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The use of fluorescent dye and site characteristics to evaluate surface erosion on harvested areas… Traynor, Janice Mae 1986

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THE USE OF FLUORESCENT DYE AND S I T E CHARACTERISTICS TO EVALUATE SURFACE EROSION ON HARVESTED AREAS IN THE VERNON FOREST DISTRICT, B.C. By JANICE MAE TRAYNOR B . S c , The U n i v e r s i t y of A l b e r t a , 1983 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES Department o f F o r e s t R e s o u r c e s Management We a c c e p t t h i s t h e s i s a s c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA A p r i l 1986 ©Janice Mae T r a y n o r , 1986 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r a g r e e 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 c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e h e a d o f my d e p a r t m e n t o r by h i s o r h e r r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f FOREST RESOURCES MANAGEMENT The U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1W5 D a t e APRIL 30, 1986 i i A b s t r a c t S u r f a c e e r o s i o n on f o r e s t l a n d s can c a u s e s t r e a m s e d i m e n t a t i o n and r e d u c e s i t e p r o d u c t i v i t y . In t h e N o r t h Okanagan downstream i r r i g a t i o n and m u n i c i p a l demand r e q u i r e low s e d i m e n t l e v e l s i n t h e i r w a t e r . H i g h e r e l e v a t i o n f o r e s t l a n d s have s h a l l o w s o i l s d e v e l o p e d f r om n u t r i e n t - p o o r g l a c i a l t i l l . To e v a l u a t e e r o s i o n o c c u r r e n c e on f o r e s t l a n d s a r e s e a r c h p r o j e c t was i n i t i a t e d i n t h e summer o f 1984 on 10 s i t e s i n m i d - e l e v a t i o n , r e c e n t l y h a r v e s t e d c u t b l o c k s i n t h e V e r n o n F o r e s t R e g i o n . The o b j e c t i v e o f t h e s t u d y was t o e v a l u a t e s u r f a c e e r o s i o n and r e l a t e e r o s i o n i n t e n s i t y t o s i t e c h a r a c t e r i s t i c s . Two s e p a r a t e methods were u s e d t o a c c o m p l i s h t h i s . L i n e t r a n s e c t s s a m p l e d s o i l d i s t u r b a n c e and e x amined c a u s a l f a c t o r s f o r e r o s i o n o c c u r r e n c e . F l u o r e s c e n t dye p l o t s , e s t a b l i s h e d on f o u r of t h e 10 s i t e s , e x amined r a t e , d i s t a n c e and p a t t e r n s of d o w n s l o p e s o i l p a r t i c l e movement. T r a n s e c t s were s u r v e y e d i n a g r i d p a t t e r n a c r o s s t h e c u t b l o c k and r e s u l t s i n d i c a t e d a r e a l d i s t r i b u t i o n o f d i s t u r b a n c e . S o i l d i s t u r b a n c e a t t h e sample p o i n t was r e c o r d e d u s i n g 10 c l a s s e s r a n g i n g f r o m b a r e s o i l and l i t t e r d i s t u r b a n c e t o d eep gouges and deep d e p o s i t s o f s o i l . A s s e s s m e n t o f c a r e - i n - l o g g i n g and i d e n t i f i c a t i o n of e x i s t i n g and p o t e n t i a l e r o s i o n s i t e s c o m p l e t e d t h e s i t e e v a l u a t i o n . D a y - G l o f l u o r e s c e n t p igment was u s e d t o t a g s o i l i n  s i t u . Dye was a p p l i e d i n A u g u s t , 1984, i n one m e t r e s t r i p s a c r o s s t h e s l o p e on p l o t s v a r y i n g i n a s p e c t , s l o p e and d i s t u r b a n c e . F i e l d measurement o f s o i l movement was c o m p l e t e d i n t h e s p r i n g o f 1985, s h o r t l y a f t e r snowmelt. Tagged p a r t i c l e s were l o c a t e d and i l l u m i n a t e d a t n i g h t by u l t r a v i o l e t l i g h t . A hand h e l d m i n e r a l lamp p r o v i d e d s u f f i c i e n t i l l u m i n a t i o n and f l u o r e s c e n c e was r e c o r d e d on c o l o r f i l m . S o i l - m o v e m e n t r a t i n g s , b a s e d on v i s u a l p e r c e p t i o n o f p a r t i c l e movement, were a s s i g n e d t o e a c h p l o t . T h e s e r a t i n g s were compared t o p l o t and s i t e c h a r a c t e r i s t i c s t o i d e n t i f y p o s s i b l e e r o s i o n t r e n d s . The r e s u l t s o f t h i s s t u d y s u p p o r t t h e c o n s e n s u s o f r e s e a r c h r e s u l t s r e p o r t e d i n t h e l i t e r a t u r e . The m a j o r s i t e s of e r o s i o n a r e s k i d t r a i l s and t h e r o a d s y s t e m . S t e e p s l o p e s , f i n e ' s o i l , n o r t h a s p e c t s and c o m p a c t i o n i n c r e a s e p o t e n t i a l e r o s i o n . F l u o r e s c e n t dye i s an e f f e c t i v e s o i l p a r t i c l e t a g a l l o w i n g d i s t a n c e and pathways o f movement t o be i d e n t i f i e d . D a y - G l o f l u o r e s c e n t p i g m e n t i n a s o l u t i o n o f a c e t o n e was f u l l y s a t i s f a c t o r y i n a d h e r e n c e t o t h e p a r t i c l e and i n p e r s i s t e n c e under p r e v a i l i n g c l i m a t i c c o n d i t i o n s . i v TABLE OF CONTENTS ABSTRACT i i L i s t o f T a b l e s v i L i s t of F i g u r e s v i i Acknowledgement i x 1. INTRODUCTION 1 2. OBJECTIVES 5 3. LITERATURE REVIEW OF SURFACE EROSION 6 FACTORS INFLUENCING SURFACE EROSION 7 V e g e t a t i o n 7 S l o p e 9 P r e c i p i t a t i o n 10 S o i l P r o p e r t i e s 11 SURFACE EROSION CYCLE 14 Detachment - O v e r l a n d F l ow 14 O v e r l a n d Flow i n F o r e s t W a t e r s h e d s 16 Detachment - R a i n s p l a s h 18 T r a n s p o r t - R a i n s p l a s h and O v e r l a n d F l ow .... 19 D e p o s i t i o n 21 ROLE OF FORESTS IN EROSION 24 An H i s t o r i c a l P e r s p e c t i v e 24 B r i t i s h C o l u m b i a - P r e s e n t P e r s p e c t i v e 27 4. LITERATURE REVIEW OF FLUORESCENT DYE 32 SOIL PARTICLE TAGGING 34 Beac h Sands 36 I n t r o d u c e d F l u o r e s c e n t P a r t i c l e s 38 A p p l i c a t i o n Onto N a t u r a l S o i l P a r t i c l e s 40 DAY-GLO FLUORESCENT PIGMENT 42 5. METHODS . 44 STUDY S I T E . 44 C l i m a t e 46 P h y s i o g r a p h y 49 S o i l s 51 V e g e t a t i o n 52 H y d r o l o g y 53 F i s h and W i l d l i f e 54 SELECTION OF METHODS 56 EROSION TRANSECT STUDY 56 S i t e S e l e c t i o n 58 F i e l d Methods 58 A n a l y s i s 61 FLUORESCENT DYE STUDY 62 S e l e c t i o n of F l u o r e s c e n t Dye 63 S i t e S e l e c t i o n 63 F i e l d Methods 64 A p p l i c a t i o n o f Dye 64 F i e l d Measurement - S p r i n g 1985 65 A n a l y s i s 67 Movement R a t i n g 67 P h o t o g r a p h i c R e c o r d 67 6. RESULTS AND DISCUSSION 68 EROSION TRANSECT STUDY 68 S i t e E v a l u a t i o n 68 T r i n i t y V a l l e y #1 68 T r i n i t y V a l l e y #2 72 D e a f i e s C r e e k #1 73 D e a f i e s C r e e k #2 74 B e e t l e C r e e k #1 75 B e e t l e C r e e k #2 76 B e a v e r L a k e #1 77 B e a v e r Lake #2 77 B e a v e r L a k e #3 78 B e a v e r Lake #4A 78 B e a v e r Lake #4B 79 C o m p a r i s o n Among S i t e s 80 FLUORESCENT DYE EROSION STUDY 87 Movement R a t i n g s - S i t e 87 T r i n i t y V a l l e y #1 87 T r i n i t y V a l l e y #2 87 B e a v e r Lake #1 89 B e a v e r L a k e #4A 90 C o m p a r i s o n of Movement R a t i n g s Among S i t e s .. 91 FLUORESCENCE STUDY 96 P h o t o g r a p h i c R e c o r d of B e a v e r L a k e #4A 96 A d d r e s s i n g P r o j e c t Unknowns 100 7. SUMMARY AND CONCLUSIONS 102 SUMMARY 102 E r o s i o n T r a n s e c t s 102 F l u o r e s c e n t Dye P l o t s 103 F l u o r e s c e n t Dye Method E v a l u a t i o n 104 CONCLUSIONS 105 S u r f a c e E r o s i o n 105 F l u o r e s c e n t Dye 106 8. RECOMMENDATIONS 108 LITERATURE CITED 110 APPENDIX 117 v i L i s t o f T a b l e s T a b l e Page I . V e g e t a t i o n and e n v i r o n m e n t c h a r a c t e r i s t i c s o f t h e s t u d y a r e a 50 I I . S o i l d i s t u r b a n c e c a t e g o r i e s 60 I I I . O v e r a l l s i t e c h a r a c t e r i s t i c s f r o m l i n e t r a n s e c t d a t a 69 IV. L i n e t r a n s e c t d a t a , S o i l d i s t u r b a n c e c l a s s d i s t r i b u t i o n e x p r e s s e d a s a p e r c e n t a g e o f a r e a . . . 71 V. C o m p a r i s o n o f s o i l d i s t u r b a n c e c l a s s d i s t r i b u t i o n f o u n d i n p r e s e n t s t u d y and f r o m o t h e r r e g i o n s as r e p o r t e d i n t h e l i t e r a t u r e 86 V I . F l u o r e s c e n t dye p l o t c h a r a c t e r i s t i c s and s o i l movement r a t i n g s 88 L i s t o f F i g u r e s v i i 1. An i l l u s t r a t i o n of t h e p h y s i c a l p r o c e s s e s o p e r a t i n g i n s u r f a c e w ater e r o s i o n and t h e n a t u r a l s i t e c h a r a c t e r i s t i c s and management t e c h n i q u e s w h i c h i m p a c t t h i s p r o c e s s 23 2. L o c a t i o n o f t h e s t u d y a r e a 45 3. P r e c i p i t a t i o n and t e m p e r a t u r e c h a n g e s w i t h e l e v a t i o n 47 4. R e g i o n a l c l i m a t e r e f l e c t e d i n f o r e s t r e g i o n s and s e c t i o n s 48 5. C o l d s t r e a m C r e e k h y d r o g r a p h s 55 6. Snow w a t e r e q u i v a l e n t ( A p r i l ) v s e l e v a t i o n f o r s e v e n Okanagan snow c o u r s e s 55 7. L o c a t i o n of t h e s t u d y s i t e s 57 8. T r i n i t y V a l l e y #2 s i t e 59 9. B e a v e r L a k e #1 s i t e 59 10. F i e l d a p p l i c a t i o n o f f l u o r e s c e n t dye 66 11. I l l u m i n a t i o n o f f l u o r e s c e n t dye s t r i p s w i t h hand h e l d m i n e r a l lamp 66 12. D i s t r i b u t i o n ( c u t b l o c k a r e a ) o f d i s t u r b a n c e c l a s s e s ( s h a l l o w + deep gouge, s h a l l o w + deep d e p o s i t ) w i t h i n c r e a s i n g s l o p e on c l e a r c u t s i t e s 82 13. D i s t r i b u t i o n of s h a l l o w d e p o s i t d i s t u r b a n c e c l a s s w i t h i n c r e a s i n g s l o p e 82 14. A s s e s s m e n t of c a r e - i n - l o g g i n g v a r i a t i o n w i t h i n c r e a s i n g s l o p e 84 15. D i s t r i b u t i o n o f b a r e s o i l a nd s o i l d i s t u r b a n c e v a l u e s w i t h i n c r e a s i n g s l o p e 84 16. R i l l i n g on s k i d r o a d i n T r i n i t y V a l l e y #1 92 17. V e h i c l e d i s t u r b a n c e on s k i d r o a d of B e a v e r L a k e #4A s i t e 92 18. Changes i n s o i l movement r a t i n g s w i t h i n c r e a s i n g s l o p e 94 v i i i 19. F l u o r e s c e n t i l l u m i n a t i o n o f B e a v e r Lake #4A P l o t 2 i l l u s t r a t i n g d o w nslope movement of p a r t i c l e s . ... 97 20. B e a v e r Lake #4A P l o t 4 i l l u s t r a t i n g a c t i v e e r o s i o n . 97 21. B e a v e r Lake #4A P l o t 3. S e diment d e p o s i t i o n f r o m o v e r l a n d f l o w 98 22. U l t r a v i o l e t i l l u m i n a t i o n of BL #4A P l o t 3 98 Acknowledgement I w o u l d l i k e t o t h a n k D r . G o l d i n g f o r h i s s u p p o r t and e n c o u r a g e m e n t t h r o u g h o u t a l l p a r t s of t h i s s t u d y ; a s p e c i a l t h a n k - y o u f o r t h e h e l p i n remeasurement of t h e f l u o r e s c e n t dye p l o t s . My c o m m i t t e e was open t o new methods and i n t e r r u p t e d p r o g r e s s . I a p p r e c i a t e t h e f r e e d o m I was g i v e n t o d e v e l o p t h i s r e s e a r c h . I t h a n k M o n i c a , Mary and J o n e e n f o r t h e a s s i s t a n c e i n f i e l d work and t h e i r good humor. Maps and i n f o r m a t i o n were c h e e r f u l l y s u p p l i e d by p e r s o n n e l i n t h e V e r n o n O f f i c e , M i n i s t r y o f F o r e s t s . F i n a n c i a l s u p p o r t f o r t h i s s t u d y was p r o v i d e d under an E n v i r o n m e n t 2000 g r a n t ( F e d e r a l Government) and a B r i t i s h C o l u m b i a , M i n i s t r y o f F o r e s t s c o n t r a c t . 1 C h a p t e r 1 INTRODUCTION The f o r e s t l a n d s s u r r o u n d i n g t h e Okanagan b a s i n a r e i m p o r t a n t i n a number o f ways. The h i g h e l e v a t i o n f o r e s t c o n t a i n s t h e h e a d w a t e r s o f most s t r e a m s i n t h e b a s i n and t h i s snowmelt s u p p l i e s t h e s p r i n g and summer f l o w s o f a r e a s t r e a m s . T h e s e s t r e a m s s u p p o r t f i s h p o p u l a t i o n s , s u p p l y w a t e r t o meet i r r i g a t i o n n eeds and m u n i c i p a l demands, r e p l e n i s h a q u i f e r s and m a i n t a i n t h e l e v e l and q u a l i t y of a r e a l a k e s , a major r e c r e a t i o n and t o u r i s m r e s o u r c e . The t i m b e r f r o m t h i s f o r e s t l a n d s u p p o r t s t h e e x t e n s i v e f o r e s t i n d u s t r y w h i c h forms an i m p o r t a n t component o f t h e r e g i o n a l economy. The Okanagan T i m b e r S u p p l y A r e a c o v e r s 2.5 m i l l i o n h e c t a r e s and c o n t a i n s 1.7 m i l l i o n h e c t a r e s o f p r o d u c t i v e f o r e s t l a n d . S i x p e r c e n t o f t h e p o p u l a t i o n i n t h e a r e a i s employed i n t h e f o r e s t i n d u s t r y and a f u r t h e r 10 p e r c e n t a r e employed i n d i r e c t l y ( R o b i n s o n 1985). The h a r v e s t i n g s c h e d u l e o f t h i s i n d u s t r y i s b a s e d on t h e c o n c e p t o f a c o n t i n u i n g p r o d u c t i v e f o r e s t r e s o u r c e t o m a i n t a i n s u p p l y a t t h e c u r r e n t l e v e l s . T h i s assumes u n d i m i n i s h e d p r o d u c t i v i t y o f t h e c u t b l o c k . F o r e s t s p l a y an i m p o r t a n t s o i l p r o t e c t i v e r o l e and d e f o r e s t a t i o n can promote s u r f a c e e r o s i o n ( G r a y .1969). 2 Bormann a n d L i k e n s (1979) a t Hub b a r d Brook E x p e r i m e n t a l W a t e r s h e d ( e a s t e r n U n i t e d S t a t e s ) f o u n d t h a t d e f o r e s t a t i o n a l t e r e d t h e n a t u r a l " p a r t i c l e - m a t t e r t r a n s p o r t " i n two ways: (1) by c h a n g i n g t h e h y d r o l o g i c c h a r a c t e r i s t i c s o f t h e e c o s y s t e m ( i n c r e a s i n g v e l o c i t y of peak s t r e a m f l o w and t i m e o f f l o w a t h i g h v e l o c i t i e s ) , and (2) t h r o u g h i n c r e a s e s i n e r o d i b i l i t y o f t h e e c o s y s t e m . T h i s s t u d y e x a mines t h e l a t t e r . A f u l l y - f o r e s t e d s i t e u s u a l l y has l i t t l e e r o s i o n . The v e g e t a t i v e s u r f a c e i s a b l e t o a b s o r b most o f t h e i n c o m i n g p r e c i p i t a t i o n and h i g h i n f i l t r a t i o n r a t e s combined w i t h t r a n s l a t o r y f l o w p r e v e n t s s u r f a c e r u n o f f . Removal o f s u r f a c e v e g e t a t i o n d i s t u r b s t h e s o i l s u r f a c e and e x p o s e s i t t o t h e e r o s i v e e n e r g y of r a i n d r o p s and o v e r l a n d f l o w . R a i n s p l a s h c a n move s o i l p a r t i c l e s , compact t h e s u r f a c e l a y e r and c l o g p o r e s t h e r e b y r e d u c i n g i n f i l t r a t i o n and p r o m o t i n g o v e r l a n d f l o w . S u r f a c e s o i l e r o s i o n p o s e s a m u l t i p l e t h r e a t t o t h e f o r e s t e c o s y s t e m : (1) t o t h e f u t u r e f o r e s t p r o d u c t i v i t y and p r e s e n t r e g e n e r a t i o n on s i t e (2) t o t h e q u a l i t y o f s t r e a m s d r a i n i n g t h e w a t e r s h e d ( s e d i m e n t a t i o n ) and (3) t o human l i v e s and s t r u c t u r e s ( G r a y 1969). In t h e N o r t h Okanagan most s o i l p a r e n t m a t e r i a l i s n u t r i e n t - p o o r g l a c i a l t i l l . On f o r e s t l a n d s much o f t h e s i t e n u t r i e n t s a r e c o n t a i n e d i n t h e s u r f a c e c e n t i m e t r e s o f s o i l . L o s s o f t h i s s o i l c a n s e v e r e l y i m p a c t s i t e 3 p r o d u c t i v i t y . H i g h e l e v a t i o n f o r e s t l a n d i s c h a r a c t e r i z e d by s h a l l o w s o i l s and l i m i t e d n u t r i e n t s so any l o s s of s o i l o r p r o d u c t i o n p o t e n t i a l may be s i g n i f i c a n t . Water q u a l i t y i s an i m p o r t a n t i s s u e i n t h e N o r t h Okanagan. I n c r e a s e d s e d i m e n t l e v e l s i n t h e s t r e a m s d r a i n i n g t h e f o r e s t a r e a d i m i n i s h w ater q u a l i t y and c a n c a u s e p r o b l e m s w i t h d r i n k i n g w ater s u p p l y , i n s t r e a m b i o l o g y , and i r r i g a t i o n works downstream. In v i e w o f t h e i m p a c t s o f s u r f a c e e r o s i o n , t h i s r e s e a r c h p r o j e c t was i n i t i a t e d t o d e t e r m i n e i f s u r f a c e e r o s i o n on t h e s e h a r v e s t e d l a n d s i s s i g n i f i c a n t and, i f s o , t o i d e n t i f y t h o s e f a c t o r s i n f l u e n c i n g t h e e r o s i o n p r o c e s s . S i t e p a r a m e t e r s t o be examined on c u t o v e r a r e a s i n c l u d e d s l o p e a n g l e , a s p e c t , g r o u n d d i s t u r b a n c e , v e g e t a t i v e c o v e r , s o i l t e x t u r e , and s l o p e p o s i t i o n . Road c o n s t r u c t i o n a s s o c i a t e d w i t h t i m b e r h a r v e s t i n g has a g r e a t e r i m p a c t on s o i l s t a b i l i t y t h a n v e g e t a t i o n r e m o v a l a l o n e . G r a y and Megahan (1981) i d e n t i f i e d p o s s i b l e s y n e r g i s t i c and c u m u l a t i v e i m p a c t s on s t a b i l i t y o f r o a d c o n s t r u c t i o n and v e g e t a t i o n r e m o v a l w h i c h a r e d i f f i c u l t t o d i s t i n g u i s h or s e p a r a t e . The p r e s e n t p r o j e c t e x amined e r o s i o n on a c t u a l c u t b l o c k s but an e v a l u a t i o n o f e r o s i o n o c c u r r i n g on r o a d s a c c e s s i n g t h e s i t e s was a l s o i n c l u d e d . 4 A n o t h e r component o f t h i s s t u d y was d e v e l o p m e n t and e v a l u a t i o n o f a method u s i n g f l u o r e s c e n t d y e s t o c h a r t s o i l movement. A s o i l - t a g g i n g t e c h n i q u e was p r o p o s e d t o a l l o w c o l o r s t r a t i f i c a t i o n of s o i l p a r t i c l e s by l o c a t i o n and t o c h a r t t h e pathway of movement and d i s t a n c e t r a v e l l e d d o w n s l o p e . A c c u r a t e measurements of s o i l e r o s i o n a r e d i f f i c u l t t o o b t a i n . E x i s t i n g methods measure o n l y n e t s o i l movement, n o t t h e r a t e o f p a r t i c l e movement o r pathways o f movement. C o s t , t i m e , and p e r s p e c t i v e may l i m i t a p p l i c a t i o n o f t h e s e methods. The f l u o r e s c e n t dye a p p l i c a t i o n method a p p l i e d h e r e p r o m o t e s e a s e o f a p p l i c a t i o n , r e l a t i v e l y low c o s t and minimum dependence on s t r u c t u r e s o r s i t e m o d i f i c a t i o n . 5 C h a p t e r 2 OBJECTIVES The o b j e c t i v e o f t h i s s t u d y i s t h r e e f o l d : 1. To i d e n t i f y and d e t e r m i n e t o what e x t e n t e r o s i o n i s o c c u r r i n g on c u t o v e r a r e a s i n t h i s r e g i o n by v i s u a l i n s p e c t i o n ( t r a n s e c t s ) and m o n i t o r i n g of f l u o r e s c e n t dye p l o t s . 2. To r e l a t e e r o s i o n i n t e n s i t y t o s i t e c h a r a c t e r i s t i c s i n c l u d i n g a s p e c t , s l o p e , g r o u n d d i s t u r b a n c e , v e g e t a t i o n , s o i l t e x t u r e and l o g g i n g method. 3. To d e v e l o p and t e s t a method o f f l u o r e s c e n t dye a p p l i c a t i o n t o t a g s o i l p a r t i c l e s and a l l o w d i s t a n c e and pathways o f d o w n s l o p e movement t o be d e t e r m i n e d . 6 C h a p t e r 3 LITERATURE REVIEW OF SURFACE EROSION S u r f a c e e r o s i o n i n v o l v e s t h e movement o f i n d i v i d u a l d e t a c h e d p a r t i c l e s downslope e i t h e r by r a i n d r o p s p l a s h ( s h e e t e r o s i o n ) o r i n s u s p e n s i o n by f l o w i n g w a t e r ( r i l l i n g or g u l l y i n g ) ( D y r n e s s 1966). Mass w a s t i n g i n v o l v e s s i m u l t a n e o u s movement o f l a r g e q u a n t i t i e s o f s o i l under t h e i n f l u e n c e o f g r a v i t y and i s o f t e n l u b r i c a t e d by l a r g e amounts o f water ( D y r n e s s 1966). B o t h o f t h e above p r o c e s s e s o p e r a t e t o v a r y i n g d e g r e e s w i t h i n t h e f o r e s t s y s t e m . E r o s i o n may be s a i d t o be t h e r e s u l t o f t h e a c t i o n o f t h e c l i m a t e on t h e s o i l w i t h t h e r e s u l t s b e i n g m o d i f i e d by t h e t o p o g r a p h y and t h e v e g e t a t i o n c o v e r . D i f f e r e n c e s i n any o f t h e s e b r i n g a b o u t d i f f e r e n c e s i n t h e e r o s i o n h a z a r d ( A n d e r s o n 1951). S m i t h (1984) i d e n t i f i e d t h e p o t e n t i a l i m p a c t of s u r f a c e e r o s i o n a s (1) r e d u c t i o n of s i t e p r o d u c t i v i t y ( l o s s of n u t r i e n t s i n s o i l f i n e s ) , (2) i m p e d i n g o f r e g e n e r a t i o n ( a b r a s i o n , l o s s of s o i l s u p p o r t , p h y s i c a l d i s p l a c e m e n t of t h e s e e d l i n g ) , (3) d e s t r u c t i o n o f r o a d s and o t h e r s t r u c t u r e s , and (4) s e d i m e n t a t i o n o f water c o u r s e s w i t h r e s u l t a n t downstream i m p a c t s . 7 S m i t h and W i s c h m e i e r (1962) i d e n t i f i e d f o u r b a s i c f a c t o r s a f f e c t i n g s u r f a c e e r o s i o n : r a i n f a l l c h a r a c t e r i s t i c s , s o i l e r o d i b i l i t y , t o p o g r a p h y and p l a n t and l i t t e r c o v e r . T h i s d i s c u s s i o n g r o u p s e r o s i o n f a c t o r s i n t o v e g e t a t i o n , s l o p e , p r e c i p i t a t i o n and s o i l s . FACTORS INFLUENCING SURFACE EROSION V e g e t a t i o n V e g e t a t i o n i s an i m p o r t a n t f a c t o r i n c o n t r o l l i n g e r o s i o n ( R u t t e r 1967). A f u l l y v e g e t a t e d s i t e i s r a r e l y e r o d e d a s g r o u n d c o v e r s t a b i l i z e s t h e s o i l and m i t i g a t e s o t h e r e r o s i v e a g e n t s e s p e c i a l l y r a i n d r o p i m p a c t . A d e n s e v e g e t a t i v e c o v e r r e d u c e s t h e i m p a c t of r a i n f a l l on t h e s o i l , i n c r e a s e s a b s o r p t i o n , c h e c k s t h e s p e e d of f l o w i n g w a t e r and b i n d s t h e s o i l ( A g r i c u l t u r e Canada 1961). Swanson and Swanston (1977) d e s c r i b e t h e s t a b i l i z i n g e f f e c t o f f o r e s t v e g e t a t i o n : " F o r e s t v e g e t a t i o n e x e r c i s e s some c o n t r o l o v e r th e amount and t i m i n g of w ater r e a c h i n g t h e s o i l and t h e amount h e l d i n s t o r a g e as s o i l w a ter and snow. F o r e s t s r e g u l a t e h y d r o l o g y t h r o u g h a c o m b i n a t i o n o f i n t e r c e p t i o n , e v a p o t r a n s p i r a t i o n and i n f l u e n c e on snowmelt r a t e s . In g e n e r a l t h e s e h y d r o l o g i c i n f l u e n c e s o f v e g e t a t i o n a r e t h o u g h t t o enhance s l o p e s t a b i l i t y " (Swanson and Swanston 1977, pg. 115). 8 V e g e t a t i o n r e d u c e s s o i l m o i s t u r e b e c a u s e i t has a s u b s t a n t i a l demand t o s a t i s f y e v a p o t r a n s p i r a t i o n . S o i l s w i t h l o w e r a n t e c e d e n t s o i l m o i s t u r e have a g r e a t e r i n f i l t r a t i o n c a p a c i t y and t h e r e b y r e d u c e o v e r l a n d f l o w . W i t h i n a f o r e s t , o v e r l a n d f l o w i s r a r e l y o b s e r v e d . Once t h e s o i l water c a p a c i t y i s s a t i s f i e d , t r a n s l a t o r y f l o w p r e d o m i n a t e s as i n f i l t r a t i o n c a p a c i t y i s m a i n t a i n e d . V e g e t a t i o n c o n t r i b u t e s o r g a n i c m a t t e r t o t h e s o i l and a l l o w s a l i t t e r l a y e r t o d e v e l o p . T h i s o r g a n i c m a t t e r h e l p s b i n d s o i l p a r t i c l e s t o g e t h e r and i n c r e a s e s t h e m o i s t u r e h o l d i n g c a p a c i t y o f t h e s o i l . L o w d e r m i l k (1934) f o u n d t h a t t h e b e n e f i c i a l e f f e c t s o f l i t t e r c o v e r were due n o t so much t o i t s w ater a b s o r b i n g c a p a c i t y , but r a t h e r t o i t s a c t i o n i n p r o t e c t i n g t h e s o i l s f r o m t h e d e s t r u c t i v e a c t i o n of r a i n d r o p s . C r o c k e t t and S h e l f o r d (1982) i d e n t i f i e d f i v e ways t h a t a n a t u r a l v e g e t a t i v e c o v e r i n c r e a s e s s i t e s t a b i l i t y ( t h e r e b y d e c r e a s i n g e r o s i o n ) . T h e s e a r e : - I n c r e a s e i n c o h e s i o n by v e r t i c a l and h o r i z o n t a l a n c h o r i n g o f t h e s o i l mass. - I n c r e a s e i n s u r f a c e r o u g h n e s s , r e d u c i n g wind s p e e d s a t t h e s u r f a c e and l i m i t i n g s l o p e l e n g t h . - I n t e r c e p t i o n of r a i n f a l l , d e c r e a s i n g i mpact v e l o c i t y o f w a t e r on t h e g r o u n d s u r f a c e . - D e c r e a s e i n r u n o f f due t o i n c r e a s e d s u r f a c e s t o r a g e i n t h e c a n o p y and l i t t e r , i n c r e a s e d s u r f a c e r o u g h n e s s and i n c r e a s e d i n f i l t r a t i o n r a t e s . - A d d i t i o n o f o r g a n i c m a t t e r t o t h e s o i l , i n c r e a s i n g a g g r e g a t e s t a b i l i t y and m o i s t u r e - h o l d i n g c a p a c i t y . 