fig. 2.3) FIGURE A.5: RELATION BETWEEN PRECIPITATION AND RUNOFF FOR TWO HOMOGENEOUS PRECIPITATION ZONES CONSIDERED IN FIGURE 2.3. - 192 -In addition to regional differences in precipitation and runoff amounts there are diss i m i l a r i t i e s in short term temporal precipitation-runoff patterns. There appears to be a tendency for large storms (e.g., October 31 to November 1, 1978, see Schaefer, 1979) to be widespread and common to a l l basins. But during low flow years individual stream's annual discharge peaks are due to localized storms. Further, the relative magnitude of flood flows differs between basins. The ratio of the highest 10 year instantaneous discharge to mean annual discharge is 18, 16.5 and 46 for Yakoun River, Pallant Creek and Premier Creek, respectively. Small watersheds without lakes respond faster and have relatively high peak discharges compared to larger watersheds containing lakes. Therefore, i t i s important that the drainage basins to being compared have similar basin sizes and drainage characteristics in addition to homogeneous climate. - 193 -APPENDIX B BASIN MORPHOMETRY OF SELECTED QUEEN CHARLOTTE ISLAND STREAMS - 194 -B. l Introduction The purpose of th i s appendix i s to provide morphometric data pertaining to the study watersheds and sub-basins. Basin morphometry constitutes one physical c h a r a c t e r i s t i c which must be s i m i l a r i n each basin p a i r . Morphometric properties are measured from a i r photographs and topographic maps and are therefore, often the main basis upon which comparable basins are selected. Geomorphometry includes a consideration of both geometric properties ( i n v o l v i n g the r e l a t i o n s h i p among dimensional properties such as elevation, length and areas) and topologic properties ( r e l a t i n g numbers of objects i n a s p e c i f i c landform u n i t ) . The morphometric v a r i a b l e s selected r e f l e c t the objective of the study. Several morphometic properties are considered here because both h i l l s l o p e and runoff c h a r a c t e r i s t i c s are important i n channel morphology studies and because no sing l e morphometric measure i s s u f f i c i e n t to determine comparable watersheds. In morphometric analysis r e s u l t s depend l a r g e l y upon the scale of the map or a i r photograph and the operational rules followed, such as d e f i n i t i o n of f i r s t order stream segments. Because the present objective i s to determine the comparability of watersheds selected for the FFIP project, rather than to explain observed geometric and topologic properties, procedures were followed r i g i d l y for each p a i r . Minor operational differences occurred between pairs; these are discussed i n Section B.2. - 195 -B.2 Background A conventional morphometric analysis involves measurement of l i n e a r and areal c h a r a c t e r i s t i c s and determination of the frequency of occurrence of s p e c i f i c features within a drainage basin. Usually this analysis includes the length and number of stream segments, c l a s s i f i e d by Strahler (1952, as presented i n Strahler, 1964). Strahlers's ordering i s convenient and i s often used as a c l a s s i f i c a t i o n technique by both geomorphologists and researchers from other d i s c i p l i n e s (e.g., b i o l o g i c a l applications by Chamberlin, 1982). Much of the r e g u l a r i t y i n the Horton-Strahler parameters i s a consequence of the rules for ordering and has nothing to do with the development of drainage basins (Smart, 1976). However, i f the objective i s , as i n the present paper, to