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The development of a border strip irrigation system in the Nicola Valley Madani, Seyed Ali 1976

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THE DEVELOPMENT OF A BORDER STRIP IRRIGATION SYSTEM I N THE NICOLA VALLEY BY SEYED A L I MADANI B . S c , P a h l a v i U n i v e r s i t y , S h i r a z , I r a n , 1972 A THESIS SUBMITTED I N PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n t h e D e p a r t m e n t o f A g r i c u l t u r a l M e c h a n i c s We a c c e p t t h i s t h e s i s as 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 B R I T I S H COLUMBIA May, 19 7 6 0 Seyed A l i Madani, 1976 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at 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 , I a g r ee t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r ag ree 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 pu rpo se s may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . 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 not 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 . Department o f Bio-Resource Engineering The U n i v e r s i t y o f B r i t i s h Co l umb i a 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date June 7, 1976. ABSTRACT The r e s e a r c h r e p o r t e d h a s b e e n c a r r i e d o u t t o d e v e l o p a b o r d e r i r r i g a t i o n s y s t e m f o r t h e s e m i - a r i d r e g i o n i n t h e N i c o l a V a l l e y i n B r i t i s h C o l u m b i a . To d e v e l o p a b o r d e r i r r i g a t i o n s y s t e m i n t h e V a l l e y a 60 a c r e f i e l d was s u r v e y e d a n d t h e d e s i g n o f l a n d g r a d i n g p r e p a r e d . A s m a l l s e c t i o n o f t h e l a r g e r p r e p a r e d f i e l d was s e l e c t e d f o r t h i s s t u d y and t h r e e b o r d e r s t r i p s , e a c h h a v i n g t h e same l e n g t h w i t h d i f f e r e n t w i d t h s , were c o n s t r u c t e d . .Formulas a n d c u r v e s w e re u s e d f o r t h e d e s i g n c a l c u l a -t i o n o f s l o p e , d i s c h a r g e , d e p t h o f w a t e r t o be a p p l i e d , r e q u i r e d amount o f w a t e r , and t h e t i m e o f a p p l i c a t i o n f o r e a c h s t r i p . I n f i l t r a t i o n r a t e s , s o i l m o i s t u r e c a p a c i t i e s and s o i l c l a s s i f i c a t i o n a r e r e p o r t e d . TABLE OF CONTENTS i i PAGE ABSTRACT i TABLE OF CONTENTS i i L I S T OF TABLE . • • i i i L I S T OF FIGURES i v ACKNOWLEDGEMENTS .v I INTRODUCTION 1 I I BORDER STRIP METHOD 8 I I I DESCRIPTION OF AREA 10 IV REVIEW OF LITERATURE 13 V INFORMATION REQUIRED 19 1) C l i m a t e 19 2) S o i l 21 V I DEVELOPING A BORDER STRIP IRRIGATION SYSTEM 2 4 E x p e r i m e n t 2 9 V I I RESULTS AND DISCUSSION 35 CONCLUSIONS 52 LITERATURE CITED , 5 4 APPENDIX I 5 6 APPENDIX I I 59 APPENDIX I I I 61 L I S T OF TABLES L e f t t o p s e c t i o n - o r i g i n a l e l e v a t i o n s and new e l e v a t i o n s / c u t s and f i l l s f o r l e f t t o p s e c t i o n . Top s e c t i o n - o r i g i n a l e l e v a t i o n s . B o t t o m s e c t i o n - o r i g i n a l e l e v a t i o n s . D a t a on s o i l p r o p e r t i e s . F a c t o r s f o r u s e i n a d j u s t i n g u n i t s t r e a m s f r o m F i g u r e 1 f o r s l o p e s o t h e r t h a n 0.5 p e r c e n t . T a k e n f r o m r e f e r e n c e ( 2 1 ) . Summary o f b o r d e r i r r i g a t i o n r e l a t i o n -s h i p s L I S T OF FIGURES G r a d e d - b o r d e r i r r i g a t i o n . (U.S.D.A. S o i l C o n s e r v a t i o n S e r v i c e ) ( 2 4 ) . S i t e o f E x p e r i m e n t . An e x a m p l e o f a r e c t a n g u l a r a r e a w h i c h i s t o be g r a d e d . I r r i g a t i o n d i t c h e s 1 and 2 d i v i d e t h e f i e l d i n t o 3 s e c t i o n s . The l o c a t i o n s o f h o l e s f o r s o i l s a m p l i n g a r e i n d i c a t e d i n e a c h b o r d e r s t r i p . I n t a k e r a t e c u r v e d e v e l o p e d f r o m i n f i l t r o m e t e r d a t a . I n t a k e r a t e c u r v e d e v e l o p e d f r o m i n f i l t r o m e t e r d a t a . C u r v e s f o r d e t e r m i n i n g d e s i r a b l e s i z e o f s t r e a m s t o u s e on a b o r d e r s t r i p 1' w i d e and 100' l o n g f o r s o i l s h a v i n g d i f f e r e n t b a s i c i n t a k e r a t e s ( I . R . ) . T a k e n f r o m r e f e r e n c e ( 1 0 ) . V ACKNOWLEDGEMENTS I u)i*h to fitcofid ^ifi*t my Aincefie. thank* to V'fio^e**oft T.L. Coulthaftd fioti hi* guidance in the initiation o& thi* fie.