9 W i t h i n f o r e s t e d s i t e s t h e v e g e t a t i v e s p e c i e s has l i t t l e i n f l u e n c e on e r o s i o n . The main i n f l u e n c e i s t h e p r e s e n c e o r a b s e n c e o f v e g e t a t i v e c o v e r and d e g r e e o f d i s t u r b a n c e of t h e l i t t e r l a y e r . Once a s i g n i f i c a n t amount o f v e g e t a t i v e c o v e r i s removed, s t a b i l i t y of t h e s o i l i s r e d u c e d . B a i l e y (1941) s t a t e d t h a t a l l v e g e t a t e d s l o p e s a r e a m a n i f e s t a t i o n of a d j u s t m e n t between a g g r a d a t i o n and d e g r a d a t i o n f o r c e s i n w h i c h t h e p l a n t c o v e r i s t h e key t o s t a b i l i t y . D e p l e t i o n o f t h e v e g e t a t i o n r e v e r s e s t h e g r a d a t i o n a l p r o c e s s e s and a c c e l e r a t e s s o i l r e m o v a l and r u n o f f . O r r (1979) i n r e s e a r c h on f o r e s t b u r n s i n S o u t h D a k o t a f o u n d t h a t 60 p e r c e n t g r o u n d c o v e r d e n s i t y ( l i v e v e g e t a t i o n p l u s l i t t e r ) was t h e minimum n e c e s s a r y f o r s o i l s t a b i l i z a t i o n . On s t e e p e r s l o p e s i n m o u n t a i n o u s r e g i o n s , Meeuwig (1971) f o u n d t h a t 90 p e r c e n t g r o u n d c o v e r was n e c e s s a r y . S l o p e S l o p e has a v e r y s i g n i f i c a n t i mpact on t h e e r o s i v e p o t e n t i a l o f a s i t e . S l o p e s t e e p n e s s and l e n g t h o f s l o p e i n f l u e n c e s o i l e r o d i b i l i t y d i r e c t l y by i n f l u e n c i n g t h e v e l o c i t y o f s o i l r u n o f f (Brown 1980). S u r f a c e s o i l e r o d e s when t h e e n e r g y o f f l o w i n g water e x c e e d s t h e f o r c e s h o l d i n g t h e i n d i v i d u a l s o i l p a r t i c l e s t o g e t h e r . The s l o p e d e t e r m i n e s t h e e n e r g y o f t h e f l o w i n g w ater ( K r a g 1980). 10 "The v e l o c i t y o f o v e r l a n d f l o w v a r i e s a s t h e s q u a r e r o o t of t h e s l o p e g r a d i e n t and t h e e n e r g y o f o v e r l a n d f l o w v a r i e s a s t h e s q u a r e of i t s v e l o c i t y . O v e r l a n d f l o w w i l l move down a 40 p e r c e n t s l o p e a t t w i c e t h e v e l o c i t y o f t h a t on a 10 p e r c e n t s l o p e . By d o u b l i n g t h e v e l o c i t y , t h e e n e r g y o f t h e f l o w w i l l be i n c r e a s e d a b o u t 4 t i m e s ; t h e s i z e o f p a r t i c l e t h a t c a n be t r a n s p o r t e d w i l l be i n c r e a s e d a b o u t 64 t i m e s ( s i x t h power o f v e l o c i t y ) ; and t h e q u a n t i t y of m a t e r i a l o f a g i v e n s i z e t h a t c a n be c a r r i e d i s i n c r e a s e d a b o u t 32 t i m e s ( f i f t h power o f v e l o c i t y ) " (Farmer and van H a v e r e n 1971, page 2 ) . The above v a l u e s a r e b a s e d on t h e c o n c e p t s o f competance o f a f l o w , a measure of t h e s i z e o f p a r t i c l e w h i c h t h e f l o w c a n move, ( p r o p o r t i o n a l t o t h e s i x t h power o f v e l o c i t y ) , and c a r r y i n g power, t h e a b i l i t y t o c a r r y p a r t i c l e s i n s u s p e n s i o n ( p r o p o r t i o n a l t o t h e f i f t h power o f v e l o c i t y ) . S l o p e has an i n t e g r a l r e l a t i o n s h i p t o v e g e t a t i v e c o v e r . The e f f e c t i v e n e s s of c o v e r d e p e n d s on t h e s l o p e g r a d i e n t ; t h e e f f e c t s o f c o v e r a r e g r e a t e r on s t e e p e r s l o p e s . S i m i l a r l y , s l o p e becomes i n c r e a s i n g l y i m p o r t a n t a s c o v e r d e c r e a s e s (Meeuwig 1971). S l o p e , a s a p a r t o f o v e r a l l t o p o g r a p h y , c a n i n f l u e n c e s o i l d e v e l o p m e n t and s u b s e q u e n t l y e r o s i o n . S l o p e , a s p e c t , and e l e v a t i o n m o d i f y t h e r a d i a t i o n , t e m p e r a t u r e , and m o i s t u r e l e v e l s o f t h e g e n e r a l c l i m a t e . As a r e s u l t , t h e w e a t h e r i n g o f p a r e n t m a t e r i a l and c o m p o s i t i o n o f p l a n t c o m m u n i t i e s may a l s o be m o d i f i e d (Brown 1980). P r e c i p i t a t i o n R a i n f a l l i s a major f a c t o r i n e r o s i o n . E r o s i o n o c c u r s when t h e f o r c e e x e r t e d by r a i n s p l a s h o r f l o w e x c e e d s t h e r e s i s t a n c e o f t h e s o i l . R a i n i m p a c t d i s l o d g e s p a r t i c l e s and p u l v e r i z e s m a t e r i a l s . I f c o n d i t i o n s a r e r i g h t , r u n o f f 11 removes s o i l by s u s p e n s i o n and e r o d e s new m a t e r i a l by h y d r a u l i c a c t i o n . On some s u r f a c e s r a i n i m p a c t may h e l p t o s e a l t h e s u r f a c e , t h u s d e c r e a s i n g i n f i l t r a t i o n , i n c r e a s i n g r u n o f f , and p r o m o t i n g e r o s i o n ( R u t t e r 1967). R a i n f a l l i n t e n s i t y i s i m p o r t a n t i n e r o s i o n . U n l e s s t h e r a i n f a l l i s i n t e n s e enough t o d e t a c h and t r a n s p o r t s o i l p a r t i c l e s i t i s u n l i k e l y t o c a u s e e r o s i o n ( G l e a s o n 1953). The k i n e t i c e n e r g y o f t h e r a i n f a l l v a r i e s w i t h d r o p v e l o c i t y and mass. The t r a n s p o r t of d e t a c h e d p a r t i c l e s i n o v e r l a n d f l o w i s c o n t r o l l e d by r u n o f f amount and t u r b u l e n c e , b o t h o f w h i c h a r e , t o some e x t e n t , f u n c t i o n s o f r a i n f a l l i n t e n s i t y ( D y r n e s s 1966) and t h e i n f i l t r a t i o n r a t e . The i n f i l t r a t i o n r a t e ( t h e s p e e d a t w h i c h w a t e r c a n be a b s o r b e d i n t o t h e s o i l ) d i c t a t e s t h e i m p o r t a n c e of r a i n f a l l i n t e n s i t y . I f t h e i n f i l t r a t i o n r a t e i s h i g h , a l l t h e a v a i l a b l e water c a n be a b s o r b e d by t h e s o i l , t h u s p r e v e n t i n g e r o s i o n ( R u t t e r 1967). S o i l P r o p e r t i e s I n h e r e n t i n t h e e r o d i b i l i t y of s o i l a r e t h e p r o p e r t i e s o f t h e s o i l i t s e l f . A s o i l ' s t e x t u r e , s t r u c t u r e and c h e m i s t r y a f f e c t i t s e r o d i b i l i t y . The e a s e w i t h w h i c h p a r t i c l e s a r e d i s l o d g e d and become a v a i l a b l e f o r e r o s i o n i s d e t e r m i n e d by t h e b i n d i n g s t r e n g t h o f t h e s o i l . Meeuwig (1971) i d e n t i f i e d o r g a n i c m a t t e r as t h e most i m p o r t a n t s o i l p a r a m e t e r i n f l u e n c i n g e r o s i o n . 1 2 S o i l t e x t u r e i s t h e p r o p o r t i o n o f v a r i o u s l y s i z e d p a r t i c l e s , ( s a n d , s i l t and c l a y ) i n t h e s o i l c o m p o s i t i o n . T h i s p a r t i c l e s i z e d i s t r i b u t i o n a f f e c t s e r o s i o n r a t e s . S i l t -s i z e p a r t i c l e s a r e more e a s i l y d e t a c h e d and moved t h a n l a r g e r p a r t i c l e s . I t a l s o i n f l u e n c e s p e r m e a b i l i t y and v e g e t a t i v e g r o w t h w h i c h have a d i r e c t i m p a c t on e r o s i o n . The i n f l u e n c e o f t e x t u r e on s o i l e r o d i b i l i t y i s c o m p l e x . Much o f t h i s c o m p l e x i t y a r i s e s b e c a u s e o f t h e i n f l u e n c e of o r g a n i c m a t t e r c o n t e n t on t e x t u r e . O r g a n i c m a t t e r d e c r e a s e s e r o s i o n o f c l a y s o i l s a nd t e n d s t o i n c r e a s e e r o s i o n o f sandy s o i l s (Meeuwig 1971). The a d v e r s e e f f e c t o f o r g a n i c m a t t e r i n sandy s o i l s i s b e l i e v e d t o be l i n k e d t o w a t e r r e p e l l a n c e o c c u r r i n g i n sandy s o i l s w i t h h i g h o r g a n i c m a t t e r c o n t e n t . T h e r e f o r e a s o i l ' s s u s c e p t i b i l i t y t o e r o s i o n i s d e p e n d e n t on p a r t i c l e s i z e d i s t r i b u t i o n i n c o n j u n c t i o n w i t h o r g a n i c m a t t e r c o n t e n t . S o i l p a r t i c l e s a r e u s u a l l y c l u m p e d t o g e t h e r a s a g g r e g a t e s . A g g r e g a t i o n i s t h e most i m p o r t a n t s o i l p r o p e r t y g o v e r n i n g r e s i s t a n c e t o e r o s i o n i n many s o i l s ( B r y a n 1969). The p e r c e n t a g e o f o r g a n i c m a t e r i a l , c a r b o n a t e s o r m o i s t u r e p r e s e n t i n t h e s o i l a l l i n f l u e n c e t h e l e v e l o f a g g r e g a t i o n . When s t a b l e a g g r e g a t e s d e v e l o p , p o t e n t i a l e r o d i b i l i t y d e c r e a s e s b e c a u s e t h e s e l a r g e r p a r t i c l e s a r e more d i f f i c u l t t o d i s l o d g e and t r a n s p o r t . The s t a b i l i t y o f t h e s e a g g r e g a t e s i s d e t e r m i n e d by " c e m e n t i n g a g e n t s " s u c h a s c a l c i u m c a r b o n a t e , o r g a n i c m a t t e r , and c o l l o i d s . C l a y 1 3 m i n e r a l s a r e i m p o r t a n t due t o t h e i r w a ter a b s o r p t i o n and e x p a n s i o n p r o p e r t i e s , a s a r e t h e k i n d and amount o f s o l u b l e s a l t s p r e s e n t ( R u t t e r 1967). S o i l c o m p a c t i o n i s a s i g n i f i c a n t p r o b l e m i n g r o u n d b a s e d f o r e s t h a r v e s t i n g p r o c e d u r e s . C o m p a c t i o n r e d u c e s p o r e s p a c e , i n c r e a s e s b u l k d e n s i t y and r e d u c e s i n f i l t r a t i o n r a t e , s u b s u r f a c e f l o w and r o o t i n g d e p t h . Measurements o f b u l k d e n s i t y on s k i d r o a d s , 25 y e a r s a f t e r h a r v e s t i n g , showed l i t t l e o r no r e c o v e r y f r o m c o m p a c t i o n (Schwab and Watt 1981). D e c r e a s i n g i n f i l t r a t i o n c a n promote o v e r l a n d f l o w and c o m p a c t e d a r e a s ( e . g . s k i d d e r t r a c k s ) c h a n n e l s u r f a c e f l o w t h u s i n c r e a s i n g v e l o c i t y , d e p t h and e n e r g y o f f l o w . 14 SURFACE EROSION CYCLE D e t a c h m e n t - O v e r l a n d F l o w O v e r l a n d f l o w a r i s e s f r o m an i n a b i l i t y of t h e l a n d s u r f a c e t o a b s o r b w a t e r o r t o p e r m i t w ater t o move t o l o w e r d e p t h s , t h a t i s , i n s u f f i c i e n t i n f i l t r a t i o n ( P i e r c e 1967). I t o c c u r s on h i l l s i d e s d u r i n g a r a i n s t o r m when s u r f a c e d e p r e s s i o n s t o r a g e and e i t h e r s o i l m o i s t u r e s t o r a g e ( w i t h p r o l o n g e d r a i n ) o r t h e i n f i l t r a t i o n c a p a c i t y o f t h e s o i l ( w i t h i n t e n s e r a i n ) a r e e x c e e d e d (Morgan 1979). D e v e l o p m e n t of o v e r l a n d f l o w i s i n f l u e n c e d b y : " s o i l t e x t u r e , s o i l d e p t h , s o i l s t r u c t u r e , s o i l p o r o s i t y , a n t e c e d e n t s o i l m o i s t u r e , p r e s e n c e o f r o c k o u t c r o p s , amount o f i n c o r p o r a t e d o r g a n i c m a t t e r , p r e s e n c e of s u r f a c e humus l a y e r s and l i t t e r , s l o p e and shape o f t h e l a n d , smoothness o f t e r r a i n and m i c r o t o p o g r a p h i c a l f e a t u r e s , amount and t y p e o f v e g e t a t i v e g r o u n d c o v e r , r a i n f a l l r a t e and d u r a t i o n , p r e s e n c e o f snow or i c e c o v e r , t y p e and e x t e n t of s o i l f r o s t and a i r t e m p e r a t u r e " ( P i e r c e 1967, pg. 2 4 8 ) . Two t y p e s o f o v e r l a n d f l o w a r e r e c o g n i z e d . ( 1 ) O v e r l a n d f l o w as o r i g i n a l l y d e f i n e d by H o r t o n (1945) o c c u r s when t h e r a i n f a l l i n t e n s i t y ( o r r a t e o f snowmelt) e x c e e d s t h e i n f i l t r a t i o n r a t e o f t h e s o i l . T h i s e x c e s s becomes H o r t o n i a n o v e r l a n d f l o w . (2) S a t u r a t i o n o v e r l a n d f l o w e ncompasses b o t h d i r e c t p r e c i p i t a t i o n o n t o s a t u r a t e d a r e a s 15 and r e t u r n f l o w ( s u b s u r f a c e f l o w w h i c h r e t u r n s t o t h e g r o u n d s u r f a c e ) . R a i n f a l l o n t o s a t u r a t e d a r e a s c a n n o t i n f i l t r a t e t h e s o i l ( f u l l s o i l s t o r a g e ) and t h e r e f o r e forms o v e r l a n d f l o w . R e t u r n f l o w (and some t h r o u g h f l o w ) c a n a l s o f o r m s u r f a c e r u n o f f a l t h o u g h some r e s e a r c h e r s ( s u c h a s H e w l e t t 1982) do n o t r e c o g n i z e t h i s as t r u e o v e r l a n d f l o w . The d y n a m i c s o f o v e r l a n d f l o w encompass t h e s e i n f u s i o n s of s u b s u r f a c e f l o w as w e l l . O v e r l a n d f l o w i s b o t h u n s t e a d y and s p a t i a l l y v a r i e d s i n c e i t i s s u p p l i e d by r a i n ( o r snowmelt) and d e p l e t e d by i n f i l t r a t i o n , n e i t h e r of w h i c h i s n e c e s s a r i l y c o n s t a n t w i t h r e s p e c t t o t i m e or l o c a t i o n (Emmett 1978). H o r t o n i a n o v e r l a n d f l o w , p r o d u c e d by p r e c i p i t a t i o n e x c e s s ( p r e c i p i t a t i o n i n t e n s i t y - i n f i l t r a t i o n c a p a c i t y ) , i s g e n e r a l l y s e e n as b e i n g p r o d u c e d r a t h e r u n i f o r m l y o v e r whole c a t c h m e n t a r e a s , as n e i t h e r p r e c i p i t a t i o n i n t e n s i t y n o r i n f i l t r a t i o n c a p a c i t y v a r y g r e a t l y o v e r s m a l l a r e a s ( P e a r c e 1976). S a t u r a t i o n f l o w r e s u l t s f r o m l o c a l , t e m p o r a r y s a t u r a t i o n o f t h e s o i l p r o f i l e up t o t h e g r o u n d s u r f a c e . I t c a n o c c u r i n v e r y l o c a l i z e d a r e a s o f s a t u r a t i o n and i s t h e r e f o r e more v a r i a b l e , i n t i m e and s p a c e , t h a n H o r t o n i a n o v e r l a n d f l o w . H o r t o n i a n o v e r l a n d f l o w g e n e r a l l y p r e v a i l s i n d r i e r c l i m a t e s , i n a r e a s where v e g e t a t i o n i s l i m i t e d o r removed an d on c u l t i v a t e d a r e a s . I n many s o i l s i t i s t h e p r o p e r t i e s o f t h e s u r f a c e and n o t t h e c o m p l e t e s o i l w h i c h d e t e r m i n e t h e f r e q u e n c y and amount o f r u n o f f ( B r y a n 1976). 16 The h y d r a u l i c c h a r a c t e r i s t i c s o f o v e r l a n d f l o w depend on p r e c i p i t a t i o n ( t y p e , i n t e n s i t y , d u r a t i o n ) , t e x t u r e and t y p e of s o i l ( i n f i l t r a t i o n c a p a c i t y ) , a n t e c e d e n t s o i l m o i s t u r e c o n d i t i o n , d e n s i t y and t y p e of v e g e t a t i o n , t o p o g r a p h i c a l f e a t u r e s (number and s i z e of s u r f a c e d e p r e s s i o n s and mounds), s l o p e s t e e p n e s s , and l e n g t h o f s l o p e (Emmett 1978). Thus, no s i m p l e d e s c r i p t i o n o f t h e h y d r a u l i c s o f o v e r l a n d f l o w i s p o s s i b l e on n a t u r a l h i l l s i d e s . H y d r a u l i c p a r a m e t e r s v a r y r a p i d l y o v e r t i m e and s p a c e . O v e r l a n d f l o w g e n e r a l l y c o n s i s t s n o t of a u n i f o r m s h e e t f l o w o f w a t e r but r a t h e r o f u n c h a n n e l l e d w a t e r f l o w i n g i n an a n a s t o m o s i n g p a t t e r n (Morgan 1980), r e s u l t i n g f r o m t o p o g r a p h i c i r r e g u l a r i t i e s . H o r t o n (1945) s t a t e d t h a t h y d r a u l i c c o n d i t i o n s do n o t p e r m i t t h e o c c u r r e n c e o f s h a l l o w s t e a d y f l o w on s t e e p s l o p e s , b u t r a t h e r t h e r u n o f f i s c o n c e n t r a t e d i n a s u c c e s s i o n o f more or l e s s u n i f o r m l y s p a c e d waves. O v e r l a n d F l o w i n F o r e s t W a t e r s h e d s O v e r l a n d f l o w i n n a t u r a l w a t e r s h e d s i s g e n e r a l l y c o n s i d e r e d by h y d r o l o g i s t s as an o b j e c t i o n a b l e c h a r a c t e r i s t i c . P i e r c e (1967) c i t e s two main r e a s o n s f o r t h i s . F i r s t l y , o v e r l a n d f l o w c a n c o n c e n t r a t e i n d e f i n e d c h a n n e l s and c a u s e g r e a t e r peak f l o w s i n a s h o r t e r t i m e t h a n 1 7 wa t e r i n f i l t r a t i n g and p a s s i n g t h r o u g h t h e s o i l l a y e r s b e f o r e e n t e r i n g s t r e a m f l o w . S e c o n d l y , h i g h v e l o c i t y o v e r l a n d f l o w c a n c a u s e e r o s i o n damage. F o r e s t l a n d s a r e g e n e r a l l y a r e a s of h i g h i n f i l t r a t i o n , m i n i m a l o v e r l a n d f l o w and l i t t l e s u r f a c e e r o s i o n . S o i l u n d e r u n d i s t u r b e d f o r e s t u s u a l l y has v e r y h i g h i n f i l t r a t i o n c a p a c i t i e s , i n e x c e s s o f u s u a l r a i n f a l l i n t e n s i t i e s . C o n d i t i o n s f a v o r i n g h i g h i n f i l t r a t i o n i n c l u d e p o r o u s c h a n n e l s due t o r o o t and a n i m a l a c t i v i t y , i n c o r p o r a t e d o r g a n i c m a t t e r i n t h e s u r f a c e l a y e r s and a c c u m u l a t i o n o f o r g a n i c d e b r i s ( P i e r c e 1967). Under n o r m a l f o r e s t e d c o n d i t i o n s a l a y e r of p l a n t l i t t e r i n a d d i t i o n t o l i v i n g v e g e t a t i o n p r o t e c t s t h e s o i l f r o m t h e e r o s i v e e n e r g y of r a i n d r o p s and l i m i t s o v e r l a n d f l o w . E v e n r e m o v a l of t h e f o r e s t c a n o p y w i l l have m i n i m a l i m p a c t i f t h e f o r e s t f l o o r i s l e f t u n d i s t u r b e d ; i n f i l t r a t i o n r e m a i n s h i g h and o v e r l a n d f l o w d o e s n o t o c c u r ( R o t h a c h e r 1965). D i s t u r b a n c e i n a w a t e r s h e d o f t e n e x p o s e s m i n e r a l s o i l and r e d u c e s i n f i l t r a t i o n . When t h i s i s s i g n i f i c a n t enough t o a l l o w o v e r l a n d f l o w , s u r f a c e e r o s i o n p r o b l e m s c an r e s u l t . As t h e s o i l r e s o u r c e i s t h e f u n d a m e n t a l component i n a f o r e s t e c o s y s t e m and s t r e a m s e d i m e n t c an have w i d e s p r e a d i m p a c t s , t h e o c c u r r e n c e o f o v e r l a n d f l o w and i t s e r o s i o n i s u n d e s i r a b l e . D i s t u r b a n c e i n a f o r e s t w a t e r s h e d c a n t a k e many f o r m s . F i r e c a n d e s t r o y v e g e t a t i o n , c a u s e s u r f a c e s e a l i n g , l i m i t i n f i l t r a t i o n , a nd e x p o s e s o i l t o r a i n d r o p i m p a c t . 18 C o m p a c t i o n , whether by humans, c a t t l e , v e h i c l e s , o r m a c h i n e r y r e d u c e s p o r e s p a c e and hence i n f i l t r a t i o n c a p a c i t y . F o r e s t h a r v e s t i n g o p e r a t i o n s c an d i s t u r b t h e n a t u r a l f o r e s t f l o o r and v e g e t a t i o n r e m o v a l d e c r e a s e s e v a p o t r a n s p i r a t i o n l o s s e s , t h e r e b y i n c r e a s i n g s o i l w a t e r and d e c r e a s i n g s t o r a g e c a p a c i t y . More s i g n i f i c a n t i s t h e e x p o s u r e of m i n e r a l s o i l t o r a i n d r o p s w h i c h d e t a c h s o i l p a r t i c l e s a n d b r e a k down s o i l s t r u c t u r e . L o g g i n g r o a d s and s k i d t r a i l s c o n c e n t r a t e w a t e r and c a n promote o v e r l a n d f l o w . H o r nbeck and R e i n h a r t (1964) s u g g e s t e d a c r i t e r i o n f o r e v a l u a t i n g t h e e f f e c t s o f l a n d use on a w a t e r s h e d i s t h e change i n i n f i l t r a t i o n r a t e r e s u l t i n g f r o m a s p e c i f i c u s e . Detachment- R a i n s p l a s h R a i n s p l a s h e r o s i o n i s t h e t r a n s p o r t o f s o i l i n t h e a b s e n c e of o v e r l a n d f l o w by w a t e r d r o p l e t s t h a t a r e e j e c t e d f r o m t h e s o i l s u r f a c e f o l l o w i n g r a i n d r o p i m p a c t . S p l a s h e r o s i o n r a t e s a r e g e n e r a l l y low. The major r o l e o f r a i n s p l a s h i s t h e detac h m e n t o f s o i l p a r t i c l e s p r i o r t o t h e i r r e m o v a l by o v e r l a n d f l o w . A l t h o u g h s p l a s h i t s e l f may not be an e r o s i o n p r o b l e m , many o f t h e p a r t i c l e s d e t a c h e d by s p l a s h a r e removed by o v e r l a n d f l o w . Morgan (1978) has shown t h a t 12 p e r c e n t o f t h e v a r i a t i o n i n s o i l t r a n s p o r t by o v e r l a n d f l o w i s a c c o u n t e d f o r by s p l a s h d e t a c h m e n t w h i c h , a f t e r t h e volume of r u n o f f and s l o p e a n g l e , was j u d g e d t h e most i m p o r t a n t f a c t o r i n f l u e n c i n g e r o s i o n by o v e r l a n d f l o w . The i m p a c t o f r a i n on b a r e s o i l c a n c a u s e c r a t e r i n g w h i c h 19 c o m p a c t s t h e s u r f a c e ( d e c r e a s i n g i n f i l t r a t i o n ) , and c a n d i s l o d g e s o i l p a r t i c l e s w h i c h a r e e l e v a t e d and, i n l a r g e p a r t , moved d o w n s l o p e . The s t e e p e r t h e s l o p e , t h e g r e a t e r t h e d i s t a n c e moved, a l t h o u g h s p l a s h i s n o t u s u a l l y s i g n i f i c a n t i n i s o l a t i o n a s a t r a n s p o r t a g e n t . When t h e s u r f a c e i s c o v e r e d by i n c r e a s i n g d e p t h s o f o v e r l a n d f l o w t h e e f f e c t s o f r a i n s p l a s h on s o i l i s d e c r e a s e d b u t r a i n d r o p s on t h e s u r f a c e l a y e r o f water i n c r e a s e t u r b u l e n c e and i n c r e a s e t h e e r o s i v e c a p a c i t y o f t h e f l o w . I n t e n s e r a i n s c o n t a i n more l a r g e d r o p s w h i c h a r e more e f f e c t i v e i n c o m p a c t i n g and d i s p e r s i n g t h e s o i l . Such r a i n i s a l s o more l i k e l y t o p r o d u c e o v e r l a n d f l o w and w i l l g e n e r a t e g r e a t e r d e p t h s of f l o w . As f l o w d e p t h i n c r e a s e s f r o m z e r o , s o i l l o s s by s p l a s h i n c r e a s e s . Then, a s f l o w d e p t h b e g i n s t o e x c e e d r a i n d r o p d i a m e t e r , t h e e n t r a i n m e n t p o t e n t i a l o f s p l a s h c a n be e x p e c t e d t o d e c r e a s e and t h e p o t e n t i a l e n t r a i n m e n t and t r a n s p o r t c a p a b i l i t i e s of wash t o i n c r e a s e ( K i l i n c and R i c h a r d s o n 1973). T r a n s p o r t - R a i n s p l a s h and O v e r l a n d F l o w Meeuwig and P a c k e r (1976) f o u n d t h a t o v e r l a n d f l o w i s n o t v e r y e f f e c t i v e a s a s o i l - d e t a c h i n g a g e n t u n l e s s c o n c e n t r a t e d i n r i l l s o r g u l l i e s , b u t t h e p r e s e n c e o f o v e r l a n d f l o w i n c r e a s e s t h e e f f e c t i v e n e s s o f r a i n d r o p s as d e t a c h i n g a g e n t s . I f t h e s o i l s u r f a c e i s s a t u r a t e d and c o v e r e d w i t h a f i l m o f water t h e r a i n d r o p s s t r i k i n g i t t e n d t o r e b o u n d and t o d i s l o d g e and t r a n s p o r t s o i l p a r t i c l e s . I f 20 t h e s o i l i s o n l y m o i s t , t h e r a i n d r o p s t e n d t o p e n e t r a t e t h e s o i l , d i s s i p a t i n g a t l e a s t p a r t of t h e i r k i n e t i c e n e r g y a s f r i c t i o n a l l o s s e s . Young and Wiersma (1973) f o u n d t h a t t h e i n t e r a c t i o n of r a i n s p l a s h and s h e e t w a s h ( o v e r l a n d f l o w ) i s i m p o r t a n t ; e a c h p r o c e s s a c t i n g s e p a r a t e l y i s l e s s e f f i c i e n t a t moving s o i l p a r t i c l e s t h a n when t h e p r o c e s s e s a r e a c t i n g t o g e t h e r . Morgan (1979) i d e n t i f i e d two t y p e s o f t r a n s p o r t i n g a g e n t s , t h o s e w h i c h a c t a r e a l l y and c o n t r i b u t e t o t h e r e m o v a l o f a r e l a t i v e l y u n i f o r m t h i c k n e s s o f s o i l and t h o s e w h i c h c o n c e n t r a t e t h e i r a c t i o n s i n c h a n n e l s . The f i r s t g r o u p i n c l u d e s r a i n s p l a s h and o v e r l a n d f l o w , w h i l e t h e s e c o n d c o v e r s w ater f l o w i n s m a l l c h a n n e l s , r i l l s , o r t h e l a r g e r g u l l i e s and r i v e r s . A t low i n t e n s i t i e s of e r o s i o n , r e m o v a l i s more o r l e s s u n i f o r m and a t h i g h e r i n t e n s i t i e s b r a i d s , r i l l s o r s m a l l g u l l i e s p l a y an i n c r e a s i n g l y i m p o r t a n t r o l e ( K i r k b y 1980). C o n c e n t r a t i o n o f r u n n i n g w a t e r i n t o r i l l s i n c r e a s e s e r o s i o n power and may a c c o u n t f o r t h e b u l k o f s e d i m e n t t r a n s p o r t e d from a h i l l s i d e i f s u c h f l o w o c c u r s . R a i n d r o p s have t h e p o t e n t i a l , f r o m an e n e r g y s t a n d p o i n t ( g r e a t e r v e l o c i t i e s ) , t o be more e r o s i v e t h a n o v e r l a n d f l o w , but most of t h i s e n e r g y i s u s e d i n d e t a c h m e n t and l i t t l e i s l e f t f o r t r a n s p o r t , l e a v i n g t h i s t o o v e r l a n d f l o w . On many n a t u r a l h i l l s i d e s a c t u a l f l o w c o n s i s t s o f a d i s t u r b e d , i r r e g u l a r and d i s c o n t i n u o u s s e r i e s o f s u r g e s w h i c h a r e l i k e l y more e f f e c t i v e i n e n t r a i n m e n t t h a n c o n t i n u o u s f l o w ( B r y a n 1974). 