determine comparability of basins, then Strahler stream segments and orders are appropriate and f a c i l i t a t e convenient and consistent applications. There are three main l i m i t a t i o n s to drainage network analysis. F i r s t , scale problems arise because headwater streams are omitted as map scale decreases (Richards, 1982). Second, f i e l d investigation of headwater stream segments i s influenced by temporal scale factors; drainage networks expand and contract during r a i n events (Day, 1983). Third, operator variance i s problematic because analysis r e l i e s on the investigator's a b i l i t y to determine f i r s t order segments from either map contour, slope or other c r i t e r i a consistently. Clearly the usefulness of morphometric data depends primarily upon the accuracy and consistency of the map used and upon the method of measurement. - 196 -A r e a l features of the drainage basin are also important i n the c h a r a c t e r i z a t i o n of basin morphometry. Hypsometric a n a l y s i s , defined by S t r a h l e r (1964), i s the r e l a t i o n between h o r i z o n t a l c r o s s - s e c t i o n a l drainage basin area and e l e v a t i o n . The hypsometric i n t e g r a l represents the volume of land underlying a drainage basin above i t s o u t l e t l e v e l as a proportion of the maximum volume between base l e v e l and the highest point on the basin perimeter. I t i s a t h e o r e t i c a l measure of the e r o s i o n a l development of the watershed. Mark (1975) found that the hypsometric i n t e g r a l i s a poor parameter when r e l a t e d to geomorphic processes but i t i s a useful d e s c r i p t i v e parameter for c l a s s i f i c a t i o n purposes. Hypsometry i s also u s e f u l because i t provides the basis for a n a l y s i s of average h i l l and v a l l e y slope estimates. B.3 Methods This s e c t i o n contains a b r i e f d e s c r i p t i o n of methods, materials and operational rules used i n the morphometric a n a l y s i s . Two sections are included: l i n e a r aspects of drainage basins, and areal and r e l i e f aspects. B.3.1 L i nea r Aspects of Drainage Basins A l l l i n e a r measurements (e.g. , stream segment lengths) were taken e i t h e r from 1976 p r o v i n c i a l a i r photographs, at scales ranging from 1:15,000 to 1:21,000, or from d e t a i l e d large scale topographic maps compiled for the B r i t i s h Columbia M i n i s t r y of Forests. These maps were based on r e c t i f i e d 1976 a i r photographs (Thomson and Associates, 1982) with scales of 1:20,000 for Bonanza Creek and 1:15,840 for Mosquito - 197 -Creek. Since no large scale topographic map i s a v a i l a b l e for Government Creek, 1976 n o n - r e c t i f i e d a i r photographs were used. Stream orders (u) were c l a s s i f i e d according to the S t r a h l e r technique ( S t r a h l e r , 1964) and the number (N) of segments f o r each order (N u) was counted. B i f u r c a t i o n r a t i o s , defined by S t r a h l e r as the r a t i o between the number of segments of a given order and the number of segments of the next higher order ( N u + ^ ) , were then c a l c u l a t e d . F i r s t order streams were i d e n t i f i e d on the a i r photographs and checked against the topographic maps. A f i r s t order stream was i d e n t i f i e d as a c l e a r l y v i s i b l e channel on the photographs; streams were not extended to the ridge top. The only extension of streams on the topograph maps was i n cases where the downstream end of the channel (the j u n c t i o n of f i r s t and higher order