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Studies of the effects of logging on stream cutbanks and of the occurrence of cutbanks as related to… Toews, David Andrew Alan 1975

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STUDIES OF THE EFFECTS OF LOGGING ON STREAM CUTBANKS AND OF THE OCCURRENCE OF CUTBANKS AS RELATED TO LAND CHARACTERISTICS  by  DAVID ANDREW ALAN TOEWS B . S c , University of B r i t i s h Columbia, 1968  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF vMASTER OF SCIENCE  i n the Faculty of Forestry (Forest Hydrology)  We accept this thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1975  In p r e s e n t i n g t h i s  thesis  in p a r t i a l  fulfilment  o f the requirements f o r  an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree the L i b r a r y s h a l l make i t I further for  available  f o r r e f e r e n c e and study.  agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying o f t h i s  thesis  s c h o l a r l y purposes may be granted by the Head o f my Department o r  by h i s r e p r e s e n t a t i v e s . of  freely  that  this  It  thesis for financial  i s understood that copying o r p u b l i c a t i o n g a i n s h a l l not be allowed without my  written permission.  Department o f The U n i v e r s i t y o f B r i t i s h Columbia  2075 Wesbrook Place Vancouver, Canada V6T 1W5  Date  *foU^ f  /  .  J  I?7.S~  i  ABSTRACT  A study was undertaken to determine the e f f e c t of streambank logging practices on salmonid cover i n four streams i n north c e n t r a l B r i t i s h Columbia.  Undercut streambanks were chosen for measurement since  they constitute a component of cover that i s e a s i l y disturbed by logging activity.  Sections of streams flowing through winter and summer logged  regions were c l a s s i f i e d as either heavily or moderately disturbed and compared to adjacent unlogged sections with regard to stream widths and cutbank areas.  Logging resulted i n increased stream widths and de-  creased cutbank areas p a r t i c u l a r l y i n the heavily disturbed sections. Results indicate that skidder operators should avoid a c t i v i t y i n and immediately adjacent to streams.  For winter logging, this can be fac-  i l i t a t e d by marking streams p r i o r to snowfall.  A second study was undertaken i n an attempt to develop a model for stream surveys which would permit p r e d i c t i o n of cutbank formation by i d e n t i f y i n g associated land and stream c h a r a c t e r i s t i c s on a i r photos. With the use of 1:63,000 a i r photographs, several streams i n the Robertson River Watershed on Vancouver Island were divided into homogeneous units on the basis of the landform adjacent to the stream, v a l l e y shape, and stream pattern. area.  Nine sections were compared with regard to cutbank  No simple relationships between land and stream c h a r a c t e r i s t i c s  were found, making i t impossible to develop a r e l i a b l e model for pred i c t i n g p o t e n t i a l bank cover with the use of a i r photos alone.  However,  i t was concluded that i t i s v a l i d to use the survey techniques described  ii  to  divide  locations  streams  into  relatively  w a r r a n t i n g ground  homogeneous  checks.  units  and  determine  i i i  TABLE OF CONTENTS  ABSTRACT ACKNOWLEDGEMENTS LIST OF TABLES LIST OF FIGURES PREFACE Chapter I INTRODUCTION THE STUDY AREA A.  C r i t e r i a for the Study Site  B.  Description of the Area  C.  1.  Location  2.  Geology  3.  Vegetation  4.  Flow c h a r a c t e r i s t i c s of streams  Logging Techniques  MATERIALS AND METHODS RESULTS AND DISCUSSION A.  Extent of Disturbance of Streambanks  B.  Width and Bankful Width Measurements  C.  1.  Karolyn Creek  2.  Rosanne Creek  3.  Pseudohah Creek  4.  Hah Creek  Cutbank Areas  iv  TABLE OF CONTENTS CONT'D Page  D.  1.  Karolyn Creek  29  2.  Rosanne Creek  31  3.  Pseudohah Creek  32  4.  Hah Creek  32  5.  Comparison with r e s u l t s i n the literature  33  Composition of the Cutbanks  MANAGEMENT IMPLICATIONS  34 36  A.  Winter Logging  36  B.  Summer Logging  36  Chapter I I INTRODUCTION  38  DESCRIPTION OF THE STUDY AREA  42  A.  Location  42  B.  Geology  42  C.  Vegetation  42  MATERIALS AND METHODS  45  RESULTS AND DISCUSSION  49  A.  Section 1  49  B.  Section 2  54  C.  Section 3  54  D.  Section 4  59  E.  Section 5  59  F.  Section 6  62  G.  Section 7  67  V  TABLE OF CONTENTS CONT'D Page H.  Section 8  67  I.  Section 9  72  J.  General Discussion  74  SUMMARY  78  REFERENCES CITED  79  APPENDIX I  82  APPENDIX I I  84  ACKNOWLEDGEMENTS  I for  would  hisdirection  Northcote,  like  t o thank  and encouragement;  Dr. J . P . Kimmins,  D r . T.G.  a n d D r . P.G. H a d d o c k f o r r e v i e w i n g t h e m a n u s c r i p t ;  Mr.  B a r r y Lam f o r a s s i s t i n g  for  identifying  for  helping with  Northwood  my a d v i s o r , D r . R.P. W i l l i n g t o n ,  Pulp  the mosses;  Rod B o e n i s c h  for  the t y p i n g .  University  f o rdrafting  I preparation  analysis;  the diagrams;  s t u d y was s u p p o r t e d  during  would  like  Columbia.  Mr. Dennis  Northwood  t o thank  Pulp  study  sites;  Biddlecombe  Research,  and Timber  provided  i n north central  my w i f e , J u d y ,  manuscript.  Araki of  and M r s . L e s l i e  on  Schofield  Demaerschalk  i n locating  by the Committee  the f i e l d work p e r i o d  o f the f i n a l  D r . W.B.  M r . Tom See a n d D r . J u l e s  the s t a t i s t i c a l  of British  room and b o a r d  the f i e l d work;  and Timber L t d . f o r a s s i s t a n c e  Mr.  The  during  f o rassistance  B.C.  during  vii  LIST OF TABLES Table 1  Page Length of stream sections surveyed i n the study (metres)  22  Percentage of the streambanks (by length) within the logged areas which are disturbed by logging a c t i v i t y ( c l a s s i f i e d as heavily disturbed) i n summer and winter logged sections.  22  Mean widths and bankful widths of Karolyn Creek i n winter and summer logged study sections and adjacent forested sections  24  Mean widths and bankful widths of Rosanne Creek i n summer and winter logged sections and adjacent forested areas  26  Mean widths and bankful widths of Pseudohah Creek  27  6  Mean widths and bankful widths of Hah Creek  29  7  Mean cutbank area per 25 metres section of Karolyn Creek (metres /25 metre section of stream)  31  Mean cutbank area per 25 metres section of Rosanne Creek (metres /25 metre section of stream)  31  Mean cutbank area per 25 metre section of Pseudohah Creek (metres2/25 metre section of stream)  32  Mean cutbank area per 25 metre section of Hah Creek (metres^/25 metre section of stream)  33  11  Description of landform units  46  12  Land and stream c h a r a c t e r i s t i c s of the study reaches  50  13  Measurements of stream c h a r a c t e r i s t i c s of the study reaches  51  Duncan's Multiple Range Test of cutbank areas  74  2  3  4  5  8  9  10  14  viii  LIST OF TABLES CONT'D. Table 15  Page Summary of section characteristics  75  ix  LIST OF FIGURES Figure 1  2  3 4  5 6 7  Page Map showing the location of study streams with respect to nearby r i v e r s with an inset showing the location of the study area in B.C.  10  Map of the stream study sections on Rosanne and Karolyn Creeks and the adjacent cutting units  11  Map of the stream study sections on Hah and Pseudohah Creeks and the adjacent cutting units  12  Examples of heavily disturbed sections of Rosanne Creek including: A. the s i t e of a skidder crossing; and B. heavy debris accumulations  17 17  A cutbank i n the upstream control section of Pseudohah Creek  19  A t y p i c a l section of overhanging cutbank i n the control section of Pseudohah Creek  20  A. B.  8  9  10 11  A heavily disturbed section of Karolyn Creek flowing through coarse, bouldery material  25  An area of Kenneth Creek flowing through s i l t y lacustrine material with extensive streambank erosion  25  Stream diversions caused by debris accumulations i n the winter logged section of Rosanne Creek  28  Heavy accumulations of debris above Pseudohah Creek  30  Map of the Robertson River watershed showing the study sections  43  Section 1 - Robertson River.  52  A.  Location of section 1 i n the watershed.  B.  Landformmap. for cutbanks.  C.  Valley cross section at x-x' . The r a t i o of v e r t i c a l to horizontal axis i s 1:2.  The  reach z-z  1  was  sampled  X  LIST OF FIGURES CONT'D. Figure 12  13  14  15.  16.  Page Section 1 - Robertson River.  53  A.  Schematic representation of the channel cross section at y-y' of the landform map. (Fig. 11.B).  B.  Photograph taken near y-y' of the landform map ( F i g . 11.A). A large quantity of coarse bedload has been deposited i n this section.  Section 2 - Robertson River.  55  A.  Location of section 2 i n the watershed.  B.  Landform map. for cutbanks.  C.  Valley cross section at x-x!.  The reach z-z  1  was  sampled  Section 2 - Robertson River.  56  A.  Schematic representation of the channel cross section at y-y' of the landform map. (Fig. 13.B). The forest f l o o r i s too high above the channel to form cutbanks.  B.  Photograph looking, downstream near y-y' ( F i g . 13.B).  Section 3 - Robertson River.  57  A.  Location of section 1 i n the watershed.  B.  Landform map. for cutbanks.  C.  V a l l e y cross section at x-x'.  The reach z-z' was  sampled  Section 3 - Robertson River. Schematic representation of the channel cross section at y-y' of the landform map (Fig.15.B).  58  xi  LIST OF FIGURES CONT'D. Figure 17  Page Section 4 - Robertson River. A.  Location of section 4 i n the watershed.  B.  Landform map. The reach y-y' was sampled for cutbanks. The channel pattern of the upstream part of section 4 i s under bedrock c o n t r o l .  C.  Valley cross section at x-x'.  60  18  Section 4 - Robertson River. Schematic representation of the channel cross section at z-z' of the landform map ( F i g . 17.B).  61  19  Section 5 - Robertson River.  63  A.  Location of section 5.  B.  Landform map. for cutbanks.  C.  V a l l e y cross section at x-x'.  The reach z-z' was sampled  20  Section 5 - Robertson River. Schematic representation of the channel cross section at y-y' of the landform map ( F i g . 19.B). Although the v a l l e y bottom i s extremely narrow, small pockets of alluvium have been deposited adjacent to the channel.  64  21  Section 6 - Unnamed Creek.  65  22  A.  Location of section 6 i n the watershed.  B.  Landform map. for cutbanks.  C.  V a l l e y cross section at x-x'.  The reach z-z' was sampled  Section 6 - Unnamed Creek. Schematic representation of the channel cross section at z-z' of the landform map (Fig.21.B). Cutbanks are found on both sides of the channel for most of this section. Dense shrub vegetation borders the stream.  66  xii  LIST OF FIGURES COOT^D.  Section 7 - Nineteen Creek. A.  Location of section 7 i n the watershed.  B.  Landform map. for cutbanks.  C.  V a l l e y cross section at x-x .  The reach z-z' was sampled  1  Section 7 - Nineteen Creek. A.  Schematic representation of the channel cross section at y-y' ( F i g . 23.B). The v a l l e y f l a t consists of coarse rubble. The few cutbanks i n the study reach are formed under roots or logs embedded i n the streambank.  B.  Photograph looking upstream at y-y' (Fig.23.B)  Sections 8 and 9 - Swamp Creek and Sixteen Creek. A.  Locations of sections 8 and 9 i n the watershed  B.  Landform map. Section 8 i s located between 1 and 2. Section 9 i s located between 3 and 4. Reaches v-v' and z - z were sampled f o r cutbanks. 1  C.  V a l l e y cross section at x - x . 1  Section 8 - Swamp Creek. Schematic representation of the channel cross section at t - t ' of the landform map.