21 On n a t u r a l s l o p e s t h e uneven s u r f a c e p r o d u c e s v a r i a t i o n s i n f l o w t h i c k n e s s and t h u s i n e r o s i v e c a p a c i t y . Where t h e r e a r e marked f l u c t u a t i o n s i n f l o w t h i c k n e s s , some d e p r e s s i o n s may be e r o d e d a t a h i g h e r r a t e , i n i t i a t i n g s m a l l c h a n n e l s i n w h i c h t h e f l o w and t r a n s p o r t a t i o n become p r o g r e s s i v e l y c o n c e n t r a t e d ( C a r s o n and K i r k b y 1972). T h i s i n i t i a t e s r i l l i n g . A l t h o u g h r i l l s do n o t f o r m on a l l s l o p e s , where t h e y do f o r m , e r o s i o n i s s e v e r a l t i m e s t h e l e v e l o f s i m p l e s h e e t f l o w . D e p o s i t i o n The f i n a l s t e p i n t h e e r o s i o n c y c l e i s d e p o s i t i o n . D e p o s i t i o n o c c u r s when t h e e n e r g y o f t h e t r a n s p o r t i n g a g e n t d i m i n i s h e s u n t i l i t i s u n a b l e t o s u p p o r t t h e d e t a c h e d p a r t i c l e . A p a r t i c l e may be d e t a c h e d , t r a n s p o r t e d , and d e p o s i t e d many t i m e s as i t moves down t h e h i l l s l o p e . G e n e r a l a r e a s o f more permanent d e p o s i t i o n i n c l u d e d i t c h e s , c u l v e r t s , s t r e a m b a n k s , and s t r e a m c h a n n e l s where t h e s o i l f o r ms p a r t o f t h e s e d i m e n t l o a d . F o r e s t h a r v e s t i n g o p e r a t i o n s o f t e n l e a v e a b u f f e r s t r i p of v e g e t a t i o n a l o n g s t r e a m s . T h i s s t r i p i s d e s i g n e d i n p a r t t o t r a p o v e r l a n d f l o w and promote d e p o s i t i o n o f s e d i m e n t b e f o r e t h e r u n o f f r e a c h e s t h e s t r e a m . In a r e a s where e r o s i o n i s n o t s e v e r e , s u c h a m e l i o r a t i o n t e c h n i q u e s c a n c o n t r o l t h e p r o b l e m o f s e d i m e n t i n p u t t o s t r e a m s a l t h o u g h o r g a n i c m a t t e r l o s s f r o m t h e s i t e may s t i l l be s i g n i f i c a n t . 22 Roads c o n s t i t u t e a m a j o r s o u r c e of s e d i m e n t f o r s t r e a m s . Up t o 90 p e r c e n t o f s e d i m e n t from f o r e s t l a n d t h a t r e a c h e s s t r e a m c h a n n e l s o r i g i n a t e s on r o a d s ( H e w l e t t 1982). T h i s may a r i s e f r o m i m p r o p e r d e s i g n w h i c h a l l o w s r u n o f f t o c o n c e n t r a t e and f l o w d i r e c t l y t o t h e s t r e a m c h a n n e l , p o o r r o a d s t r e a m c r o s s i n g s and d r a i n a g e s y s t e m s , o r r o a d c u t s w h i c h i n t e r c e p t s u b s u r f a c e f l o w r o u t e s and t h e n a l l o w s u b s u r f a c e f l o w s t o become o v e r l a n d f l o w . S t u d i e s have shown t h a t , w i t h p r o p e r d e s i g n and c o n s t r u c t i o n , r o a d s c a n have a m i n i m a l impact on s t r e a m s e d i m e n t l o a d s . R o t h w e l l (1977) f o u n d w ater q u a l i t y u n changed b e f o r e and a f t e r l o g g i n g i n a s u b a l p i n e w a t e r s h e d i n A l b e r t a . T h i s was a t t r i b u t e d t o c a r e f u l p l a n n i n g , s p e c i f i c a l l y , l o c a t i o n o f r o a d s away f r o m s t r e a m c h a n n e l s , a v o i d i n g s t e e p r o a d g r a d i e n t s , m i n i m i z i n g r o a d - s t r e a m c r o s s i n g s , and s c h e d u l i n g o p e r a t i o n s when r u n o f f , s o i l m o i s t u r e , and r a i n f a l l were a t minimum l e v e l s . In a d d i t i o n t o t h e s e d e s i g n f a c t o r s , c a r e f u l s u p e r v i s i o n of t h e c o n s t r u c t i o n p h a s e s i s n e c e s s a r y t o a v o i d m i s t a k e s and e n s u r e a d h e r e n c e t o s p e c i f i c a t i o n s . An o v e r v i e w of t h e e r o s i o n p r o c e s s s h o w i n g i n t e r r e l a t i o n s h i p s among t h e f a c t o r s i n f l u e n c i n g s u r f a c e e r o s i o n f o l l o w s ( F i g u r e 1 ) . D e v e l o p e d by Novak and van V l i e t (1983) f o r i l l u s t r a t i o n o f t h e e r o s i o n p r o c e s s on an a g r i c u l t u r a l s i t e , t h i s f l o w c h a r t i s m o d i f i e d t o i n d i c a t e s p e c i f i c p r o c e s s e s and i m p a c t s w h i c h o c c u r i n t h e s u r f a c e w a t e r e r o s i o n p r o c e s s on t h e f o r e s t l a n d b a s e . 23 SCHEMATIC OF SURFACE WATER EROSION EXPOSURE OF SURFACE TO RAINFALL IMPACT DEFORESTATION GROUND DISTURBANCE SURFACE PREPARATION-AGGREGATE BREAKDOWN, SMOOTHING, CRUSTING SPLASH EROSION-TRANSPORT-LIMITED SURFACE PONDING BEGINS-DUNNE OR HORTONIAN TOPOGRAPHY CHANNELS SURFACE FLOW ENTRAINMENT OF SOIL PARTICLES OR AGGREGATES-RILL DEVELOPMENT CROP COVER FOREST & GROUND COVER TILLAGE SITE PREPARATION M A N A G E M E N T HARVESTING SYSTEM ROAD CONSTRUCTION TECHNIQUES KINETIC ENERGY OF RAIN SOIL TEXTURE AND STRUCTURE ORGANIC MATTER SLOPE RAINFALL RATE SOIL I N F I L T R A B I L I T Y DRAINAGE PROFILE DEPTH SURFACE ROUGHNESS .^ . CONTOUR TILLAGE SITE PREPARATION VEGETATION COVER SOIL TEXTURE AND STRUCTURE VEGETATIVE ROOTS OVERLAND FLOW VELOCITY TURBULENCE TRANSPORT OF SOIL SLOPE DOWNSLOPE IN R I L L S SLOPE LENGTH BY SUSPENSION/ RAINSPLASH TURBULENCE SALTATION, CREEP- SOIL TEXTURE AND STRUCTURE DETACHMENT-LIMITED RAINFALL RATE DEPOSITION OF SORTED MATERIAL IN F I E L D , LOSS TO MAINSTREAM /WATERSHED AND STREAMS SEDIMENTATION CHANNEL HYDROLOGY CHANGES LOSS OF SITE PRODUCTIVITY WATER QUALITY PROBLEMS TOPOGRAPHY SOIL TEXTURE AND STRUCTURE VEGETATIVE COVER MODIFIED FROM: NOVAK 6. VAN VLIET (1983) Figure 1. An i l l u s t r a t i o n of the p h y s i c a l processes operating i n surface water erosion and the natural s i t e c h a r a c t e r i s t i c s and management which impact t h i s process. « 24 THE ROLE OF FORESTS IN EROSION An H i s t o r i c a l P e r s p e c t i v e I t i s r e l e v a n t b e f o r e making any a s s e s s m e n t o f t h e p r e s e n t knowledge of e r o s i o n , t o c o n s i d e r t h e d e v e l o p m e n t o f t h i s s c i e n c e (Hudson 1971). S t u d i e s of t h e e f f e c t s of e r o s i o n on e a r l y c i v i l i z a t i o n s have shown t h a t a m a j o r c a u s e o f t h e d o w n f a l l of many e m p i r e s was s o i l d e g r a d a t i o n ( L o w d e r m i l k 1953). Much of t h e M e d i t e r r a n e a n r e g i o n was once a l u s h , f o r e s t e d r e g i o n . In 400 B.C. s o u t h e r n I t a l y was a l a n d of f o r e s t s t h a t c o v e r e d t h e s o u t h e r n end o f t h e I t a l i a n p e n n i s u l a . Today t h e f o r e s t o f a s h , e v e r g r e e n oak, l a u r e l and m y r t l e s u r v i v e s o n l y i n t h e r e l a t i v e l y h i g h , i n a c c e s s i b l e C a l a b r i a n m o u n t a i n s . Between t h e s i x t h and f o u r t h c e n t u r i e s B.C., t h e e x t e n s i v e m o u n t a i n f o r e s t o f G r e e c e d w i n d l e d , l e a v i n g f o r e s t o n l y i n remote a r e a s ( T h i r g o o d 1 9 81). O r i g i n a l l y 60 p e r c e n t o f t h e c o u n t r y was c o v e r e d by f i n e f o r e s t s . Now o n l y 5 p e r c e n t i s so c o v e r e d ( O s b o r n 1948). The B i b l e d e s c r i b e s P a l e s t i n e as a g r e e n and f e r t i l e l a n d . By t h e n i n e t e e n t h c e n t u r y P a l e s t i n e was d e s c r i b e d i n v e r y d i f f e r e n t t e r m s . L y n c h , an A m e r i c a n , n o t e d i n 1849 " t h e f i r s t t h i n g . . . w h i c h s t r i k e s a v i s i t o r f r o m t h e w e s t e r n w o r l d , i s t h e a b s e n c e o f f o r e s t t r e e s " ( i n T h i r g o o d 1981). 25 Even w i t h t h e p r e s e n t u n d e r s t a n d i n g o f s o i l e r o s i o n and knowledge o f c a u s a l f a c t o r s , t h e e r o s i o n c y c l e c o n t i n u e s t o o p e r a t e i n t h e M e d i t e r r a n e a n . The F o o d and A g r i c u l t u r e O r g a n i z a t i o n warns t h a t t h e p r e s e n t e x p a n s i o n o f c i v i l i z a t i o n , o v e r g r a z i n g and d e f o r e s t a t i o n may undermine f u t u r e s t a b i l i t y (Sen 1959). In t h e M e d i t e r r a n e a n a r e a d e f o r e s t a t i o n and l a c k o f p r o p e r l a n d management l e d t o s e v e r e s u r f a c e e r o s i o n . S o i l l o s s r e d u c e d t h e p r o d u c t i v e c a p a b i l i t y of t h e l a n d b a s e and l e f t an a r i d , denuded l a n d s c a p e w h i c h i s t o d a y u n a b l e t o meet t h e needs of i t s p o p u l a t i o n . As a whole, E u r o p e , w i t h a m o d e r a t e c l i m a t e , s t a b l e g o v e r n m e n t s , and good a g r i c u l t u r a l p r a c t i c e s has l i t t l e s e v e r e e r o s i o n . However, e x t e n s i v e d e f o r e s t a t i o n i n t h e h i g h m o u n t a i n f o r e s t s of t h e E u r o p e a n A l p s i n t h e 19th c e n t u r y l e d t o s e v e r e l o s s o f l i f e and p r o p e r t y f r o m d e b r i s t o r r e n t s , a v a l a n c h e s , and f l o o d s . O n l y a r e l a t i v e l y dense p o p u l a t i o n t o be p r o t e c t e d i n t h e A l p s made i t w o r t h w h i l e ( f o r t h e g o v e r n m e n t s c o n c e r n e d ) t o s p end money on t o r r e n t c o n t r o l ( K e l l e r 1970). F o r e s t s became r e c o g n i z e d as v a l u a b l e n o t o n l y e c o n o m i c a l l y but i n a p r o t e c t i v e f u n c t i o n . F o r e s t management i n t h e A l p s expanded t o e v a l u a t e t h e b e n e f i t s f r o m t h e f o r e s t i n a p r o t e c t i v e r o l e a s w e l l a s t i m b e r p r o d u c t i o n . In u n s t a b l e a r e a s where f o r e s t s were n e c e s s a r y t o s t a b i l i z e t h e s l o p e , p r o t e c t i o n f o r e s t s were e s t a b l i s h e d , r e c o g n i z i n g t h a t t h e m a i n t e n a n c e o f s l o p e s t a b i l i t y i n many c a s e s e x c e e d e d t h e r e t u r n s f r o m l o g g i n g . 26 Management t e c h n i q u e s i n c l u d e d r e f o r e s t a t i o n o f c u t o v e r l a n d s , a f f o r e s t a t i o n o f many p r e v i o u s c l e a r i n g s ( e s p e c i a l l y a t c l i m a t i c t i m b e r l i n e ) , and r e s t r i c t i o n of l a n d use t o s u i t a b l e s i t e s . " D u r i n g t h e p e r i o d of t a k i n g s t o c k t h e i d e a o f s o i l c o n s e r v a t i o n has d e v e l o p e d f u r t h e r , a n d f r o m b e i n g c o n f i n e d t o e r o s i o n c o n t r o l has e x panded t o become l i n k e d w i t h t h e i d e a o f r a t i o n a l u t i l i z a t i o n o f t h e e n v i r o n m e n t " ( F o u r n i e r 1972 pg. 1 4 ) . C o l o n i z a t i o n t h r o u g h o u t t h e U n i t e d S t a t e s seemed t o p r o c e e d w i t h an i d e a of " c o n q u e r i n g " t h e l a n d r a t h e r t h a n a d a p t i n g t o t h e n a t u r a l s y s t e m . L a n d use p r a c t i c e s , i n c l u d i n g d e f o r e s t a t i o n , l a n d c l e a r i n g , and o v e r g r a z i n g , o f t e n l e d t o a c c e l e r a t e d e r o s i o n . C o l o n i z a t i o n i n Canada o c c u r r e d w i t h much t h e same d e f o r e s t a t i o n b u t a l e s s e r p o p u l a t i o n i n f l u x p r o t e c t e d much o f t h e f o r e s t a r e a f r o m e x p l o i t a t i o n . M i g r a t i o n westward i n N o r t h A m e r i c a was g r a d u a l and t h e p o p u l a t i o n d e n s i t i e s were q u i t e low. The t i m b e r r e s e r v e s were g e n e r a l l y e x p l o i t e d f o r l o g g i n g but an a b u n d a n t s u p p l y and l o w e r l e v e l s o f f o r e s t c l e a r i n g p r e v e n t e d w i d e s p r e a d d e f o r e s t a t i o n . E a r l y l o g g i n g methods w h i c h i n c l u d e d hand f a l l i n g and h o r s e s k i d d i n g , m a i n l y on snow, had l i t t l e d i s t u r b a n c e , t h u s l i t t l e a c c e l e r a t e d e r o s i o n o c c u r r e d . W i t h t h e c o n t i n u e d e x p l o i t a t i o n o f t h e m o u n t a i n f o r e s t s o f t h e w e s t e r n U n i t e d S t a t e s , f l o o d s , d e b r i s t o r r e n t s , and mudflows c a u s e d damage s i m i l a r t o t h a t i n t h e E u r o p e a n A l p s . Lower p o p u l a t i o n d e n s i t i e s l i m i t e d t h e l o s s o f l i f e and 27 p r o p e r t y b u t t h e p r o b l e m s t i l l e x i s t e d . S e a r s ( 1 9 5 5 ) , r e c o g n i z i n g t h a t d e f o r e s t a t i o n p r e c i p i t a t e d ( i n p a r t ) t h e s e d e s t r u c t i v e e v e n t s , r e m a r k e d , " w h i l e t h i s i s assumed as a b a s i c e l e m e n t i n n a t i o n a l f o r e s t p o l i c y f a r g r e a t e r f u n d s a r e e x p e n d e d upon e f f o r t s t o c o n t r o l f l o o d s a f t e r w a t e r has r e a c h e d t h e r i v e r c h a n n e l s t h a n a r e d e v o t e d t o s e c u r i n g p r o p e r l a n d use on t h e t r i b u t a r y u p l a n d s t o r e t a i n t h e w a t e r where i t f a l l s . T h i s i s an i n t e r e s t i n g a s p e c t of a t e c h n o l o g i c a l c u l t u r e whose e m p h a s i s i s on e n g i n e e r i n g r a t h e r t h a n on b i o l o g i c a l c o n t r o l s " ( S e a r s 1955, p g . 4 8 0 ) . B r i t i s h C o l u m b i a - P r e s e n t P e r s p e c t i v e Mr. W. Young, f o r m e r c h i e f f o r e s t e r of B r i t i s h C o l u m b i a , i n an a d d r e s s on " F o r e s t r y and S o i l P r o d u c t i v i t y i n B.C." ( 1 9 8 3 ) , s t a t e d t h a t "We, i n B.C. n eed e v e r y b i t o f f o r e s t l a n d we have t o meet t h e demands p u t on i t by s o c i e t y - n o t t h e l e a s t o f w h i c h i s t o s u p p l y t i m b e r t o meet t h e needs of i n d u s t r y . " He i d e n t i f i e d s e v e r a l s o i l management p r o b l e m s w h i c h r e d u c e p r o d u c t i v e f o r e s t l a n d a r e a and s t a t e d , " t h e g r e a t e s t t h r e a t i s e r o s i o n - s o i l l o s s " i n c o n n e c t i o n w i t h f o r e s t l o g g i n g o p e r a t i o n s . H i g h e l e v a t i o n f o r e s t s (1200-2000 m e t r e s ) c o n t a i n most of t h e t i m b e r c u t on t h e c o a s t i n B r i t i s h C o l u m b i a and t h e m a j o r r e s e r v e o f s awtimber i n t h e I n t e r i o r o c c u r s i n t h i s zone (Weetman 1983). F o r e s t o p e r a t i o n s a t t h e s e e l e v a t i o n s 28 must overcome c l i m a t i c and t o p o g r a p h i c s t r e s s e s . Young (1983) s t a t e d t h a t "nowhere e l s e i n t h e w o r l d does t e r r a i n p o s e s u c h d i f f i c u l t p r o b l e m s f o r l o g g e r s . .. . f o r e s t e r s . . . and s o i l s c i e n t i s t s . " S o i l d e g r a d a t i o n o c c u r s t h r o u g h f i r e , s o i l c o m p a c t i o n , and n u t r i e n t d e p l e t i o n on l a n d i n g s but t h e m a j o r t h r e a t i d e n t i f i e d by Young was e r o s i o n on f o r e s t l a n d . T h i s i n c l u d e d m a s s - w a s t i n g c a u s e d by h a r v e s t i n g u n s t a b l e s l o p e s , s u r f a c e e r o s i o n l e a d i n g t o g u l l y e r o s i o n and, ( s i n g u l a r l y most i m p o r t a n t ) , t h e c o n s t r u c t i o n o f f o r e s t r o a d s . The C a n a d i a n F o r e s t r y S e r v i c e has p r o d u c e d a s i t u a t i o n a p p r a i s a l o f f o r e s t o p e r a t i o n s i n B r i t i s h C o l u m b i a . I t gave a g e n e r a l , c o n c i s e o v e r v i e w of p r o v i n c i a l e r o s i o n h a z a r d s : "The d i v e r s i t y of t o p o g r a p h y , g e o l o g y , s o i l s , v e g e t a t i o n , and c l i m a t e i n B r i t i s h C o l u m b i a , t o g e t h e r w i t h h i s t o r i c a t t i t u d e s and e c o n o m i c s have r e s u l t e d i n a v a r i e t y o f t i m b e r management p r a c t i c e s . T h i s c o m b i n a t i o n of f a c t o r s has p r o d u c e d a marked r e g i o n a l v a r i a t i o n i n i m p a c t s on t h e s o i l and w ater r e s o u r c e s , and, by i m p l i c a t i o n , a need f o r l o c a l o r r e g i o n a l i n f o r m a t i o n c o n c e r n i n g t h e s e i m p a c t s or i n t e r a c t i o n s . In v e r y g e n e r a l t e r m s i t can be s t a t e d t h a t : - The s i g n i f i c a n c e o f i m p a c t s may i n c r e a s e f r o m s o u t h t o n o r t h as t h e c l i m a t e becomes more r i g o r o u s . - A c c e l e r a t e d e r o s i o n o c c u r s t o some e x t e n t w h e r e v e r t h e r e i s l o g g i n g , w i t h v a r i a t i o n s r e s u l t i n g f r o m d i f f e r e n c e s i n i n t r i n s i c s o i l e r o s i o n h a z a r d and s t a n d a r d of l o g g i n g p r a c t i c e . - The g r e a t e r t h e a r e a l e x t e n t o f d i s t u r b a n c e t h e g r e a t e r t h e i m p a c t . The e x t e n t of d i s t u r b a n c e i s a f u n c t i o n o f h a r v e s t i n g method, l o g g i n g t e c h n i q u e , r o a d d e n s i t y and s l o p e . .29 - The d e g r e e o f i m p a c t on t h e s t r e a m e n v i r o n m e n t t e n d s t o be i n v e r s e l y r e l a t e d t o t h e d i s t a n c e between t h e a c t i v i t y and t h e w ater c o u r s e . - The l o g g i n g p r a c t i c e s u s e d i n s t e e p t e r r a i n i n t h e I n t e r i o r t e n d t o be more d e s t r u c t i v e t h a n on t h e c o a s t b e c a u s e of t h e t y p e o f e q u i p t m e n t u s e d " ( F i n n i s e t a l . 1 9 7 3 ) . B a l l a r d (1983) a t t e m p t e d t o a s s e s s "how s e r i o u s and how e x t e n s i v e a r e v a r i o u s k i n d s o f f o r e s t s o i l d e g r a d a t i o n a s s o c i a t e d w i t h t i m b e r h a r v e s t i n g and s i t e p r e p a r a t i o n i n B r i t i s h C o l u m b i a . " No q u a n t i t a t i v e v a l u e s were a v a i l a b l e but an i d e n t i f i c a t i o n o f t h e m a j o r e r o s i o n p r o b l e m s i n t h e v a r i o u s r e g i o n s was o b t a i n e d . In t h e Kamloops, N e l s o n , and C a r i b o o r e g i o n s t i m b e r h a r v e s t i n g i m p a c t s i n t e r m s o f c o m p a c t i o n , p u d d l i n g , and s u r f a c e e r o s i o n were r a t e d r e l a t i v e l y i m p o r t a n t . N u t r i e n t l o s s e s from h a r v e s t i n g and s l a s h b u r n i n g , as w e l l as d e g r a d a t i o n from m e c h a n i c a l s i t e p r e p a r a t i o n , were a l s o i m p o r t a n t i m p a c t s . M a s s - e r o s i o n was a l o c a l i z e d c o n c e r n i n s e v e r a l r e g i o n s but i t s m a j o r impact was i n t h e P r i n c e R u p e r t r e g i o n , n o t a b l y i n t h e Queen C h a r l o t t e I s l a n d s . The mandate f o r f o r e s t management by t h e B r i t i s h C o l u m b i a M i n i s t r y o f F o r e s t s i s , i n p a r t : " t o p l a n t h e use of t h e F o r e s t s and r a n g e r e s o u r c e s o f t h e Crown so t h a t t h e p r o d u c t i o n of t i m b e r and f o r a g e , t h e h a r v e s t i n g o f t i m b e r , t h e g r a z i n g o f l i v e s t o c k and t h e r e a l i z a t i o n o f f i s h e r i e s , w i l d l i f e , w a t e r , o u t d o o r r e c r e a t i o n and o t h e r n a t u r a l r e s o u r c e v a l u e s a r e c o o r d i n a t e d and i n t e g r a t e d , i n c o n s u l t a t i o n and c o o p e r a t i o n w i t h o t h e r m i n i s t r i e s and a g e n c i e s of t h e Crown and w i t h t h e p r i v a t e s e c t o r . . . " ( S e c t i o n 5, S u b s e c t i o n C, MOF A c t ) . 30 The B r i t i s h C o l u m b i a M i n i s t r y o f F o r e s t s i n t e r i m g u i d e t o l o g g i n g on s e v e r e s i t e s (B.C.M.O.F 1968) s t a t e d t h a t : " t o m a i n t a i n r e a s o n a b l e s i t e p r o d u c t i v i t y , by m i n i m i z i n g e r o s i o n and e n c o u r a g i n g r e g e n e r a t i o n , a d j u s t m e n t s i n s t a n d t r e a t m e n t s and l o g g i n g t e c h n i q u e s a r e n e e d ed on any s i t e where e x t r e m e s o f c l i m a t e , e d a p h i c o r t o p o g r a p h i c f e a t u r e s a r e e n c o u n t e r e d . B e c a u s e of s i t e v a r i a b i l i t y , s i l v i c u l t u r a l t r e a t m e n t must be d e t e r m i n e d on t h e b a s i s o f s i t e s p e c i f i c r e commendation f o r a l l f o r e s t u n i t s under management and p r e - l o g g i n g e x a m i n a t i o n i s e s s e n t i a l . " T h e s e g o v e r n m e n t a l d i r e c t i v e s , a s w e l l a s d e s i g n a t i o n o f some h i g h e l e v a t i o n s e n s i t i v e s i t e s t o E n v i r o n m e n t a l P r o t e c t i o n A r e a s and o t h e r l a n d o f f - l i m i t s t o h a r v e s t i n g i n P r o v i n c i a l and N a t i o n a l P a r k s , has p r o t e c t e d B r i t i s h C o l u m b i a . The h a z a r d f o r e r o s i o n i s o n l y p r e s e n t l y a c c e l e r a t i n g t o d a n g e r o u s l e v e l s . L o g g i n g o p e r a t i o n s a r e e x p a n d i n g t o more m a r g i n a l l y s t a b l e s l o p e s a s our wood s u p p l y d i m i n i s h e s . S m i t h (1962) s t a t e d t h e r e l a t i o n s h i p between s i l v i c u l t u r e and w a t e r s h e d management becoming o f p r i m a r y i m p o r t a n c e . In B r i t i s h C o l u m b i a r e g e n e r a t i o n , o r l a c k t h e r e o f , i s a p r i m e s i l v i c u l t u r a l c o n s i d e r a t i o n . M a i n t e n a n c e o f s i t e p r o d u c t i v i t y i s i m p o r t a n t , a s i s t h e s t a b i l i t y o f t h e s o i l . Management a l t e r n a t i v e s t o l i m i t e r o s i o n c a n o f t e n i n c r e a s e r e g e n e r a t i o n s u c c e s s . S e l e c t i o n l o g g i n g , i f p r o p e r l y p l a n n e d , c a n m a i n t a i n s i t e s t a b i l i t y and a l s o promote n a t u r a l r e g e n e r a t i o n i n some s p e c i e s . P a t c h o r s t r i p c l e a r c u t t i n g p r o v i d e s more f a v o r a b l e m i c r o s i t e s f o r s e e d l i n g s , e s p e c i a l l y on s o u t h e r n s l o p e s . 31 In most i n s t a n c e s , f o r e s t management s h o u l d m i n i m i z e e r o s i o n , e s p e c i a l l y i f o t h e r n o n - t i m b e r v a l u e s a c c r u e t o t h e l a n d . "We c a n n o t however, condemn f o r e s t p r a c t i c e s m e r e l y b e c a u s e t h e y c a u s e s o i l d e g r a d a t i o n . The a p p r o p r i a t e n e s s o f f o r e s t p r a c t i c e s c a n o n l y be d e t e r m i n e d by c o m p a r i n g c o s t s and b e n e f i t s of d i f f e r e n t management o p t i o n s " ( B a l l a r d 1983, pg. 175). The p r o b l e m a l a n d manager f a c e s i s t h a t v a l u e s f o r b e n e f i t s and c o s t s o f n o n - t i m b e r o p t i o n s a r e d i f f i c u l t , i f n o t i m p o s s i b l e , t o q u a n t i f y . E v a l u a t i o n s a r e t h e r e f o r e b o t h s u b j e c t i v e and d i f f i c u l t . R e c o g n i z i n g t h e i m p o r t a n c e o f t h e f o r e s t l a n d base i n B r i t i s h C o l u m b i a , i t i s i m p e r a t i v e t h a t s o i l d e g r a d a t i o n be e v a l u a t e d i n c o n j u n c t i o n w i t h v a r i o u s management o p t i o n s . 