streams), was not v i s i b l e on the photograph. This was the case i n some areas of dense vegetation. A possible error i n t h i s a n a l y s i s i s that f i r s t order streams are more evident, but not n e c e s s a r i l y more frequent, i n logged areas. F i e l d checking i n d i c a t e s that mapped f i r s t order streams are a c t u a l l y second or higher order streams. Thus, the scale problem p e r s i s t s . But because a consistent method of i d e n t i f y i n g " f i r s t " order stream segments was used, t h i s e r r o r i s constant and can be adjusted by consideration of stream number versus frequency p l o t s . Adjustments of t h i s kind were not made for the present study. The t o t a l length of stream segment f o r each stream order was measured from the topographic map and mean lengths ( L u ) per order were c a l c u l a t e d by using S t r a h l e r ' s (1964) method. The length r a t i o s (K-L), - 198 -s i m i l a r to the b i f u r c a t i o n r a t i o but for successive length-order p a i r s , were c a l c u l a t e d . Distances were measured with an opisometer, introducing e r r o r both because of problems inherent i n the instument and because lengths are shortened due to p r o j e c t i o n upon the h o r i z o n t a l map surface. The former er r o r i s probably somewhat consistent but the l a t t e r w i l l be influenced by t e r r a i n , and hence the worst p r o j e c t i o n e r r o r occurs i n the Mosquito Creek length r a t i o . These errors were not assessed and no adjustments of the measured values were performed. A l l basin perimeter measurements were obtained from large scale maps or photographs. Longitudinal p r o f i l e concavity was ca l c u l a t e d using the Langbein (1964) method. B.3.2 A rea l and R e l i e f Aspects of Drainage Basins In order to maintain consistency, a l l measurements of area were obtained from 1:50,000 topographic maps with contour i n t e r v a l s of 30 meters. This map scale was selected because coverage was a v a i l a b l e f o r a l l basins; no large scale topographic maps (1:20,000) were a v a i l a b l e f o r Government Creek. Areas (A) were measured with a polar planimeter. The geometric shape f a c t o r , defined as the maximum stream length squared d i v i d e d by drainage area (Smart 1975), was c a l c u l a t e d . For hypsometric a n a l y s i s , areas were determined f or each contour i n t e r v a l . Therefore, the number of p a r t i a l areas used to construct the r e l a t i v e hypsometric curve (Monkhouse and Wilkinson, 1969) ranged between 17 f o r Government to 36 f o r Mosquito basins and between 15 and 36 for sub-basins. The hypsometric i n t e g r a l was determined - 199- -graphically. Clinographs, which express average gradients between contours, were constructed by methods outlined by Monkhouse and Wilkinson (1969). B.4 Resu l t s and D i scus s ion B.4.1 Basin and Sub—Basin Morphometry The morphometric data are used to consider basin conditions which may influence channel conditions. Basin morphometric analyses have been conducted in two parts. The f i r s t considers the major basins and the second involves the subdivision of these main basins into several sub-basins. These data are summarized in Appendix Tables B.l and B.2. It is not the main objective of the present paper to deal rigorously with the interpretation of these results, rather, comparison of the morphometric data for selected paired watersheds is more central to the study. The summarized data are included here. 2 Watershed total areas range from 16 km for the entire Government 2 