(Fig.25.B). Section 9 - Sixteen Creek. A.  Schematic representation of the channel cross section at y-y' of the landform map (Fig.25.B)  B.  Photograph looking upstream at y-y' (Fig.25.B) Cutbanks have formed under the roots of the alder trees adjacent to the channel.  1  PREFACE  Whenever logging adjacent to streams occurs, the streambanks are i n danger of being p h y s i c a l l y damaged and, because physical changes i n streams a f f e c t salmonid habitat, such logging i s p o t e n t i a l l y hazardous to f i s h (Chapman, 1962; H a l l and Lantz, 1969;  Burns, 1972).  A number of studies have found that population size of s a l monids i s p o s i t i v e l y correlated with the amount of cover available (Boussu, 1954; Gunderson, 1969; Lewis, 1969; Chapman and Bjorrn, Hunt, 1971).  1969;  This r e l a t i o n s h i p of salmonid populations to suitable  habitat i s not simple, since a number of variables besides cover are important i n determining f i s h populations (Allen, 1969).  Further,  cover requirements may vary with species of salmonid (Hartman, 1965; A l l e n , 1969; Chapman and Bjorrn, 1969), i n t e r a c t i o n among species (Hartman, 1965; Chapman and Bjorrn, 1969), season (Hartman, 1965; Chapman, 1966), and f i s h size (Allen, 1969; Chapman and Bjorrn, 1969).  The present study was undertaken i n order to ascertain whether streambank logging practices adversely a l t e r available cover. Chapter I deals with research i n north central B r i t i s h Columbia related to this problem. was  A p a r t i c u l a r component of cover, stream  selected for measurement.  cutbank,  Undercut banks were defined for this  study as any projection of the bank protruding at least 15 centimeters over the stream surface.^  Undercut banks are a portion of what might  _ This figure was used by Hunt (1971) when measuring  cover.  2  c o n s t i t u t e cover; also important are overhanging v e g e t a t i o n , submerged objects (rocks, l o g s ) , f l o a t i n g and f i x e d debris (log jams, stumps), and water turbulence.  Undercut banks were chosen for measurement  because they c o n s t i t u t e a component of cover that i s e a s i l y disturbed by logging a c t i v i t y .  P r e l i m i n a r y observations  i n d i c a t e d that i n second  and t h i r d order streams where there i s l i t t l e a c t i v e e r o s i o n , re-establishment of cutbanks i s l i k e l y to take a number of years, whereas some other components of cover (e.g. overhanging vegetation) are r e - e s t a b l i s h e d more r a p i d l y and can be adjusted r e l a t i v e l y q u i c k l y by r e h a b i l i t a t i o n measures. The occurrence of cutbanks i s a r e s u l t of i n t e r a c t i o n s between the stream and the channel bank m a t e r i a l .  Chapter I I r e l a t e s bank mat-  e r i a l s and landforms to the occurrence of cutbanks on a watershed on Vancouver I s l a n d . Land surveys of wildlands i n Canada g e n e r a l l y employ a b i o p h y s i c a l system as a basis for mapping; the mapping i s done on air- photos using photo features r e l a t e d to geomorphology and s u r f i c i a l deposits as w e l l as vegetation (Lacate, 1969).  A s i m i l a r system i s used i n Chapter  I I ; the streams of the watershed were categorized i n t o homogeneous u n i t s on the basis of stream p a t t e r n , v a l l e y shape, and landform adjacent the streams.  to  Reaches of streams with these s i m i l a r i t i e s could be expected  to have comparable cutbank c h a r a c t e r i s t i c s since the flow patterns  and  the bank m a t e r i a l s adjacent to the s e c t i o n of stream are somewhat s i m i l a r . This i s a s i m i l a r approach to that taken by P l a t t s (1974) when he  tried  to r e l a t e factors relevant to f i s h h a b i t a t to the geomorphic mapping of an area.  The aim i n Chapter I I i s to develop an approach to surveys of streams that takes the land component into account.  When land use  a c t i v i t i e s adjacent to streams are being contemplated,  the s e n s i t i v i t y  to damage of the p a r t i c u l a r reach of stream i s important i n addition to the b i o l o g i c a l values of the streams. The f i e l d work i n north c e n t r a l B r i t i s h Columbia was done during July and August, 1973 with the help of a f i e l d a s s i s t a n t .  The  f i e l d work on Vancouver Island took approximately f i v e days and was done i n August, 1974.  4  CHAPTER I  INTRODUCTION  T h i s study examined stream morphology and the stream l a n d face d e a l i n g p r i m a r i l y with and  the f a t e o f undercut streambanks a f t e r l o g g i n g  the i m p l i c a t i o n s f o r f i s h h a b i t a t .  The purpose was to document a  change i n a p a r t i c u l a r component o f c o v e r , u n d e r c u t banks, i n f o u r i n north  central British  inter-  streams  Columbia.  The  specific  o b j e c t i v e s of t h i s  a.  to determine the e f f e c t o f l o g g i n g on the c h a n n e l dimensions o f s m a l l streams f l o w i n g  b.  study were:  through e r o d i b l e m a t e r i a l s ;  to determine the e f f e c t o f l o g g i n g on the a r e a o f undercut streambanks;  c.  to measure the e x t e n t  of p h y s i c a l disturbance  o f the stream-  banks by l o g g i n g equipment; d.  t o compare the e f f e c t s o f w i n t e r disturbance  e.  and summer l o g g i n g on the  o f streambanks;  to examine the p h y s i c a l c o m p o s i t i o n  o f the u n d e r c u t banks  ( i . e . whether the mosses, the f o r b r o o t s , the shrub r o o t s , the  t r e e r o o t s , o r the s o i l was important  i n b i n d i n g the  streambanks); and f.  to determine which stream and watershed c h a r a c t e r i s t i c s a r e important i n a s s e s s i n g damage.  a stream's s e n s i t i v i t y  to l o g g i n g  5 A number of studies have demonstrated  a positive correlation  between salmonid populations and available overhead cover. which generally have been used are:  The methods  1) to compare f i s h populations i n  adjacent sections of streams with d i f f e r i n g amounts of cover; and 2) to compare the populations i n a given section of stream before and a f t e r manipulation of cover.  Boussu (1954), Gunderson (1968), and E l s e r (1968)  used the f i r s t approach, measuring  the amount of cover i n d i f f e r e n t  reaches of a stream and r e l a t i n g this cover to f i s h populations. (1971), using the second approach, was  Hunt  able to s i g n i f i c a n t l y increase  brook trout (Salvelinus f o n t i n a l i s ) populations i n a given area by building cover devices and deflectors to scour deeper pools.  Similarly,  Saunders and Smith (1962) found, i n a short term study, that the number of one-year-old and older brook trout was approximately doubled with i n s t a l l a t i o n of cover devices and current d e f l e c t o r s .  Overhead cover functions p r i m a r i l y to enable predator avoidance.  However, during the winter, i t could also serve as a refuge to  prevent unprofitable energy expenditure and physical damage (Chapman and Bjorrn, 1969).  A number of variables including species, f i s h s i z e , and  season,  influence the relationship between cover and salmonid populations. The importance and role of cover, varies with the species and size of salmonid.  Stewart (1970) i n a study of physical factors a f f e c t i n g  trout density i n a small stream, found that mean section depth and underwater, overhanging rock cover were important i n determining brook trout density and rainbow trout (Salmo gairdneri) density.  Undercut banks and  6 areas of deep turbulent water were of importance but not to rainbow trout density.  to brook trout density,  Bustard (1973), i n a study of winter  habitat, found that steelhead f r y were most often associated with rubble whereas coho and older steelhead were associated with upturned logs, debris, and overhanging banks.  roots,  Butler and Hawthorne (1969), i n  a laboratory study, found that brown trout (Salmo trutta) u t i l i z e overhead cover to a greater extent than do rainbow trout. The importance of cover also varies with season or, more s p e c i f i c a l l y , temperature. 1969;  A number of studies (Hartman, 1965; Everest,  Bustard, 1973) indicate that juvenile salmonids occupy d i f f e r e n t  habitat areas i n summer than i n winter, being more c l o s e l y associated with cover and e x h i b i t i n g a c h a r a c t e r i s t i c hiding response with lower temperatures.  Although there i s considerable v a r i a t i o n with location  and species, Chapman and Bjorrn (1969) c i t e references from around  the  world where salmonids take on this hiding behavior at temperatures below 7 degrees Celsius.  S i m i l a r l y , i n t h e i r own work they found that for  young steelhead and chinook salmon (Oncorhynchus tshawytscha) a decrease i n temperature  resulted i n increased hiding behavior i n a flume with rock  substrate (Chapman and Bjorrn, 1969).  Suitable winter cover may  d i f f e r e n t from summer cover for the same species.  be quite  Coho, for example,  have been found associated with bank cover and submerged logs and stumps i n the winter (Hartman, 1965;  Bustard, 1973) while during their  first  summer they occupy shallow waters i n small bays at the stream margin and small, shallow r i f f l e s  (Hartman, 1965).  The amount of e f f e c t i v e cover w i l l vary with the l e v e l of water i n a stream.  Kraft (1972) mapped overhead cover on streams i n which water  7  flow was  a r t i f i c i a l l y reduced.  With flow reductions of 25 to 75 percent  of  long term base flow, loss of cover was not s u b s t a n t i a l .  of  39 to 56 percent was  Kraft (1972) concluded  A cover loss  reported with 90 percent flow reduction. that overhead cover was  However,  not greatly influenced by  flow reduction.  In order to measure cover u s e f u l for salmonids, i t i s necessary, therefore, to define species and size of f i s h , season, and perhaps streamflow l e v e l at the s i t e i n question.  8  THE STUDY AREA  A.  C r i t e r i a for the Study Site In the planning stages the following c r i t e r i a were suggested  as requirements a.  of the study area.  The stream should flow through a forested area and then through a clearcut.  b.  The stream should be small enough i n order to f a c i l i t a t e measurement of the cutbank.  c.  The stream should have obvious undercut banks.  d.  The t e r r a i n and s u r f i c i a l geology of the forested stand and the clearcut should be reasonably s i m i l a r .  The lower mainland and Vancouver Island were explored f o r study sites.  However, there were few areas l e f t unlogged i n which small streams  flowed through a l l u v i a l materials.  The Slim-Tumuch watershed, located  100 kilometres east of Prince George, was therefore chosen.  Advantages  of this s i t e were: there were at least four small streams i n the area that would be suitable f o r the study; a co-operative study by the Fish and W i l d l i f e Branch and the Fisheries Service of the Department of the Environment was already i n progress i n the area; the Forestry Department of Northwood Pulp and Timber Ltd. was interested i n the study and offered to provide assistance; the t e r r a i n i n logged and unlogged sections of the streams was reasonably s i m i l a r .  9  B.  Description of the Area 1.  Location.  The locations of the four streams are shown i n  Figure 1 while Figure 2 shows the locations of the logged sections on Rosanne and Karolyn Creeks and Figure 3 shows Hah and Pseudohah Creeks. The winter logged section on Karolyn i s compared to a downstream control 90 metres i n length where the stream passes through a buffer s t r i p adjacent to Centenial Creek.  