32 C h a p t e r 4 LITERATURE REVIEW OF FLUORESCENT DYE S t u d i e s o f w a t e r o r s o i l movement a r e d i f f i c u l t b e c a u s e d i s t i n g u i s h i n g c h a r a c t e r i s t i c s r a r e l y a l l o w d i f f e r e n t i a t i o n between t h e s u b s t a n c e i n i t s o r i g i n a l s i t e a nd a f t e r movement. Water and s o i l " t r a c e r s or t a g s " s e r v e as l a b e l s on t h e s u b s t a n c e and a l l o w movement t o be o b s e r v e d and documented. Normal c o l o r ( n o n - f l u o r e s c e n t ) d yes have been u s e d b o t h t o " t a g " s o i l p a r t i c l e s and t o m o n i t o r water f l o w s . T h e s e l a b e l s g i v e a new c o l o r t o t h e sample s u b s t a n c e . The r e s o l u t i o n , o r a b i l i t y t o d i s t i n g u i s h l a b e l l e d p a r t i c l e s , i n t h i s method i s l i m i t e d by t h e d i f f i c u l t y i n v i s u a l d e t e c t i o n o f t a g g e d p a r t i c l e s o r s l i g h t f l u i d c o l o r c h a n g e s once m i x i n g has o c c u r r e d . To i m p r o v e r e s o l u t i o n a t a g d e p e n d e n t upon more t h a n v i s u a l d e t e c t i o n was d e v e l o p e d . T h i s t e c h n i q u e u s e s r a d i o a c t i v i t y t o t a g p a r t i c l e s o r t o a c t as t r a c e r s i n water s t u d i e s . D e t e c t i o n of p a r t i c l e and f l u i d movement i s s u c c e s s f u l w i t h t h i s method. The use of r a d i o a c t i v i t y i s l i m i t e d b e c a u s e i t i s e x p e n s i v e , p o t e n t i a l l y h a z a r d o u s , and f r e q u e n t l y t h e s u b j e c t of p u b l i c c o n c e r n . A t e c h n i q u e w h i c h o v e r c o m e s t h e s e l i m i t a t i o n s , y e t has h i g h r e s o l u t i o n , i s t h e use o f f l u o r e s c e n c e t o m o n i t o r o r i l l u s t r a t e movement. T h i s method has many a p p l i c a t i o n s i n s o i l a nd w a t e r s t u d i e s . 33 The a p p e a r a n c e of n o r m a l c o l o r a r i s e s f r o m s e l e c t i v e a b s o r p t i o n and r e f l e c t i o n of segments of w h i t e l i g h t i n t h e v i s i b l e s p e c t r u m . The p o r t i o n r e f l e c t e d y i e l d s t h e c h a r a c t e r i s t i c c o l o r w h i l e t h e p o r t i o n a b s o r b e d i s d i s s i p a t e d a s h e a t . F l u o r e s c e n c e r e s u l t s f r o m t h e e m i s s i o n o f r a d i a n t e n e r g y as a m o l e c u l e d r o p s from an e x c i t e d o r h i g h e r e n e r g y l e v e l t o i t s p r e v i o u s s t a t e . The i n p u t o f u l t r a v i o l e t l i g h t ( w a v e l e n g t h s below t h e v i s i b l e s p e c t r u m ) a l l o w s a f l u o r e s c e n t m o l e c u l e t o a c c e p t an e x t r a p h o t o n , t h u s i n c r e a s i n g i t s e n e r g y l e v e l . T h i s e n e r g y s t a t e i s u n s t a b l e and s h o r t l i v e d . As t h e m o l e c u l e r e t u r n s t o i t s o r i g i n a l s t a t e i t e m i t s r a d i a n t e n e r g y . T h i s e m i s s i o n i s c a l l e d f l u o r e s c e n c e and has a l o n g e r w a v e l e n g t h t h a n t h e i n c i d e n t u l t r a v i o l e t l i g h t . T h i s means t h a t t h e i n p u t o f u l t r a v i o l e t l i g h t , w h i c h i s , e s s e n t i a l l y , i n v i s i b l e t o t h e naked e y e , r e s u l t s i n t h e e m i s s i o n o f v i s i b l e , l i g h t . T h u s , when t h e s u r r o u n d i n g p a r t i c l e s a r e u n a b l e t o be seen ( i . e . a t n i g h t ) f l u o r e s c e n t p a r t i c l e s w i l l e m i t l i g h t and a r e t h e r e f o r e e a s i l y d i s t i n g u i s h e d . I t i s t h i s e m i s s i o n of v i s i b l e l i g h t from u l t r a v i o l e t i n p u t w h i c h a l l o w s f l u o r e s c e n c e t o be u s e d s u c c e s s f u l l y as a t r a c e r i n s e d i m e n t , s o i l , and water movement s t u d i e s . Smart and L a i d l a w (1977) summarized t h e use o f f l u o r e s c e n t dye t r a c i n g t e c h n i q u e s i n h y d r o l o g y . They f o u n d a m u l t i t u d e o f u s e s : f o r s u r f a c e w a t e r s t u d i e s , where f l u o r e s c e n t d y e s a r e commonly u s e d f o r dye d i l u t i o n g a u g i n g ; f o r t h e c a l i b r a t i o n of s t r u c t u r e s , where c u r r e n t m e t e r i n g i s 34 d i f f i c u l t ; and, f o r t i m e - o f - t r a v e l s t u d i e s . The t r a c i n g o f k a r s t g r o u n d w a t e r has a l s o been a c c o m p l i s h e d u s i n g d y e s . In s o i l w a ter s t u d i e s w a t e r s o l u b l e d y e s have been u s e d t o i d e n t i f y t h e o c c u r r e n c e o f o v e r l a n d f l o w , t o t r a c e w a t e r t r a n s m i s s i o n r o u t e s i n t h e s o i l , and t o e v a l u a t e i n f i l t r a t i o n . F l u o r e s c e n t p a r t i c l e s i n d e x s o i l movement and a i d i n t h e e v a l u a t i o n o f wave a c t i o n on b e a c h e s . The m a g n i t u d e and l o c a t i o n o f t h e s e t r a n s p o r t f o r c e s c a n be i l l u s t r a t e d by d i f f e r e n t i a l movement o f p a r t i c l e s c o l o r -s t r a t i f i e d by s i z e and o r i g i n a l l o c a t i o n . SOIL PARTICLE TAGGING O v e r v i e w In e v a l u a t i n g s u r f a c e e r o s i o n most s t u d i e s use measurements o f s o i l and w a t e r c o l l e c t e d a t t h e b o t t o m of th e s l o p e , t h e p l o t b o u n d a r y , o r t h e w a t e r s h e d o u t l e t . T h e s e d a t a i l l u s t r a t e s o i l l o s s f r o m t h e a r e a b u t t e l l l i t t l e a b o u t t h e p o i n t s o u r c e o f t h e e r o d e d m a t e r i a l o r t h e p a t t e r n s o f s o i l movement w i t h i n t h e a r e a (Young and M u t c h l e r 1969). L a b e l l i n g s o i l p a r t i c l e s a l l o w s o r i g i n and r a t e s of movement t o be c h a r t e d . In s o i l s t u d i e s , c o l o r e d d y e s a r e o f l i m i t e d v a l u e b e c a u s e o f t h e d i f f i c u l t y i n d i s t i n g u i s h i n g marked and unmarked p a r t i c l e s on t h e b a s i s o f c o l o r a l o n e . T h i s i s e s p e c i a l l y e v i d e n t when an a n a l y s i s o f l a r g e numbers o f p a r t i c l e s i s n e c e s s a r y . The use of r a d i o a c t i v e compounds i s 35 a l w a y s s u b j e c t t o p u b l i c c o n c e r n s and p o s s i b l e h e a l t h h a z a r d s . O t h e r f a c t o r s l i m i t i n g t h i s p r o c e d u r e a r e h i g h c o s t , d i f f i c u l t y i n t a g g i n g p a r t i c l e s , and no v i s u a l r e c o r d of t a g g e d p a r t i c l e s . F l u o r e s c e n t d y e s a r e r e l a t i v e l y s i m p l e and i n e x p e n s i v e t o u s e . They a r e e n v i r o n m e n t a l l y s a f e and a l l o w e a s y d i f f e r e n t i a t i o n between t a g g e d and unmarked p a r t i c l e s . L a r g e volumes o f s e d i m e n t can be t a g g e d r e a s o n a b l y q u i c k l y and a v a r i e t y o f " c o l o r s " c a n be p r e p a r e d t o s e p a r a t e p a r t i c l e s a m p l e s . The s t a b i l i t y o f f l u o r e s c e n t dye u n d e r e n v i r o n m e n t a l c o n d i t i o n s i s s t i l l p a r t i a l l y unknown, a l t h o u g h d i f f e r e n t a p p l i c a t i o n t e c h n i q u e s y i e l d d i f f e r e n t p e r s i s t e n c e t i m e s . D i f f i c u l t i e s i n d e t e c t i n g f l u o r e s c e n c e w i l l sometimes e x i s t , o f t e n due t o e n v i r o n m e n t a l c o n d i t i o n s . A v a r i e t y of m a r k i n g compounds and c o l o r s e x i s t , w h i c h a l l o w s t r a t i f i c a t i o n o f p a r t i c l e s i z e s and s l o p e l o c a t i o n . When l a b e l l i n g p a r t i c l e s w i t h a f l u o r e s c e n t c o a t i n g f o u r p o i n t s s h o u l d be c o n s i d e r e d : 1) The c h a r a c t e r i s t i c s ( d e n s i t y , s i z e and s u r f a c e t e x t u r e ) of t h e n a t u r a l o r i n t r o d u c e d p a r t i c l e s s h o u l d n o t be s i g n i f i c a n t l y a l t e r e d by a p p l i c a t i o n of t h e m a r k i n g compound. 2) The t a g g e d p a r t i c l e s s h o u l d be r e a d i l y d i s t i n g u i s h e d f r o m unmarked p a r t i c l e s . 3) The p r o c e d u r e s h o u l d be r e l a t i v e l y q u i c k and e a s y . 4) The t a g g e d compound s h o u l d be p e r s i s t e n t a l t h o u g h t h e d e s i r e d l e n g t h of t i m e w i l l depend upon t h e o b j e c t i v e s o f t h e p r o j e c t . 36 The r e v i e w of r e s e a r c h u s i n g f l u o r e s c e n c e i n p a r t i c l e movement s t u d i e s i s d i v i d e d i n t o t h r e e s e c t i o n s : t h e o r i g i n a l m a r k i n g o f b e a c h s a n d s ; t h e i n t r o d u c t i o n o f f l u o r e s c e n t p a r t i c l e s ( g l a s s o r n a t u r a l m a t e r i a l ) t o a s o i l s y s t e m ; and t h e t a g g i n g o f a c t u a l s o i l p a r t i c l e s e i t h e r by s p r a y i n g ijn s i t u o r e x t r a c t i o n , m a r k i n g and r e p l a c e m e n t . B e a c h Sands The o r i g i n a l e x t e n s i v e s t u d y o f s e d i m e n t t r a n s p o r t u s i n g f l u o r e s c e n c e was c o n d u c t e d by t h e I n s t i t u t e o f O c e a n o l o g y o f t h e S o v i e t U n i o n ( Z e n k o v i t c h 1958, i n W r i g h t 1962). Two f l u o r e s c e n t compounds were u s e d , a n t h r a c e n e , w h i c h f l u o r e s c e s y e l l o w - g r e e n u n d e r u l t r a v i o l e t l i g h t , and lumogene w h i c h f l u o r e s c e s r e d - o r a n g e . T h e s e were combined w i t h a v a r i e t y o f s u b s t a n c e s , a g a r - a g a r , b o n e - g l u e , gum and s t a r c h , a d j u s t e d t o d i s s o l v e a t a p r e d e t e r m i n e d r a t e ( f r o m 1 week t o 3 months) i n s e a - w a t e r . Y a s s o (1962) e v a l u a t e d c o m m e r c i a l l y a v a i l a b l e d a y l i g h t and n e a r - u l t r a v i o l e t f l u o r e s c e n t d y e s i n s u r f a c e c o a t i n g s on s e d i m e n t s . Many o f t h e s e c o a t i n g s were v i s i b l e b o t h i n d a y l i g h t and under u l t r a v i o l e t l i g h t a l l o w i n g day and n i g h t -t i m e e v a l u a t i o n s . W r i g h t (1962) c o n d u c t e d t e s t s t o d e v e l o p t h e s i m p l e s t p o s s i b l e t e c h n i q u e f o r m a r k i n g b e a c h s a n d w i t h an u l t r a v i o l e t - s e n s i t i v e d y e . I t was f o u n d t h a t t h e c h o i c e o f dye and m a r k i n g t e c h n i q u e was i n t e r d e p e n d e n t . . Many of t h e a v a i l a b l e d y es would f l u o r e s c e p r o p e r l y o n l y i n s o l u t i o n 37 i n s p e c i f i c s o l v e n t s o r w o u l d r e a c t w i t h p o t e n t i a l c o a t i n g m a t e r i a l s or were s o l u b l e i n w a t e r i f a t t e m p t s were made t o a p p l y them d i r e c t l y t o g r a i n s u r f a c e s . The most s u c c e s s f u l r e s u l t s were o b t a i n e d w i t h a n t h r a c e n e , a r e a d i l y a v a i l a b l e o r g a n i c c h e m i c a l (a c o a l - t a r d e r i v a t i v e ) . L a t e r e x p e r i m e n t s c o n c e n t r a t e d on d e v e l o p i n g s u i t a b l e t e c h n i q u e s u s i n g t h i s f l u o r e s c i n g a g e n t . A s i m p l e t e c h n i q u e was d e v e l o p e d . Sand was s c o o p e d f r o m t h e s u r f a c e a l o n g s u r v e y e d l i n e s , r a p i d l y marked i n a s h a k e r w i t h t h e f l u o r e s c e n t compound, and r e t u r n e d t o t h e same l o c a t i o n . The d i s p e r s a l of marked s e d i m e n t was c h e c k e d a f t e r d a r k w i t h an u l t r a v i o l e t lamp and s a m p l e s were c o l l e c t e d f o r q u a n t i t a t i v e a n a l y s i s i n t h e l a b . Y a s s o (1962) d e v e l o p e d a f i e l d p h o t o m e t e r t o sample l i g h t i n t e n s i t y f r o m t h e s u r f a c e d i s t r i b u t i o n o f marked p a r t i c l e s o v e r a g i v e n s a m p l i n g a r e a , t h e r e b y s u p p l a n t i n g o r e l i m i n a t i n g t h e c o n v e n t i o n a l c o u n t i n g p r o c e d u r e . T h i s p r o c e d u r e was h e l p f u l as i t i s d i f f i c u l t t o sample a u n i f o r m l a y e r o f s e d i m e n t by m e c h a n i c a l means. A l s o , t h e use of a p h o t o m e t e r y i e l d s r e s u l t s e s t i m a t i n g t h e r e l a t i v e abundance of marked p a r t i c l e s i n a f r a c t i o n of t h e t i m e n e eded f o r c o u n t i n g . Y a s s o (1964) u s e d a t i m e - i n t e g r a t i o n s a m p l i n g t e c h n i q u e w i t h c o l o r - c o d e d s i z e s o f f l u o r e s c e n t t r a c e r p a r t i c l e s t o d e t e r m i n e t h e n a t u r e o f s i z e - v e l o c i t y r e l a t i o n s h i p s i n wave a c t i o n . The' p r o c e d u r e i n v o l v e d r e m o v i n g s e d i m e n t f r o m t h e f o r e s h o r e zone, s i e v i n g i t i n t o f o u r s i z e c l a s s e s and 38 c o a t i n g t h e s e w i t h a m i x t u r e o f S w i t z e r D a y - G l o a c r y l i c l a q u e r and A m e r i c a n Cyanamid b e e t l e r e s i n . E a c h s i z e c l a s s was c o a t e d w i t h a d i f f e r e n t d a y l i g h t and u l t r a v i o l e t f l u o r e s c e n t dye c o l o r . The c o a t e d s e d i m e n t was dumped o n t o t h e f o r e s h o r e j u s t b e f o r e a wave came i n and t h e n t h e a r e a was s a m p l e d f o r marked s e d i m e n t c o n c e n t r a t i o n b o t h o n s i t e and w i t h a s m a l l e r subsample i n t h e l a b . I n t r o d u c e d F l u o r e s c e n t P a r t i c l e s F l u o r e s c e n t g l a s s p a r t i c l e s and w i l l e m i t e , a n a t u r a l l y f l u o r e s c i n g o r e , have been u s e d i n s o i l s t u d i e s t o t r a c e movement and t o i d e n t i f y o v e r l a n d f l o w v e l o c i t y - p a r t i c l e s i z e r e l a t i o n s h i p s . Young and H o l t (1968) and Young and M u t c h l e r (1969) u s e d f l u o r e s c e n t g l a s s p a r t i c l e s t o t r a c e s o i l movement. T h e s e g l a s s p a r t i c l e s have a d e n s i t y s i m i l a r t o n a t u r a l s o i l p a r t i c l e s and a r e assumed t o r e a c t t h e same. T h i s e x p e r i m e n t a l t e c h n i q u e was d e v e l o p e d i n German e r o s i o n s t u d i e s . O r d i n a r y soda g l a s s i s i m p r e g n a t e d w i t h s o d ium d i u r a n a t e , a c o m m e r c i a l l y f l u o r e s c i n g a g e n t i d e n t i f i e d a s " u r a n i u m y e l l o w . " O t h e r f l u o r e s c i n g a g e n t s may be s u b s t i t u t e d t o v a r y t h e f l u o r e s c e n c e c h a r a c t e r i s t i c s and t h e amount of a g e n t u s e d d epends upon t h e d e g r e e of f l u o r e s c e n c e d e s i r e d . The m i x t u r e i s h e a t e d u n t i l m o l t e n and t h e n t h e g l a s s i s c o o l e d , c r u s h e d and s i e v e d t o t h e d e s i r e d p a r t i c l e s i z e d i s t r i b u t i o n . 39 Young and M u t c h l e r (1969) u s e d f l u o r e s c e n t g l a s s p a r t i c l e s t o e v a l u a t e s o i l movement on i r r e g u l a r s l o p e s . The use o f f l u o r e s c e n t p a r t i c l e s ( o f s i m i l a r d e n s i t y and s i z e as e x i s t i n g s o i l ) and m i c r o r e l i e f measurements a l l o w e d s o i l l o s s , t h e p o i n t s o u r c e of e r o d e d m a t e r i a l , and o n s l o p e s o i l e r o s i o n p a t t e r n s t o be e v a l u a t e d . Two l i n e s o f g l a s s p a r t i c l e s were p l a c e d a c r o s s t h e s l o p e . C o l l e c t i n g t r o u g h s were e s t a b l i s h e d a t t h e base o f t h e s l o p e and a f t e r e a c h h a l f hour i n c r e m e n t o f s i m u l a t e d r a i n f a l l t h e s i l t - l a d e n r u n o f f was c o l l e c t e d and a n a l y z e d i n t h e l a b f o r f l u o r e s c e n t p a r t i c l e s . The v e l o c i t y o f t h e r u n o f f o c c u r r i n g f r o m t h e s i m u l a t e d r a i n was measured by t h e a d v a n c e o f u r a n i n e (a f l u o r e s c e n t dye) i n j e c t e d i n t o t h e f l o w a t v a r i o u s p o i n t s . The use of f l u o r e s c e n t p a r t i c l e s a l l o w s e r o s i o n p l o t s t o y i e l d d a t a on more t h a n n e t s o i l l o s s . P l o t s " s e e d e d " w i t h d i f f e r e n t i a t e d f l u o r e s c e n t p a r t i c l e s i l l u s t r a t e how v a r i o u s p o r t i o n s o f t h e s l o p e c o n t r i b u t e t o t o t a l s e d i m e n t y i e l d and c h a r t t h e movement of t h e f l u o r e s c e n t p a r t i c l e s d o w n s l o p e . F o w l e r and B e r n d t (1969) and H e l v e y and F o w l e r (1979) u s e d a n a t u r a l o r e c o n t a i n i n g f l u o r e s c e n t W i l l e m i t e ( z i n c s i l i c a t e w i t h a manganese a c t i v a t o r ) a s an i n d i c a t o r of s o i l movement. The o r e was c r u s h e d and g r a d e d t o s i z e s r e p r e s e n t i n g t h e e x i s t i n g s o i l o n s i t e . When i l l u m i n a t e d u n d e r u l t r a v i o l e t l i g h t W i l l e m i t e g l o w s y e l l o w - g r e e n . 40 H e l v e y and F o w l e r (1979) " s a l t e d " 10 p l o t s w i t h s i z e -g r a d e d f l u o r e s c e n t m a t e r i a l t o i n d e x movement o f p a r t i c l e s of v a r i o u s s i z e s . E a c h p l o t v a r i e d i n s u r f a c e s o i l d i s t u r b a n c e and was s a l t e d i n t h r e e s e p a r a t e s e c t i o n s , one e a c h w i t h f i n e , medium, and c o a r s e - g r a i n e d p a r t i c l e s . R a t e s of movement under d i f f e r e n t d i s t u r b a n c e l e v e l s and maximum do w n s l o p e movement were d e t e r m i n e d . A p p l i c a t i o n Onto N a t u r a l S o i l P a r t i c l e s A p p l i c a t i o n of dye d i r e c t l y o n t o s o i l p a r t i c l e s e n s u r e s t h a t t a g g e d p a r t i c l e s r e p l i c a t e s o i l p r o p e r t i e s on t h e s i t e . S t r i f f l e r ( 1 9 6 9 ) , i n C o l o r a d o , e v a l u a t e d a l p i n e s o i l movement by e s t a b l i s h i n g e r o s i o n t r a n s e c t s u s i n g f l u o r e s c e n t d y e s . S i t e s v a r i e d i n a s p e c t , s l o p e p o s i t i o n , and s l o p e l e n g t h . P a r t i c l e s were t a g g e d w i t h f l u o r e s c e i n , a f l u o r e s c e n t dye t o i n d e x s o i l movement. S m a l l m i c r o p l o t s were f i t t e d w i t h s o i l c o l l e c t o r s and p a r t i c l e s were a n a l y z e d f o r f l u o r e s c e n c e i n t h e l a b . The p r o c e d u r e i n c l u d e d s p r a y i n g a water s t a b l e f l u o r e s c e n t dye ( f l u o r e s c e i n ) d i r e c t l y o n t o t h e s o i l s u r f a c e o r e x c a v a t i n g s o i l p a r t i c l e s f r o m a 2.5 cm by 2.5 cm t r e n c h a c r o s s t h e s l o p e , s i e v i n g i n t o s i z e c l a s s e s , d y e i n g e a c h s i z e c l a s s a s e p a r a t e , d i s t i n c t c o l o r ( f l u o r e s c e n t ) , and r e p l a c i n g them i n t h e t r e n c h . S m a l l m e t a l c o l l e c t i o n t r o u g h s were a l s o imbedded i n t h e s l o p e t o c o l l e c t s u r f a c e r u n o f f and s e d i m e n t a c c u m u l a t i o n s . F l u o r e s c e n t dye o f v a r i o u s c o l o r s was 41 s p r a y e d a l o n g t h e t r a n s e c t s a t i n t e r v a l s u p s l o p e f r o m t h e c o l l e c t o r t o a l l o w t h e i d e n t i f i c a t i o n of a p a r t i c l e ' s o r i g i n a l s i t e and t h u s t h e d i s t a n c e moved. S t r i f f l e r f o u n d s u c h p a r t i c l e t a g g i n g w i t h f l u o r e s c e n t d y e s s i m p l e and i n e x p e n s i v e , y e t e f f e c t i v e . The dye r e m a i n e d s u f f i c i e n t l y v i s i b l e f o r n i g h t i l l u m i n a t i o n o v e r a two y e a r p e r i o d . In c o n j u n c t i o n w i t h S t r i f f l e r , Zoghet (1969) e s t a b l i s h e d f u r t h e r e r o s i o n t r a n s e c t s . He u s e d D a y - G l o f l u o r e s c e n t p i g m e n t s m i x e d w i t h a c e t o n e t o t a g p a r t i c l e s e i t h e r i_n s i t u o r a f t e r e x c a v a t i o n . F i v e d i f f e r e n t f l u o r e s c e n t p i g m e n t s were u s e d a l l o w i n g b o t h a q u a n t i t a t i v e and q u a l i t a t i v e i n d e x o f s o i l movement. S p r a y i n g o f t h e s o i l s u r f a c e in s i t u has t h e a d v a n t a g e of no s o i l d i s t u r b a n c e . However, as i t i s i m p o s s i b l e t o c o a t t h e c o m p l e t e s o i l p a r t i c l e , some p a r t i c l e s may n o t be d e t e c t e d a f t e r d o w nslope t r a n s p o r t . E x c a v a t i o n o f p a r t i c l e s a l l o w s t h e c o m p l e t e s u r f a c e t o be marked but when r e p l a c e d o n t o t h e s l o p e , t h e t a g g e d p a r t i c l e s may n o t r e f l e c t t h e a c t u a l s u r f a c e s o i l s t a b i l i t y . Zoghet f o u n d t h a t d a y t i m e d i f f e r e n t i a t i o n o f p a r t i c l e s t a g g e d w i t h D a y - G l o p i g m e n t s was p o s s i b l e i n t h e e a r l y s t a g e s of t h e e x p e r i m e n t b u t t h a t t h i s c o l o r f a d e d a f t e r t i m e . N i g h t - t i m e i l l u m i n a t i o n was s u c c e s s f u l even a f t e r a f u l l y e a r on t h e s i t e . 42 DAY-GLO FLUORESCENT PIGMENT A d a y l i g h t f l u o r e s c e n t p i g m e n t has t h e same r e f l e c t i o n p r o p e r t i e s a s a n o n - f l u o r e s c e n t c o l o r but i s a l s o a b l e t o a b s o r b w a v e l e n g t h s from t h e l o w e r end of t h e s p e c t r u m ( u l t r a v i o l e t ) and c o n v e r t t h e s e t o v i s i b l e l i g h t o f a s i m i l a r w a v e l e n g t h as t h e r e f l e c t e d l i g h t . A b r i g h t non-f l u o r e s c i n g c o l o r m i g h t r e f l e c t 90 p e r c e n t o f a c o l o r p r e s e n t i n t h e e x c i t i n g s p e c t r u m b u t i n c o m b i n i n g r e f l e c t e d and e m i t t e d l i g h t a f l u o r e s c e n t c o l o r c a n r e f l e c t 200 t o 300 p e r c e n t ( D a y - G l o T e c h . B u l l , no d a t e ) . T h e s e e x t r a - b r i g h t p i g m e n t s were f i r s t d e v e l o p e d i n t h e 1940s f o r use i n m i l i t a r y s i g n a l p a i n t . Much o f t h e i m p e t u s f o r d e v e l o p m e n t o f c o m m e r c i a l a v a i l a b i l i t y was i n s i l k s c r e e n p r o c e s s p a i n t s . D a y - G l o d a y l i g h t f l u o r e s c e n t p i g m e n t s a r e t r a n s p a r e n t . o r g a n i c r e s i n p a r t i c l e s c o n t a i n i n g d y e s . The f l u o r e s c e n c e of t h e s e o r g a n i c d y e s i s a s s o c i a t e d w i t h t h e i n d i v i d u a l dye m o l e c u l e s and t h e o r g a n i c r e s i n a c t s a s a c a r r i e r f o r t h e dye m o l e c u l e s a l l o w i n g them t o go i n t o s o l u t i o n . The p h y s i c a l s t r u c t u r e o f t h e pi g m e n t i s amorphous o r n o n - c r y s t a l l i n e . The compound i s a f i n e powder w h i c h d i s p e r s e s e a s i l y i n most m e d i a . D a y - G l o p i g m e n t s a r e n o t r e s i s t a n t t o s t r o n g s o l v e n t s b u t a r e s t a b l e t o i n d o o r and o u t d o o r l i g h t . D i r e c t s u n l i g h t may change t h e i r c o l o r c h a r a c t e r i s t i c s d e p e n d i n g on p i g m e n t ( c o n c e n t r a t i o n and c o l o r ) , v e h i c l e / b i n d e r ( d i s s o l v i n g s o l v e n t ) u s e d , and t h i c k n e s s o f a p p l i c a t i o n . The m a n u f a c t u r e r recommends o u t d o o r e x p o s u r e t e s t s t o t e s t l i g h t f a s t n e s s . F o r p r o p e r t i e s o f t h e dyes and t o x i c i t y v a l u e s see A p p e n d i x 44 Chapter 5 METHODS STUDY S I T E T h i s s t u d y i s l o c a t e d i n t h e N o r t h Okanagan a r e a o f I n t e r i o r B r i t i s h C o l u m b i a ( F i g u r e 2 ) . I t i s p a r t o f t h e V e r n o n F o r e s t D i s t r i c t w i t h i n t h e Kamloops F o r e s t R e g i o n . The o v e r a l l p r o j e c t a r e a i s bounded by T r i n i t y V a l l e y on t h e n o r t h , B e a v e r ( S w a l w e l l ) Lake on t h e s o u t h , W i n f i e l d and V e r n o n on t h e west and Lumby on t h e e a s t . S t u d y s i t e s a r e l o c a t e d i n m i d - e l e v a t i o n f o r e s t a r e a s h a r v e s t e d w i t h i n t h e p r e v i o u s f o u r y e a r s . G e n e r a l i n f o r m a t i o n on t h e s t u d y a r e a was o b t a i n e d f r o m f i e l d s u r v e y s c o n d u c t e d i n t h e summer o f 1984, government maps ( f o r e s t r e g i o n s , t o p o g r a p h i c and s u r f i c i a l g e o l o g y ) and p u b l i s h e d r e p o r t s . R e p o r t s c o m p i l e d by W i l l i n g t o n e t a l . ( 1 9 7 3 ) , Hawthorn and K a r a n k a (1982) and B r i t i s h C o l u m b i a M i n i s t r y o f E n v i r o n m e n t (1981) g i v e i n f o r m a t i o n on t h e h y d r o l o g y o f t h e r e g i o n . S p r o u t and K e l l e y (1960) c o m p l e t e d a s o i l s u r v e y o f t h e N o r t h Okanagan w h i c h b r i e f l y c o n s i d e r e d f o r e s t e d r e g i o n s w h i l e Clement ( 1 9 8 1 ) , i n d e t a i l i n g v e g e t a t i o n r e s o u r c e s of t h e V e r n o n Map S h e e t , d e t e r m i n e d t h e r e l a t i o n s h i p o f v e g e t a t i o n t o o t h e r e n v i r o n m e n t a l components i n c l u d i n g t o p o g r a p h y , s o i l s , and c l i m a t e . 