Creek basin to over 68 km for Bonanza Creek. Sub-basin areas range 2 from less than 4 km (Government Reach D, see location map Figure 2a) to 2 over 45 km for Bonanza. The i n i t i a l selection of study reaches was based on comparable areas and stream gradients. A l l main basins are fourth order except Bonanza ( f i f t h order). Sub-basin stream orders range from third in Mosquito Main and Tributary (see Figure 2.4) to fourth order in the sub-basins of Government and Bonanza. Drainage density, the ratio of total stream lengths to the basin area, range from 1.44 km/km2 in Government Reach D to 2.66 in upper Bonanza (Table B.l and B.2). - 200 -Table B.l Summary of morphometric data: main basins . Bonanza * 2 Mosquito Government' 2 Basin Area, km 68.289 17.345 16.205 Basin Perimeter, km 38.980 19.689 20.850 Maximum Stream Length, km 15.800 6.970 4.800 Number of Streams Order ( b i f u r c a t i o n r a t i o ) 1 190 (5.14) 36 (4.0) 46 (4.2) 2 37 (3.36) 9 (4.5) 11 (2.5) 3 11 (5.50) 2 '(2.0) 4 (2.8) 4 2 (2.20) 1 2 (2.0) 5 1 1 Mean Stream Length, m Order (length r a t i o ) 1 516.7 618.2 331.0 2 738.9 827.2 (1.34) 974.8 (2.95) 3 1,550.9 (2.10) 3,389.8 (10.02) 1,060.0 (1.09) 4 7,280.0 (4.69) 2,122.6 (0.63) 1,091.8 (1.03) 5 2,920.0 (0.40) 803.4 (0.74) Geometric Mean Bi f u r c a t i o n Ratio 4.56 3.30 2.77 Geometric Mean Length Ratio 1.54 2.04 1.25 Drainage Density, km/km 2.34 2.23 2.05 Geometric Shape Factor 3.66 2.80 1.42 Relative R e l i e f , m 750 1,145 505 Mean Elevation, m 295 285 160 Hypsometric Integral 0.418 0.309 0.359 Average H i l l s l o p e Angle , degree 15 36 25 (standard deviation) (16) (24) (19) Longitudinal P r o f i l e Concavity 0.727 0.915 0.607 Notes: *1982 topographic map 1:20,000 and 1976 p r o v i n c i a l a i r photograph (approx. 1:20,500) 1982 topographic map 1:15,840 and 1976 p r o v i n c i a l a i r photograph (approx. 1:20,500) 31976 p r o v i n c i a l a i r photographs, approx. 1:20,500 Table B.2 Summary of morphometric data: sub-basins . Bonanza above Mosquito Mosquito Government Hangover Hangover Main above Tributary Confluence Mosq.Trb.Conf • B C D 2 Basin Area, km 45.243 20.183 10.504 5.410 6.914 6.768 3.930 Basin Perimeter, km 29.780 24.860 12.957 11.928 11.350 11.500 9.200 Maximum Stream Length, km 12.900 9.320 4.910 4.815 3.960 3.100 2.400 Number of Streams Order ( b i f u r c a t i o n r a t i o ) 1 140 (4.83) 45 (6.43) 21 (3.0) 10 (5.0) 22 (4.4) 19 (3.8) 14 (4.7) 2 29 (3.22) 7 (3.50) 7 (7.0) 2 (2.0) 5 (1.7) 5 (2.5) 3 (3.0) 3 9 (9.0) 2 (2.0) 1 1 3 (3.0) 2 (2.0) 1 4 5 1 1 1 1 Mean Stream Length, m Order (length r a t i o ) 1 482 630 631 421 368 253 226 2 1,034 (2.15) 866 (1.37) 833 (1.32) 808 (1.92 1,129 (3.07) 723 (2.86) 629 (2.78) 3 1,344 (1.30) 2,480 (2.86) 3,770 (4.53) 3,010 (3.73) 577 ( .51) 1,545 (2.14) 2,266 (3.60) 4 5 10,960 (8.15) 3,600 (1.45) 1,669 (2.89) 515 (0.33) Geometric Mean Bifurcation Ratio 5.19 3.56 4.58 3.16 2.80 2.67 3.74 Geometric Mean Length Ra t i o 2.83 1.78 2.45 2.68 1.65 1.26 3.16 Drainage Density, km/km 2.66 2.13 2.16 1.63 2.48 1.78 1.86 Geometric Shape Factor 3.68 4.30 2.30 4.29 2.27 1.42 1.51 Relative R e l i e f , m 745 745 1,115 1,080 440 - 490 455 Mean Elevation, m 275 395 275 355 175 245 260 Hypsometric Integral 0.347 0.462 0.252 .332 .318 .411 .414 Average H l l l s l o p e Angle, degree 17 20 41 43 25 20 31 (standard deviation) (17) (20.5) (27) (22) (20) (19) (22) Longitudinal P r o f i l e Concavity 0.849 0.613 0.893 0.888 0.654 0.635 0.554 Notes: '1982 topographic map 1:20,000 and 1976 provin c i a l a i r photograph (approx. 1:20,500) *1982 topographic map 1:15,840 and.1976 provin c i a l a i r photograph (approx. 