An upstream section above the winter logged  clearcut i s compared to the winter logged area. On Rosanne Creek the control section i s above the summer logged section.  A downstream control was not used because the stream passes  through a swamp i n this section.  Karolyn and Rosanne Creeks do not con-  t a i n indigenous populations of salmonids. Hah and Pseudohah Creeks drain into the Bowron River.^ upstream and downstream control were established on Pseudohah. cent sections are compared on Hah Creek.  An  Two adja-  These streams have natural pop-  ulations of rainbow trout.  2.  Geology.  The area i s c l a s s i f i e d by Holland (1964) as being  i n the Fraser physiographic region.  The t e r r a i n exhibits abundant evidence  _  Both of these creeks have been referred to as "Hah" Creek. In the report of Slaney, Chamberlin and Halsey (1973), an unnamed stream was referred to as "Hah" Creek. Another stream located north of this stream i s l a b e l l e d "Hah" Creek i n the National Topographical Series. To d i s t i n g u i s h between these two streams, the unnamed stream w i l l be referred to as "Pseudohah". Hah Creek runs through the area assigned cutting permit 307; Pseudohah runs through the area assigned cutting permit 311.  Figure 1.  Map showing the location of study streams with respect to nearby r i v e r s with an inset showing the location of the study area i n B.C.  Figure 2.  Map of the stream study sections on Rosanne and Karolyn Creeks and the adjacent cutting units.  12  F i g u r e 3.  Map o f the stream study s e c t i o n s on Hah Creeks and the a d j a c e n t c u t t i n g u n i t s .  and  Pseudohah  13 of g l a c i a t i o n .  The s u r f i c i a l material surrounding upper Rosanne and  Karolyn Creeks i s colluvium.  The lower portions are surrounded  by org-  anic and a l l u v i a l materials.  The study sections on Hah and Pseudohah  Creeks run through coarse t i l l materials.  3.  Vegetation.  The study streams are i n the I n t e r i o r Western  Hemlock Biogeoclimatic Zone proposed by Krajina (1965).  P r i n c i p a l conifer  tree species are white spruce, subalpine f i r , and western hemlock.^ Deciduous species are mainly speckled alder, black cottonwood, and trembling aspen.  The p r i n c i p a l trees found along the streambanks are alder, willow, white spruce, and subalpine f i r .  The shrub component i s dense  with black twinberry, thimbleberry, and red raspberry.  Adjacent to the stream there i s a dense layer of forbs and mosses.  In this area the mosses appear to play an important role i n  protecting the streambanks from erosion.  4.  Flow c h a r a c t e r i s t i c s of streams.  The flow v a r i a t i o n s i n  the study streams are not as pronounced as they are on the coast despite reasonably high r a i n f a l l s .  The fluctuations i n flow are exemplified by  measurements taken i n Centenial Creek below the confluence of Rosanne and Karolyn Creeks. kilometres.  The area drained at this point i s approximately 50  square  Freshets i n the spring and f a l l have been measured at 4.5  5.0 m /s r e s p e c t i v e l y . _  The s c i e n t i f i c and common names of plant species are l i s t e d i n Appendix 1.  and  14  The baseflow i n the summer i s approximately  0 . 4 m /s.  The stream has  r i s e n to 1.7 and 2 . 3 m /s during the summer but shows a slow response to p r e c i p i t a t i o n because of a moisture d e f i c i t i n the s o i l .  The  flow c h a r a c t e r i s t i c s are somewhat s i m i l a r i n Rosanne and  Karolyn Creeks.  Spring maximum and minimum flows, i n the streams i n 1973  were as follows:  Area Rosanne  11.7  km  Karolyn  4.4  km  2  2  Maximum  Minimum  1 . 1 0 m /s  0 . 1 1 m /s  0 . 9 1 m /s  0 . 0 3 m /s  3  3  3  3  The maximum and minimum flows for July and August i n 1973 were as follows:  Rosanne  11.7  km  Karolyn  4.4  km  2  2  0 . 2 0 m /s 3  o  0 . 4 2 m°/s  0 . 0 6 m /s 3  o  0.006 iri/s  The areas indicated are approximate since the watershed divides were d i f f i c u l t to define on the topographic maps.  C.  Logging Techniques  Two d i s t i n c t types of logging take place i n the northern ior.  inter-  On poorly drained organic, a l l u v i a l , and lacustrine s o i l s , the logging  takes place i n the winter when the ground i s frozen and there i s a snow cover.  I f the stream i s too large to cross d i r e c t l y , a temporary bridge  i s i n s t a l l e d using available logs.  I f the stream i s small i t i s often  not seen and logging proceeds as i f i t were not there.  Many of the  15  problems with this type of logging arise during spring break-up.  With  skidder t r a c t o r s , the logs are yarded as tree lengths to a landing where they are limbed and bucked.  During the summer season, logging i s carried out on the w e l l drained, steeper t e r r a i n which provides better t r a c t i o n and a firm footing for skidding equipment. shape of the t e r r a i n .  Often the skidding pattern i s regulated by the Problems can arise where the skid roads are adja-  cent to the stream.  The methods used i n the winter logged study sections are typi c a l of those used i n the area.  Special guidelines were used on the  summer harvested areas on Rosanne and Karolyn Creeks. (as reported by Slaney, Chamberlin, and Halsey,  1973)  These guidelines are:  a.  Where f e a s i b l e , f a l l trees away from, streambanks.  b.  Locate  skid t r a i l s so as to avoid in-stream a c t i v i t y by  placing them p a r a l l e l to the stream and 5 m.  approximately  (15 f t . ) away.  c.  Contour skid t r a i l s to adjacent  slopes.  d.  Employ a d i f f e r e n t contractor on each side of the stream. Both contractors are to u t i l i z e s i m i l a r operating procedures.  Since the contractors knew a watershed study was care was There was tractors.  to take place, extra  probably exercised when yarding along Rosanne and Karolyn Creeks. some manual removal of debris from these streams by the conThe  logging practices employed on Pseudohah and Hah  more t y p i c a l of the region i n that l i t t l e bank protection.  concern was  Creeks were  given for stream-  16  MATERIALS AND METHODS  Various parameters of channel morphology were studied i n the f i e l d and the following measurements were made: a.  Each 25 metre section of stream was c l a s s i f i e d as e i t h e r heavily or moderately disturbed.  I f there was obvious  disturbance of the streambank by logging equipment, timber f e l l i n g , or road b u i l d i n g , the stream was c l a s s i f i e d as heavily disturbed.  The remaining portion of the stream  which showed less evidence of disturbance by logging was c l a s s i f i e d as moderately disturbed.  Examples of sections  of the stream c l a s s i f i e d as heavily disturbed are shown i n Figure 4.  Figure 8.B i s an example of a section of  stream c l a s s i f i e d as moderately disturbed. b.  The widths, bankful widths, and depths of the streams were measured every 5 metres except i n some r e l a t i v e l y uniform or inaccessible areas where measurements were made every 25 metres.  On Rosanne Creek measurements were taken every  25 metres.  The measurements were made during low summer  flows i n July and August of 1973. Bankful width i s the width measured between the high water raarks on the streambanks . c.  The plan areas of the undercut streambanks were measured. The length of each cutbank was measured.  The width of the  cutbank was measured every 50 cm. along i t s length by probing under the cutbank with a metre s t i c k . was computed using the formula  The cutbank area  17  Figure  4.  Examples o f h e a v i l y d i s t u r b e d Rosanne C r e e k i n c l u d i n g : A.  the s i t e  of a skidder  B.  heavy d e b r i s  sections  crossing;  accumulations.  and  of  18  Area = Length x Summation of widths (Number of widths + 1) The numerator  i s divided by the number of width readings  plus one to account for 0 width at each end. d.  Samples 20 cm. wide were taken from 31 t y p i c a l cutbanks. The t o t a l volume of s o i l i n the sample and the t o t a l lengths of roots i n 6 size classes (0.3 - 0.5 cm; 0.5  cm  1.0 cm; 1.0 cm - 2.0 cm; 2.0 cm - 3.0 cm;~>3.0 cm) were measured.  Using these data, root volume as a percentage  of t o t a l s o i l volume of the samples was  computed.  The experimental design assumes that widths, bankful widths, and cutbank areas are similar i n harvested and control sections before logging and any differences between stream sections are the r e s u l t of harvesting a c t i v i t i e s .  Notes were taken on the vegetative composition of these cutbanks. the  T y p i c a l cutbanks are shown i n Figures 5 and 6.  Observations of  following were recorded: a.  Damage obviously r e s u l t i n g from logging a c t i v i t y within each 25 metre section was noted, e.g. introduction of logging debris, evidence of skidding i n the stream, or post-logging scouring of the banks.  b.  Instances of natural slumping or debris accumulations i n the  c.  control section were recorded.  Presence and extent of s i l t accumulation i n the streams were noted but not measured.  19  Figure 5.  A cutbank i n the upstream c o n t r o l of Pseudohah Creek.  section  20  Figure  6.  A t y p i c a l s e c t i o n of overhanging cutbank i n the c o n t r o l s e c t i o n o f Pseudohah Creek.  The differences i n cutbank areas and i n stream widths were compared using analysis of variance completely randomized design (Snedecor and Cochran, 1967).  A Duncan's multiple range test was used  to test for differences between i n d i v i d u a l means (Walpole, 1968).  In  those instances where only two groups were being compared a group comparison test (t - test) was used.  Since both of these tests require  homogeneous variances, B a r t l e t t ' s test for homogeneous variances was carried out a f t e r performing logarithmic transformations.  In those  instances where the variances were heterogeneous, a t-test for data with heterogeneous variances and unequal sample size was used (Snedecor and Cochran, 1967).  A significance l e v e l of 0.05 was used throughout the  s t a t i s t i c a l analysis.  22  RESULTS AND DISCUSSION  A.  Extent of Disturbance of Streambanks  The percentage of the streambanks disturbed by logging a c t i v i t y varied between 12% and 83% (Table 1 and 2 ) .  Table 1.  Length of stream sections surveyed i n the study Karolyn  (metres)  Rosanne  Pseudohah  Hah  75  408  NA  50  225  86  NA  350  90  None  NA  325  Heavily Disturbed  200  275  575  NA  Moderately Disturbed  450  350  Control  400  500  Winter Logged Heavily Disturbed Moderately Disturbed Control Summer Logged  1125  NA  600  NA  * NA - Not applicable, Table 2.  Percentage of the streambanks (by length) within the logged areas which are disturbed by logging a c t i v i t y ( c l a s s i f i e d as heavily disturbed) i n summer and winter logged sections.  Stream  Karolyn Rosanne Pseudohah Hah  Winter Logged  25 83 NA 12  Summer Logged  31 44 34 NA  23  Both the highest and lowest values occurred i n the winter logged sections suggesting that the amount of disturbance i s probably dependent on the snow l e v e l during the harvesting operation. sing on Rosanne Creek ( F i g . 4.A)  An obvious skid t r a i l cros-  indicates that snow did not  cover the stream during logging and consequently of debris accumulated i n this section ( F i g . 4.B).  completely  a considerable quantity This debris caused  diversions and scouring of the stream during the high flows of spring break-up.  