45 Figure 2. Location of Study Area . 46 Climate The N o r t h Okanagan i s c h a r a c t e r i z e d by m o d e r a t e p r e c i p i t a t i o n , warm t o h o t summers and c o o l w i n t e r s . The s t u d y a r e a i s l o c a t e d i n a t r a n s i t i o n zone between t h e I n t e r i o r r a i n shadow ( e a s t of t h e C o a s t M o u n t a i n s ) and t h e w e t t e r west s l o p e s o f t h e Monashee M o u n t a i n s . An i n c r e a s i n g p r e c i p i t a t i o n g r a d i e n t e x i s t s s o u t h t o n o r t h and west t o e a s t . Most p r e c i p i t a t i o n i s s u p p l i e d by low p r e s s u r e s y s t e m s p a s s i n g f r o m west t o e a s t . D u r i n g t h e summer months t h e s e s y s t e m s a r e w i d e l y s p a c e d and any p r e c i p i t a t i o n o c c u r r i n g i s f r o m l o c a l i z e d c o n v e c t i o n a l c o o l i n g , g e n e r a l l y i n t e n s e t h u n d e r s t o r m s . S p r i n g and f a l l r a i n s t o r m s a l s o t r a c k f r o m west t o e a s t , w h i l e w i n t e r s t o r m s u s u a l l y e x t e n d s o u t h w a r d from t h e A r c t i c . P r e c i p i t a t i o n a l s o i n c r e a s e s w i t h e l e v a t i o n and t e m p e r a t u r e d e c r e a s e s ( F i g u r e 3 ) . W i l l i n g t o n e t a l . ( 1 9 7 3 ) s t a t e t h a t a t any l a t i t u d e t h r o u g h t h e Okanagan b a s i n p r e c i p i t a t i o n on t h e r i d g e t o p s (1000+m) may be as much as d o u b l e t h a t o c c u r r i n g a t t h e l a k e e l e v a t i o n . The h i g h e s t a c c u m u l a t i o n of p r e c i p i t a t i o n , r a i n and snow, o c c u r s i n t h e Monashee M o u n t a i n s . The p r o p o r t i o n of a n n u a l p r e c i p i t a t i o n i n t h e f o r m of snow i s 50 p e r c e n t a t t h e l a k e l e v e l ( v a l l e y b o t tom) and a l a r g e r p e r c e n t a g e a t h i g h e r e l e v a t i o n s ( W i l l i n g t o n e t a l . 1973). 47 6 5 6 2 i c o > 328M LU 1640 / / / / 100 3 0 0 r 2 0 0 0 5 0 0 M a y - S e p t e m b e r P r e c i p i t a t i o n (mm) 6 5 6 2 - \ 1640 v. V - 8 . 0 - 4 . 0 0 +4.0 M e a n D a i l y T e m p e r a t u r e (°C) —r-o2 0 0 0 09 0 1500 | •1000 ca > o LU 5 0 0 3a. Estimated i n c r e a s e i n seasonal p r e c i p i t a t i o n with e l e v a t i o n 3b. Estimated decrease i n annual temperature with e l e v a t i o n F i g u r e 3. P r e c i p i t a t i o n and temperature changes with e l e v a t i o n , (B.C.M.O.E. 1981). Throughout much of the area moisture a v a i l a b i l i t y i s a l i m i t i n g f a c t o r i n v e g e t a t i v e growth. The southern h a l f of the study s i t e i s l o c a t e d i n the Dry I n t e r i o r F o r e s t Region while the north i s i n the I n t e r i o r Wet B e l t ( F i g u r e 4 ) . In the Dry I n t e r i o r Region mean annual p r e c i p i t a t i o n ranges from 260 - 450 mm and mean annual s n o w f a l l i n the v a l l e y bottoms i s 70 - 200 cm. In the I n t e r i o r Wet B e l t p r e c i p i t a t i o n i n c r e a s e s to an average of 425 - 1100 mm and s n o w f a l l to 120 - +350 cm (Clement 1981). 51° 00' W rt cu •< CU H ro H" CL ro ro • o rt W H- ro O iQ a H-cn o 3 fu rt ro n ro H i i—• ro o rt ro PJ H-3 i-h O H ro CO rt h ro o 3 to 49 H i g h e r i n c o m i n g r a d i a t i o n r e s u l t s i n l o w e r snow a c c u m u l a t i o n s on s o u t h and w e s t - f a c i n g s l o p e s ( e s p e c i a l l y i n t h e Dry I n t e r i o r R e g i o n ) , h i g h e r p o t e n t i a l e v a p o t r a n s p i r a t i o n (PET) and m o i s t u r e d e f i c i t s (PPT - PET) may o c c u r . S i t e s p e c i f i c c l i m a t i c d a t a i s b a s e d on t h e i d e n t i f i e d v e g e t a t i o n b i o p h y s i c a l ^ 1 ^ z o n e s ( T a b l e I ) . P h y s i o g r a p h y The s t u d y a r e a l i e s w i t h i n t h e I n t e r i o r s y s t e m of t h e C a n a d i a n C o r d i l l e r a . I t s t r a d d l e s t h e Thompson P l a t e a u ( n o r t h ) and t h e Okanagan H i g h l a n d s ( s o u t h ) p h y s i o g r a p h i c r e g i o n s ( H o l l a n d , 1976). The Thompson p l a t e a u i s c h a r a c t e r i z e d by g e n t l e o r m o d e r a t e l y - s l o p i n g p l a t e a u s w h i l e d i f f e r e n t i a l w e a t h e r i n g i n t h e Okanagan H i g h l a n d s p r o d u c e s g e n t l e s t e p - l i k e s l o p e s . The a r e a i s u n d e r l a i n by g n e i s s i c b e d r o c k , g r a n i t i c p l u t o n i c ( a c i d i c ) b e d r o c k and b a s a l t i c ( b a s i c ) b e d r o c k . S u r f i c i a l g e o l o g y d e p o s i t s were mapped by F u l t o n ( 1 9 7 5 ) . Most f o r e s t e d a r e a s o c c u r on u n d i f f e r e n t i a t e d m o r a i n a l d e p o s i t s f r o m t h e P l e i s t o c e n e I c e Age a l t h o u g h y o u n g e r e r o s i o n a l f e a t u r e s a r e a l s o f o r e s t e d . The s t u d y a r e a encompasses a wide ra n g e o f e l e v a t i o n f r o m t h e C o l d s t r e a m v a l l e y (600 m) t o h i g h p e a k s (1650 m). The e l e v a t i o n of t h e s t u d y s i t e s i s 800 - 1000 m i n t h e n o r t h e r n h a l f o f t h e a r e a and 1200 - 1400 m i n t h e s o u t h . . I B i o p h y s i c a l c l a s s i f i c a t i o n i s d i f f e r e n t i a t i o n o f l a n d s c a p e u n i t s on t h e b a s i s o f g e o l o g y , t e r r a i n , c l i m a t e , s o i l and v e g e t a t i o n (Walmsley and van B a r n e v e l d 1977). 50 T A B L E I . V E G E T A T I O N AND ENVIRONMENT C H A R A C T E R I S T I C S OF T H E STUDY A R E A F o r e s t r e g i o n S e c t i o n Zone Subzone Summers W i n t e r s Snow a n n u a l (w.e.) u n t i l TRINITY VALLEY IWB SALMON ARM (IWH-WC) ID-wL warm,moist c o o l , w e t 130-220cm A p r i l g r o w i n g deg d a y s ( 1 > r e e 900-1700 c l i m a t i c m o i s t u r e ^ 2 ' - 100/+100 d e f i c i t / s u r p l u s f r e e z e y f r e e p e r i o d ^ ) 80-120days g r o w i n g s e a s o n 250-350mm p r e c i p i t a t i o n DEAFIES CREEK IWB SALMON ARM (IWC) ID-wL hot,warm,dry c o o l , m o i s t 130-180cm M a r c h - A p r i l 900-1300 -20.0/+1 00 80-140days 200-300mm BEETLE CREEK DI VERNON (ID) IP h o t , d r y c o o l , d r y 1 40cm March 700-1500 -200/+100 60-1OOdays 200-250mm BEAVER LAKE DI VERNON ( S A e S a l F ) ID-IP h o t , d r y c o l d , d r y 100-200cm A p r i l - M a y 700-1100 -200/+100 6 0 - l 0 0 d a y <250-300mm p o s s i b l e l i m i t s t o p r o d u c t i v i t y - c l i m a t i c m o i s t u r e d e f i c i t s i n g r o w i n g s e a s o n l e a c h e d s o i l s S o i l T y p e s - O r t h i c D y s t r i c B r u n i s o l s -s h o r t g r o w i n g s e a s o n - O r t h i c G r a y L u v i s o l s -S o i l T e x t u r e E l u v i a t e d D y s t r i c B r u n i s o l s loam B r u i n i s o l i c G r a y L u v i s o l s s i l t loam O r t h i c E u t r i c B r u n i s o l s O r t h i c D y s t r i c B r u n i s o l s sandy loam s i l t loam T T ) g r o w i n g d e g r e e d a y s - The a c c u m u l a t e d d i f f e r e n c e between t h e mean d a i l y t e m p e r a t u r e and s t a n d a r d b a s e t e m p e r a t u r e of 5 degC on d a y s when t h e mean d a i l y t e m p e r a t u r e i s above 5 degC. (2) c l i m a t i c m o i s t u r e d e f i c i t / s u r p l u s - The a l g e b r a i c d i f f e r e n c e between May t o September p r e c i p i t a t i o n and p o t e n t i a l e v a p o t r a n s p i r a t i o n . D e f i c i t s ( n e g a t i v e ) and s u r p l u s e s ( p o s i t i v e ) . (3) f r e e z e - f r e e p e r i o d - The g r e a t e s t number o f c o n s e c u t i v e d a y s i n a c a l e n d e r y e a r f r e e o f a t e m p e r a t u r e of 0 degC o r l e s s (B.C.M.O.E. 1978). 51 S o i l s The s o i l s o f t h i s a r e a o r i g i n a t e from g l a c i a l d e p o s i t s . The p a r e n t m a t e r i a l i s g e n e r a l l y n u t r i e n t p o o r , w i t h most of t h e n u t r i e n t c a p i t a l o f t h e s i t e c o n c e n t r a t e d i n t h e o r g a n i c m a t t e r o f t h e upper few c e n t i m e t r e s o f s o i l ( S m i t h 1984). The s o i l s i n f o r e s t e d a r e a s a r e g e n e r a l l y d r y d u r i n g t h e summer; however, t h e y have g r e a t e r m o i s t u r e c o n t e n t and l o w e r a v e r a g e t e m p e r a t u r e s t h a n s o i l s i n t h e s u r r o u n d i n g a g r i c u l t u r a l a r e a s . Many s o i l s a r e s l i g h t l y a c i d i c . S p r o u t and K e l l e y (1960) c l a s s i f i e d t h e major f o r e s t s o i l a s a P o d z o l . I n t h i s e a r l y s o i l s u r v e y P o d z o l i c Grey-Wooded s o i l s were mapped ( w i t h l i m i t e d f i e l d s a m p l i n g ) i n t h e f o r e s t a r e a s a d j a c e n t t o a g r i c u l t u r a l l a n d s . In a more e x t e n s i v e and r e c e n t s t u d y , C l e m e n t (1981) mapped B r u n i s o l s and L u v i s o l s i n t h e a r e a ( T a b l e 1 ) . The D r y I n t e r i o r i s c h a r a c t e r i z e d by E u t r i c B r u n i s o l s w h i c h a r e b a s i c and p o o r l y d e v e l o p e d , and G r a y L u v i s o l s w h i c h have l e a c h e d s u r f a c e s and a c c u m u l a t i o n s o f c l a y and m i n e r a l s i n t h e l o w e r h o r i z o n s . The I n t e r i o r Wet B e l t i s c h a r a c t e r i z e d by Gray L u v i s o l s and D y s t r i c B r u i n i s o l s a t l o w e r e l e v a t i o n s w h i c h c h a r a c t e r i s t i c a l l y e x h i b i t l e a c h e d s u r f a c e s and m i n i m a l a c c u m u l a t i o n o f c l a y s and m i n e r a l s . H u m o - F e r r i c P o d z o l s a r e f o u n d a t t h e h i g h e r e l e v a t i o n s (above 1380 m) and e x h i b i t l e a c h e d u p p e r l a y e r s and h i g h a c c u m u l a t i o n s o f i r o n and aluminum (C l e m e n t 1981). 52 V e g e t a t i o n on many s i t e s s e r v e s t o c o n t r o l s o i l e r o s i o n , e s p e c i a l l y on s t e e p e r s l o p e s and a r e a s of f i n e t e x t u r e d s o i l s . The r u n o f f f r o m snowmelt and i n t e n s e r a i n s t o r m s c a n c a u s e p r o b l e m s . I n some a r e a s c l i m a t i c m o i s t u r e d e f i c i t s and h i g h s o i l a nd a i r t e m p e r a t u r e s make r e g e n e r a t i o n d i f f i c u l t and t h u s make s u r f a c e s o i l s l e s s s t a b l e . V e g e t a t i o n The s t u d y a r e a encompasses a v a r i e t y of f o r e s t t y p e s ( T a b l e 1 ) . The major t r e e s p e c i e s a r e I n t e r i o r D o u g l a s - f i r (ID) ( P s e u d o t s u g a m e n z i e s i i v a r g l a u c a ) , Engelmann s p r u c e (eS) ( P i c e a e n g e l m a n i i ) , l o d g e p o l e p i n e ( I P ) ( P i n u s c o n t o r t a v a r l a t i f o l i a ) , w e s t e r n r e d c e d a r (wC) ( T h u j a p i i c a t a ) , w e s t e r n l a r c h (wL) ( L a r i x o c c i d e n t a l i s ) and a l p i n e f i r ( a l F ) ( A b i e s l a s i o c a r p a ) . The v e g e t a t i o n i s s i g n i f i c a n t l y d i f f e r e n t between t h e Dr y I n t e r i o r and t h e I n t e r i o r Wet B e l t as a r e s u l t o f t e m p e r a t u r e and p r e c i p i t a t i o n d i f f e r e n c e s . The Dry I n t e r i o r i s c h a r a c t e r i z e d by I n t e r i o r D o u g l a s - f i r i n t h e v a l l e y s i n a s s o c i a t i o n w i t h p o n d e r o s a p i n e ( P i n u s p o n d e r o s a ) a t low e l e v a t i o n , c h a n g i n g t o l o d g e p o l e p i n e a s e l e v a t i o n i n c r e a s e s . A b e l t d o m i n a t e d by w e s t e r n r e d c e d a r f o r m s a t r a n s i t i o n t o t h e I n t e r i o r Wet B e l t and m o i s t e r , c o o l e r c o n d i t i o n s . 53 C l e m e n t i d e n t i f i e s t h e m a j o r u n d e r s t o r y ( i n d i c a t o r ) s p e c i e s a s S o o p a l a l l i e ( S h e p h e r d i a c a n a d e n s i s ) , h e a r t - l e a v e d a r n i c a ( A r n i c a c o r d i f o l i a ) and p i n e g r a s s ( C a l a m a g r o s t i s spp.) i n t h e Dry I n t e r i o r p o r t i o n o f t h e s t u d y a r e a . I n t h e I n t e r i o r Wet B e l t p o r t i o n , c h a r a c t e r i s t i c s h r u b s and h e r b s a r e U t a h h o n e y s u c k l e ( L o n i c e r a u t a h e n s i s ) , Oregon boxwood ( P a x i s t i m a m y r s i n i t e s ) , C a l i f o r n i a f i l b e r t ( C o r y l u s c o r n u t a v a r . c a l i f o r n i c a ) , w e s t e r n t h i m b l e b e r r y (Rubus p a r v i f l o r u s ) , b l u e - b e a d c l i n t o n i a ( C l i n t o n i a u n i f l o r a ) , n o r t h e r n t w i n f l o w e r ( L i n n a e a b o r e a l i s ) and l a r g e - l e a v e d r a t t l e s n a k e o r c h i d ( G o o d y e r a o b l o n g i f o l i a ) . The m a j o r s i l v i c u l t u r a l s y s t e m of f o r e s t management emp l o y e d i n t h e a r e a i s c l e a r c u t t i n g and s i n g l e o r g r o u p t r e e s e l e c t i o n , e s p e c i a l l y i n D o u g l a s - f i r and p o n d e r o s a p i n e t y p e s . I n s e c t and p a t h o g e n a t t a c k s o f f o r e s t v e g e t a t i o n v a r y i n s c o p e and l o c a t i o n . R e c e n t m o u n t a i n p i n e b e e t l e o u t b r e a k s have l e d t o s a l v a g e c u t s s o u t h and e a s t o f t h e s t u d y a r e a . H y d r o l o g y The s t u d y a r e a c o m p r i s e s of a number o f b a s i n s . B e a v e r L a k e s i t e s i n t h e s o u t h d r a i n i n t o V e r n o n C r e e k , w h i c h f l o w s i n t o t h e Okanagan B a s i n , w h i l e B e e t l e C r e e k , D e a f i e s C r e e k and T r i n i t y V a l l e y s i t e s d r a i n n o r t h t o t h e Shuswap R i v e r . 54 The s t r e a m f l o w h y d r o g r a p h i s snow d o m i n a t e d and f o l l o w s t h e g e n e r a l p a t t e r n f o r i n t e r i o r C a n a d i a n r i v e r s w i t h s h a r p s p r i n g snowmelt p e a k s and low summer f l o w s i l l u s t r a t e d by t h e C o l d s t r e a m C r e e k h y d r o g r a p h , a b a s i n s i t u a t e d j u s t west of t h e s t u d y a r e a a t s l i g h t l y l o w e r e l e v a t i o n s t h a n t h e s t u d y s i t e s ( F i g u r e 5 ) . Snow a c c u m u l a t i o n (snow w a t e r e q u i v a l e n t ) i n c r e a s e s w i t h e l e v a t i o n and most snowmelt r u n o f f o r i g i n a t e s a t h i g h e r e l e v a t i o n s t h a n t h e s t u d y s i t e s ( F i g u r e 6 ) . F i s h and W i l d l i f e The s t u d y a r e a c o n t a i n s many s m a l l l a k e s , some m a i n t a i n i n g good r a i n b o w t r o u t p o p u l a t i o n s . The s t r e a m s d r a i n i n g t h e a r e a a r e i m p o r t a n t s a l m o n i d p r o d u c e r s (anadromous salmon and k o k a n e e ) . A v a r i e t y of h a b i t a t s e x i s t f o r w i l d l i f e i n t h i s a r e a . T h e r e a r e mule d e e r , moose, some sh e e p , and b l a c k b e a r p o p u l a t i o n s . 55 S t a t i o n 08NM179 (Near Nouth) !• r e g u l a t e d f low Jan. Feb. March Aprl May June July Aug. Sept. Oct. Nov. Dec. F i g u r e 5. C o l d s t r e a m C r e e k h y d r o g r a p h s (Hawthorn and K a r a n k a 1982). a 25 38 51 63 76 89 102 114 127 ( c e n t i m e t r e * ) S n o w W a t e r Equ iva lent F i g u r e 6. Snow w a t e r e q u i v a l e n t ( A p r i l ) v e r s u s e l e v a t i o n f o r s e v e n Okanagan snow c o u r s e s (B.C.M.O.E. 1981). 56 SELECTION OF METHODS F o w l e r and B e r n d t (1969) i d e n t i f i e d a "need f o r e a s y t o use methods of r e c o g n i z i n g o r i d e n t i f y i n g a c t i v e e r o s i o n , d e t e r m i n i n g i t s c a u s e and a p p r a i s i n g r e l a t i v e e r o s i o n r a t e s i n m o u n t a i n w a t e r s h e d s " ( p g . 1 ) . T h i s s t u d y i n c o r p o r a t e s two r e l a t i v e l y e a s y - t o - u s e methods t o e v a l u a t e e r o s i o n on h a r v e s t e d a r e a s : (1) e r o s i o n t r a n s e c t s , an e s t a b l i s h e d method p r e v i o u s l y u s e d i n B r i t i s h C o l u m b i a and (2) f l u o r e s c e n t dye, a r e l a t i v e l y new method u n t e s t e d i n C a n a d i a n c o n d i t i o n s . The f i r s t method, s a m p l i n g s o i l d i s t u r b a n c e w i t h l i n e t r a n s e c t s , was a p p l i e d i n t h e summer of 1984 t o 10 s i t e s w h i c h d i f f e r e d i n s l o p e , a s p e c t , s o i l s , l o c a t i o n and t y p e o f l o g g i n g , t o examine c a u s a l f a c t o r s f o r e r o s i o n o c c u r r e n c e . The s e c o n d , s p r a y i n g f l u o r e s c e n t dye t o l a b e l s o i l p a r t i c l e s , was a p p l i e d t o f o u r o f t h e 10 s i t e s t o examine r a t e , d i s t a n c e , and p a t t e r n s of d o w n s l o p e s o i l p a r t i c l e movement. EROSION TRANSECT STUDY E s t i m a t e s o f s o i l d i s t u r b a n c e on h a r v e s t e d s i t e s , t o g e t h e r w i t h t o p o g r a p h i c , s o i l , a nd c l i m a t i c i n f o r m a t i o n , a r e r e c o g n i z e d a s i n d i c a t o r s o f p o t e n t i a l e r o s i o n and s e d i m e n t a t i o n ( B o c k h e i m e_t a l . 1975). On a h a r v e s t e d a r e a , s o i l d i s t u r b a n c e v a r i e s i n l o c a t i o n and i n t e n s i t y a c r o s s t h e F i g u r e 7. L o c a t i o n o f t h e s t u d y s i t e s . ( T r i a n g l e s i n d i c a t e f l u o r e s c e n t dye p l o t s ) . 58 c u t b l o c k . I t i s not u n i f o r m l y o r ran d o m l y d i s t r i b u t e d , w h i c h p r e c l u d e s many s a m p l i n g t e c h n i q u e s . The l i n e t r a n s e c t method a l l o w s t h e a r e a l d i s t r i b u t i o n of v a r i o u s d i s t u r b a n c e c l a s s e s t o be d e t e r m i n e d . In B r i t i s h C o l u m b i a , B o c k h e i m e t a l . ( 1 9 7 5 ) , S m i t h and Waas (1976) and Schwab and Watt (1981) have u s e d t h i s method. S i t e S e l e c t i o n Ten s t u d y s i t e s were l o c a t e d on r e c e n t l y h a r v e s t e d a r e a s t h r o u g h t h e s t u d y a r e a ( F i g u r e 7 ) . The s i t e s i n c l u d e d two s e l e c t i v e l y l o g g e d a r e a s on t h e B e e t l e C r e e k Road and c l e a r c u t s i t e s n e a r D e a f i e s C r e e k , T r i n i t y V a l l e y Road and B e a v e r ( S w a l w e l l ) L a k e . The s i t e s v a r i e d i n a s p e c t , s o i l t y p e and d e g r e e of s l o p e . T r a n s e c t s were l o c a t e d i n two c l i m a t i c z o n e s and on b o t h s e l e c t i o n and c l e a r c u t h a r v e s t e d s i t e s ( F i g u r e s 8 and 9 ) . F i e l d M ethods E r o s i o n t r a n s e c t s were done by a t h r e e - p e r s o n crew. T r a n s e c t s were l a i d o u t i n a r e c t a n g u l a r g r i d p a t t e r n on t h e c u t b l o c k t o e s t i m a t e g e n e r a l s i t e p a r a m e t e r s . The s u r v e y p r o c e d u r e r e s e m b l e d t h a t f o l l o w e d by Schwab and Watt ( 1 9 8 1 ) , S m i t h and Wass (1976) and Boc k h e i m e t a l . ( 1 9 7 5 ) . The t r a n s e c t l i n e s were r u n a l o n g a b e a r i n g p e r p e n d i c u l a r t o t h e o v e r a l l s i t e c o n t o u r s . L i n e s r a n up and down s l o p e and sample i n t e n s i t y v a r i e d w i t h c u t b l o c k s i z e . Sample p o i n t s were e s t a b l i s h e d e v e r y 10 t o 25 m e t r e s d e p e n d i n g on t r a n s e c t 59 60 l e n g t h , t o o b t a i n a minimum o f 100 p o i n t s p e r c u t b l o c k . G r o u n d d i s t u r b a n c e was r a t e d s u b j e c t i v e l y f r o m no-d i s t u r b a n c e t o a v e r y - d e e p - g o u g e or v e r y - d e e p - d e p o s i t o f s o i l a t t h e p o i n t . A l t h o u g h s u b j e c t i v e , l i t t l e v a r i a t i o n i n crew members' r a t i n g s was f o u n d . D i s t u r b a n c e c a t e g o r i e s were b a s e d on d e p t h , t y p e , and e x t e n t of g r o u n d d i s t u r b a n c e ( T a b l e I I ) . T a b l e I I . SOIL DISTURBANCE CATEGORIES ( m o d i f i e d f r o m Schwab and Watt 1981) A t t h e p o i n t d i r e c t l y below meter mark on c h a i n r e c o r d : ND - no d i s t u r b a n c e NBS - n a t u r a l b a r e s o i l BS - m i x t u r e o f m i n e r a l s o i l and humus SG - s h a l l o w gouge ( m i n e r a l s o i l e x p o s e d t o 5 cm d e p t h ) DG - d eep gouge (5-25 cm d e p t h ) VDG - v e r y deep gouge ( o v e r 25 cm d e p t h ) SD - s h a l l o w d e p o s i t ( m i n e r a l s o i l d e p o s i t t o 5 cm d e p t h ) DD - d eep d e p o s i t (5-25 cm d e p t h ) VDD - v e r y deep d e p o s i t ( o v e r 25 cm d e p t h ) L - l i t t e r d i s t u r b e d and s l a s h p i l e s A l o n g t h e t r a n s e c t l i n e s k i d t r a i l s were r e c o r d e d on a s k e t c h map. L o c a l s l o p e p e r c e n t a g e s ( p o i n t t o p o i n t ) and g r o u n d v e g e t a t i o n were r e c o r d e d and a few random s o i l s a m p l e s (3-4 p e r s i t e ) were c o l l e c t e d . A t t h e edge o f t h e c u t b l o c k a p e r p e n d i c u l a r o f f s e t o f 25-50 m ( d i s t a n c e d e t e r m i n e d by c u t b l o c k s i z e ) was t r a v e r s e d and t h e l i n e r e v e r s e d d o w n s l o p e . T h i s c o n t i n u e d u n t i l t h e c u t b l o c k was 6 1 c o v e r e d . In t h e v e r y l a r g e s e l e c t i o n c u t b l o c k two r a n d o m l y s e l e c t e d a r e a s were sampl e d i n t h i s manner. A n a l y s i s A w r i t t e n r e p o r t was c o m p l e t e d f o r e a c h c u t b l o c k i n c l u d i n g g e n e r a l s i t e p a r a m e t e r s a s a s p e c t , s l o p e , map l o c a t i o n , c u t b l o c k s i z e , number and s i z e o f l a n d i n g s and s t r e a m s d r a i n i n g t h e a r e a . F i e l d t r a n s e c t i n f o r m a t i o n was c o m p i l e d t o g i v e p e r c e n t a g e and d e g r e e o f g r o u n d d i s t u r b a n c e . L i n e p r o f i l e s were drawn, a r o u g h map o f t h e c u t b l o c k i n c l u d i n g s t r e a m s , s k i d t r a i l s , h a u l r o a d s and l a n d i n g s was s k e t c h e d , and a l i s t o f g r o u n d v e g e t a t i o n i n c l u d e d . A s i t e e v a l u a t i o n was c o m p l e t e d f o r e a c h o f t h e s i t e s b a s e d on an a r e a r e c o n n a i s a n c e w h i c h n o t e d e r o s i o n o c c u r r e n c e , d e p o s i t i o n s i t e s , s t r e a m l o c a t i o n , p o s s i b l e s e d i m e n t a t i o n s o u r c e s , and b u f f e r s t r i p s . E r o s i o n o c c u r r e n c e i s a s u b j e c t i v e e v a l u a t i o n b a s e d on v i s u a l e v i d e n c e o f s o i l movement i n c l u d i n g r i l l s , g u l l i e s , d e p o s i t i o n a r e a s and b a r e s o i l . S i t e e v a l u a t i o n i n c l u d e d a c a r e - i n - l o g g i n g a s s e s s m e n t c o m p a r i n g h a r v e s t i n g o p e r a t i o n s and d i s t u r b a n c e l e v e l s among s i t e s . S u r f a c e s o i l s a m p l e s were h a n d - t e x t u r e d i n t h e l a b . The a n a l y s i s o f s i t e d a t a u t i l i z e d d i s t r i b u t i o n o f d i s t u r b a n c e c l a s s e s , t h e w r i t t e n s i t e e v a l u a t i o n , a s i t e d e s c r i p t i o n , l i n e p r o f i l e s , and a p h o t o g r a p h i c r e c o r d . A v e r a g e d a t a v a l u e s , v a r i a b i l i t y i n s i t e e v a l u a t i o n and s i t e s p e c i f i c f e a t u r e s were u s e d t o i d e n t i f y t r e n d s and draw p r e l i m i n a r y c o n c l u s i o n s . 62 FLUORESCENT DYE STUDY T h i s s t u d y method u s e d D a y - G l o f l u o r e s c e n t pigment t o l a b e l s o i l p a r t i c l e s and u l t r a v i o l e t l i g h t t o i d e n t i f y s o i l movement. T h i s p r o c e d u r e , t h e s p r a y i n g o f f l u o r e s c e n t d y e s o n t o s o i l p a r t i c l e s , i s q u i t e new and few examples e x i s t i n t h e l i t e r a t u r e . No l i t e r a t u r e d e s c r i b e s r e s e a r c h s t u d i e s u s i n g f l u o r e s c e n t d y e s under C a n a d i a n c l i m a t i c c o n d i t i o n s and o n l y one s t u d y ( f r o m t h e U n i t e d S t a t e s ) u s e s a s i m i l a r ' method. T h e r e f o r e many unknowns e x i s t , i n c l u d i n g : - W i l l t h e dye d e g r a d e i n s u n l i g h t ? - W i l l f l u o r e s c e n c e p e r s i s t a f t e r f r e e z i n g and snow c o v e r ? - What s o l v e n t s h o u l d be u s e d t o b i n d t h e dye t o t h e s o i l p a r t i c l e s ? How s h o u l d s u c h be a p p l i e d ? - W i l l a p p l i c a t i o n c h ange t h e c h a r a c t e r i s t i c s o f t h e s o i l p a r t i c l e s ( s i z e , d e n s i t y , s h a p e ) ? - What l e v e l of u l t r a v i o l e t i l l u m i n a t i o n i s n e c e s s a r y t o d e t e c t p a r t i c l e s ? I s a hand h e l d f i e l d lamp s u f f i c i e n t ? - Can movement p a t t e r n s be r e c o r d e d on f i l m ? I f so what c o l o r and s p e e d o f f i l m i s b e s t ? - What s i z e o f p a r t i c l e s w i l l h o l d t h e dye and r e m a i n v i s i b l e f o r measurement? 