1:20,500) 31976 pr o v i n c i a l a i r photographs, approx. 1:20,500 - 202 -Basin o u t l i n e form was characterized by use of the geometric shape f a c t o r . Values range from 1.42 for Government Creek, which i s a wide short basin, to 4.3 for Hangover Creek which i s long and narrow. Relative r e l i e f and mean elevations are also v a r i a b l e , as indicated i n Appendix Tables B.l and B.2. Mosquito Creek has the highest r e l a t i v e r e l i e f of almost 1,150 m and i s the only basin which has continual snow cover during the winter season. Hypsometric curves are presented i n Appendix Figure B.l and B.2 and the i n t e g r a l values are l i s t e d i n Tables B.l and B.2. The curves show considerable v a r i a b i l i t y ; the i n t e g r a l values for the main basins range from .31 to .42 for Mosquito Main and Bonanza, r e s p e c t i v e l y . Sub-basin values range from .25 to .46. The low values indicate that r e l a t i v e l y large proportions of the drainage basin area are at r e l a t i v e l y low elevations, compared to t o t a l basin r e l i e f . For example, Mosquito Main has a large low-lying v a l l e y and steep, high v a l l e y w a l l s . Mean basin elevations were obtained from the hypsometric curves and are, i n a l l cases, low compared to r e l a t i v e r e l i e f . Average h i l l s l o p e angles were also determined from the area-e l e v a t i o n data and plotted as clinographic curves. These curves are not presented here but the mean h i l l s l o p e angles are tabulated (Appendix Tables B.l and B.2). These values are rough approximations at best and are included here only to show the r e l a t i v e range of slope angles i n the study basins. The lowest h i l l slopes occur i n Bonanza and the steepest occur i n Mosquito. Longitudinal p r o f i l e s of the main and sub-basins are given i n - 203 -1.0-0.8-I- 0.6-X o LU X I U > < -1 LU K 0.4-1 0.2H V \ \ \ \ b MAIN BASINS 0.2 0.4 0.6 0.8 RELATIVE AREA -§-A FIGURE B.1: HYPSOMETRIC CURVES FOR THE STUDY BASINS. - 204 -— — BONANZA CREEK ABOVE HANGOVER CONFLUENCE. — — — HANGOVER CREEK. MOSQUITO TRIBUTARY. '••<••••"»• — MOSQUITO MAIN CREEK. GOVERNMENT CREEK ABOVE DETAILED STUDY SITE B. . — G O V E R N M E N T CREEK ABOVE DETAILED STUDY SITE C — — GOVERNMENT CREEK ABOVE DETAILED STUDY SITE D. FIGURE B.2: HYPSOMETRIC CURVES FOR STUDY SUB-BASINS. - 205 -Appendix Figures B.3, B.4 and B.5. P r o f i l e c o n c a v i t i e s (Appendix Table B.l and B.2) range between 0.61 and 0.92 i n the main basins and between 0.61 to 0.89 i n the sub-basins. B .4.2 Basins and Sub-Basins Compared In order to compare the geometrical s i m i l a r i t y of the study watersheds, the l i n e a r scale and dimensionless number r a t i o s are considered i n a manner s i m i l a r to that presented by Strah l e r (1958). The length measures compared for each main basin and sub-basin are as follow s : 1. mean length of f i r s t order streams, L i 2. mean length of second order streams, L 2 3. mean length of t h i r d order streams, L3 4. drainage density, D 5. mean basin e l e v a t i o n , H 6. r e l a t i v e r e l i e f , R The dimensionless number r a t i o s compared are as follo w s : 1. geometric b i f u r c a t i o n r a t i o , R D 2. mean stream length r a t i o , Lb 3. geometric shape f a c t o r , S 4. hypsometric i n t e g r a l , HI 5. l o n g i t u d i n a l p r o f i l e concavity If geometrical s i m i l a r i t y e x i s t s between two areas then r a t i o values approach unity. As the degree of s i m i l a r i t y decreases, the r a t i o DISTANCE (km) FIGURE