Hah Creek, with only 12% of i t s length disturbed, probably  had a deep covering of snow during logging.  The summer logged sections i n the three streams have a r e l a t i v e l y constant percentage of their length heavily disturbed (between 31% and  B.  44%).  Width and Bankful Width Measurements  1.  Karolyn Creek.  The widths and bankful widths of the winter  harvested section (both moderately and heavily disturbed) are s i g n i f i c a n t l y larger than i n the control section (Table 3).^ or may  These differences may  not be attributable to logging a c t i v i t y i n the experimental section.  For example, the control section had a well-defined channel as compared to a s l i g h t l y braided pattern i n the harvested section, which that differences i n stream width and bankful width may p r i o r to logging.  The  suggests  have occurred  large difference i n bankful width between the  heavily disturbed and the moderately disturbed areas may  be attributed  A P=0.05 has been used throughout this study to test for significant differences.  24 Table 3.  Mean widths and bankful widths of Karolyn Creek i n winter and summer logged study sections and adjacent forested sections.  Winter Logged Control  Moderately Disturbed  Stream width (metres)  2.50  2 .99  Bankful width (metres)  3.68  5.58  Heavily Disturbed 3.99* 10.41  Summer Logged Control  Moderately Disturbed  Heavily Disturbed  Stream width (metres)  3.38  3.43  4.07  Bankful width (metres)  5.10  4.64  7.48  * The means connected by a line are not s i g n i f i c a n t l y d i f f e r e n t at P=0.05; those not connected are s i g n i f i c a n t l y d i f f e r e n t . to a skidder crossing s i t e i n an area of f i n e l y textured, poorly drained soils.  During winter harvesting, this stream was not v i s i b l e and skidding  took place as i f i t were not there.  In comparing the summer logged section with i t s c o n t r o l , i t would seem that logging had l i t t l e a f f e c t except possibly where bankful widths were increased i n the heavily disturbed section.  However, since  the stream flows through a V-shaped g u l l y for most of the summer harvested section, skidder a c t i v i t y adjacent to the channel did not occur. Where bankful widths were s i g n i f i c a n t l y wider ( i . e . i n the heavily d i s turbed section) there was a skid road d i r e c t l y i n the stream as shown i n Figure 7.A.  25  Figure  7.  A.  A h e a v i l y d i s t u r b e d s e c t i o n of K a r o l y n Creek flowing through coarse, bouldery materials.  B.  An  area  of  lacustrine erosion.  Kenneth  Creek  material  with  flowing  through  extensive  silty  streambank  The summer harvested section of Karolyn Creek with i t s coarse bouldery material i s not as susceptible to widening as the winter harvested section of Karolyn Creek with i t s a l l u v i a l m a t e r i a l , or nearby Kenneth Creek with lacustrine material (Figure 7.B).  2.  Rosanne Creek.  Widths i n the heavily disturbed section  were almost double those i n the moderately disturbed section (Table 4).^" Despite these apparent differences, r e s u l t s were not s t a t i s t i c a l l y signi f i c a n t , possibly because the widths were measured every 25 metres rather  Table 4.  Mean widths and bankful widths of Rosanne Creek i n summer and winter logged sections and adjacent forested areas. Winter Logged Moderately Disturbed  Heavily Disturbed  Stream width (metres)  2.40  4.13  Bankful width (metres)  4.47  8.32  Summer Logged Control  Moderately Disturbed  Heavily Disturbed  Stream widths (metres)  3.39  3.66  3.27  Bankful widths (metres)  4.40  4.87  4.87  than every 5 metres r e s u l t i n g i n a small sample s i z e .  Observations indi-  There was no suitable section available to serve as a control.  cated that i n the heavily disturbed section the stream channel was widened by skidder t r a f f i c on the streambed.  Accumulations of debris  below a skid road crossing of the stream caused extensive diversions (Figure 8 ) .  The widths and bankful widths i n the summer logged section are s i m i l a r to those i n the control section (Table 4).  The stream widths  i n the heavily disturbed section (3.27 m.) are smaller than those i n the  moderately disturbed section (3.66 m.) because s o i l from the adja-  cent skid road was pushed into the stream.  3.  Pseudohah Creek.  Results indicate that logging d i s t u r -  bance caused an increase i n stream widths and bankful widths (Table 5). The comparison i s p a r t i c u l a r l y v a l i d due to the r e l a t i v e l y long study  Table 5.  Mean widths and bankful widths of Pseudohah Creek.  Summer Logged Control  Moderately Disturbed  Heavily Disturbed  Stream width (metres)  1.99  2 .42  2 .52  Bankful width (metres)  2.34  2.89  3.62  reaches and the considerable uniformity of s o i l materials and landforms between the control and harvested sections.  Damage to the streambanks was evident i n swampy areas where the streambed was used for skidder t r a f f i c .  There were heavy debris accumu-  Figure 8.  Stream diversions caused by debris accumulations i n the winter logged section of Rosanne Creek.  29  lations on portions of this stream (Figure 9.A). In some sections this debris protected the streambanks while i n others i t formed small dams up to 70 cm. i n height. 4.  Hah Creek.  Hah Creek had r e l a t i v e l y l i t t l e damage to i t s  banks from harvesting a c t i v i t y (Table 6). While some debris accumulated  Table 6.  Mean widths and bankful widths of Hah Creek.  Winter Logged Control  Moderately Disturbed  Heavily Disturbed  Stream width (metres)  2 .88  2.99  3.54  Bankful width (metres)  3.25  3.50  4.23  i n the stream, i t was not as dense as i n Rosanne Creek.  Probably part  of the reason for this difference i s the r e l a t i v e l y shallow g u l l y shape. I f the stream i s well covered by snow during logging a c t i v i t y , there i s no depression where excessive amounts of debris can accumulate.  In  some cases debris can create better f i s h habitat by forming deeper pools.  C.  Cutbank Areas  1.  Karolyn Creek.  Results i n Table 7 would seem to indicate  that winter logging caused a decrease i n cutbank area.  However, this  assumption cannot be made since streambank materials d i f f e r e d i n the winter logged section from those i n the c o n t r o l .  Figure  9.  Heavy a c c u m u l a t i o n s Pseudohah Creek.  of debris  above  31 Table 7.  Mean cutbank area per 25 metres section of Karolyn Creek (metres^/25 metre section of stream)  Control  Moderately Disturbed  Heavily Disturbed  Winter Logged  5.52  0.56  0.71  Summer Logged  1.15  1.19  0.29  The cutbank area i n the moderately disturbed part of the summer logged section i s not appreciably d i f f e r e n t from the control cutbank area. The decrease i n cutbank area i n the heavily disturbed section resulted from skidder a c t i v i t y i n and adjacent to the stream.  2.  Rosanne Creek.  Cutbank area was smaller where logging  a c t i v i t y was more extensive as indicated i n Table 8.  Table 8.  Mean cutbank area per 25 metres section of Rosanne Creek (metres /25 metres of stream) 2  Control  Moderately Disturbed  Heavily.Disturbed  Winter Logged  NA*  2.55  0.52  Summer Logged  1.74  1.62  1.09  * Not applicable  The reduction i n cutbank area was the r e s u l t of yarding a c t i v i t y i n the stream, scouring of the banks, and s i l t deposition on the banks.  32  Summer logging did not s i g n i f i c a n t l y a f f e c t cutbank area (Table 8).  The main cause of disturbance on this section was the en-  croachment of skid roads. 3.  Pseudohah Creek.  The disturbance of the banks on Pseudohah  Creek was p a r t i c u l a r l y severe (Table 9 ) .  Table 9.  Mean cutbank area per 25 metre section of Pseudohah Creek (metres'/25 metres of stream) Moderately Disturbed  Control  Summer Logged  Heavily Disturbed  2.13  5.27  0.79  The control area adjacent to the winter logged section had the highest value (5.27 metres'/25 metres of stream)  measured i n this study.  The  stream runs through a small g u l l y with uniform terraces of a l l u v i a l materials forming the banks.  The comparison between the c o n t r o l , mod-  e r a t e l y disturbed, and heavily disturbed sections i s probably more v a l i d i n this stream than any of the others examined.  The comparatively long  study reaches add to the v a l i d i t y of the comparison (Table 2 ) .  A.  Hah Creek.  There i s l i t t l e difference between the area of  cutbank i n the control and the moderately disturbed sections (Table 10). There were no cutbanks  i n the heavily disturbed sections.  Hah Creek were r e l a t i v e l y l i t t l e disturbed.  The banks of  33 Table 10.  Mean cutbank area per 25 metre section of Hah Creek (metres /25 metres of stream) Control  Winter Logged  5.  Moderately Disturbed  2.75  2.68  Comparison with r e s u l t s in the l i t e r a t u r e .  Heavily Dis turbed  None  An extensive  comparison of the values of cutbank area reported elsewhere with those reported here would be of limited use because of v a r i a t i o n i n stream conditions. made.  However, several comparisons of a g'eneral nature can be  In Hunt's (1967) study of responses of a brook trout stream to  habitat a l t e r a t i o n , the lengths of cutbank per 100 metre length of stream i s reported.  His median values are i n the range of 10 m./lOO m.  100 m. of stream.  m./  The median value i n the Slim-Tumuch data i s 22 m./lOO m.  of stream which i s the value f o r the moderately section of Karolyn Creek. comparable.  - 25  disturbed summer logged  The ranges of values appear to be reasonably  To c l a s s i f y as bank cover i n Hunt's study, the bank had to  extend at least 15 cm. over the stream and cover 30 cm. of water depth. In this study, a minimum water depth was  not required.  Hunt, did not  measure the area of bank cover. Two  other workers, Gunderson (1968) and Elser (1968) measured  the amount of cover and compared altered and unaltered sections of streams. Elser (1968) reported that two unaltered sections of a Montana trout stream i n mountainous t e r r a i n had 44% and 81% more cover than the adjacent  34 altered section.  The cover measured included overhanging brush, under-  cut banks, stumps, rocks, and log jams. he reported was 739 m /ha. of stream.  A median value for cover which For comparison purposes, median  value of cutbank area reported here was used.  converted to the units E l s e r  The value of 177 m /ha. for the moderately disturbed section of  Rosanne Creek i s reasonably comparable considering that cover as used i n this study was more narrowly defined. Gunderson (1968) compared the amount of cover i n grazed and ungrazed portions of a stream i n Montana.  Although there was 76% more  t o t a l cover i n the ungrazed zone, the amount of undercut banks i n the two zones was r e l a t i v e l y s i m i l a r .  Values of 150 m'/ha. and 163 m'/ha.  of undercut bank were reported i n the grazed and ungrazed sections respectively.  These values are comparable to the value of 177 m /ha. re-  ported herein.  A major problem i n the present study i s the q u a n t i f i c a t i o n of f i s h habitat.  The water depth under a number of the cutbanks included i n  the survey i s too shallow to be used by f i s h during low summer flow. The mean depths i n the study reaches varied between 12 cm. and 18 cm. during low summer flows.  The water depths under the cutbanks measured  were usually less than 15 cm.  The usefulness of the banks as cover would  vary with water l e v e l .  D.  