63 Selection of Fluorescent Dye In a s o i l movement s t u d y c o n d u c t e d i n C o l o r a d o , Zoghet (1969) u s e d D a y - G l o f l u o r e s c e n t p i g m e n t i n a s o l u t i o n o f a c e t o n e and S t r i f f l e r (1969) u s e d f l u o r e s c e i n i n s o l u t i o n w i t h x y l e n e ( p e r s o n a l c o m m u n i c a t i o n 1984). B o t h r e p o r t e d s a t i s f a c t o r y r e s u l t s a p p l y i n g dye t o s o i l ijn s i t u . F i e l d t e s t s w i t h D a y - G l o S a t u r n y e l l o w f l u o r e s c e n t p i g m e n t i n a c e t o n e and f l u o r e s c e i n i n x y l e n e were c o n d u c t e d on s o i l s a m p l e s from t h e D e a f i e s C r e e k #2 s i t e . Twenty grams o f f l u o r e s c e i n were m i x e d w i t h 200 ml of x y l e n e and a p p l i e d t o one s o i l s a m p l e . Twenty grams o f S a t u r n y e l l o w p i g m e n t were mixed w i t h 200 ml o f a c e t o n e and s p r a y e d on a s e c o n d s o i l s ample. B o t h s a m p l e s t e s t e d p o s i t i v e l y f o r f l u o r e s c e n c e under n i g h t - t i m e u l t r a v i o l e t i l l u m i n a t i o n . The t e s t boxes o f s o i l were s e t o u t s i d e f o r t h r e e weeks and were s u b j e c t t o h i g h t e m p e r a t u r e , l o n g h o u r s of s u n l i g h t , and p e r i o d i c heavy r a i n s . A t t h e end o f t h i s t i m e t h e D a y - G l o pigment y i e l d e d s a t i s f a c t o r y i l l u m i n a t i o n under u l t r a v i o l e t l i g h t b u t t h e f l u o r e s c e i n m i x t u r e was f o u n d t o have d e g r a d e d ( l i k e l y due t o s u n l i g h t ) . T h e r e f o r e , dye a p p l i c a t i o n o f D a y - G l o f l u o r e s c e n t pigment m i x e d w i t h a c e t o n e was c h o s e n . Site Selection In l a t e A u g u s t 1984, f o u r s t u d y s i t e s were s e l e c t e d f o r f l u o r e s c e n t dye a p p l i c a t i o n . The s i t e s v a r i e d i n a s p e c t and s l o p e b ut a l l were l o c a t e d w i t h i n w a l k i n g d i s t a n c e o f m a j o r 64 r o a d s t o a l l o w n i g h t - t i m e a c c e s s and a c c e s s s h o r t l y a f t e r snowmelt i n t h e s p r i n g o f 1985. The s t u d y s i t e s c h o s e n were T r i n i t y V a l l e y #1 and #2 and B e a v e r L a k e #1 and #4. The number of dye p l o t s e s t a b l i s h e d on e a c h s i t e v a r i e d . T r i n i t y V a l l e y #2 has 15 dye p l o t s , T r i n i t y V a l l e y #1 has 11, B e a v e r Lake #4 has 6 and B e a v e r L a k e #1 has 6. The numbers r e f l e c t somewhat l o o s e l y t h e v a r i a t i o n i n s i t e c o n d i t i o n s seen on t h e c u t b l o c k s . The l o c a t i o n of dye p l o t s was q u i t e a r b i t r a r y . P l o t s were e s t a b l i s h e d b o t h i n u p p e r s l o p e p o s i t i o n s and l o w e r s l o p e p o s i t i o n s , on h e a v i l y d i s t u r b e d and c o m p a c t e d s k i d t r a i l s and i n r e l a t i v e l y u n d i s t u r b e d a r e a s b e s i d e them, and on a v a r i e t y o f s l o p e s and a s p e c t s . L o c a t i o n s g e n e r a l l y f r e e of g r o u n d v e g e t a t i o n were c h o s e n t o e n s u r e p r o p e r a d h e r e n c e o f t h e dye t o s o i l p a r t i c l e s . A c l i n o m e t e r was u s e d t o measure immediate s l o p e above t h e p l o t . F i e l d Methods A p p l i c a t i o n o f Dye D u r i n g A u g u s t , 1984, v a r i o u s a p p l i c a t o r s were t e s t e d f o r an e v e n d i s t r i b u t i o n o f m e asured s o l u t i o n s o f p i g m e n t on t h e dye p l o t s . The v o l a t i l e n a t u r e o f a c e t o n e l i m i t e d t h e a v a i l a b l e s p r a y e r s , f o r s a f e t y r e a s o n s , t o t h o s e w h i c h d i d not have a b u i l d - u p of h i g h p r e s s u r e . The f i n a l 65 s e l e c t i o n was a h a n d - h e l d pump-type s p r a y e r , a l t h o u g h i t s d u r a b i l i t y was m a r g i n a l due t o t h e c o r r o s i v e p r o p e r t i e s o f a c e t o n e . Dye was a p p l i e d d i r e c t l y t o s o i l , p r e c l u d i n g f u r t h e r d i s t u r b a n c e o f s o i l and s i t e a l t e r a t i o n . L i n e s o f pigment were s p r a y e d p e r p e n d i c u l a r t o t h e s l o p e ( F i g u r e 1 0 ) . The dye s o l u t i o n c o n s i s t e d o f one gram D a y - G l o f l u o r e s c e n t p i g m e n t ( S a t u r n y e l l o w ) i n 10 ml a c e t o n e t o c o v e r 25 cm 2 s u r f a c e a r e a ( s i m i l a r t o Zoghet 1969). T e m p l a t e s o f wood l i n e d w i t h sponge were u s e d t o e n s u r e p r o p e r a p p l i c a t i o n r a t e s and a r e a b o u n d a r i e s . Dye s t r i p s were one metre l o n g and f i v e c e n t i m e t r e s w i d e , marked w i t h m e t a l p i n s and t i e d i n t o s i t e f e a t u r e s . Two p l o t s were e s t a b l i s h e d on l e v e l g r o u n d t o e v a l u a t e r a i n d r o p s p l a s h and pigment d e t e r i o r a t i o n o v e r t i m e . On s e l e c t e d a r e a s f l u o r e s c e n c e was t e s t e d a f t e r dye a p p l i c a t i o n and a p h o t o g r a p h i c r e c o r d o f t h e a p p l i c a t i o n p r o c e s s and f l u o r e s c e n c e was c o m p i l e d . F i e l d Measurement - S p r i n g 1985 In s p r i n g 1985, s h o r t l y a f t e r snowmelt, t h e f i e l d p l o t s were v i s i t e d a t n i g h t t o e v a l u a t e t h e f l u o r e s c e n c e o f t h e dye and q u a n t i f y s o i l movement. A hand h e l d MSL-48 b a t t e r y o p e r a t e d m i n e r a l i g h t was u s e d f o r u l t r a v i o l e t i l l u m i n a t i o n ( F i g u r e 1 1 ) . Downslope movement o f p a r t i c l e s was i d e n t i f i e d a n d m e a s u r e d . A c o m p a r i s o n e v a l u a t i o n o f movement was a l s o r e c o r d e d by r a t i n g s i t e s on a s c a l e o f 1 t o 10, b a s e d on a F i g u r e 10. F i e l d a p p l i c a t i o n o f f l u o r e s c e n t dye. F i g u r e 11. I l l u m i n a t i o n o f f l u o r e s c e n t dye s t r i p w i t h hand h e l d m i n e r a l lamp ( N a t u r a l l i g h t i s c a u s i n g much of t h i s i l l u m i n a t i o n ) . v i s u a l p e r c e p t i o n of movement. E a c h o f t h e dye s t r i p s was p h o t o g r a p h e d under u l t r a v i o l e t l i g h t u s i n g a t r i p o d and v a r i o u s f i l m c o l o r s and t y p e s . C o l o r and b l a c k and w h i t e p r i n t s and 100, 400 and 1600 ASA f i l m were compared t o d e t e r m i n e w h i c h was most e f f e c t i v e f o r use i n p h o t o g r a p h i c r e c o r d . N a i l s s p r a y e d w i t h f l u o r e s c e n t p a i n t were u s e d t o i n d i c a t e and l o c a t e p a r t i c l e s d o w n s l o p e and a l l o w measurement o f d i s t a n c e moved i n d a y l i g h t c o n d i t i o n s . A n a l y s i s Movement R a t i n g The s o i l movement o c c u r r i n g on dye p l o t s was r a n k e d f r o m most t o l e a s t , b a s e d on t h e number of i n d i v i d u a l s o i l p a r t i c l e s moved and t h e d i s t a n c e moved d o w n s l o p e ( s o i l -m o v e m e n t - r a t i n g ) . The s i t e v a r i a b l e s d i s t i n g u i s h i n g e a c h p l o t were e v a l u a t e d and t r e n d s r e l a t i n g d e g r e e o f movement t o p a r t i c u l a r s i t e v a r i a b l e s i d e n t i f i e d . P h o t o g r a p h i c R e c o r d The v a r i o u s f i l m s and p h o t o g r a p h i c methods u s e d were j u d g e d f o r e f f e c t i v e n e s s i n c a p t u r i n g t h e f l u o r e s c e n c e and i n d o c u m e n t i n g movement. 68 C h a p t e r 6 RESULTS AND DISCUSSION EROSION TRANSECT STUDY S i t e E v a l u a t i o n T r i n i t y V a l l e y #1 The c u t b l o c k s e l e c t e d i s p a r t of a p r o g r e s s i v e c l e a r c u t e x t e n d i n g a c r o s s t h e c o n t o u r and u p s l o p e . L o g g i n g was done i n t h e w i n t e r and t h i s b l o c k c o n t a i n e d windrowed s l a s h . No s l a s h b u r n i n g had y e t t a k e n p l a c e . O l d e r s u r r o u n d i n g c u t s had been b u r n e d and some a r e a s had been p l a n t e d . B e d r o c k was c l o s e t o t h e s u r f a c e t h r o u g h o u t t h e c u t b l o c k . B a r e r o c k was v i s i b l e i n some a r e a s and i n o t h e r s was c o v e r e d by t h i n s o i l a nd g r o u n d v e g e t a t i o n ( m a i n l y h e r b s and m o s s e s ) . The a v e r a g e s l o p e was 30-35% and 15% of t h e s i t e was r e v e g e t a t e d . T h e r e was l i t t l e i n d i c a t i o n of e r o s i o n on t h e s i t e a l t h o u g h t h e s p u r r o a d i n t o t h e s i t e was s e v e r e l y e r o d e d and s k i d r o a d s showed e v i d e n c e of r i l l i n g ( F i g u r e 16 pg. 9 2 ) . S o i l - d i s t u r b a n c e and b a r e - s o i l v a l u e s f o r TV #1 were 77% and 66% r e s p e c t i v e l y ( T a b l e I I I ) . TV #1 had t h e h i g h e s t v a l u e f o r s o i l d i s t u r b a n c e c l a s s e d as s h a l l o w - d e p o s i t s (48.4%) ( T a b l e I V ) . W i t h b e d r o c k c l o s e t o t h e s u r f a c e t h e r e i s l e s s m o i s t u r e s t o r a g e c a p a c i t y . T h e r e f o r e , s h a l l o w s o i l s 69 TABLE I I I . OVERALL S I T E CHARACTERISTICS FROM LINE TRANSECT DATA % S i z e %*** % S o i l C a r e * * B a r e i n S l o p e A s p e c t (ha) D i s t S o i l T e x t u r e L o g g i n g B e e t l e C r e e k 8 2 - L - 2 - e ( 3 2 ) 1 8 2 - L - 2 - e ( 2 0 ) 2 27 SW 186 26 22 f - s - l o a m 8.0 s e l e c t i v e 25 gen NW 45 29 24 g - s - l o a m 8.5 s e l e c t i v e & s e e d t r e e D e a f i e s C r e e k 8 2 - L - 7 - d ( 2 5 ) 1 20 8 2 - L - 6 - a ( 1 3 ) 2 25 T r i n i t y V a l l e y SW 17 69 68 s i - l o a m 4.0 c l e a r c u t SW 15 67 62 s i - l o a m 4.5 c l e a r c u t 82-L-7 -d ( 4 5 ) 1 35 W 1 5 77 66 loam 5. 0 c l e a r c u t 82-L-7 -d ( 2 3 ) 2 45 SE 10* 50 46 l o a m - s l 9. 0 c l e a r c u t B e a v e r Lake 82-L-3 - c ( 3 9 ) 1 10 S 1 6 44 44 s i - l o a m 6. 0 c l e a r c u t 82-L-3 - c ( 3 4 ) 2 10 NW 1 2 64 64 s i - l o a m 4. 0 c l e a r c u t 82-L-3 - c ( 3 1 ) 3 8 SW 1 5 37 28 s i - l o a m 7. 0 c l e a r c u t 82-L-3 - c ( 5 3 ) 4A 50 SW 7.5 60 43 s i - l o a m 7. 0 c l e a r c u t 82-L-3-- c ( 5 3 ) 4B 20 SW 7.5 53 28 s i - l o a m 7. 0 c l e a r c u t * a r e a t r a v e r s e d ( a p p r o x i m a t e l y 25% o f t o t a l c u t b l o c k a r e a ) ** s u b j e c t i v e e v a l u a t i o n by crew s u p e r v i s o r 82-L-2-e F o r e s t C o v e r Map L o c a t i o n (32) C u t b l o c k number *** % D i s t ( S o i l d i s t u r b a n c e ) and % B a r e S o i l f r o m T a b l e IV. 70 have g r e a t e r r i s k of becoming s a t u r a t e d d u r i n g r a i n f a l l o r snowmelt and y i e l d i n g o v e r l a n d f l o w . T h e r e i s an o l d e r c l e a r c u t l o c a t e d i m m e d i a t e l y u p s l o p e o f TV #1 w h i c h may i n p u t s e d i m e n t t o t h e s i t e . G r a y and Megahan ( 1 9 8 1 ) , i n a s t u d y on s i m i l a r t e x t u r e d s h a l l o w s o i l s i n t h e I d a h o b a t h o l i t h , f o u n d t h a t a f t e r b u r n i n g t h e r e was a s i g n i f i c a n t i n c r e a s e i n s u r f a c e e r o s i o n on p r e v i o u s l y s t a b l e s i t e s . The b u r n i n g u p s l o p e o f TV #1 m i g h t i n c r e a s e s e d i m e n t i n p u t f r o m t h e upper c l e a r c u t . The f a c t t h a t t h i s s i t e was w i n t e r l o g g e d was r e f l e c t e d i n l o w e r v a l u e s f o r d e e p - d e p o s i t s and s h a l l o w and deep-g o u g i n g ( 8 . 4 % & 9.5%) ( T a b l e I V ) . TV #1 had a h i g h amount of d i s t u r b a n c e ( l o w e s t n o - d i s t u r b a n c e v a l u e 2 3 . 2 % ) . T h i s i s somewhat u n e x p e c t e d i n view o f t h e r e l a t i v e l y c o a r s e -t e x t u r e d s o i l and w i n t e r l o g g i n g . The h i g h d i s t u r b a n c e v a l u e c a n l i k e l y be a t t r i b u t e d t o t h e low a s s e s s m e n t o f c a r e - i n -l o g g i n g ( 5 . 0 ) ( T a b l e I I I ) and t o t h e f a c t t h a t t h e s i t e f orms p a r t o f a p r o g r e s s i v e c l e a r c u t . R o t h w e l l (1978) s t a t e d t h a t p r o g r e s s i v e c l e a r c u t s m a x i m i z e t h e p o t e n t i a l f o r s o i l d i s t u r b a n c e , o v e r l a n d f l o w , and e r o s i o n . S l o p e g r a d i e n t becomes i n c r e a s i n g l y i m p o r t a n t a s v e g e t a t i v e c o v e r i s r e d u c e d (Meeuwig and P a c k e r 1976). TV #1 had l e s s c o v e r t h a n TV #2, t h e r e f o r e s o i l movement m i g h t be e x p e c t e d t o be g r e a t e r , as was shown. 71 TABLE IV. LINE TRANSECT DATA S o i l d i s t u r b a n c e c l a s s e s f o r s t u d y ( p e r c e n t a g e o f c u t b l o c k a r e a ) T r i n i t y D e a f i e s B e e t l e V a l l e y C r e e k C r e e k B e a v e r Lake D i s t u r b a n c e C l a s s 1 2 1 2 1 2 1 2 3 4A 4B No d i s - 23. 2 45. 1 30. 9 33. 3 72 .4 70.5 56.0 36.5 59.2 38. 1 47.2 t u r b a n c e N a t u r a l / 3.5 / / 1 .6 / / / 4.1 0.9 / b a r e s o i l B a r e s o i l / / / / 6 .3 / / / / / / S h a l l o w 6. 3 4.4 9. 5 7. 5 6 .3 / 3.0 18.8 3.1 11.5 5.6 gouge V e r y deep 3. 2 3.5 4. 8 6. 5 1 .6 1 .0 3.7 1.0 1 .0 0.9 / gouge S h a l l o w 48. 4 23.9 32. 1 32. 3 4 .7 19.6 27.6 29.2 10.2 23.9 18.1 d e p o s i t V e r y deep 8. 4 10.6 21 . 4 16. 0 1 .6 3.6 9.7 14.6 9.2 6.2 4.2 d e p o s i t L i t t e r & 10. 5 8.0 1 . 2 4. 3 5 .5 5.0 / / 13.3 17.7 25.0 s l a s h % B a r e S o i l % D i s -t u r b a n c e 66.3 45.9 67.8 62.3 22.1 24.2 44.0 63.6 27.6 43.2 27.9 76.8 50.4 69.0 66.6 26.0 29.2 44.0 63.6 36.8 60.2 52.9 72 T r i n i t y V a l l e y #2 T h i s c u t b l o c k was r e l a t i v e l y s t e e p (45% a v e r a g e s l o p e ) and c a r e i n l o g g i n g was r a t e d h i g h . P a t c h e s o f a d v a n c e d r e g e n e r a t i o n were l e f t u n d i s t u r b e d and s k i d r o a d s g e n e r a l l y r a n p a r a l l e l t o c o n t o u r s . S k i d d e r use was c o n f i n e d t o t h e s k i d r o a d s and t h e s t e e p e r s k i d r o a d s were " p u t - t o - b e d " w i t h w a t e r b a r s ( s o i l mounds) e s t a b l i s h e d a t i n t e r v a l s a l o n g t h e i r l e n g t h . No s t r e a m s c r o s s e d t h e b l o c k and l i t t l e e r o s i o n o r r i l l i n g o c c u r r e d on t h e b l o c k . T h i s was i n f l u e n c e d a t l e a s t i n p a r t by t h e m o d e r a t e l y c o a r s e s o i l s ( l o a m - s a n d y loam t e x t u r e ) . TV #2 had v a l u e s f o r d i s t u r b a n c e and b a r e s o i l o f 50% and 46%. I t was one of t h e s t e e p e s t s i t e s , y e t a l s o one of t h e most s t a b l e , r e f l e c t e d i n d i s t u r b a n c e v a l u e s ( h i g h no-d i s t u r b a n c e v a l u e 45.1%) and c a r e i n l o g g i n g (9) a s s e s s m e n t . In a g r o u n d b a s e d s k i d d i n g o p e r a t i o n on s t e e p s l o p e s , s a f e t y and o p e r a t i o n a l c o n s t r a i n t s l i m i t s k i d d e r movement t o e s t a b l i s h e d s k i d r o a d s . T h i s r e s u l t s i n a r e d u c t i o n i n d i s t u r b a n c e between t h e s k i d r o a d s and, on a c u t b l o c k b a s i s , l e s s a r e a w i l l be d i s t u r b e d . TV #2 had a h i g h e r p r o p o r t i o n o f d i s t u r b a n c e c l a s s e d a s d e p o s i t s t h a n as gouges. I t has a c o a r s e t e x t u r e d s o i l and was t h e r e f o r e more r e s i s t a n t t o g o u g i n g , e s p e c i a l l y when c o m p a c t e d on a s k i d t r a i l . 73 The w a t e r b a r s e s t a b l i s h e d on TV #2 d i v e r t e d r u n o f f o n t o t h e u n d i s t u r b e d c u t o v e r . T h i s p r e v e n t e d a c c u m u l a t i o n o f r u n o f f on s k i d r o a d s and l a n d i n g s ( R o t h w e l l 1978). D e a f i e s C r e e k #1 T h i s s m a l l c u t b l o c k was o r i e n t e d p e r p e n d i c u l a r t o t h e c o n t o u r s . T h e r e were few d e f i n e d s k i d t r a i l s and s k i d d e r t r a c k s d i s t u r b e d much of t h e a r e a w i t h v e r y d eep gouges and d e p o s i t s . Most damage o c c u r r e d on m o d e r a t e s l o p e s where s k i d d e r movement was u n c o n f i n e d . The r o a d s y s t e m was r i l l e d a l t h o u g h c u l v e r t s were e s t a b l i s h e d and f l o w t h r o u g h them was o c c u r r i n g . The o v e r a l l d r a i n a g e i n t h e r o a d s y s t e m was i n s u f f i c i e n t , m a i n l y due t o t h e r o a d s w i t c h b a c k s w h i c h i n t e r c e p t e d s u b s u r f a c e f l o w . O v e r a l l s i t e e v a l u a t i o n i n d i c a t e d a m o d e r a t e amount o f e r o s i o n on s i t e . Much o f t h e s e d i m e n t i n p u t t o D e a f i e s C r e e k would o r i g i n a t e on t h e r o a d s y s t e m . DC #1 had h i g h d i s t u r b a n c e and b a r e - s o i l v a l u e s , 69% and 68% r e s p e c t i v e l y . T h i r t y - t w o p e r c e n t of t h e s i t e was u n d e r s h a l l o w - d e p o s i t and 21% d e e p - d e p o s i t ( T a b l e I V ) . T h e s e v a l u e s a r e q u i t e h i g h . I t i s l i k e l y t h a t s o i l e r o d e d f r o m t h e r o a d s y s t e m and f r o m s k i d d e r d i s t u r b a n c e on t h e c u t b l o c k s u p p l i e d much of t h i s s e d i m e n t . The g e n t l e s l o p e s a t t h e base o f t h e c u t b l o c k s e r v e d a s a d e p o s i t i o n zone f o r s e d i m e n t f r o m u p s l o p e and a l l o w e d t h e b u i l d - u p of d eep d e p o s i t s . 74 The low v a l u e s f o r g o u g i n g on t h i s s i t e may r e f l e c t t h e p r e s e n c e o f s h e e t e r o s i o n r a t h e r t h a n i n d i c a t i n g t h a t no g o u g i n g t o o k p l a c e . I f o v e r l a n d f l o w was o c c u r r i n g , e s p e c i a l l y w i t h t h e e r o d i b i l i t y o f t h e s i l t loam s o i l o n s i t e , s h a l l o w gouges w o u l d be o b l i t e r a t e d . The low c a r e - i n - l o g g i n g v a l u e (4) ( T a b l e I I I ) , r e f l e c t e d t h e u n c o n f i n e d s k i d d e r movement and l a c k o f d r a i n a g e on t h e r o a d s y s t e m . E r o s i o n and damage t o w a t e r q u a l i t y i s g r e a t l y r e d u c e d by p r o v i d i n g e f f e c t i v e d r a i n a g e of s k i d t r a i l s and s k i d r o a d s t o e l i m i n a t e c o n c e n t r a t i o n o f o v e r l a n d f l o w (Meeuwig and P a c k e r 1976). D e a f i e s C r e e k #2 T h i s s m a l l c u t b l o c k was o r i e n t e d p e r p e n d i c u l a r t o t h e c o n t o u r s a n d was m o s t l y g e n t l y s l o p e d . A s m a l l c r e e k r a n t h r o u g h t h e c e n t e r o f t h e c u t b l o c k d r a i n i n g i n t o C o l d s t r e a m C r e e k . Much o f t h e l o w l a n d s (20-25%) was marshy, r e s u l t i n g i n d e ep r u t s f r o m s k i d d e r movement. The c r e e k was d i v e r t e d b e c a u s e o f c h a n n e l d i s t u r b a n c e . The r o a d s i n t h e a r e a e x h i b i t e d m o d e r a t e r i l l i n g . The m a j o r d i s t u r b a n c e was i n t h e marshy l o w l a n d s b ut e r o s i o n t h e r e was l i m i t e d b e c a u s e of low s l o p e s . Much o f t h e c u t b l o c k ( a s i d e f r o m r o a d s and l a n d i n g s ) was r e v e g e t a t e d w i t h h e r b s and f o r b s . DC #2 had 67% d i s t u r b a n c e and a low a s s e s s m e n t o f c a r e -i n - l o g g i n g ( 4 . 5 ) . T h e r e were s i g n i f i c a n t s h a l l o w and deep-75 d e p o s i t s (32% and 1 6 % ) . The h i g h d i s t u r b a n c e f r o m s k i d d e r movement i n t h e l o w l a n d s would s u p p l y s e d i m e n t . D e a f i e s C r e e k s i t e s had h i g h g o u g i n g i n c o m p a r i s o n w i t h many o f t h e o t h e r p l o t s . T h i s r e s u l t e d , i n p a r t , f r o m t h e f i n e r s i l t loam s o i l s on s i t e a nd t h e f a c t t h a t i t was summer l o g g e d (Schwab and Watt 1981). The h i g h amount of d i s t u r b a n c e i n t h e l o w l a n d s and i n t h e d i v e r s i o n o f t h e c r e e k c h a n n e l d i d n o t a p p e a r t o be a c t i v e l y e r o d i n g a s o v e r l a n d f l o w was l i m i t e d by low s l o p e a n g l e s . I t i s l i k e l y , however, t h a t s p r i n g r u n o f f w i l l move much o f t h i s s e d i m e n t and i n c o r p o r a t e i t i n t o t h e s e d i m e n t l o a d o f t h e s t r e a m . R o t h w e l l (1978) i d e n t i f i e d s k i d d i n g a l o n g or a c r o s s c r e e k b o ttoms o r draws as a c a u s e of e r o s i o n and d e t e r i o r a t i o n of water q u a l i t y . B e e t l e C r e e k #1 T h i s l a r g e c u t b l o c k was s e l e c t i v e l y l o g g e d . L i t t l e s i t e d i s t u r b a n c e o c c u r r e d and o n l y s l i g h t s o i l movement o c c u r r e d on s k i d t r a i l s . T h i s m i n o r damage was c o n f i n e d t o f a i r l y s t e e p s l o p e s ( g r e a t e r t h a n 30%) w i t h gouges (and r i l l s ) on s h o r t l e n g t h s o f t r a i l . Most s k i d t r a i l s were p u t t o bed b e f o r e t h e l a n d i n g a t t h e b a s e of t h e s l o p e . The s o i l s a r e f a i r l y c o a r s e ( f i n e s andy l o a m ) , p r o m o t i n g i n f i l t r a t i o n and r e s i s t i n g c o m p a c t i o n . T h i s c u t b l o c k had low d i s t u r b a n c e (72% n o - d i s t u r b a n c e ) , as e x p e c t e d on a s e l e c t i v e l y l o g g e d s i t e . The o n l y 76 s i g n i f i c a n t d i s t u r b a n c e v a l u e was 6% s h a l l o w - g o u g i n g o n s i t e w h i c h l i k e l y r e f l e c t e d t h e r i l l s d e v e l o p i n g on some s k i d r o a d s . B.C. #1 was t h e o n l y s i t e r e c o r d i n g a b a r e - s o i l c l a s s (6.3%) w h i c h r e f l e c t e d a m i x t u r e o f m i n e r a l s o i l and humus. T h i s m i g h t r e p r e s e n t , a t a l o w e r i n t e n s i t y , t h e p r o c e s s w h i c h forms t h e s h a l l o w - d e p o s i t s on o t h e r s i t e s . W i t h l i t t l e movement o n s i t e , t h i s b a r e s o i l c a n r e m a i n s t a b l e , w h i l e on more a c t i v e s i t e s i t would e v o l v e t o form s h a l l o w d e p o s i t s o r s h a l l o w g o u g e s . The e x i s t e n c e of b a r e s o i l m i g h t a l s o r e s u l t f r o m t h e d i f f i c u l t y i n r e v e g e t a t i n g s o u t h w e s t s l o p e s i n t h e Dry I n t e r i o r R e g i o n ( C l e m e n t 1981). The more n o r t h e r l y a s p e c t of #2 might a l l o w s i m i l a r a r e a s t o e s t a b l i s h v e g e t a t i v e c o v e r . B e e t l e C r e e k #2 T h i s l a r g e c r o s s c o n t o u r c u t b l o c k was h a r v e s t e d u s i n g s h e l t e r w o o d and s e e d t r e e methods. A few o l d s k i d t r a i l s r a n up n a t u r a l g u l l i e s and c o n c e n t r a t e d s u r f a c e d r a i n a g e . A l t h o u g h some s k i d t r a i l s were e s t a b l i s h e d s t r a i g h t u p s l o p e w i t h no d i v e r s i o n o f o v e r l a n d f l o w , l i t t l e e r o s i o n was o c c u r r i n g . The s o i l s were r e l a t i v e l y c o a r s e t e x t u r e d ( g r a v e l l y sandy l o a m ) . The i d e n t i f i e d e r o s i o n was a s s o c i a t e d w i t h t h e r o a d and i t s d r a i n a g e ( c u l v e r t s ) . T h e r e was v e r y l i t t l e g o u g i n g on t h i s s i t e (1%) w h i c h 77 r e f l e c t e d c a r e - i n - l o g g i n g ( 8 . 