B.3: LONGITUDINAL PROFILE OF GOVERNMENT CREEK (REACH A, B, C, D). - 207 -FIGURE B.4: LONGITUDINAL PROFILE OF MOSQUITO MAIN CREEK AND MOSQUITO TRIBUTARY CREEK. - 208 -7 3 2 -DISTANCE (km) FIGURE B.5: LONGITUDINAL PROFILE OF BONANZA AND HANGOVER CREEKS. - 209 -values increase; however, no absolute l i m i t can be drawn between s i m i l a r and d i s s i m i l a r . S t r a h l e r ( 1 9 5 8 ) used q u a l i t a t i v e terms to describe the degree of s i m i l a r i t y . Comparisons of morphometric values are summarized i n Appendix Table B . 3 . Linear scale r a t i o s for the main basin i n d i c a t e that Mosquito and Bonanza basins are most s i m i l a r , p a r t i c u l a r l y i n mean basin e l e v a t i o n ( H B / H M = 1 . 0 4 ) and drainage density ( D B / D M = 1 . 0 5 ) . Government and Mosquito are s i m i l a r only i n mean length of t h i r d order streams L3Q/L314 = 0 . 9 3 . Dimensionless number r a t i o s show that Bonanza and Mosquito are r e l a t i v e l y s i m i l a r i n basin o u t l i n e form ( S J J / S M ) , Government and Bonanza are s i m i l a r i n length r a t i o s and hypsometric i n t e g r a l s . Government and Mosquito are also s i m i l a r i n hypsometric i n t e g r a l s ( H I Q / H I M 3 0 . 8 5 ) and b i f u r c a t i o n r a t i o s ( R D Q / R D M = 0 . 7 8 ) . No consistent pattern emerges from these comparisons. Based s o l e l y on geology, Government and Mosquito are s i m i l a r . Based on geometrical s i m i l a r i t y i t appears that they are comparable but s u b s t a n t i a l d i f f e r e n c e s do e x i s t , p a r t i c u l a r l y i n mean f i r s t order lengths and basin shape. Linear scale r a t i o s for sub-basins i n d i c a t e that Hangover and Bonanza are f a i r l y s i m i l a r i n mean second order stream lengths ( L 2 H / L 2 B = 0 . 8 4 ) and r e l a t i v e r e l i e f (basins share a common drainage d i v i d e ) . Dimensionless number r a t i o s i n d i c a t e that these sub-basins are s i m i l a r i n shape but unlike i n terms of stream length r a t i o s . Mosquito Main and Tr i b u t a r y are s i m i l a r i n stream length and basin r e l i e f . Dimensionless length r a t i o s are also s i m i l a r . Basin shape i s - 210 -Table B.3 Comparison of basin c h a r a c t e r i s t i c s ; r a t i o s of l i n e a r scale features and dimensionless numbers, WATERSHED PAIRS LINEAR SCALE RATIOS DIMENSIONLESS NUMBER RATIOS HI Main Basins Bonz/Mosq Gov't/Bonz Gov't/Mosq 1.20 0.65 0.55 1.12 0.76 0.85 2.19 0.68 0.93 1.05 0.83 0.83 1.04 0.54 0.56 1.53 0.56 0.44 1.38 0.56 0.78 1.32 0.81 0.61 1.31 0.39 0.51 1.35 0.86 0.85 0.67 0.79 0.79 0.80 0.83 0.66 Sub-Basins GB/GC 1.42 1.73 0.36 1.62 0.71 0.90 1.11 1.32 1.60 0.77 1.25 1.03 GB/GD 1.62 2.55 0.25 1.72 1.42 0.97 0.84 0.52 1.50 0.77 0.81 1.18 GC/GD 1.14 1.48 0.68 1.06 0.94 1.08 0.76 0.40 0.94 0.99 0.65 1.14 GB/MM 0.58 0.83 0.15 0.87 0.64 0.40 0.61 0.68 0.95 1.26 0.61 0.73 GC/MM 0.41 0.79 0.41 0.70 0.89 0.44 0.55 0.51 0.62 1.63 0.49 0.71 GC/MT 0.62 0.81 0.51 0.93 0.69 0.45 0.80 0.47 0.33 1.24 0.47 0.71 GD/MT 0.54 0.55 0.75 0.88 0.73 0.42 1.05 1.18 0.35 1.25 0.72 0.62 Hang/Bonz. 1.31 0.84 1.85 0.80 1.44 1.0 • 0.69 0.63 0.85 1.33 1.18 0.72 Symbols are defined i n the text. - 211 -considerably different and hypsometric integrals have a ratio of 1.32, indicating there is over 30% difference in area-elevation relations between the two areas. The three sub-basins in the Government watershed exhibit a wide range in similarity ratios. In almost a l l cases, Government reaches C and D are most alike. In linear ratios, values range from 1.06 for