Composition of the Cutbanks  A number of samples were taken from t y p i c a l undercut banks to determine which components of vegetation were important i n maintaining  35  the i n t e g r i t y of the banks (Figure 5).  The banks were usually covered  with a thick layer of mosses, the main species of which are given i n Appendix I I .  The mosses shield the surface of the banks from erosion  during high flows.  They do not bind the s o i l to any extent because their  rhizoids do not penetrate  the s o i l .  Forbs do not appear to be  except i n areas with thick growths of lady-fern.  important  The rhizomes of this  plant often form thick mats within the surface 10-15  cm.  of s o i l .  In almost a l l instances i n the streams examined, the s o i l i t s e l f , rather than a mat important  i n maintaining  the study, only 1.5% 0.3  of vegetation or roots on top of the s o i l , , was In 31 s o i l samples of cutbanks from  of the s o i l volume consisted of roots greater than  cm. i n diameter.  were d i f f i c u l t  the banks.  There were also numerous smaller roots but  to separate from the s o i l .  these  Although small roots may  the s o i l , their role i n this regard i s d i f f i c u l t  to determine.  bind  Obser-  vations indicated that the very small roots of trees and shrubs function to bind the s o i l mass.  Large tree roots are r e l a t i v e l y unimportant i n forming Roots greater than 2 cm.  i n diameter occupied only 0.6%  the banks.  by volume of the  cutbank sections.  In the moderately disturbed areas, the streambanks were genera l l y i n t a c t i f the vegetation was  not disturbed.  I f guideline b. on  page 12 had been s t r i c t l y followed, the streambanks would have been r e l a t i v e l y undisturbed  by logging.  This guideline states that skid  roads are to be placed so as to avoid in-stream a c t i v i t y by placing them p a r a l l e l to the stream and approximately  5 m. away.  MANAGEMENT IMPLICATIONS  The problems of streambank management arc d i f f e r e n t with summer and winter logging since the t e r r a i n and  lodging conditions  d i f f e r somewhat i n each.  A.  Winter Logging  1.  During winter logging the positions of streams are  often not obvious.  I f the streams were marked p r i o r to snowfall,  the skidder operators could avoid crossing the streams. 2.  Stream crossings should be c a r e f u l l y constructed  as few i n number as possible.  and  In the study streams there were con-  siderable amounts of exposed s o i l at skidder crossings which served as a sediment source. 3.  Accumulations of debris i n stream channels should be  removed before break-up since t h i s debris can cause scouring of the channel during break-up.  B.  Summer Logging  1. preserve  During the skidding operation, care should be taken to  the i n t e g r i t y of the stream and the stre<unbanks .  of the streams can provide important 2.  cover for  The banks  H;\lmonids.  Equipment operating i n the stream I t s e l f can modify the  character of the stream.  Natural stream channel.'! have a character-  i s t i c r i f f l e - p o o l sequence.  The r i f f l e areas are often areas of high  production i n the stream whereas the pool arc.'iM .'ire usually more important as f i s h habitat.  A l t e r a t i o n s of thin  Mcquence  can cause a  decrease i n f i s h populations (Whitney and B a l l r y , 1959; E l s e r , 1968). 3.  Care should be taken to avoid 1 <H;I 1 i.ng skid roads im-  mediately adjacent to the stream. as a sediment source.  Material from these roads can act  38  CHAPTER II  INTRODUCTION  A second study was undertaken i n an attempt to develop a model for stream surveys which would include consideration of stream cutbanks.  The hypothesis was  that cutbank areas could be predicted on  the basis of landform c h a r a c t e r i s t i c s v i s i b l e on a i r photos. The objectives of the study were: a.  to measure cutbank area on selected reaches of streams within the Robertson River, B.C., watershed; and  b.  to r e l a t e the occurrence of stream cutbanks to land and stream c h a r a c t e r i s t i c s that can be detected on a i r photographs.  I f i t were possible to i d e n t i f y land c h a r a c t e r i s t i c s associated with cutbanks, i t would be possible to p r e d i c t their occurrence.  This  would be of p r a c t i c a l importance i n conducting stream inventories with the use of a i r photos.  Stream c h a r a c t e r i s t i c s such as cutbanks are  not v i s i b l e on r e a d i l y available a i r photographs  (scales 1:15,000 and  1:63,000) but larger features of the landscape such as landforms are visible. The occurrence of stream cutbanks i s a function of the flow processes of the stream and the r e l a t i v e e r o d i b i l i t y of the streambank.  Leopold et a l . (1964) state that the shape of the cross-section of a r i v e r channel at any location i s a function of the flow, t:ho quantity and character of the sediment i n movement through the section, and the character or composition of the mate r i a l s making up the bed and banks of tho channel. The  flow and i t s sediment load impose a shear stress on the banks and  bed of the channel.  The r e l a t i v e strength of the bed and bank material  w i l l determine the depth-width r e l a t i o n s h i p of the channel; the  stronger  the bank material i n r e l a t i o n to the bed material, the deeper the channel w i l l be.  In uniform, noncohesive materials  section w i l l be sinusoidal (Leopold et a l . , 1964).  the channel crossIn most cases i n  nature, a stream does not flow through uniform, noncohesive materials and the channel cross-section i s trapezoidal i n straight stretches asymmetric at curves or bends (Leopold e t _ a l . , 1964).  The  and  shape of  the banks i s dependent on the strength of the streambank materials, vegetation, roots, and various kinds of debris such as log jams, a l l of which are considered  as part of the streambank.  It i s almost impossible  to detect b i o l o g i c a l parameters such  as presence of salmonids with the use of air-photos, but i t i s possible to i d e n t i f y stream c h a r a c t e r i s t i c s relevant to salinonid habitat.  Many workers have attempted to divide streams into physiographic units that correspond with the fauna of that reach.  A l l e n (1951)  divided the Horokiwi stream into s i x d i s t i n c t zones based on differences i n physical features and  their trout population.  Iltiet (1959) i d e n t i f i e d  four major fauna zones i n Western European stream.-! which he related to  40 stream slope, cross-section of the stream, and v a l l e y cross-section. He suggested that v a l i d b i o l o g i c a l zones can be established on the basis of stream gradient and v a l l e y  shape.  Hartman and G i l l (1968) examined data from 66 streams i n southwestern B r i t i s h Columbia i n order to detect r e l a t i o n s h i p s between juvenile steelhead and cutthroat trout d i s t r i b u t i o n and p h y s i c a l charac t e r i s t i c s of streams such as gradient, pH, t o t a l dissolved s o l i d s , temperature, and discharge. The p r i n c i p a l differences i n d i s t r i b u t i o n of these two species appeared to be related to stream size and p r o f i l e .  Recently, P l a t t s (1974) has attempted to q u a l i t a t i v e l y r e l a t e f i s h populations to the geomorphic  land units on the streams of a 1000  2 km  area i n Montana.  The geomorphic  land c l a s s i f i c a t i o n was  a good i n d i c a t o r of the physical structure of streams.  found to be  Also, c e r t a i n  s t r u c t u r a l c h a r a c t e r i s t i c s of streams ( i . e . stream depth, stream width, and elevation of the channel) were found to influence f i s h populations and f i s h species composition, and consequently the geomorphic  units can  be used as an indicator of f i s h density and species. The approach used here i s somewhat s i m i l a r .  Landforms are an  expression of the geomorphology of a region and are therefore a useful basis for separating the streams into geomorphic  units.  If p a r t i c u l a r landforms are r e l i a b l e indicators of stream cutbanks, then i d e n t i f i c a t i o n of such c h a r a c t e r i s t i c s on a i r photos should prove useful i n conducting stream surveys.  The study reported here relates only one aspect of the aquatic  41  environment to landforms but the approach could be extended to include other relevant physical stream data.  42  DESCRIPTION OF THE STUDY AREA  A.  Location  The Robertson River watershed, which drains approximately 130 square kilometres, i s located on the southern shore of Lake Cowichan on Vancouver Island (Figure 10). The main stem of the Robertson River has a mean annual flow estimated to be 6 m^/s.  B.  Geology  The bedrock i n most of the v a l l e y i s volcanic with some grano d i o r i t e s i n the southeastern portion of the watershed.  There i s a large  U-shaped v a l l e y running through the center of the watershed.  The sur-  f i c i a l materials on the v a l l e y bottom are undifferentiated g l a c i a l d r i f t and a l l u v i a l terrace deposits.  The t r i b u t a r i e s are streamcut V-shaped  v a l l e y s showing l i t t l e evidence of g l a c i a t i o n .  The v a l l e y walls are  covered with a thin capping of g l a c i a l t i l l and colluvium.  There i s an  area of fine textured a l l u v i a l m a t e r i a l on a t r i b u t a r y stream i n the southern portion of the watershed.  C.  Vegetation  The study streams are i n the Coastal Western Hemlock Biogeoclimatic Zone proposed by Krajina (1965).  P r i n c i p a l conifer species  are Douglas-fir , western hemlock, western redcedar, and P a c i f i c fir.^  silver  The main deciduous-species are red alder and b i g l e a f maple.  I The s c i e n t i f i c names are l i s t e d i n Appendix I.  43  44  Salmonberry, stink current and various willows are the main shrubs adjacent to the streams.  45  MATERIALS AND METHODS  A reconnaisance survey of cutbank cover was undertaken on streams within the Robertson River, B.C., watershed (Figure 10).  on Vancouver Island  With the use of 1:63,000 a i r photos, the streams were  divided into homogeneous units on the basis of the landform adjacent to the stream, the v a l l e y shape and the stream pattern (Figure 10).  Landforms were c l a s s i f i e d and mapped using 1:15,000 a i r photos on the basis of t h e i r mode of o r i g i n according to the system described by Lacate (1969).  Landforms i d e n t i f i e d were:  a.  a l l u v i a l terrace;  b.  colluvium;  c.  outwash terrace;  d.  glacial  e.  bedrock; and  f.  a l l u v i a l fan.  till;  A description of the landform units and the associated materials i s presented i n Table Vb. V a l l e y shape was a r b i t r a r i l y designated as: a.  V-shaped; or  b.  truncated V.  With reference to the c l a s s i f i c a t i o n of channels by Bray and K e l l e r h a l s (1972), the stream pattern was designated as: a.  s t r a i g h t : very l i t t l e curvature within the reach;  b.  sinuous: s l i g h t curvature with a belt width or deviation of less than approximately two channel widths; or  c.  i r r e g u l a r : a channel pattern which cannot be considered  Table I I .  SYMBOL  Description of landform units.  