5 ) , s e l e c t i o n l o g g i n g methods, and c o a r s e t e x t u r e d s o i l s , w h i c h a l l m i n i m i z e d i s t u r b a n c e l e v e l s . B e a v e r L a k e #1 T h i s was a s m a l l s t r i p c l e a r c u t , p a r t o f an o l d e r , v e r y l a r g e p r o g r e s s i v e c l e a r c u t . H i g h water t a b l e and c l a y s o i l s i n a p o r t i o n o f t h e c u t b l o c k c a u s e d some p r o b l e m s w i t h r u t t i n g , d r a i n a g e and blowdown. The d r a i n a g e c h a n n e l s were somewhat o b s c u r e and were c r o s s e d s e v e r a l t i m e s by s k i d d e r s . Much o f t h e a r e a had r e v e g e t a t e d w i t h moss and g r a s s . C a t t l e movement had c o m p a c t e d and p o t t e d p o r t i o n s of t h e c u t b l o c k . The low d i s t u r b a n c e v a l u e may r e f l e c t , i n p a r t , r e v e g e t a t i o n w h i c h o c c u r r e d on t h e w e t t e r s e c t i o n s . H i l l s (1971) i n d i c a t e d p o c k e t s formed by h o o f p r i n t s may i n c r e a s e s u r f a c e s t o r a g e on s i t e w h i c h w o u l d l i m i t o v e r l a n d f l o w and r e d u c e d i s t u r b a n c e . B e a v e r Lake #2 T h i s c u t b l o c k was c u t , i n p a r t , w i t h a f e l l e r b u n c h e r and some hand f a l l i n g . The m e c h a n i z e d h a r v e s t i n g c a u s e d s e v e r e s o i l d i s t u r b a n c e o v e r much of t h e b l o c k . Most o f t h e e r o s i o n o c c u r r e d on l e s s s t e e p s l o p e s a c c e s s e d by t h e f e l l e r b u n c h e r . Though t h e s o i l was h i g h l y d i s t u r b e d , l i t t l e e v i d e n c e o f e r o s i o n was o b s e r v e d . BL #2 has t h e h i g h e s t s h a l l o w - g o u g e i n c i d e n c e ( 1 9 % ) . T h i s l i k e l y r e s u l t e d f r o m m e c h a n i z e d h a r v e s t i n g on a s i l t 78 loam s o i l . The w e i g h t o f m a c h i n e r y , u n c o n f i n e d s k i d d e r movement on t h e s h a l l o w s l o p e s and t h e movement o f l o g s c o u l d c a u s e t h i s . N o r t h w e s t s l o p e s i n t h e D r y I n t e r i o r c l i m a t i c zone have more r e v e g e t a t i o n due t o i n c r e a s e d m o i s t u r e a v a i l a b i l i t y . The h i g h e r l e v e l s o f d i s t u r b a n c e on t h i s s l o p e may be s t a b i l i z e d w i t h v e g e t a t i o n and t h e low s l o p e a n g l e w i l l l i m i t e r o s i o n by o v e r l a n d f l o w . B e a v e r L a k e #3 T h i s r e l a t i v e l y f l a t c u t b l o c k had l i m i t e d d i s t u r b a n c e . L a c k of d r a i n a g e c u l v e r t s on t h e h a u l r o a d s y s t e m a c c e s s i n g t h i s s i t e c a u s e d s e v e r e r i l l i n g a nd p a r t i a l r o a d c o l l a p s e . The a r e a below t h e r o a d s y s t e m was more d i s t u r b e d w i t h l e s s r e v e g e t a t i o n but e r o s i o n was s t i l l low. S i x t y p e r c e n t o f t h i s c u t b l o c k had n o - d i s t u r b a n c e . The d i s t u r b a n c e w h i c h d i d o c c u r was on t h e c u t b l o c k s u r f a c e below t h e a c t i v e l y e r o d i n g r o a d s y s t e m . The h i g h e r d i s t u r b a n c e and l o w e r r e v e g e t a t i o n below t h e r o a d l i k e l y r e s u l t e d f r o m i n c r e a s e d o v e r l a n d f l o w and s e d i m e n t i n p u t from u p s l o p e . B e a v e r L a k e #4A T h i s s m a l l c l e a r c u t was c u t i n w i n t e r and r i s e s s t e e p l y from t h e l a n d i n g . S i g n i f i c a n t a c c u m u l a t i o n s of s l a s h were l e f t o n s i t e and s k i d d e r s were c o n f i n e d t o e s t a b l i s h e d t r a i l s . S i d e c u t s o f s k i d t r a i l s and t h e e n t i r e s k i d t r a i l 79 and r o a d s y s t e m e x h i b i t e d e r o s i o n b u t t h e r e s t of t h e c u t was s t a b l e . E ven w i t h s i g n i f i c a n t e r o s i o n o c c u r r i n g , 38% had no-d i s t u r b a n c e . T h i s i s a r e s u l t o f s k i d d e r movement b e i n g c o n f i n e d t o t r a i l s . The h i g h v a l u e f o r s h a l l o w - d e p o s i t s (23.9%) l i k e l y r e s u l t e d f r o m e r o s i o n on s k i d r o a d s . The h i g h amounts of s l a s h l e f t f r o m w i n t e r l o g g i n g w o u l d t r a p s e d i m e n t and i n c r e a s e t h e d e p o s i t i o n . The amount of s h a l l o w - g o u g i n g was f a i r l y h i g h (11.5%) and l i k e l y r e f l e c t e d t h e r i l l s f o r m i n g on s k i d t r a i l s . The v a l u e f o r d e e p - g o u g i n g was low, as e x p e c t e d i n w i n t e r l o g g i n g . B e a v e r L a k e #4B T h i s c u t b l o c k was u p s l o p e f r o m #4A and was a g e n t l y s l o p i n g p l a t e a u . Much o f t h e a r e a had p o o r d r a i n a g e (swamp). S i g n i f i c a n t g r o u n d c o v e r v e g e t a t i o n was l e f t and w i n t e r l o g g i n g m i n i m i z e d d i s t u r b a n c e l e a v i n g a f a i r l y s t a b l e s i t e . BL #4B had t w i c e as much s o i l d i s t u r b a n c e as b a r e - s o i l c l a s s e s ( 5 3 % vs 2 8 % ) . T h i s i s i n d i c a t i v e o f w i n t e r l o g g i n g and t h e p r o t e c t i o n o f t h e snow c o v e r d u r i n g o p e r a t i o n s . I t a l s o had l i t t l e g o u g i n g . Deep d i s t u r b a n c e i n - t h e f o r m o f g o u g i n g i s g r e a t e s t i n summer l o g g i n g and d e p o s i t s f o r m a g r e a t e r p r o p o r t i o n of t o t a l d i s t u r b a n c e i n w i n t e r (Schwab and Watt 1981). 80 C o m p a r i s o n Among S i t e s O b s e r v a t i o n and s i t e e v a l u a t i o n i n d i c a t e s t h a t t h e major d i s t u r b a n c e f a c t o r w i t h i n a c u t b l o c k was random s k i d d i n g . However, s o i l d i s t u r b a n c e v a l u e s d i d n o t n e c e s s a r i l y c o r r e l a t e w i t h e r o s i o n o c c u r r e n c e . I t was shown t h a t d i s t u r b a n c e on g e n t l e s l o p e s c a u s e d l i t t l e e r o s i o n (BL #2). T h i s i s l i k e l y due t o l a c k o f o v e r l a n d f l o w a s a t r a n s p o r t a g e n t , t h e r e f o r e t h e s e c o n d s t e p o f t h e e r o s i o n c y c l e was l i m i t i n g . H i g h s l o p e a n g l e s , e s p e c i a l l y i n f i n e - t e x t u r e d s o i l s , showed s i g n i f i c a n t e r o s i o n (BL #4A). On c o a r s e r t e x t u r e d s o i l s , where s k i d r o a d s were p u t - t o - b e d , e r o s i o n r a t e s on c l e a r c u t s were low (TV #2). The d e n s i t y o f s k i d t r a i l s was g e n e r a l l y c o r r e l a t e d w i t h i n c r e a s e d e r o s i o n , e s p e c i a l l y i f r o a d s were l o c a t e d a c r o s s t h e c o n t o u r s and a l l o w e d t o c h a n n e l f l o w . L o g g i n g i n h i g h m o i s t u r e a r e a s c a n c a u s e s e v e r e d i s t u r b a n c e . The h i g h d i s t u r b a n c e v a l u e s o f DC #2 and BL #2 i l l u s t r a t e t h i s . D i s t u r b a n c e i n c r e e k beds w i l l l i k e l y d i r e c t l y i n c r e a s e s e d i m e n t l e v e l s , e s p e c i a l l y i n s t o r m and snowmelt r u n o f f . The l o w e r d i s t u r b a n c e v a l u e s f o r BL #4B, a h i g h m o i s t u r e s i t e , i l l u s t r a t e s a management o p t i o n , w i n t e r l o g g e d , t h a t r e d u c e s s i t e i m p a c t . Many o f t h e c u t b l o c k s l i m i t s e d i m e n t movement from t h e c u t b l o c k by l e a v i n g b u f f e r s t r i p s of f o r e s t v e g e t a t i o n a l o n g s t r e a m c h a n n e l s . T h i s a p p e a r e d t o be s u c c e s s f u l and 81 d e p o s i t i o n o f s e d i m e n t on g r o u n d v e g e t a t i o n a t t h e edge of t h e s t r i p ( p e r s o n a l o b s e r v a t i o n i n DC #1) showed i t s r o l e i n s l o w i n g o v e r l a n d f l o w and c a p t u r i n g s e d i m e n t . Much of t h e e r o s i o n comes d i r e c t l y f r o m t h e r o a d s y s t e m a s e v i d e n c e d by d eep r i l l i n g and r o a d b e d f a i l u r e (BL #3 and DC #1). S k i d t r a i l s on c u t b l o c k s were a l s o e r o s i o n s i t e s ( s e e d i s c u s s i o n o f f l u o r e s c e n t dye e r o s i o n p l o t s ) . The s e l e c t i v e l y l o g g e d s i t e s showed l i t t l e , i f any, e r o s i o n . T h i s c a n be a t t r i b u t e d t o p r e s e r v a t i o n o f v e g e t a t i o n c o v e r , c o a r s e t e x t u r e d s o i l s w h i c h r e s i s t c o m p a c t i o n and promote i n f i l t r a t i o n , and m i n i m a l s i t e d i s t u r b a n c e . I t i s e x p e c t e d ( a s p e r R o t h a c h e r 1965) t h a t m a i n t a i n i n g v e g e t a t i o n w i l l r e d u c e e r o s i o n . The B e e t l e C r e e k s i t e s i l l u s t r a t e d t h i s . E v a l u a t i o n of BL #4 a l s o s u p p o r t s t h i s s t a t e m e n t . A l t h o u g h e r o s i o n r a t e s were h i g h , t h e e r o s i o n was t a k i n g p l a c e on t h e s k i d t r a i l s n o t t h e a c t u a l c u t o v e r . P r e s e r v a t i o n of g r o u n d v e g e t a t i o n ( i n w i n t e r l o g g i n g ) and l e a v i n g s l a s h on t h e s i t e i s b e l i e v e d t o have s t a b i l i z e d t h i s a r e a . The r e l a t i o n s h i p between s l o p e and t h e v a r i o u s d i s t u r b a n c e c l a s s e s f o r c l e a r c u t s i t e s v a r i e s ( F i g u r e 1 2 ) . The s h a l l o w - d e p o s i t c l a s s was shown t o i n c r e a s e i n p e r c e n t a g e w i t h i n c r e a s i n g s l o p e ( F i g u r e 13) a l t h o u g h n e i t h e r were s t a t i s t i c a l l y s i g n i f i c a n t . I d e n t i f i c a t i o n o f t h o s e s i t e s w h i c h l i e below t h e r e g r e s s i o n l i n e ( F i g u r e 13), i n d i c a t e d t h a t s i t e s w i t h l o w e r c a r e - i n - l o g g i n g have h i g h e r s h a l l o w - d e p o s i t s on an e q u a l s l o p e . 82 CL O _ J 00 60 n 50 4 0 3 0 -2 0 -1 0 -0 0 I 10 20 — I — 30 ~ i — 4 0 I — 50 60 D I S T U R B A N C E C L A S S % a r e a Legend X SG • DG H SD E DD F i g u r e 12. D i s t r i b u t i o n ( c u t b l o c k a r e a ) o f d i s t u r b a n c e c l a s s e s ( s h a l l o w + deep gouge, s h a l l o w + deep d e p o s i t ) w i t n i n c r e a s i n g s l o p e on c l e a r c u t s i t e s . 6 0 -D_ o _ l GO 5 0 -4 0 H 3 0 -2 0 -1 0 -0-0 13 BL 4A H T V 2 EJBL ^4 C3DC 2 B D C 1 3 BL 1 B BBL 2 I 10 20 30 40 50 S H A L L O W D E P O S I T D I S T U R B A N C E C L A S S % a r e a i 4 0 I 60 F i g u r e 13. D i s t r i b u t i o n o f s h a l l o w d e p o s i t d i s t u r b a n c e c l a s s w i t h i n c r e a s i n g s l o p e . 83 S t e e p e r s l o p e s r e q u i r e i n c r e a s e d c a r e i n l o g g i n g ( F i g u r e 1 4 ) . T h i s t r e n d , a l t h o u g h n o t s t a t i s t i c a l l y s i g n i f i c a n t , was a l s o r e p o r t e d by Schwab and Watt (1981) who a t t r i b u t e d i t t o t h e p h y s i c a l and s a f e t y c o n s t r a i n t s w h i c h l i m i t s k i d d e r movement i n o p e r a t i o n on s t e e p s l o p e s . Below 35% s l o p e t h e r e l a t i o n s h i p between c a r e - i n - l o g g i n g and s l o p e v a r i e d . When e v a l u a t e d as a g r o u p , s e l e c t i v e s i t e s , w i n t e r -l o g g e d s i t e s and t h o s e s i t e s s t e e p e r t h a n 35% showed h i g h c a r e - i n - l o g g i n g . A t a g i v e n s l o p e , t h o s e s i t e s w i t h c o a r s e r s o i l s have l e s s d i s t u r b a n c e and l o w e r b a r e - s o i l p e r c e n t a g e t h a n t h o s e w i t h f i n e s o i l s ( F i g u r e 1 5 ) . B e a v e r L a k e 4A p r e s e n t s an anomaly t o t h e above t r e n d . I t had s t e e p s l o p e s b u t l o w e r s o i l d i s t u r b a n c e and b a r e s o i l p e r c e n t a g e t h a n t h e o t h e r f i n e s o i l p l o t s . T h i s i s l i k e l y e x p l a i n e d by t h e f a c t t h a t B e a v e r L a k e 4 was w i n t e r l o g g e d . I t may a l s o be i n f l u e n c e d by t h e o r g a n i c m a t t e r c o n t e n t of t h e s o i l . T a b l e V shows a v e r a g e v a l u e s o f p r o p o r t i o n d i s t r i b u t i o n among d i s t u r b a n c e c l a s s e s f o r t h i s s t u d y and compares t h i s w i t h o t h e r s t u d i e s r e p o r t e d i n t h e l i t e r a t u r e . S u ch a c o m p a r i s o n must be e v a l u a t e d w i t h c a r e , as s i t e v a r i a b i l i t y and d i f f e r e n c e s i n d e f i n i t i o n o f d i s t u r b a n c e c l a s s w i l l a f f e c t v a l u e s . The mean n o - d i s t u r b a n c e v a l u e o f 46.2% ( r a n g e o f 23 t o 59) was l o w e r t h a n v a l u e s o f Schwab and Watt (1981) (55.9%) but o f s i m i l a r m a g n i t u d e . Schwabb a n d Watt (1981) e s t a b l i s h e d l i n e t r a n s e c t s on h a r v e s t e d s i t e s i n t h e C a r i b o o F o r e s t R e g i o n o f B r i t i s h C o l u m b i a . T h e i r s t u d y most 84 o _l to 60-j 50-40-30 20-10-0 T 0 13 -T 5 - r 6 —T" 8 C A R E IN L O G G I N G i 10 Legend A T V X D C • B C El B L F i g u r e 14. A s s e s s m e n t o f c a r e - i n - l o g g i n g v a r i a t i o n w i t h i n c r e a s i n g s l o p e . o_ O _i to 60-. 50-40-30-20 10 H X A BL 4A X A TV 2 X A B C 1 X A BC 2 X 4B A TV 1 X A rjc 2 >A DC 1 H BL 1 K B L 2 X A B L 3 - i 1 1 1 1 1 1 i r— 0 10 . 20 30 40 50 60 70 80 B A R E SOIL A N D D I S T U R B A N C E (% a r e a ) Legend A D C X B S F i g u r e 15. D i s t r i b u t i o n o f b a r e s o i l and s o i l d i s t u r b a n c e v a l u e s w i t h i n c r e a s i n g s l o p e . 85 c l o s e l y r e p l i c a t e d t h e p r e s e n t s t u d y . The v a l u e s o f Bockheim e t a l . (1975) were c o n s i d e r a b l y l o w e r ( 1 2 . 5 % ) . T o t a l a r e a o f d i s t u r b a n c e was 65% i n t h i s s t u d y and 62.6% i n t h e s t u d y by Schwabb and Watt. The v a l u e of B ockheim e t a _ l . was 87.5%. S h a l l o w - d i s t u r b a n c e was g r e a t e r i n t h i s s t u d y and d e e p - d i s t u r b a n c e l e s s t h a n t h o s e r e p o r t e d i n t h e l i t e r a t u r e . The c l o s e agreement w i t h t o t a l d i s t u r b a n c e v a l u e s o f Schwab and Watt and t h e l a c k o f s o i l d i s t u r b a n c e c l a s s e d a s d e ep-d e p o s i t i n t h e p r e s e n t s t u d y , s u g g e s t e d some v a r i a t i o n i n e s t i m a t i n g d e p t h of d i s t u r b a n c e , p a r t i c u l a r l y i n s h a l l o w -d e p o s i t s . B ockheim e t a l . p r e s e n t e d a v e r a g e v a l u e s from s t u d i e s i n t h e U n i t e d S t a t e s u t i l i z i n g a s i m i l a r method. The r a n g e o f v a l u e s was l a r g e but o v e r a l l a v e r a g e s were l o w e r t h a n t h o s e of t h e B r i t i s h C o l u m b i a n s t u d i e s ( T a b l e V ) . 86 TABLE V. C o m p a r i s o n o f s o i l d i s t u r b a n c e c l a s s d i s t r i b u t i o n f o u n d i n p r e s e n t s t u d y and from o t h e r r e g i o n s as r e p o r t e d i n t h e l i t e r a t u r e D i s t u r b a n c e C l a s s No % d i s t u r b a n c e P r e s e n t S t u d y 46.2 ++ Schwabb & W a t t * 55.9 Bockheim Avg. v a l u e s + e t a l . * * i n l i t e r a t u r e 72.5 / S h a l l o w gouge % S h a l l o w d e p o s i t % Deep Gouge % Deep D e p o s i t % 39.4 15.6 16.3 27.8 1 1 58.5 12.2 24.5 T o t a l s o i l D i s t u r b a n c e 65 62.6 87.5 50 ++ D a t a a r e a v e r a g e d and a r e p r e s e n t e d as a p e r c e n t o f l a n d a r e a . * Schwab and Watt (1981) C a r i b o o F o r e s t R e g i o n , B. C. ** B o c k h e i m e t a l . d 9 7 5 ) V a n c o u v e r F o r e s t D i s t r i c t , B.C. + a v e r a g e s f r o m d a t a i n l i t e r a t u r e and p r e s e n t e d i n B o c k h e i m e t a l . (1975) G a r r i s o n and Rummell (1951) E a s t e r n Oregon & W a s h i n g t o n W o o l r i d g e (1960) N o r t h C e n t r a l W a s h i n g t o n D y r n e s s (1965) S o u t h C e n t r a l Oregon 87 FLUORESCENT DYE EROSION STUDY Movement R a t i n g s - S i t e T r i n i t y V a l l e y #1 TV #1 had a m e d i u m - t e x t u r e d s o i l (loam) and m o d e r a t e (15-35%) s l o p e s . N o r t h a s p e c t s had h i g h e r s o i l - m o v e m e n t r a t i n g s ( a v e r a g e r a t i n g 2.9) ( T a b l e V I ) t h a n s o u t h a s p e c t s ( a v g . 2 . 2 ) , a l t h o u g h s l o p e was t h e same. T h i s a g r e e d w i t h H a r t (1984) who f o u n d t h a t h i g h e r a n t e c e d e n t m o i s t u r e l e v e l s on n o r t h f a c i n g s l o p e s had a s t r o n g e f f e c t on s u r f a c e e r o s i o n r a t e s . To e v a l u a t e s l o p e p o s i t i o n , p l o t s were l o c a t e d i n a s e r i e s d o w n s l o p e on t h e same c u t b l o c k . The t h r e e s e t s o f p l o t s a l l showed i n c r e a s i n g s o i l - m o v e m e n t - r a t i n g s f r o m t h e u p p e r p l o t i n t h e s e r i e s t o t h e p l o t f u r t h e s t d o w n s l o p e . T h i s may i n d i c a t e l o w e r s l o p e p o s i t i o n s c o n t r i b u t e more s e d i m e n t t o t h e e r o s i o n p r o c e s s o r t h a t s e d i m e n t d e p o s i t e d on t h e l o w e r s l o p e i s more e a s i l y moved. Such r e s u l t s a r e e x p e c t e d b e c a u s e a s o v e r l a n d f l o w i s c h a n n e l l e d and f l o w s d o w n s l o p e , i t s d e p t h and a b i l i t y t o d e t a c h and t r a n s p o r t p a r t i c l e s i n c r e a s e s . T r i n i t y V a l l e y #2 TV #2 had a c o a r s e t e x t u r e d ( l o am-sandy loam) s o i l and s l o p e s o f 10-32% above t h e p l o t s . Movement r a t i n g s were q u i t e u n i f o r m o v e r t h e b l o c k . A v e r a g e s l o p e was h i g h e r on s o u t h a s p e c t s t h a n on n o r t h (28% v s . 23%) but s o i l - m o v e m e n t 88 TABLE V I . FLUORESCENT DYE PLOT CHARACTERISTICS AND SOIL-MOVEMENT-RATINGS DYE PLOT DATA TRINITY VALLEY #1 A s p e c t S l o p e SMR L o c a t i o n % 1 N27W - 33 3 s k i d t r a i l 2 N63W u 21 2 s k i d t r a i l 3 N31W u 21 2 s k i d t r a i l 4 S70W - 31 3 s k i d t r a i 1 5 S37W u 23 2 s k i d t r a i 1 6 S70W u 28 2 s k i d t r a i l 7 N06W - 15 2 s k i d t r a i 1 8 N45W d 35 3 s k i d t r a i 1 9 N45W d 35 4 s k i d t r a i l 10 N35W d 25 4 s k i d t r a i l 1 1 S66W - 1 5 2 s k i d t r a i l a v g . 25.6 2.6 BEAVER LAKE #1 A s p e c t S l o p e SMR L o c a t i o n % 1 S20W - 30 2 c u t s l o p e 2 S30W - 30 1 s k i d t r a i l 3 S40W u 20 1 s k i d t r a i l 4 S80E - 15 2 s k i d t r a i l 5 S80E u 5 1 s k i d t r a i l 6 S — 25 1 c u t s l o p e a v g . 21 . 1 1 .3 TRINITY VALLEY #2 A s p e c t S l o p e SMR L o c a t i o n 1 S10W - -& 50 2 s o i l mound 2 S34E - 32 2 s k i d t r a i l 3 S35E d 32 2 s k i d t r a i l 4 N44W - 10 1 s k i d t r a i l 5 N44W d 20 3 s k i d t r a i l 6 S20W - 25 2.5 s k i d t r a i l 7 S20W d 25 3 s k i d t r a i l 8 S50E - 25 3 s k i d t r a i l 9 S80E u 33 2.5 s k i d t r a i l 10 N10W - 25 3 c u t s l o p e 1 1 N10W d 25 3 c u t s l o p e 1 2 N08E - 30 2 c u t s l o p e 13 N08E d 30 2 c u t s l o p e 1 4 L e v e l 2 r i d g e t o p 1 5 S24E - 25 2 s k i d t r a i l a v g . 27 .6 2.3 BEAVER LAKE #4A A s p e c t S l o p e SMR L o c a t i o n % 1 N60W - 35 5 s k i d t r a i l 2 W d 30 5 s k i d t r a i l 3 N68W d 20 6 s k i d t r a i l 4 N35W - 30 4.5 s k i d t r a i l 5 W u 40 2 c u t s l o p e 6 N35W d 35 6 s k i d t r a i l a v g . 32 .0 4.7 no r e l a t i o n t o p r e v i o u s p l o t l o c a t i o n u l o c a t e d u p s l o p e f r o m p r e c e d i n g p l o t d l o c a t e d d o wnslope from p r e c e d i n g p l o t SMR S o i l - m o v e m e n t - r a t i n g 89 r a t i n g s were t h e same (2.4 v s . 2.3) ( T a b l e V I ) . The r a t e of movement on t h e c u t s l o p e was t h e same as t h a t on t h e s k i d r o a d s . I t would be e x p e c t e d t h a t l o w e r c u t s l o p e c o m p a c t i o n w o u l d l i m i t o v e r l a n d f l o w and hence s o i l movement. I n t h i s s t u d y t h e c o a r s e s o i l s r e q u i r e d s i g n i f i c a n t o v e r l a n d f l o w o r r a i n f a l l i n t e n s i t y t o move s o i l p a r t i c l e s . The e s t a b l i s h m e n t of w a t e r b a r s p r e v e n t e d c h a n n e l l i n g of o v e r l a n d f l o w a n d t h e c o a r s e s o i l s p r o m o t e d i n f i l t r a t i o n so i t i s u n l i k e l y o v e r l a n d f l o w o c c u r r e d w i t h s u f f i c i e n t e r o s i o n p o t e n t i a l t o move much s o i l . P l o t 14, w i t h a s o i l movement r a t i n g o f 2.0 on a l e v e l s u r f a c e , i n d i c a t e d r a i n s p l a s h e r o s i o n p l a y e d a do m i n a n t r o l e i n t h e e r o s i o n p r o c e s s on s i t e . T h i s was e x p e c t e d , a s summer r a i n s a r e u s u a l l y h i g h i n t e n s i t y t h u n d e r s t o r m s t h a t c a n c a u s e s e v e r e e r o s i o n p r o b l e m s ( C l e m e n t 1981, H e l v e y and F o w l e r 1979). B e a v e r L a k e #1 BL #1 was a f i n e t e x t u r e d ( s i l t l o a m ) , l e s s s t e e p ( 5-30% s l o p e s ) , s o u t h f a c i n g c u t b l o c k . L i t t l e movement was o b s e r v e d and t h e main d i s t u r b a n c e f a c t o r was r a i n s p l a s h and some t r a m p l i n g by c a t t l e . The s o i l movement r a t i n g f o r p l o t 1 on t h e c u t s l o p e was h i g h e r t h a n t h e a d j a c e n t p l o t on t h e s k i d r o a d . T h i s may r e s u l t f r o m a n i m a l b r o w s i n g o r a l o o s e r s o i l s u r f a c e on t h e uncompacted c u t s l o p e , a l l o w i n g e a s i e r movement by r a i n d r o p s . 90 B e a v e r L a k e #4A BL #4A was a f i n e t e x t u r e d ( s i l t l o a m ) , r e l a t i v e l y s t e e p ( 20-40% s l o p e ) c u t b l o c k and dye p l o t s were g e n e r a l l y on n o r t h e r n a s p e c t s . T h i s s i t e had t h e h i g h e s t s o i l movement r a t i n g s i n t h e s t u d y . P l o t s 1 and 2 were s e v e r e l y d i s t u r b e d b o t h by o v e r l a n d f l o w and v e h i c l e t r a c k s ( F i g u r e 1 7 ) . S o i l movement r a t i n g s on a l l s k i d r o a d p l o t s were h i g h but t h e c u t o v e r v a l u e was low. T h i s dye p l o t on t h e c u t o v e r s u r f a c e had t h e s t e e p e s t s l o p e (40%) on t h e s i t e w i t h h i g h e s t s o i l movement r a t i n g s , y e t i t s s o i l movement r a t i n g was o n l y 2 ( c o m p a r a b l e t o a l e v e l p l o t i n TV #2). Young and M u t c h l e r (1969) On a S o u t h D a k o t a s i t e w i t h a s i l t loam s o i l f o u n d t h a t s o i l l o s s f r o m a s l o p e d e pended on s t e e p n e s s o f a s h o r t segment i m m e d i a t e l y above p o i n t of measurement. The c u t o v e r p l o t i n d i c a t e s t h a t on h a r v e s t e d s i t e s t h e d i s t u r b a n c e f a c t o r was more i m p o r t a n t t h a n s l o p e a l o n e . B o c k h e i m e t a l . (1975) c o n c l u d e d t h a t e x p o s e d m i n e r a l s o i l i s l i k e l y t h e b e s t i n d e x o f h a r v e s t i n g d i s t u r b a n c e and h ence e r o s i o n s u s c e p t i b i l i t y and f o r e s t r e g e n e r a t i o n p o t e n t i a l . R e s u l t s f r o m t h i s s t u d y i n d i c a t e d d e g r e e o f s l o p e may be more i m p o r t a n t i n c o m p a r i n g s o i l movement o f p l o t s l o c a t e d on s k i d r o a d s but d i s t u r b a n c e v a l u e s were more s i g n i f i c a n t when c o m p a r i n g c u t o v e r s u r f a c e t o s k i d r o a d s . 91 C o m p a r i s o n o f Movement R a t i n g s Among S i t e s B e a v e r L a k e #4 had t h e h i g h e s t a v e r a g e s o i l - m o v e m e n t -r a t i n g (4.7) and B e a v e r Lake #1 had t h e l o w e s t ( 1 . 3 ) . T r i n i t y V a l l e y #1 (2.6) had more movement t h a n #2 (2.3) ( T a b l e V I ) . In g e n e r a l , n o r t h f a c i n g s l o p e s a p p e a r t o have more movement (3.3) t h a n s o u t h f a c i n g s l o p e s (2.0) and a r e a s on c u t o v e r s (2.1) had l e s s movement t h a n p l o t s on a d j a c e n t s k i d r o a d s ( 2 . 9 ) . S i x t y - s e v e n p e r c e n t (8/12) o f p l o t s on s l o p e s 30% or more had s o i l - m o v e m e n t - r a t i n g s o f 3 o r g r e a t e r . T h o s e f o u r p l o t s w i t h r a t i n g s l e s s t h a n 3 were on t h e more s t a b l e c u t b l o c k s and had SW o r SE a s p e c t s . F o u r t e e n p l o t s had a r a t i n g g r e a t e r t h a n or e q u a l t o 3 and a l l o f t h e s e p l o t s were l o c a t e d on s k i d t r a i l s . O n l y t h r e e o f t h e s e p l o t s were on SW o r SE a s p e c t s . The s o i l - m o v e m e n t - r a t i n g s f o r p l o t s l o c a t e d on t h e c u t s l o p e b e s i d e s k i d t r a i l s were a l l 3 o r l e s s t h o u g h s l o p e s r a n g e d from 25-40%. F o u r t e e n s e t s of dye p l o t s were e s t a b l i s h e d . T h e s e were g r o u p s o f two o r t h r e e p l o t s i n w h i c h one p l o t was l o c a t e d d o w n s l o p e of a n o t h e r . None o f t h e s o i l movement r a t i n g s f o r t h e s e s e t s d e c r e a s e d f r o m t h e u p s l o p e p l o t d o w n s l o p e t o t h e n e x t p l o t ( s ) . T h o s e s e t s of p l o t s w i t h no change i n s o i l movement r a t i n g d o w n s l o p e were l o c a t e d on TV #2 and BL #1 t h e more s t a b l e s i t e s . The r e l a t i o n s h i p of i n c r e a s i n g s o i l movement r a t i n g s w i t h i n c r e a s i n g s l o p e ( F i g u r e 18) was b a s e d on o b s e r v a t i o n s o f t h e f l u o r e s c e n t dye l i n e . The l o w e r s l o p e o f t h e F i g u r e 16. R i l l i n g on S k i d road i n T r i n i t y V a l l e y #1 . F i g u r e 17. V e h i c l e d i s t u r b a n c e on s k i d road, Beaver Lake #4A. N a i l (beside stone) l o c a t e s dye p l o t . 