drainage density and r e l i e f to 1.48 for mean length of second order streams. Dimensionless number ratios indicate that Reaches C and D are similar in hypsometry (R T Q Q / H I Q D = 0.99) and shape factor (0.94). No clear pattern i s evident for the sub-basins. The previously paired Hangover and Bonanza appear well suited in certain morphometric parameters but not in others (e.g., bifurcation and length r a t i o s ) . Government Reach C and D appear most similar and are best suited for comparison. Linear ratios for Government Reach B and Mosquito Main are highly variable, with the best relation existing between drainage density (0.87) and the poorest relation occurring between mean third order lengths. Dimensionless ratios show close similarity between basin shape (0.95) and poorest agreement between bifurcation ratios. When comparing Government and Mosquito Main, linear scale similarity is evident in drainage density (0.87) between Reach C and Mosquito Main, and hypsometry is similar for Reach B and Mosquito. It appears that Government Reaches C and D are equally well suited for comparison with Mosquito Main. It appears from Appendix Table B.3 that Mosquito Tributary and Government Reach D are most comparable. - 212 -Only r a r e l y does a c l e a r pattern emerge to i n d i c a t e which basins are best suited f o r comparison. The rather high degree of v a r i a b i l i t y w ithin a basin characterized by s i m i l a r climate, geology and land use (Government Creek) makes the s e l e c t i o n of comparable basins based on a unique parameter u n l i k e l y . Probably the best l i n e a r scale measures of morphometry are the mean length of intermediate order streams, drainage density and r e l a t i v e r e l i e f . B i f u r c a t i o n r a t i o s , shape and hypsometric i n t e g r a l s are probably the most r e l i a b l e dimensionless number r a t i o s . A d e f i n i t e drawback to the approach used here i s that no c l e a r d i s t i n c t i o n has been made between s i m i l a r and d i s s i m i l a r comparison r e s u l t s . To e s t a b l i s h such l i m i t s i t would be necessary to consider the possible range of values for each measure to be compared. The main l i m i t a t i o n to t h i s work i s the i n a b i l i t y to accurately i d e n t i f y f i r s t order stream segments. This reduces the r e l i a b i l i t y of other morphometric values, p a r t i c u l a r l y drainage d e n s i t i e s . However, because consistent methods were used, the morphometic data do provide a basis upon which to compare drainage basin p r o p e r t i e s . Based on the morphometic a n a l y s i s the following sub-basin p a i r s were selected for channel morphology studies: Government sub basin B - Mosquito Main Government sub basin D - Mosquito T r i b u t a r y Hangover - Bonanza. - 213 -APPENDIX C TEXTURAL ANALYSIS OF SURFACE, SUB-SURFACE AND MCNEIL SEDIMENT SAMPLES - 214 -Table C.l Summary of textural a n a l y s i s 1 of surface , subsurface and McNeil sediment samples (phi u n i t s ) . Stream 2 Sample Percentile Finer Mean Standard Skewness Kurtosis Reach Type No. D 5 0 D 9 0 Deviation GB SS 1 - 4 . 3 2 - 5 . 7 4 - 3 . 7 9 - 1 . 9 6 - 0 . 4 0 0 . 9 5 . S 1 - 4 . 8 6 - 6 . 6 7 - 4 . 9 4 - 1 . 2 7 0 . 0 9 0 . 9 5 S 2 - 4 . 8 1 - 6 . 0 6 - 4 . 8 4 - 1 . 0 1 0 . 0 5 0 . 8 7 S 3 - 5 . 0 6 - 6 . 1 2 - 5 . 0 0 - 0 . 9 5 - 0 . 1 0 0 . 7 7 GC SS 1 - 4 . 8 7 - 6 . 1 5 - 4 . 4 8 - 1 . 8 1 - 0 . 3 2 1 . 0 0 S 1 - 5 . 3 1 - 6 . 6 1 - 5 . 2 3 - 1 . 0 4 - 0 . 1 1 1 . 0 7 S 2 - 4 . 5 8 - 6 . 9 3 - 4 . 7 7 - 1 . 3 0 0 . 2 1 0 . 9 5 S 3 - 6 . 1 7 - 7 . 