LANDFORM  DESCRIPTION  DEGREE OF SORTING  COMPACTION  TEXTURE  Tc  Glacial t i l l and colluvium  Thin d r i f t of varying thickness on slopes generally greater than 15%  Unsorted  Compact  Moderately coarse  Tv  Glacial  Undifferentiated d r i f t on v a l l e y bottom with slopes less than 15%  Unsorted  Compact  Moderately fine  At  Alluvial terrace  Valley f l a t adjacent to present stream  Well sorted  Loose  Moderately coarse to very coarse  Af  A l l u v i a l fan  Fan shaped deposit adjacent to present stream  Poorly sorted  Loose  Coarse  Ac  Channel alluvium  Material deposited by present stream  Well sorted  Loose  Very coarse  Av  Valley alluvium  Material that has accumulated adjacent to present stream by c o l l u v i a l and alluvi a l processes  Poorly sorted  Loose  Very coarse  0  QJutwash terrace  F l a t surfaced bench above present r i v e r level  Well sorted  Loose  Very coarse  till  47  straight or sinuous and does not have a pattern.  repeatable  This includes s t r u c t u r a l l y controlled patterns.  Although the term "homogeneous u n i t s " has been used, i t must be understood  that the sections were not e n t i r e l y uniform throughout.  Design-  ation of units on the basis of the physical c h a r a c t e r i s t i c s described above resulted from subjective judgments rather than precise measurements. For p r a c t i c a l purposes, s l i g h t deviations from predominant configurations were ignored.  For example, Sixteen Creek (Figures 25 and 27) has a  V-shaped v a l l e y for most of i t s length with the exception a l l u v i a l fan deposit at i t s mouth.  The  fan deposit was  of a short  not  considered  large enough to warrant designation of a separate stream u n i t .  A further q u a l i f i c a t i o n of the homogeneity of the units must be made because most of the stream segments had a v a r i e t y of landforms.  For example, stream section No.  4 on the Robertson River i s  bordered by an outwash terrace on one bank and by a l l u v i a l on the other bank.  I t was  not p r a c t i c a l to designate  unit with each change of landform.  adjacent  Therefore  fan and  till  a separate stream  section 4 was  separated  from section 5 on the basis of v a l l e y shape.  Representative  study reaches were marked on 1:15,000 a i r  photographs near the centres of each of the 9 study sections.^ reaches were located on the ground and  These  the cutbanks were measured for  distances of between 150 and 400 metres.  The cutbank areas were measured  The 9 lengths of stream separated on a i r photos w i l l be c a l l e d sections (numbered 1-9) and the parts of the sections sampled for cutbanks w i l l be c a l l e d study reaches.  48  as described i n Chapter I using 25 metre lengths of stream as sampling units.  Widths and depths of the stream were measured at each end of the  study reaches.  Graphs of the v a l l e y cross sections were prepared using 1:50,000 National Topographic Series contour maps. were computed using these maps.  Gradients of the study sections  The t o t a l lengths of the study sections  were measured using 1:15,000 a i r photos.  The differences i n cutbank areas were compared using analysis of variance completely randomized  design (Snedecor and Cochran, 1967).  A Duncan's multiple range test was used to test for differences between i n d i v i d u a l means (Walpole, 1968). On the basis of f i e l d notes, schematic diagrams were drawn of the channel cross section within each reach.  These diagrams represent  an i n t e r p r e t a t i o n of the probable streambank structure throughout the study reach.  Several of the larger t r i b u t a r i e s of the Robertson, p a r t i c u l a r l y those on the west side of the r i v e r , were not sampled.  These  streams had extremely steep gradients which made them unsuitable for f i s h habitat.  Preliminary examination revealed excessive bedload and  debris movement i n these streams with l i t t l e a l l u v i a l bank material where cutbanks might be formed.  Because of .the low p r o b a b i l i t y of f i n d -  ing cutbanks, n e g l i g i b l e value as f i s h habitat, and poor access, these reaches were not sampled.  49 RESULTS AND DISCUSSION  Results of a study of land and stream c h a r a c t e r i s t i c s associated with cutbanks are summarized i n Tables 12 and 13.  These data  are best discussed on a stream section basis to permit evaluation of the survey technique and interpretation of r e s u l t s .  A.  Section 1  Section 1 (Figures 11 and 12) i s a r a p i d l y aggrading portion of the stream with bedload accumulating to the extent that during late summer and early autumn there i s l i t t l e surface flow. cutbanks i n the study reach (Table 13).^  There were no  The banks were too high above  the streambed to provide cutbanks that would be useful as f i s h habitat except during peak flows.  Also, the streambed i s extremely wide and  the streamflow impinges on the bank only on the outer bends which constitute a very small percentage of this section (Figure 11.B).  Section 1 i s separated from Section 2 on the basis of stream pattern.  In Section 1, the stream forms wide bends impinging on the  channel banks as indicated' by Figure 11.B.  There does not appear to  be r e s t r a i n i n g bedrock that might l i m i t l a t e r a l erosion. 1 The study reach refers to that section of the stream sampled for cutbanks (z-z on Figure 11.A). 1  Table  12.  Land and stream c h a r a c t e r i s t i c s  STREAM SECTION  LANDFORM  Robertson River  Alluvial terrace  Robertson River  Robertson River  of  the  study reaches.  VALLEY SHAPE  STREAM PATTERN  Well sorted Bands and gravels  Truncated V  Irregular  R i f f l e pool sequence  Alluvial terrace  Well s o r t e d sands and gravels  Truncated V  Irregular  R i f f l e pool sequence  Alluvial terrace  Well sorted sands and gravels .  Truncated V  Irregular  R i f f l e pool sequence  TEXTURE  glacial  t i l l gravelly loan bedrock o u t crops  FLOW TYPE  sandy  Robertson River  Glacial  t i l l G r a v e l l y sandy loam outwash well sorted terrace graveIs alluvium well sorted sands and gravels  Truncated V  Irregular  R i f f l e pool sequence  Robertson River  Glacial  t i l l G r a v e l l y sandy loam alluvium v e i l sorted sands  V-shaped  Sinuous  Tumbling  Unnamed Creek  alluvium  Truncated V  Irregular  R i f f l e pool sequence  Nineteen Creek  Glacial  t i l l G r a v e l l y sandy loan alluvium well sorted sands and gravels  V-shaped  Sinuous  Tumbling f l o w and r i f f l e p o o l  Swamp Creek  Glacial  Truncated V  Sinuous  Riffle  Sixteen Creek  Glacial  V-shaped  Sinuous  Tumbling f l o w and r i f f l e p o o l  S i l t s and f i n e sands  t i l l Gravelly  sandy  loamt i l l G r a v e l l y sandy loam alluvium well sorted sands and gravels  pool  Table 13. Measurements of stream c h a r a c t e r i s t i c s of the study reaches.  SECTION  SLOPE  (%)  MEAN DEPTH (cm.)  LENGTH (m.)  1.  Robertson River  0.4  *  4523  2.  Robertson River  0.6  25  2331  3.  Robertson River  0.7  15  4.  Robertson River  0.4  5.  Robertson River  6.  7.  MEAN WIDTH (m )  LENGTH SAMPLED (m )  *  AREA OF CUTBANK (m ) 2  AREA OF CUTBANK / 25 m. (km /25m) 2  400  none  0.00  9.25  375  4.88  0.33  1276  9.30  400  14.64  1.28  15  3866  5.10  200  1.90  0.24  3.9  11  5457  3.65  375  none  0.00  Unnamed Creek  0.4  11  2608  4.00  250  13.30  1.33  Nineteen Creek  4.0  10  4273  6.82  150  • 3.51  0.58  8 . Swamp Creek  1.3  6  1221  1.70  375  2.41  0.16  9.  3.8  10  2747  3.73  400  20.32  1.13  Sixteen Creek  * no surface flow at the time of the survey, August, 1974.  52  LEGEHO Glacial  Tv At Af Ac Av  Glacial t i l l Alluvial terrace A l l u v i a l fan Channel a l l u v i u m Boulder alluvlure Outwash t e r r a c e B o u n d a r y between landforms Stream channel Edge o f v a l l e y flat Ephemeral s t r e a m channel  0  Figure 11. A.  Section 1 - Robertson River. Location of section 1 i n the watershed,  200 m  .  Landform map.  The reach z-z  V a l l e y c r o s s s e c t i o n n t x-x . t o h o r i z o n t a l a x i s i s 1:2. 1  1  was sampled  The  ratio  till  co11uv1uro  x  B.  and  tc  for cutbanks  of v o r t i c a l  53  Figure 12.  Section 1 - Robertson River. A.  Schematic representation of the channel cross s e c t i o n at y-y of the landform map. ( F i g . 11.B). 1  *  The above and the following schematic representations do not imply any p a r t i c u l a r depth of material below the channel ( eg. v a l l e y alluvium i n the above diagram).  B.  B.  Photograph taken near y-y' of the landform map ( F i g . 11.A). A large quantity of coarse bedload has been deposited in t h i s s e c t i o n .  54  R e h a b i l i t a t i o n measures i n this portion of stream would have to consist of gravel removal.  Fish habitat i s provided by debris i n  the form of stumps and trees on the streambed and this material should not be removed i n any stream improvement program.  B.  Section 2  This section of stream (Figures 13 and 14), d i r e c t l y upstream from Section 1, i s characterized on a i r photos by a narrow channel and tight bends which are l i k e l y the r e s u l t of bedrock c o n t r o l , although no bedrock outcrops were observed i n the study  reach.  The area of cutbank i n the study reach i s very small (0.33 m / 25 m.).  The adjacent v a l l e y alluvium i s made up of cohesionless gravels  similar to those i n Section 1 (Figure 13.B).  The cutbanks present are  the r e s u l t of alder roots slumping into the stream (Figure 14.B).  How-  ever, since the banks are generally about 2 metres above the stream, they do not provide suitable cover for f i s h except perhaps during periods of high discharge  C.  (Figure 14.A).  Section 3  The streambanks of this section are made up of t i l l and c o l l u vium on the r i g h t bank and alluvium on the l e f t bank (Figure 15.B). The r e l a t i v e l y large amount of cutbank (1.28 m /25 m) i s formed by the roots of trees, p a r t i c u l a r l y alder, slumping into the stream (Figure 16.). The  s o i l materials are r e l a t i v e l y cohesionless and coarse textured and  0 Figure 13.  I  2K  Section 2 - Robertson River. A.  Location of section 2 i n the watershed. LEGEND Tc Tv At Af Ac Av  0  G l a c i a l t i l l and colluvlura Glacial t i l l A11uvI a I t e r r a c a A l l u v i a l fan Channel a l l u v i u m B o u l d e r a l luvlun) Outwash t e r r a c e Boundary between landforms Stream channel Edge o f v a l l e y  flat  200 Landform map, for cutbanks,  m  The reach z-z' was  x-x' 300  <D 4-  200  £  C.  Valley cross section at  x-x'.  sampled  56 A.  Figure 14.  Section 2 - Robertson River.  A.  Schematic representation of the channel cross section at y-y' of the landform map. (Fig.13.B). The forest f l o o r i s too high above the channel to form cutbanks.  B.  Photograph looking downstream near y - y '  B.  ( F i g .13.B).  O• — i1— J2K  Figure 15. A.  Section 3 - Robertson River.  Location of section 1 i n the watershed.  / Tv  Tc —  z  LEGEND  Av  / "N*  ^  Tv At Af Ac Av 0  y' Tc  G l a c i a l t i l l and col luvluia Glacial t i l l A l l u v i a l terraca A l l u v i a l fan Channel alluvium Boulder alluvlura Outwash t e r r a c e Boundary between landforms Stream channel Edge of v a l l e y flat Ephemeral channel  stream  200 m Landform map. cutbanks.  C.  The reach z - z was sampled f o r  Valley cross section  1  at  x-x'.  58  Figure  16.  Section 3 - Robertson River. Schematic representation of the channel cross section at y-y of the landform map(Fig. 15.B). 1  could not i n themselves provide cutbanks  (Figure 15.B).  The streambanks  are r e l a t i v e l y lower i n this reach than i n Section 2 permitting formation of cutbanks.  On the right bank there are several bedrock outcrops.  Willows  are colonizing the gravel bars i n the study reach but are not providing bank cover.  D.  Section 4  There i s bedrock control of the channel pattern throughout Section 4 as indicated by the sharp bends seen on the map  (Figure 17.B).  