* cafich, hi* help in facing it* une.xpe.cttd obstacle.*, and hi* *tead^a*tne** in encoufiaging it* completion. Hy thank* extend al*o to Vfi. T.H. Podmofie ion invaluable. a**i*tance in fieviiion, to the. U.B.C. Soil Science. Ve.pafitme.nt fa on thein kind loan ofa faacilitie*, and to Mn* . E. Stewant Ion. he.fi patience, and *kill in typing thit> the*i* . I . INTRODUCTION I r r i g a t i o n i s t h e c o n t r o l l e d a p p l i c a t i o n o f w a t e r t o a g r i c u l t u r a l l a n d t o s u p p l y c r o p r e q u i r e m e n t s n o t s a t i s f i e d by n o r m a l r a i n f a l l . I n a r i d and s e m i - a r i d l a n d s , c r o p g r o w t h may be e n t i r e l y d e p e n d e n t on t h e s u p p l y o f s u p p l e m e n t a r y w a t e r ; a d e p t h o f up t o 48 i n c h e s o r more p e r s e a s o n may be r e q u i r e d d e p e n d i n g on t h e c l i m a t i c a nd g r o w i n g c o n d i t i o n s ( 2 6 ) Numerous i r r i g a t i o n m ethods a r e a p p l i e d t h e w o r l d o v e r . T h e s e d i f f e r i n d i f f e r e n t p l a c e s f r o m t h e most p r i m i -t i v e " w i l d " o r u n c o n t r o l l e d f l o o d i n g t o v e r y s o p h i s t i c a t e d s p r i n k l e r i r r i g a t i o n s y s t e m s . I r r i g a t i o n w a t e r a p p l i c a t i o n i s commonly d e s i g n a t e d a c c o r d i n g t o t h e manner i n w h i c h w a t e r i s a p p l i e d t o t h e s o i l . I r r i g a t i o n , w a t e r i s a p p l i e d t o l a n d by t h r e e g e n e r a l methods ( 1 5 ) ; n a m e l y ( a ) s u r f a c e i r r i g a t i o n , i n w h i c h w a t e r i s a p p l i e by c o m p l e t e f l o o d i n g , o r i n f u r r o w s , w e t t i n g p a r t o f . t h e s u r f a c e ; ( b ) s u b s u r f a c e ' i r r i g a t i o n , i n w h i c h w a t e r i s a p p l i e d b e n e a t h t h e s u r f a c e , w e t t i n g t h e s u r f a c e l i t t l e i f a t a l l ; and ( c ) s p r i n k l e r i r r i g a t i o n , i n w h i c h t h e s o i l s u r f a c e i s w e t t e d as much as i t i s by r a i n f a l l . M e t h o d s o f a p p l y i n g i r r i g a t i o n . w a t e r v a r y w i t h t o p o -g r a p h y , s o i l c o n d i t i o n , amount o f l a n d p r e p a r a t i o n n e c e s s a r y , c r o p t o be g r o w n , v a l u e o f c r o p s , c u l t u r a l p r a c t i c e s , and a v a i l a b l e w a t e r s u p p l y ( 2 4 ) . The s o c i a l c o n d i t i o n s a l s o p l a y a r o l e i n s e l e c t i o n o f i r r i g a t i o n m e t h o d s . The s o c i a l c o n d i -t i o n s i n c l u d e t h e t y p e o f g o v e r n m e n t i n p o w e r , p e o p l e ' s l e v e l o f c o n s c i o u s n e s s , m o t i v e s f o r p r o d u c t i o n ( t h a t i s , p r o f i t s , s e l f s u f f i c i e n c y ) , a v a i l a b i l i t y o f t e c h n o l o g y t o t h e a v e r a g e f a r m e r s , and rniode o f p r o d u c t i o n ( t h a t i s , c o l l e c t i v e o r i n d i v i d u a l ) . E a c h method h a s c e r t a i n l i m i t a t i o n s . On some s i t e s s e v e r a l methods o f w a t e r a p p l i c a t i o n a r e s u i t a b l e . I n some a r e a s f a r m e r s h a v e become a c c u s t o m e d t o p a r t i c u l a r methods o f a p p l y i n g w a t e r and c o n t i n u e t o u s e them e v e n t h o u g h o t h e r s a r e more e f f i c i e n t . F a c t o r s s u c h as i n i t i a l c a p i t a l c o s t , l a b o r , t h e c o s t and e a s e o f i n s