2 5 - 6 . 0 9 - 0 . 9 3 - 0 . 1 3 1 . 1 3 GD SS 1 - 5 . 1 5 6 . 1 8 - 4 . 4 9 - 1 . 9 8 0 . 5 0 0 . 8 7 S 1 - 6 . 7 1 - 8 . 0 6 - 6 . 5 0 - 1 . 4 9 - 0 . 2 1 0 . 9 5 S 2 - 5 . 6 4 - 8 . 3 0 - 6 . 0 6 - 1 . 7 5 0 . 3 6 0 . 9 0 MM S 1 - 5 . 6 7 - 7 . 0 1 - 5 . 5 8 - 1 . 2 2 - 0 . 1 1 0 . 9 1 S 2 - 5 . 7 7 - 7 . 0 2 - 5 . 6 7 - 1 . 1 9 0 . 1 2 0 . 9 9 s 3 - 5 . 2 2 - 6 . 5 8 - 5 . 3 9 - 1 . 0 4 - 0 . 1 9 0 . 9 7 MT SS 1 - 5 . 6 6 - 6 . 1 9 - 4 . 7 3 - 1 . 8 8 - 0 . 7 4 1 . 1 4 s 1 - 6 . 5 4 - 7 . 4 0 - 6 . 4 4 - 0 . 8 4 - 0 . 1 8 1 . 2 0 s 2 - 6 . 2 4 - 7 . 6 0 - 6 . 2 0 - 1 . 2 2 - 0 . 0 4 0 . 9 7 s 3 - 5 . 5 7 - 6 . 7 5 - 5 . 5 1 - 1 . 3 4 - 0 . 0 7 0 . 8 4 Hang s s 1 - 4 . 2 9 - 5 . 8 6 - 3 . 7 9 - 2 . 1 2 - 0 . 3 5 0 . 9 1 s 1 - 5 . 8 0 - 6 . 6 2 - 5 . 7 0 - 0 . 8 0 - 0 . 2 0 0 . 9 6 s 2 - 5 . 8 4 - 6 . 7 4 - 5 . 6 9 - 0 . 8 6 - 0 . 2 7 0 . 7 5 M 1 - 5 . 1 1 - 6 . 2 7 - 4 . 8 2 - 1 . 4 8 - 0 . 2 9 1 . 1 3 M 2 - 4 . 4 3 - 6 . 3 5 - 4 . 2 1 - 2 . 1 6 - 0 . 1 5 0 . 8 7 M 3 - 3 . 9 5 - 5 . 7 7 - 3 . 5 2 - 2 . 0 0 - 0 . 3 3 0 . 8 7 Bonz SS 1 - 4 . 1 1 - 5 . 8 0 - 3 . 6 7 - 2 . 1 1 - 0 . 3 1 0 . 9 0 S 1 - 5 . 3 2 - 6 . 3 9 - 5 . 3 1 - 0 . 8 7 - 0 . 0 2 0 . 9 9 S 2 - 5 . 1 9 - 6 . 2 6 - 5 . 1 3 - 1 . 0 0 - 0 . 0 8 0 . 7 8 S 3 - 4 . 5 8 - 5 . 4 7 4 . 6 0 - 0 . 6 8 0 . 0 6 1 . 0 1 S 4 - 5 . 3 1 - 6 . 0 0 - 5 . 1 5 - 0 . 8 2 - 0 . 2 8 0 . 8 0 M 1 - 3 . 5 3 - 4 . 6 1 - 3 . 3 3 - 1 . 3 0 - 0 . 2 3 1 . 0 2 M 2 - 3 . 2 5 - 4 . 6 1 - 2 . 9 1 - 1 . 7 9 - 0 . 2 9 0 . 8 7 M 3 - 3 . 8 8 - 4 . 6 5 - 3 . 6 6 - 1 . 0 5 t - 0 . 3 2 1 . 0 4 ^ e x t u r a l analysis based on graphic measures a f t e r Folk and Ward ( 1 9 5 7 ) where: mean size - (a>16 + <t>50 + *8I»)/3 standard deviation" (<(>8I» - $ i 6 ) / 4 + ( $ 9 5 - <t>5)/6.6 Skewness - [U 1 6 + <J>8«* - 2 $s0)/2($Bk - + [(4>5 + ^ _ 2<J>50)/2( a>95 - + 5 0 ) ] Kurtosis - ( $ 9 0 - 4>t ) / l . 9 ( * 7 5 - 1(125) and where $n - the grain size ( i n phi units) at which n percent of the d i s t r i b u t i o n i s coarser $ " -Log2 mm Sample type: SS - Subsurface bulk; S - Surface transect; M = McNeil bulk r i f f l e sample Sample No: refers to locations i n Figures 5 . 1 - 5 . 7 ; No 1 i s at the downstream end of the reach in a l l cases. - 215 -APPENDIX D AT-A—STATION HYDRAULIC GEOMETRIES OF SELECTED QUEEN CHARLOTTE ISLAND STREAMS - 216 -_ - -Gl - -DEPTH, m -0.2 -0.1 a a A 20.0-10.0-9.0" 8.0-7.0--0.40 ® --0.30 -0 -0.20 ® -T CS E ® -0.10 ELOCIT\ -0.09 -0.08 -0.07 -0.06 -> -0.05 -0.04 I ® 0. i i i i 1 i 1. i i i i • 0 1 i 4.0-3.0-2.0-1 1 I l I l DISCHARGE, m3 3 H FIGURE D.1: GOVERNMENT CREEK (CSG 1A): "AT -A -STAT ION" HYDRAULIC GEOMETRY. - 217 DISCHARGE, m's"1 FIGURE 0 . 2 : MOSQUITO M A « O J B K (MSG 2>: " A T - A - S T A T I O N " - 218 -f-0.3 0.2 Ma— 0.9 0.8 0.7 ho.e 0.5 A f-0.3 0.2 M).03 a El -A. ® 3 0.1 I I I I -I ' 1 1.0 ml I I I I 20.0H -10.0-J 9.0 8.0-7.0-6.0-4.0H 3.0H 2.04 -1.0-0.9-0.8-0.7-0.6-0.5-0 . 4 -0.3-DISCHARGE, m3s 3-H FIGURE D.3: MOSQUITO TRIBUTARY (MSG 3): "AT-A-STATION" HYDRAULIC GEOMETRY. - 219 -0.7 -0.6 -0.5 -0.4 -0.3 0.2 a a a a a A A — A & A A 0.60 0.50 0.40 0.30 1-0.20 • % h o . 1 0 — 0.09 0.08 0.07 0.06 ® s 0.05 El A A A 1.0 _l_ 10.0 20.0 -10.0J 9.0-I 8.0 -10.0 9.0 , 8.0H 7.0-I 6.0 5.0-| 4.0 3.0-I 2.0-\ DISCHARGE, m3s 3_-l FIGURE D.4: HANGOVER CREEK: " A T - A - S T A T I O N " HYDRAULIC G E O M E T R Y - 220 -1-0.7 0.6 0.5 r-0.4 1-0.7 0.6 -0.5 -0.4 -0.3 0.2 0.1-a GI (GE) a a 4 » A © 0 - A -20.0--10.0-9.0-8.0-1.0 10.0 ' I ' l l 1 1 l I 9.0H 8 . 0 -7 . 0 j 6.0-j 5.0-I 4.0-3.0-I DISCHARGE, m 3 s - ' FIGURE D.5: BONANZA CREEK: "AT -A -STAT ION" HYDRAULIC GEOMETRY. 

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