Much of this section i s a canyon with steep bedrock walls (Figure 18)  which allow l i t t l e opportunity for formation of  cutbanks  o  as shown i n the low value (0.24 m /25 m) of cutbank measured i n the study reach.  The outwash on the r i g h t bank i s on a bedrock terrace and  consequently has l i t t l e e f f e c t on channel c h a r a c t e r i s t i c s . of  For the part  Section 4 adjacent to Nineteen Creek, the channel i s bordered by  a l l u v i a l fan material consisting of coarse rubble deposited by Sixteen Creek. This section i s a t r a n s i t i o n zone between the broad v a l l e y of Sections 1, 2, and 3 and the V-shaped v a l l e y of Section 5 (Figures 13.C,  E.  15.C,  11.C,  19.C and 21.C).  Section 5  The stream flows through a V-shaped v a l l e y i n this section with  LEGEND ' Tc  Figure 17. Section 4 - Robertson River. A. Location of section 4 i n the watershed,  Tv At Af Ac Av 0  M.M.JL.  X  Glacial t i l l and colluvlura Glacial t i l l Alluvial terrace Alluvial fan Channel alluvium Boulder alluvlum Outwash terraca Boundary between landforms Stream channel Edge of valley flat  ° 200 m  Landform map. The reach y-y was sampled for cutbanks. The channel pattern of the upstream part of section 4 i s under bedrock control. 1  c <B l_  +-  <D  300 200 o  CM  C. Valley cross section at x-x'.  o  metres  «>  61  Figure 18.  Section 4 - Robertson River. Schematic representation of the channel cross section at z-z' of the landform map (Fig.17.B).  the v a l l e y walls r i s i n g steeply on each side of the channel (Figure 19 . C).  Small pockets of a l l u v i a l materials have accumulated on the v a l l e y  bottom as depicted i n Figure 20. t i o n surveyed  Cutbanks did not occur i n the por-  and are not l i k e l y to occur on the remainder of Section 5.  Cover i s provided, however, by debris i n the  channel.  Several t r i b u t a r i e s enter the Robertson River i n this section. These were not established as study reaches because their steep gradients would l i m i t their value for f i s h habitat.  F.  Section 6  Section 6 flows through a large, r e l a t i v e l y f l a t area to a pasture  (Figure 21.B and C).  adjacent  I t i s underlain by fine textured,  s l i g h t l y cohesive a l l u v i a l materials and surrounded by dense shrub vegetation.  This combination provides i d e a l conditions for the form-  ation of cutbanks.  The study reach (z-z' on Figure 21.B) along most of i t s length.  i s bordered  by cutbanks  Although the area of cutbank (1.33 m /25 m) 2  i s comparable to that i n Nineteen Creek (0.58 m /25 m), Sixteen Creek 2  (1.13 m /25 m), and Section 3 of Robertson River (1.28 m /25 m), the 2  2  cutbanks are more important  as f i s h habitat i n this reach.  the e n t i r e streambed (Figure 22.)  and consequently  Water covers  the cutbanks provide  cover at any water l e v e l .  The  federal fishery o f f i c e r and the p r o v i n c i a l conservation  o f f i c e r for the area have stated that this small stream i s one of the most important  spawning and rearing streams i n the Robertson River  LEGEND  Tv At Af Ac Av  0  Figure 19. Section 5 - Robertson River, A. Location of section 5.  B  G l a c i a l t i l l and co11uv1um Glacial t i l l A l l u v i a l terrace A l l u v i a l fan Channel a Iluvlum Boulder alluvlum Outwash terrace Boundary between landforms Stream channel Edge of v a l l e y flat  300  o o CM  o o  o o  metres C.  o o o  Valley cross section at x-x'  64  Figure 20.  Section 5 - Robertson River. Schematic representation of the channel cross section at y-y' of the landform map (Fig.19.B). Although the v a l l e y bottom i s extremely narrow small pockets of alluvium have been deposited adjacent to the channel.  65  LEGEND G l a c i a l t i l l and col Iuvlum Glacial t i l l A l l u v i a l terrace A l l u v i a l fan Channel at luvlum Boulder alluvium Outwash t e r r a c e Boundary between landforms Stream channel Edge of v a l ley  Av 0  LJI. JI  flat  i00 m The reach z-z' was sampled f o r 1  B.  Landform map. cutbanks.  c —  1 o o CM  1 o o  Jt  1 o o  metres C.  V a l l e y cross section at x-x'.  U3  66  Figure 22.  Section 6 - Unnamed Creek. Schematic representation of the channel cross section at z-z' of the landform map (Fig.21.B). Cutbanks are found on both sides of the channel f o r most of this section. Dense shrub vegetation borders the stream.  Watershed. "  It has a stable flow regime which provides a r e l a t i v e l y  1  large amount of habitat for most of the season.  It flows from a swamp,  which buffers the i n t e n s i t y of peak discharge.  Although the stream i s important for the f i s h e r y , i t s small size makes i t d i f f i c u l t to detect on the 1:15,000 or 1:63,000 scale a e r i a l photographs.  G.  Section 7  Nineteen Creek flows through a V-shaped v a l l e y for most of i t s length (Figure 23).  The  study reaches (0.58 m^/25  cutbank area i s moderate r e l a t i v e to the other m).  The right bank i s composed of bedrock  for much of i t s length and therefore there i s l i t t l e opportunity for the establishment  of vegetation.  Most of the cutbanks are formed on the  l e f t bank under the roots of alder trees situated adjacent (Figure 24  )•  to the channel  The s u r f i c i a l material on the l e f t bank i s mostly large  rubble 20 to 80 cm.  i n diameter, although there are some small pockets  of a l l u v i a l sand immediately adjacent  to the channel.  The bed and bank  materials are r e l a t i v e l y coarse textured i n comparison to the materials of the other reaches considered i n this study.  H.  Section 8  Section 8 i s a r e l a t i v e l y short, low energy stream flowing through g l a c i a l t i l l material (Figure 25.B). g u l l y about 8 m. deep and 20 m. across. deposited adjacent  The stream flows i n a  A l l u v i a l material has not been  to the stream; the streambanks are composed of the  same coarse material as that found in the streambed (Figure 26.). 1 A. Ackerman and E.W.  Armstrong personal communication  Figure 23. Section 7 - Nineteen Creek. A. Location of s e c t i o n 7 i n the watershed.  C.  V a l l e y cross section at x-x'  B ' •  T  Tc  /  \  I  /  v  \ L  r  i>\  ». **"  V  Z  I  Z  '  IJ-^ s—sLf 1 i  {1  Tc * <-<<  >*  /  V\Av  /  I  \  Tc  **>  /  <  i Av  I  N£  Tv At Af Ac Av 0  LEOENO Glacial f i l l and coI IuvIum Glacial t i l l AIluvial terraca Alluvial fan CnanneI a M uvlum Bouleer a I 1uvium Outwash terrace • Boundary between landforms Stream channel Edge of valley flat  CO  B.  Landform map.  The reach z-z' was sampled f o r cutbanks.  ^00 m'  69  A,  Figure 24.  Section 7 - Nineteen Creek.  A.  Schematic representation of the channel cross section at y-y'(Fig.23.B). The valley f l a t consists of coarse rubble. The few cutbanks in the study reach are formed under roots or logs embedded i n the streambank.  B.  Photograph looking upstream at y-y (Fig.23.B). 1  70  LEGEND  Tc Tv At Af Ac Av  G l a c i a l t i l l and colluvium Glacial t i l l A l l u v i a l terrace A l l u v i a l fan Channel alluvium Boulder alluvlum Outwash t e r r a c e • Boundary between landforms Stream channel Edge of v a l l e y flat  Landform map. Section 8 i s located between 1 and 2. Section 9 i s located between 3 and 4. Reaches v-v* and z-z' were sampled f o r cutbanks.  C.  Valley cross section at x-x'.  71  Figure 26.  Section 8 - Swamp Creek. Schematic representation of the channel cross section at t - t ' of the landform map (Fig.25.B).  72 In order for cutbanks to be formed, the streamflow must impinge on an erodible bank. m /25 m).  There are almost no cutbanks i n the study reach (0.16  Although there i s dense shrub and deciduous vegetation adja-  cent to the channel, the roots of this vegetation have had l i t t l e tunity to form cutbanks that might be useful as habitat.  oppor-  The r e l a t i v e l y  large rubble and dense shrub vegetation adjacent to the stream probably supplies adequate cover for coho f r y i n the stream.  I.  Section 9  Sixteen Creek has a r e l a t i v e l y steep gradient with bed and bank material composed of large rubble approximately 30-100 cm. i n diameter.  The stream flows over a fan deposit (Figure 25.B).  Very  small pockets of alluvium have accumulated immediately adjacent to the channel.  Cutbanks have been formed under the roots of vegetation growing alongside the channel (Figure 27 A. and B) .  The  relatively  large cutbank area i n this reach (1.13 m /25 m) i s a r e s u l t of dense 2  alder vegetation adjacent to the stream.  These cutbanks are probably  not extremely useful as cover for f i s h ; they are r e l a t i v e l y high above the  l e v e l of the water surface and usually do not provide cover over  water deeper than 10 cm.  Section 9 i s located i n a t r a n s i t i o n zone between the V-shaped v a l l e y on the southern portion of Sixteen Creek and the a l l u v i a l fan near i t s mouth.  This stream poses the same sampling problem that was  encountered  73  Figure 27. Section 9 - Sixteen Creek. A. Schematic representation of the channel cross section at y-y' of the landform map (Fig.25.B).  B.  B.  Photograph looking upstream at y-y (Fig.25.B). Cutbanks have formed under the roots of the alder trees adjacent to the channel. 1  in the headwater portions of other study reaches (5,6,7,8, and 9): of deciding the upper extent  of the study reach.  that  On a watershed such as  t h i s , the t e r r a i n makes i t impractical to investigate those portions of streams close to headwater areas.  Often there i s a b a r r i e r to f i s h  passage making these reaches inaccessible to anadromous f i s h . these streams may  support resident populations  the f i s h are often extremely small. their presence, i t may of t h e i r habitat.  While  such as cutthroat trout,  While i t may  be useful to know of  not be worthwhile to undertake extensive  analysis  The economic and s o c i a l value of the downstream pop-  ulations are much greater and therefore their habitat warrants more intensive study.  J.  General Discussion  Analysis of variance and Duncan's multiple range test were used to determine s t a t i s t i c a l differences among sections with regard mean cutbank area.  Each of the nine sections of stream i s considered  a separate treatment since d i f f e r e n t land and i n each.  The  14.  Stream Section Cutbank Area m /25 m  stream conditions p r e v a i l  sections f e l l into two overlapping, homogeneous subsets  as indicated by Table Table  14.  Duncan 's Multiple Range Test of cutbank areas.  5  1  8  4  2  9  .7  3  6  -  0.00  to  0.,00 • 0.16  0.24  0.33  0.58  1.13 1.28  1.33  1  2  1 Figures connected by a line are not s i g n i f i c a n t l y d i f f e r e n t at P=0.05.  75 The above could be interpreted to mean that certain conditions are conducive to cutbank formation  ( i . e . those i n sections 9, 3, and 6)  while other conditions are not ( i . e . those i n sections 5, 1, and 8 ) . One disadvantage of the multiple range test i s that i t sometimes gives ambiguous r e s u l t s (Woolf, 1968) as i s the case here where there i s some degree of overlap between the two homogeneous groups making i t imposs i b l e to appraise conditions i n Sections 4, 2, and 7 with respect to cutbank-forming c a p a b i l i t i e s .  The above sections have been compared without reference to s p e c i f i c conditions p r e v a i l i n g i n each.  In an attempt to find r e l a t i o n -  ships between treatments ( i . e . land and stream c h a r a c t e r i s t i c s i n each section) and cutbank area, reference i s made to Tables 12 and 13 which summarize section c h a r a c t e r i s t i c s .  