93 r e g r e s s i o n l i n e f o r s k i d t r a i l p l o t s i n d i c a t e d t h a t movement on s k i d t r a i l s i n c r e a s e d a t a g r e a t e r r a t e w i t h i n c r e a s i n g s l o p e . T h i s was e x p e c t e d b e c a u s e c o m p a c t i o n o f t h e s k i d t r a i l s c a n i n c r e a s e o v e r l a n d f l o w w h i c h i s v e r y d e p e n d e n t on s l o p e l e n g t h ( r e g r e s s i o n i s s i g n i f i c a n t a t t h e 85% l e v e l ) . F o w l e r and B e r n d t ( 1 9 6 9 ) , i n a s i m i l a r s t u d y i n n o r t h e a s t O r e g o n , f o u n d s u r f a c e w a t e r r e l e a s e d by snowmelt was t h e m a j o r c a u s e o f s o i l movement. Dye p l o t s i n t h e p r e s e n t s t u d y were e s t a b l i s h e d a t t h e end of t h e summer so most o f t h e movement was a t t r i b u t a b l e t o snowmelt r u n o f f . A l t h o u g h measurements from t h e f a l l of 1985 w o u l d be n e c e s s a r y t o d e t e r m i n e t h e movement as a r e s u l t o f summer s t o r m s t h e r e s u l t s i n d i c a t e d s i g n i f i c a n t movement w i t h snowmelt. The snowpack was l i k e l y g r e a t e r on t h e B e a v e r L a k e s i t e s ( h i g h e r e l e v a t i o n s ) . The s i t e s were s t i l l snow c o v e r e d i n A p r i l when measurement o f dye p l o t s was c o m p l e t e d on T r i n i t y V a l l e y s i t e s . T h i s i n c r e a s e d d e p t h and d u r a t i o n o f snowpack may i n f l u e n c e t h e h i g h e r o s i o n r a t i n g s on BL #4A. Be t h l a h m y (1967) f o u n d i n Idah o t h a t r u n o f f and e r o s i o n were g r e a t e r on s o u t h w e s t t h a n on n o r t h e a s t e x p o s u r e s , t h e o p p o s i t e o f t h e r e s u l t s o f t h i s s t u d y . T h i s i s e a s i l y e x p l a i n e d when s i t e c h a r a c t e r i s t i c s a r e i d e n t i f i e d . In h i s s t u d y , s o u t h w e s t f a c i n g p l o t s a v e r a g e d 41.9% b a r e g r o u n d w h i l e n o r t h e a s t p l o t s a v e r a g e d o n l y 2.7%. He a l s o h y p o t h e s i z e d t h a t i f n o r t h e a s t and s o u t h w e s t e x p o s u r e s were e q u a l l y b a r e , o v e r l a n d f l o w w o u l d be e q u a l . 4 0 -3 0 -TV 2 2 0 - ""SL 1 1 0 - Legend A A L L X S K I D 1 2 3 4 5 SOIL M O V E M E N T RATING F i g u r e 18. Changes i n s o i l - m o v e m e n t r a t i n g s w i t h i n c r e a s i n g s l o p e . S t a t i s t i c s : ' A l l ' r e g r e s s i o n i s s i g n i f i c a n t a t 90% c o n f i d e n c e l e v e l r 2 .88 ' S k i d * r e g r e s s i o n i s s i g n i f i c a n t a t 85% c o n f i d e n c e l e v e l r 2 .76 95 In t h e p r e s e n t s t u d y , s k i d t r a i l s were e q u a l l y b a r e i n d e p e n d e n t o f a s p e c t . I n c r e a s e d s o i l movement on n o r t h f a c i n g s l o p e s was n o t u n e x p e c t e d . I f i n f i l t r a t i o n r a t e s a r e s i m i l a r , and i t i s l i k e l y s k i d r o a d s a r e f a i r l y u n i f o r m l y c o m p a c t e d , a n t e c e d e n t m o i s t u r e l e v e l s w i l l be g r e a t e r on n o r t h e r n e x p o s u r e s b e c a u s e o f r e d u c e d s o l a r r a d i a t i o n i n p u t . W i t h l e s s s t o r a g e , o v e r l a n d f l o w w i l l o c c u r s o o n e r on n o r t h f a c i n g s l o p e s c a u s i n g g r e a t e r amounts of movement. Some g e n e r a l t r e n d s e v i d e n c e d by t h i s s t u d y ( r e c o g n i z i n g t h e s m a l l sample s i z e and h i g h v a r i a b i l i t y o f s i t e s ) a r e : - s t e e p e r s l o p e s l e a d t o h i g h e r r a t e s of s o i l movement - s k i d r o a d s have more e r o s i o n t h a n c u t s l o p e s - n o r t h w e s t and n o r t h e a s t a s p e c t s have more s o i l movement t h a n s o u t h e r n a s p e c t s - s i l t loams g e n e r a l l y have i n c r e a s e d movements when compared w i t h sandy loams, e s p e c i a l l y a t h i g h e r s l o p e a n g l e s . - r a i n s p l a s h a p p e a r s t o be a s i g n i f i c a n t e r o s i o n a g e n t ( e v i d e n c e d by r a t i n g on TV #2 p l o t 1 4 ) . 96 FLUORESCENCE STUDY P h o t o g r a p h i c R e c o r d o f B e a v e r Lake #4A P h o t o g r a p h s p r o v i d e a v i s u a l r e c o r d o f t h e f l u o r e s c e n t dye p l o t s . F i g u r e 19 r e c o r d s t h e i l l u m i n a t i o n of t h e dye s t r i p by u l t r a v i o l e t l i g h t . T h i s p l o t was l o c a t e d on a s k i d r o a d d i s t u r b e d by v e h i c l e t r a c k s and shown i n F i g u r e 17. The l e f t p o r t i o n o f t h e dye s t r i p was d i s t u r b e d by t i r e t r a c k s and some d y e d p a r t i c l e s were removed from t h e s i t e . F i g u r e 20 i l l u s t r a t e s d a y t i m e v i s i b i l i t y of t h e Day G l o p i g m e n t . The n o r m a l c o l o r had d e g r a d e d o v e r t h e w i n t e r b u t was s t i l l e a s i l y v i s i b l e , e s p e c i a l l y when c o n c e n t r a t e d i n t h e dye s t r i p . The f l u o r e s c e n t c o l o r a p p e a r e d unchanged o v e r t h e s t u d y p e r i o d . F i g u r e s 21 and 22 show d a y l i g h t and u l t r a v i o l e t p h o t o g r a p h s o f t h e same p l o t . O v e r l a n d f l o w i s o c c u r r i n g on t h e dye s t r i p ( f r o m m e l t i n g snow) but p a r t i c l e s r e m a i n v i s i b l e t h r o u g h t h e t h i n s h e e t o f w a t e r . M a r k i n g d o w n s l o p e movement w i t h n a i l s c o a t e d w i t h f l u o r e s c e n t s p r a y p a i n t i s u s e f u l t o l o c a t e p a r t i c l e s f o r p h o t o g r a p h y . I t i s a l s o u s e f u l when t h e s e d i m e n t l o a d o f t h e water r e d u c e s l i g h t p e n e t r a t i o n and f l u o r e s c i n g p a r t i c l e s w o u l d n o t be e a s i l y s e en on a p h o t o . 97 F i g u r e 19 P l o t 2 F l u o r e s c e n t i l l u s t r a t i n g i l l u m i n a t i o n o f Beaver Lake #4A downslope movement o f p a r t i c l e s . F i g u r e 20. Beaver Lake #4 P l o t 4 i l l u s t r a t i n g a c t i v e e r o s i o n (on l e f t o f p h o t o ) . 9 8 F i g u r e 21. BL #4A P i 3 Sediment d e p o s i t i o n from o v e r l a n d f l o w . N a i l s on r i g h t s i d e i n d i c a t e p a r t i c l e movement ( F i g . 22). F i g u r e 22. U l t r a v i o l e t i l l u m i n a t i o n o f BL #4A P 3 Much o f p l o t i s under water, L i g h t c o l o r o f t h e water r e f l e c t s sediment l o a d . 99 T h e s e p h o t o s i l l u s t r a t e t h e i l l u m i n a t i o n and t h e movement of s o i l p a r t i c l e s on t h e dye p l o t s . A l t h o u g h p h o t o g r a p h y i s not r e q u i r e d t o o b t a i n s o i l movement r a t i n g s p h o t o s can be u s e f u l r e c o r d s o f s i t e p r o c e s s e s and a l l o w l a t e r c o m p a r i s o n among p l o t s . 1 00 A d d r e s s i n g t h e P r o j e c t Unknowns In o u t l i n i n g t h e f l u o r e s c e n t dye method a l i s t o f p r o j e c t unknowns was l i s t e d (Page 6 2 ) . The f a c t o r s a r e d i s c u s s e d h e r e b a s e d on r e s u l t s o f t h e f l u o r e s c e n t dye p l o t s and on o b s e r v a t i o n s made d u r i n g t h e s t u d y p e r i o d . The p e r s i s t e n c e of D a y - G l o p i g m e n t was f u l l y s a t i s f a c t o r y n i n e months a f t e r a p p l i c a t i o n . I t was s t a b l e i n s u n l i g h t and a l s o t h r o u g h w i n t e r f r e e z i n g and u nder t h e snowpack. The c h o i c e o f a c e t o n e a s t h e v e h i c l e f o r s o l u t i o n p r o v i d e d e x c e l l e n t a d h e r e n c e . The a p p l i c a t i o n was a t h i n l a y e r w h i c h had l i t t l e i m p a c t on s i z e or d e n s i t y of s o i l p a r t i c l e s ( s i t e o b s e r v a t i o n s and Zoghet 1969). A hand h e l d u l t r a v i o l e t lamp p r o v i d e d ample s t r e n g t h of u l t r a v i o l e t i l l u m i n a t i o n , a l t h o u g h t h e use o f more t h a n one lamp would i l l u m i n a t e more a r e a , g i v i n g a b e t t e r p h o t o g r a p h i c r e c o r d . B l a c k and w h i t e p h o t o g r a p h y e f f e c t i v e l y showed g r o u n d s u r f a c e r o u g h n e s s and s o i l p a r t i c l e s but was i n s u f f i c i e n t i n d a y l i g h t or n i g h t e v a l u a t i o n o f f l u o r e s c e n c e . C o l o r p h o t o g r a p h y was f o u n d t o be most s u i t a b l e . The h i g h s p e e d (1600 ASA) f i l m was u n n e c e s s a r y and r e s u l t e d i n o v e r e x p o s u r e or a c o a r s e - g r a i n e d p h o t o . The r e s o l u t i o n and c l a r i t y of 400 ASA was f o u n d t o be s u i t a b l e . P h o t o s were t a k e n on a t r i p o d a t a h e i g h t o f 0.5 m e t r e s w i t h a 30-60 s e c o n d e x p o s u r e t i m e . P a r t i c l e s v i s i b l e by eye were g e n e r a l l y e a s i l y c a p t u r e d on f i l m , p r o v i d e d t h a t t h e p o s i t i o n o f t h e u l t r a v i o l e t lamp f o r p h o t o g r a p h y i l l u m i n a t e d t h a t p o r t i o n . 1 0 1 The u l t r a v i o l e t lamp i l l u m i n a t e d f l u o r e s c e n t p a r t i c l e s under f l o w i n g w a t e r and even t h r o u g h a t h i n snow c o v e r . The w i d t h o f t h e dye s t r i p was c o n s t a n t on a l l s i t e s and p r o v i d e d a t e r m of r e f e r e n c e f o r c o m p a r i s o n between p h o t o s but t h e i n c l u s i o n of a f l u o r e s c e n t r u l e r on t h e edge of t h e p h o t o would a i d e v a l u a t i o n . The m a j o r l i m i t a t i o n t o d i r e c t a p p l i c a t i o n o f f l u o r e s c e n t p i g m e n t t o t h e s o i l was t h e l a r g e amount o f v e r y s m a l l s o i l p a r t i c l e s and o r g a n i c m a t t e r w h i c h a c c e p t e d t h e dye and was f u l l y i l l u m i n a t e d by t h e u l t r a v i o l e t lamp. The l a r g e numbers of p a r t i c l e s p r e c l u d e d a q u a n t i t a t i v e e s t i m a t e o f t h e number of p a r t i c l e s moved. I t i s l i k e l y n e c e s s a r y t o e x c a v a t e a s o i l sample and s i e v e t o v a r i o u s s i z e s o f p a r t i c l e s . The s m a l l o r g a n i c s c o u l d t h e n be e x c l u d e d f r o m dye a p p l i c a t i o n and o t h e r p a r t i c l e s i z e s c o u l d be c o l o r s t r a t i f i e d t o a l l o w s i z e - v e l o c i t y r e l a t i o n s h i p s ( p a r t i c l e s i z e - o v e r l a n d f l o w v e l o c i t y ) t o be documented. T h i s e x c a v a t i o n would d i s t u r b t h e s o i l s u r f a c e b u t dye a p p l i c a t i o n c o u l d t h e n c o a t t h e e n t i r e p a r t i c l e p r e v e n t i n g " l o s s " of p a r t i c l e s b e c a u s e t h e f l u o r e s c e n t t a g i s t u r n e d t o t h e u n d e r s i d e o f t h e p a r t i c l e . 102 Chapter 7 SUMMARY AND CONCLUSIONS SUMMARY Erosion Transects S i t e c h a r a c t e r i s t i c s i n f l u e n c i n g s u r f a c e s o i l movement on h a r v e s t e d a r e a s i n t h e N o r t h Okanagan were i d e n t i f i e d by l i n e t r a n s e c t d a t a . S l o p e was an i m p o r t a n t c h a r a c t e r i s t i c . On g e n t l e s l o p e s h i g h d i s t u r b a n c e l e v e l s c a u s e d l i t t l e e r o s i o n . On s t e e p s l o p e s , e s p e c i a l l y f i n e r t e x t u r e d s i l t l oams, s i g n i f i c a n t e r o s i o n was t a k i n g p l a c e . The major e r o s i o n s i t e s were n o t t h e h a r v e s t e d l a n d i t s e l f but r a t h e r s k i d t r a i l s a nd r o a d s b u i l t t o e x t r a c t t h e t i m b e r . Some h a r v e s t i n g o p e r a t i o n s on s t e e p e r s l o p e s ' s u c c e s s f u l l y c o n t r o l l e d e r o s i o n by i n s t a l l a t i o n o f water b a r s (TV #2). A n o t h e r s i g n i f i c a n t f a c t o r l i m i t i n g e r o s i o n was " c a r e - i n -l o g g i n g . " T h i s f a c t o r c o r r e l a t e d w e l l w i t h R o t h w e l l ' s (1977) i d e n t i f i c a t i o n o f c a r e f u l p l a n n i n g a s t h e major component i n r o a d c o n s t r u c t i o n t o m i n i m i z e water q u a l i t y d e t e r i o r a t i o n . Some t r e n d s i n t h e r e s u l t s a p p e a r e v i d e n t a l t h o u g h o f l i t t l e s t a t i s t i c a l s i g n i f i c a n c e . The a r e a under s h a l l o w d e p o s i t s i n c r e a s e d w i t h i n c r e a s i n g s l o p e . S i t e s w i t h l o w e r c a r e - i n - l o g g i n g v a l u e s had h i g h e r amounts o f s o i l d e p o s i t s w h i c h may r e s u l t from o v e r l a n d f l o w a nd d e p o s i t i o n o n s i t e . 1 0 3 N o r t h e r n a s p e c t s , s t e e p s l o p e s and f i n e r s o i l s were i d e n t i f i e d as h a v i n g h i g h e r e r o s i o n r a t e s on s k i d t r a i l s . The c u t o v e r s u r f a c e had l e s s s o i l d i s t u r b a n c e and e r o s i o n r a t e s were low. C o a r s e r sandy loam s o i l s showed l e s s d i s t u r b a n c e t h a n f i n e r s i l t loams on s i m i l a r s l o p e s . H i g h m o i s t u r e s i t e s were s u s c e p t i b l e t o deep g o u g i n g and h i g h s o i l d i s t u r b a n c e a l t h o u g h low s l o p e a n g l e s o f t e n l i m i t e d e r o s i o n . D i s t u r b a n c e l e v e l s i n c l e a r c u t s v a r i e d g r e a t l y but p r o g r e s s i v e c l e a r c u t s a p p e a r e d t o have more s o i l movement t h a n o t h e r s i t e s w h i l e s e l e c t i o n h a r v e s t i n g had t h e l e a s t d i s t u r b a n c e . F l u o r e s c e n t Dye P l o t s The f l u o r e s c e n t dye p l o t s y i e l d e d i n f o r m a t i o n on t h e e r o s i o n p r o c e s s o c c u r r i n g on t h e s l o p e . S o i l movement r a t i n g s were h i g h e r on s t e e p e r s l o p e s and on n o r t h f a c i n g s l o p e s . The r e l a t i o n s h i p between s o i l - m o v e m e n t - r a t i n g and s l o p e was l i n e a r showing h i g h e r r a t i n g s on s t e e p e r s l o p e s . The movement of t h e t a g g e d p a r t i c l e s was i n d i c a t i v e o f e r o s i o n p r o c e s s e s o c c u r r i n g on t h e s i t e . R a i n s p l a s h e r o s i o n o c c u r r e d a t a l l l o c a t i o n s . O v e r l a n d f l o w a l s o c a u s e d e r o s i o n e s p e c i a l l y on s t e e p e r s l o p e s and on f i n e s o i l s . 104 F l u o r e s c e n t Dye Method E v a l u a t i o n The f l u o r e s c e n t dye a p p l i c a t i o n was s t a b l e under c l i m a t i c c o n d i t i o n s o f t h e s t u d y a r e a f o r a t l e a s t n i n e months. As l i t t l e d e g r a d a t i o n o f f l u o r e s c e n c e was n o t e d , i t i s l i k e l y p e r s i s t e n c e i s c o n s i d e r a b l y l o n g e r t h a n n i n e months. The a p p l i c a t i o n of D a y - G l o f l u o r e s c e n t p igment i n a c e t o n e t h i n l y c o a t e d t h e s u r f a c e w i t h l i t t l e i m p a c t on s i z e , d e n s i t y o r t e x t u r e of p a r t i c l e s and gave s t a b l e a d h e r e n c e o f t h e dye t o s o i l p a r t i c l e s . The f l u o r e s c e n c e was e a s i l y v i s i b l e w i t h a hand h e l d u l t r a v i o l e t m i n e r a l lamp. A l t h o u g h some m o d i f i c a t i o n s were s u g g e s t e d , t h i s method f o r a p p l i c a t i o n o f f l u o r e s c e n t dye t o i n d e x s o i l movement was recommended. S p r a y i n g dye on s o i l ir\ s i t u t a g g e d v e r y f i n e o r g a n i c and s o i l p a r t i c l e s w h i c h " c l u t t e r " t h e f i e l d o f v i e w under u l t r a v i o l e t i l l u m i n a t i o n and make measurement d i f f i c u l t . To q u a n t i f y movement and d e t e r m i n e p a r t i c l e - s i z e r e l a t i o n s h i p s t h e e x t r a c t i o n o f a s u r f a c e s o i l sample and s i e v i n g t o s i z e c l a s s e s was recommended. 105 CONCLUSIONS Surface E r o s i o n S u r f a c e e r o s i o n i s an a c t i v e p r o c e s s on t h e f o r e s t l a n d b a s e o f t h e N o r t h Okanagan. The major s i t e s o f e r o s i o n a r e s k i d t r a i l s and t h e r o a d s y s t e m c o n s t r u c t e d i n h a r v e s t i n g o p e r a t i o n s . The d a t a c o l l e c t e d i n t h i s s t u d y c o n f i r m e d t h e g e n e r a l c o n s e n s u s of r e s e a r c h r e s u l t s r e c o r d e d i n t h e l i t e r a t u r e . The t r e n d s i n s o i l movement on t h e s t u d y s i t e s showed: - s l o p e i s a s i g n i f i c a n t component i n e r o s i o n on d i s t u r b e d s i t e s . - e r o s i o n i s much h i g h e r on s k i d t r a i l s t h a n on t h e s u r f a c e o f t h e c u t o v e r . - more e r o s i o n o c c u r s on f i n e , s i l t loam t e x t u r e d s o i l s t h a n on loams and sandy l o a m s . - s o i l movement i n c r e a s e s d o w n s l o p e . - w a t e r b a r s a r e e f f e c t i v e i n l i m i t i n g s o i l movement on s k i d r o a d s . - s e l e c t i o n l o g g i n g p r a c t i c e s c a u s e l e s s e r o s i o n t h a n c l e a r c u t t i n g . - i t i s t h e r o a d s y s t e m , n o t t h e a c t u a l c u t o v e r s u r f a c e , w h i c h has t h e h i g h e s t e r o s i o n . 106 Fluorescent Dye D a y - G l o f l u o r e s c e n t p i g m e n t i n s o l u t i o n w i t h a c e t o n e i s u s e f u l as a s o i l t a g . Such l a b e l l i n g of s o i l p a r t i c l e s does n o t s i g n i f i c a n t l y a l t e r p h y s i c a l p r o p e r t i e s o f t h e p a r t i c l e s , i s s t a b l e under s u n l i g h t and p e r s i s t s f o r a t l e a s t n i n e months. U s i n g n o r m a l c o l o r f i l m and an u l t r a v i o l e t m i n e r a l lamp f o r i l l u m i n a t i o n , a p h o t o g r a p h i c r e c o r d of f l u o r e s c e n c e c an be o b t a i n e d . E x c a v a t i o n and s i e v i n g o f p a r t i c l e s i s recommended on f o r e s t h a r v e s t e d s i t e s t o r e d u c e t h e l a r g e numbers of v e r y f i n e m a t e r i a l s ( l a r g e l y o r g a n i c m a t t e r ) w h i c h c l u t t e r t h e do w n s l o p e v i e w i n g f i e l d and makes q u a n t i f i c a t i o n o f s o i l movement d i f f i c u l t . F l u o r e s c e n t dye i s an i n e x p e n s i v e , e a s y - t o - a p p l y s o i l t a g w h i c h e f f e c t i v e l y i l l u s t r a t e s s o i l movement and a l l o w s r a t e s o f s o i l movement, s o u r c e s of e r o d i n g m a t e r i a l and pathways o f movement t o be o b s e r v e d . S o i l movement on a c t u a l c u t o v e r s i n t h i s r e g i o n i s r e l a t i v e l y low, i n d i c a t i n g l i t t l e l o s s o f p r o d u c t i v e p o t e n t i a l f r o m s u r f a c e e r o s i o n o f t h i s s o i l . The e r o s i o n p r o c e s s was most a c t i v e on s k i d r o a d s , a c c e s s r o a d s , and l a n d i n g s , a l l s i t e d i s t u r b a n c e s r e s u l t i n g f r o m t h e h a r v e s t i n g s y s t e m . On many s i t e s , h a r v e s t i n g o p e r a t i o n s r e s u l t e d i n s i g n i f i c a n t s o i l movement. I t was shown t h a t 107 w i t h h i g h c a r e i n l o g g i n g s t e e p s i t e s c an be h a r v e s t e d w i t h l i t t l e i m p a c t on t h e s o i l movement p r o c e s s o n s i t e i f p r o p e r p l a n n i n g and s k i d r o a d m a i n t e n a n c e i s c o m p l e t e d . S o i l movement i s n o t n e c e s s a r i l y i n d i c a t i v e o f s e d i m e n t l e v e l s i n a r e a s t r e a m s . The p r o x i m i t y o f s t r e a m c o u r s e s t o t h e c u t b l o c k s and t h e d r a i n a g e c h a n n e l s e s t a b l i s h e d w i l l i n f l u e n c e t h i s . A l t h o u g h a d e t a i l e d s t r e a m c o u r s e e v a l u a t i o n was n o t c o m p l e t e d , i t was n o t e d t h a t r u n o f f f r o m some c u t b l o c k s f l o w e d d i r e c t l y i n t o a s t r e a m . In a r e g i o n w i t h h i g h w a t e r v a l u e s and a need f o r h i g h q u a l i t y w a ter t o s a t i s f y t h e needs of downstream u s e r s , s u c h i n d i c a t o r s o f e r o s i o n s h o u l d i n i t i a t e a c t i o n t o s t a b i l i z e t h e s o i l s u r f a c e . S e l e c t i o n l o g g i n g methods promote s u r f a c e s o i l s t a b i l i t y . They a r e , however, n o t u n i v e r s a l l y a p p l i c a b l e . Much o f t h e f o r e s t i n t h i s r e g i o n w i l l be c l e a r c u t h a r v e s t e d f o r b o t h e c o n o m i c and s i l v i c u l t u r a l r e a s o n s . M o d i f i c a t i o n of s i z e and shape of c l e a r c u t s , and c a r e i n s i t e p r e p a r a t i o n and r o a d l o c a t i o n c an r e d u c e d i s t u r b a n c e l e v e l s . Such c l e a r c u t h a r v e s t i n g methods s t i l l h ave p o t e n t i a l t o a d v e r s e l y i n f l u e n c e s o i l s t a b i l i t y b u t p r o p e r p l a n n i n g , and c a r e f u l l o g g i n g and r o a d c o n s t r u c t i o n c an r e d u c e t h i s i m p a c t and m a i n t a i n s o i l s t a b i l i t y . -108 Chapter 8 RECOMMENDATIONS Some m o d i f i c a t i o n s t o t h e f l u o r e s c e n t dye methods u s e d i n t h e s t u d y a r e recommended. T h i s method f o r f l u o r e s c e n t dye a p p l i c a t i o n m i g h t f o l l o w t h e s t e p s l i s t e d b e l o w : 1) e x c a v a t e s o i l u p s l o p e and s i e v e i n t o d e s i r e d s i z e c l a s s e s . E a c h c l a s s c a n be s p r a y e d w i t h a d i f f e r e n t Day-G l o p igment i n s o l u t i o n w i t h a c e t o n e . D i f f e r e n t s l o p e l o c a t i o n s c a n a l s o be c o l o r - s t r a t i f i e d . 2) r e p l a c e t h e e x t r a c t e d s o i l and a t t e m p t t o r e c r e a t e f o r m e r c o n d i t i o n s . 3) m o n i t o r d o w n s l o p e movement w i t h a h a n d - h e l d m i n e r a l l i g h t . 4) p h o t o g r a p h f l u o r e s c e n c e . 5) q u a n t i f y movement d o w n s l o p e and l o c a t i o n o f p a r t i c l e s ( e s p e c i a l l y medium and l a r g e r s i z e s ) by m a r k i n g w i t h c o l o r c o d e d n a i l s . In d a y l i g h t a s k e t c h of movement pathways and d i s t a n c e s d o w n s l o p e c a n be o b t a i n e d . Forest Management Uses The e a s e o f a p p l i c a t i o n and r e l a t i v e l y low c o s t of f l u o r e s c e n t dye methods s u p p o r t t h e i r use i n e r o s i o n a s s e s s m e n t o f r o a d s and s k i d t r a i l s . Much of t h e e r o s i o n on r o a d s b e g i n s a s s h a l l o w s h e e t f l o w . A l t h o u g h s h e e t f l o w i s c a p a b l e o f t r a n s p o r t i n g s e d i m e n t , t h e e r o s i o n p r o b l e m i s m i n o r u n t i l t h e f l o w i s c h a n n e l l e d and r i l l i n g and g u l l y i n g 1 0 9 t a k e p l a c e . On r o a d s , i f r i l l s a r e i d e n t i f i e d e a r l y i n t h e i r f o r m a t i o n and t h e o v e r l a n d f l o w p a t t e r n d i s r u p t e d , e r o s i o n a l i m p a c t c an be r e d u c e d . S p r a y i n g f l u o r e s c e n t dye on c u t and f i l l s l o p e s and on p a r t s o f t h e a c t u a l r o a d s u r f a c e w o u l d i l l u s t r a t e movement o c c u r r i n g b e f o r e s i g n i f i c a n t r i l l i n g had t a k e n p l a c e and a l l o w use o f s i m p l e , i n e x p e n s i v e measures t o s t a b i l i z e t h e s u r f a c e . A l t h o u g h n i g h t i l l u m i n a t i o n i s n e c e s s a r y f o r q u a n t i t a t i v e r e s u l t s , D a y - G l o p i g m e n t i s e a s i l y v i s i b l e i n d a y l i g h t and a c t s a s an e x t r a b r i g h t n o r m a l c o l o r dye t o t a g p a r t i c l e s . T h i s means t h a t much o f t h e m o n i t o r i n g w o u l d r e q u i r e no n i g h t - t i m e i l l u m i n a t i o n . An i n t e r e s t i n g and u s e f u l f o l l o w - u p t o t h i s s t u d y would be t o r e v i s i t t h e s t u d y s i t e s and e v a l u a t e p e r s i s t e n c e of f l u o r e s c e n c e and s o i l movement a f t e r two t o t h r e e y e a r s . T h i s would y i e l d n e c e s s a r y d a t a on p e r s i s t e n c e and s t a b i l i t y o f t h i s f l u o r e s c e n t dye under l o c a l c l i m a t i c c o n d i t i o n s . 1 10 LITERATURE CITED A g r i c u l t u r e Canada. 1961. 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Oil Absorption (g/ lOOg pigment) 47 TOXICITY A , A X T, G T H M H M S Z S A c u t e O r a l T o x i c i t y L D 5o 9 / k 9> 16.0 23.1 15.38 10.0 A c u t e D e r m a l T o x i c i t y L D 5 0 g /kg> 23.0 • 10.2 3.0 2.15 A c u t e Dust Inhalat ion L C 50 m g / L air> 4 . 4 (4 hrs.) 3.0 2.88 8.3 E y e Irr i tat ion N o s i g -n i f icant i r r i ta-t ion m i l d l y i r r i -tat ing m i l d l y i r r i -tat ing s l ight t rans ient i r r i tant 

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