The sections are grouped i n Table  15 according to the c h a r a c t e r i s t i c s which may be conducive to cutbank formation.  Table 15.  Summary of section c h a r a c t e r i s t i c s  Predominantly a l l u v i a l banks  Predominantly g l a c i a l t i l l banks  Sections 1, 2, 3, 6  Sections 4, 5, 7, 8, 9  Low gradient - 0-2%  Steeper gradient- 3-5%  Sections 1, 2, 3, 4, 6, 8  Sections 5, 7, 9  Truncated-V v a l l e y  V-shaped v a l l e y  Sections 1, 2, 3, 4, 6, 8  Sections 5, 7, 9  The largest values f o r cutbank area might be predicted f o r sections 1, 2, 3, and 6 since they have predominantly a l l u v i a l streambanks, low gradients, and truncated V-shaped v a l l e y s .  However, only  Sections 3 and 6 from this group had r e l a t i v e l y large cutbank areas (1.28 and 1.33 m /25 m of stream, respectively) while Section 1 had 2  no cutbanks and Section 2 had a small cutbank area (0.33 m /25 m stream). 2  Hence, factors other than those described i n the above Table must have intervened.  The streambed i n Section 1 i s extremely wide and the flow  impinges on the banks only at the outer bends, providing l i t t l e  oppor-  tunity f o r cutbank formation. Furthermore, i n Sections 1 and 2 the ground surface i s too high above the water l e v e l to provide useful cover for  fish.  Sections 5, 7, and 9 do not appear to have the p o t e n t i a l f o r  cutbank formation due to few a l l u v i a l banks, steep gradients, and Vshaped v a l l e y s .  Section 5 was lacking i n cutbanks but Sections 7 and 9  had r e l a t i v e l y large cutbank areas (0.58 and 1.13 m2/25 m of stream, respectively).  The cutbanks i n these sections were formed by alder roots  and logs embedded i n the coarse channel bank material which contained very l i t t l e  soil.*  Therefore, although c e r t a i n c h a r a c t e r i s t i c s are associated with undercut banks, they are not r e l i a b l e indicators of cutbank forming p o t e n t i a l since other factors may intervene.  The survey technique  described i s useful provided i t i s supplemented with ground checks. A i r photos can be used to s t r a t i f y streams into r e l a t i v e l y homogeneous units on the basis of landscape c h a r a c t e r i s t i c s which are not obvious on the ground.  This technique provides an e f f i c i e n t , systematic approach to  making ground checks .  Extensive land surveys are presently being carried out i n B r i t i s h Columbia providing a bank of data which might be of use i n performing stream surveys.  However, since only one factor influencing  salmonid habitat was examined in the present study, further studies are required to determine useful correlations between land and stream characteristics.  Because no simple relationships were found between stream cutbanks and land c h a r a c t e r i s t i c s , i t was not possible to develop a r e l i a b l e model for predicting cutbanks on the basis of landforms as viewed on a i r photos.  However, the sampling technique described i s  u s e f u l for stream surveys provided additional procedures (eg. supplemental ground checks)  are employed to compensate for l i m i t a t i o n s i n  the method for predicting cutbanks.  SUMMARY  Following the assumption that certain land c h a r a c t e r i s t i c s are conducive to the formation of stream cutbanks, a survey of a descriptive nature was  conducted i n order to ascertain possible r e l -  ationships between land c h a r a c t e r i s t i c s and cutbank area. aim was  The ultimate  to develop a model for predicting cutbank-forming p o t e n t i a l on  the basis of landforms v i s i b l e on a i r photographs.  Cutbanks of a s i g n i f i c a n t size were found to be present i n a limited number of stream segments within the watershed.  No simple  r e l a t i o n s h i p s between land and stream c h a r a c t e r i s t i c s were found, perhaps due to various factors which interfered with predicted outcomes regarding cutbanks.  It was not possible to develop a model for predicting cutbank formation with the use of a i r photos alone.  I t was concluded  that the survey techniques described are useful for geomorphic i n t e r pretation of the stream, establishment of units that might be used when undertaking stream surveys, and the determination of locations which warrant ground checks.  79  REFERENCES CITED  A l l e n , K.R. 1951. The Horokiwi Stream - A study of a trout population. New Zealand Marine Department F i s h e r i e s B u l l e t i n No. 10. 288p. A l l e n , K.R. 1969. Limitations on production i n salmonid populations i n streams,p. 3-18. In T.G. Northcote (Ed.) Symposium on Salmon and Trout i n Streams. H.R. MacMillan Lectures i n F i s h e r i e s . University of B.C., Vancouver. Boussu, M.F. 1954. Relationship between trout populations and cover on a small stream. Jour. W i l d l . Mgmt., 18: 229-239. Bray, P.I., and R. K e l l e r h a l s 1971. Numeric coding of the major geomorphic and physiographic c h a r a c t e r i s t i c s of a r i v e r reach. Unpublished report. Dept. of C i v i l Engineering, U n i v e r s i t y of A l b e r t a , Edmonton. Burns, J.W. 1972. Some e f f e c t s of logging and associated road cons t r u c t i o n on northern C a l i f o r n i a streams. Trans. Amer. Fish. Soc. 101: 1-17. Bustard, D.R. 1973. Some aspects of the winter ecology of juvenile salmonids with s p e c i a l reference to possible habitat a l t e r ation by logging i n Carnation Creek, Vancouver Island. Unpublished M.Sc. thesis, U n i v e r s i t y of B.C. 85p. Butler, R.L. and V.M. Hawthorne. 1968. The reactions of dominant trout to changes i n overhead a r t i f i c i a l cover. Trans. Amer. F i s h . Soc. 97: 37-41. Chapman, D.W. 1962. E f f e c t s of logging upon f i s h resources of the west coast. J . Forestry 60: 533-537. Chapman, D.W. 1966. Food and space as regulators of salmonid ions i n streams. Am. Natur. 100: 345-357.  populat-  Chapman, D.W. and T.C. Bjorrn 1969. D i s t r i b u t i o n of salmonids i n streams with s p e c i a l reference to food and feeding, p. 153-176. In_ T.G. Northcote (Ed.) Symposium on Salmon and Trout i n Streams. H.R. MacMillan Lectures i n F i s h e r i e s . U n i v e r s i t y of B.C., Vancouver. E l s e r , A.A. 1968. Fish populations of a trout stream i n r e l a t i o n to major habitat zones and channel a l t e r a t i o n s . Trans. Amer. F i s h . Soc. 97: 389-397.  80  Everest, F.H. 1969. Habitat selection and s p a t i a l i n t e r a c t i o n of juvenile chinook salmon and steelhead trout i n two Idaho streams. Ph.D. thesis. University of Idaho. 77p. Gunderson, D.R. 1968. Floodplain use related to stream morphology and f i s h populations. Jour. W i l d l . Mgmt. 32: 507-514. H a l l , J.D. and R.L. Lantz. 1969. E f f e c t s of logging on the habitat of coho salmon and cutthroat trout i n coastal streams, p. 355-375. In T.G. Northcote (Ed.) Symposium on Salmon and Trout i n Streams. H.R. MacMillan Lectures i n F i s h e r i e s . University of B.C., Vancouver. Hartman, G.F. 1965. The role of behavior i n the interaction-of underyearling coho and steelhead (Oncorhynchus kisutch and Salmo gairdneri ). Ph.D. thesis, University of B.C., Vancouver. Hartman, G.F. and C.A. G i l l . 1968. Distributions of juvenile s t e e l head and cutthroat trout (Salmo gairdneri and Salmo c l a r k i c l a r k i ) within streams i n southwestern B r i t i s h Columbia. J . F i s h . Res. Bd. Canada 25: 33-48. Holland, S.S. 1964. Landforms of B r i t i s h Columbia a physiographic o u t l i n e . B u l l e t i n No. 48. B.C. Dept. of Mines and Petroleum Resources, V i c t o r i a , B.C. Huet, M.  1959. P r o f i l e s and biology of western European streams as related to f i s h management. Trans. Amer. F i s h . Soc. 88: 155-163.  Hunt, R.C.  1971. Responses of a brook trout population to habitat development i n Lawrence Creek. Tech. B u l l . No. 48. Wis. Dep. Nat. Resour., Madison, Wis,  Kraft, M.E. 1972. Effects of controlled flow reduction on a trout stream. J . F i s h . Res. Bd. Canada 29: 1405-1411. Krajina, V.J. 1965. Biogeoclimatic zones and c l a s s i f i c a t i o n of B r i t i s h Columbia. E c o l . West. N.A. 1:1-19. Dept. of Botany, University of B.C., Vancouver. Lacate, D.S. 1969. Guidelines for bio-physical land c l a s s i f i c a t i o n . Canadian Forestry Service Publication No. 1264. 61p. Leopold, L.B., M.G. Wolman and J.P. M i l l e r . 1964. F l u v i a l Processes in Geomorphology Freeman. San Francisco. 522p. #  Lewis, S.L. 1969. Physical factors influencing f i s h populations i n pools of a trout stream. Trans. Amer. F i s h . Soc. 98:14-19.  81 P l a t t s , W.S. 1974. Geomorphic and aquatic conditions influencing salmonids and stream c l a s s i f i c a t i o n i n the Salmon River drainage, Idaho, 1970-1972. Unpublished Ph.D. thesis. Utah State University. Logan, Utah. Saunders, J.W., and M.W. Smith. 1962. Physical a l t e r a t i o n of stream habitat to improve brook trout production. Trans. Amer. F i s h . Soc. 91: 185-188. Slaney, P.A., T.W. Chamberlin, and T.G. Halsey. 1973. E f f e c t s of forest harvesting on the aquatic environment of watersheds i n the central i n t e r i o r of B r i t i s h Columbia, A progress report of f i s h e r y - f o r e s t r y studies at the Slim-Tumuch Watershed. Fish and W i l d l i f e Branch, Fisheries Research Section, University of B.C., Vancouver. Snedecor, G.W. and W.G. Cochran. 1967. S t a t i s t i c a l Methods. Sixth E d i t i o n . Iowa State University Press, Ames, Iowa. 593p. Stewart, P.A. 1970. Physical factors influencing trout density i n a small stream. Ph.D. thesis. Colorado State University, Fort C o l l i n s . 78p. Walpole, R.E. 1968. Introduction to S t a t i s t i c s . Co. Inc. New York. 365 p.  MacMillan Publishing  Whitney, H.N. and J.E. Bailey. 1959. Detrimental e f f e c t s of highway construction on a Montana stream. Trans. Amer. F i s h . Soc. 88:72-73. Woolf, CM. 1968. 359p.  P r i n c i p l e s of Biometry.  Van Nostrand.  Toronto.  82  APPENDIX I  A L i s t of Plants Mentioned  i n the Text  Nomenclature i s according to the following manual. Hitchcock, C.L. and A. Cronquist. 1973. Flora of the P a c i f i c Northwest, An I l l u s t r a t e d Manual. University of Washington Press Seattle. 730p.  Trees S c i e n t i f i c Names  Common Names  Abies amabilis (Dougl.) Forbes  Pacific silver f i r  Abies lasiocarpa (Hook.) Nutt.  subalpine f i r  Acer macrophyllum Pursh  b i g l e a f maple  Alnus rubra Bong.  red alder  Alnus incana (L.) Moench  speckled alder  Picea glauca (Moench) Voss  white spruce  Populus tremuloides  trembling aspen  Populus  black cottonwood  triocharpa  Pseudotsuga menziesii (Mirbel) Franco  Douglas f i r  Thuja p l i c a t a  western  Donn.  Tsuga heterophylla (Raf.) Sarg.  redcedar  western hemlock  Shrubs Lonicera involucrata (Rich.) Banks  black twinberry  Ribes bracteosum  stink current  Dougl.  Rubus idaeus L.  red raspberry  Rubus p a r v i f l o r u s Nutt.  thimbleberry  S c i e n t i f i c Names  Common Names  Rubus s p e c t a b i l i s Pursh  salmonberry  S a l i x sp.  willow  Ferns Athyrium f i l i x - f e m i n a (L.) Roth  lady fern  84 APPENDIX II  A L i s t of Common Mosses Found on the Streambanks of Study Streams i n North Central B.C. Nomenclature i s according to the following manual. Lawton, E. 1971. Moss Flora of the P a c i f i c Northwest. i c a l Laboratory. Nichinan, Japan. 362p.  Brachythecium r i v u l a r e B.S.G. Bryum sp. Bryum w e i g s I i i Spreng. Drepanocladus uncinatus (Hedw.) Warnst. Hylocomium sp. Rhizomnium personii Koponen Rhytidiadelphus triquetrus (Hedw.) Warnst. Rhytidiadelphus squarrosus (Hedw.) Warnst. Timmia austriaca Hedw.  Hattori Botan-  

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