t a l l a t i o n , m a i n t e n a n c e r e q u i r e d , s k i l l o f o p e r a t o r , f l e x i b i l i t y o f t h e s y s t e m , and t h e i r r i g a t o r ' s p r e f e r e n c e s must be c o n s i d e r e d i n s e l e c t i n g t h e b e s t m e t h o d o f i r r i g a t i o n . I n t h e s u b - i r r i g a t i o n m e t h o d w a t e r i s a p p l i e d t h r o u g h open d i t c h e s o r t i l e d r a i n s . A s u b - i r r i g a t i o n s y t e m i s v e r y e x p e n s i v e and g e n e r a l l y i s u s e d o n l y f o r h i g h v a l u e c r o p s and i n g l a s s h o u s e s . The s u b - i r r i g a t i o n method i s s u i t e d t o s o i l h a v i n g r e a s o n a b l y u n i f o r m t e x t u r e and p e r m e a b l e enough f o r w a t e r t o move r a p i d l y b o t h h o r i z o n t a l l y a nd v e r t i c a l l y . The s o i l p r o f i l e must a l s o c o n t a i n a b a r r i e r a g a i n s t e x c e s s i v e l o s s e s t h r o u g h deep p e r c o l a t i o n . W a t e r h a v i n g a h i g h s a l t c o n t e n t c a n n o t be u s e d f o r s u b - i r r i g a t i o n b e c a u s e i t r a i s e s s a l i n i t y p r o b l e m s and d e t e r i o r a t e s t h e s o i l s t r u c t u r e . I n some a r i d a r e a s s o i l s become s a l i n e u n l e s s a d e q u a t e l y d r a i n e C h o i c e o f c r o p s i s l i m i t e d i n some a r e a s . Deep r o o t e d c r o p s g e n e r a l l y c a n n o t be s u b - i r r i g a t e d b e c a u s e o f a h i g h w a t e r t a b l e . S i n c e t h i s m e t hod o f a p p l y i n g w a t e r r e q u i r e s an u n u s u a l c o m b i n a t i o n o f n a t u r a l c o n d i t i o n s , i t c a n be u s e d i n o n l y a few a r e a s ( 2 4 ) . S p r i n k l e r m e t h o d s u s e p i p e s t o d i s t r i b u t e w a t e r t o v a r i o u s p a r t s o f t h e f i e l d w h ere i t i s s p r a y e d i n t o t h e a i r and f a l l s more o r l e s s u n i f o r m l y ( i f t h e s y s t e m i s p r o p e r l y , d e s i g n e d ) on a l l p a r t s o f t h e s u r f a c e . The d e s i g n o f a s p r i n k l e r i r r i g a t i o n s y s t e m r e q u i r e s d e t a i l e d a n a l y s i s o f s o i l , c r o p , t o p o g r a p h y , and w e a t h e r . A l t h o u g h t h i s s y s t e m o f a p p l y i n g w a t e r i s v e r y s o p h i s t i c a t e d , M a c D o n a l d ( 1 7 ) i n d i c a t e s t h i s s y s t e m u s u a l l y r e q u i r e s t h e h i g h e s t i n i t i a l i n v e s t m e n t a n d h i g h e r a n n u a l c o s t t h a n any o t h e r m e t h o d i n B r i t i s h C o l u m b i a . A l s o a c c o r d i n g t o t h e S o i l C o n s e r v a t i o n S e r v i c e B u l l e t i n ( 2 4 ) , w i n d d i s t o r t s s p r i n k l e r p a t t e r n s a nd c a u s e s u n e v e n d i s t r i b u t i o n o f w a t e r w h i c h r e d u c e s c r o p p r o -d u c t i o n . The w a t e r must be c l e a n a n d f r e e o f s a n d , d e b r i s , and l a r g e amounts o f d i s s o l v e d s a l t s i n o r d e r t o a v o i d c l o g g i n g o f t h e p i p e s , p r e s s u r e f a l l , and s a l i n i z a t i o n o f t h s o i l . More s p e c i a l e q u i p m e n t i s n e e d e d . a n d power r e q u i r e -m ents a r e u s u a l l y h i g h s i n c e s p r i n k l e r s o p e r a t e w i t h a w a t e r p r e s s u r e o f 15 t o more t h a n 100 pounds p e r s q u a r e i n c h ( 2 4 ) . A s t a b l e w a t e r s u p p l y i s n e e d e d f o r t h e most e c o n o m i c a l u s e o f t h e e q u i p m e n t . A d d i n g t o t h e above l i m i t a t i o n s , i t s h o u l d be n o t e d t h a t t h e e n e r g y r e q u i r e m e n t s f o r t h i s t y p e o f i r r i g a t i o n method r e n d e r s i t u n s u i t a b l e f o r some f a r m e r s . I n s u r f a c e methods w a t e r i s a p p l i e d d i r e c t l y t o t h e s o i l s u r f a c e by t h r e e i m p o r t a n t methods ( 1 5 ) ; n a m e l y , ( a ) u n c o n t r o l l e d o r " w i l d " f l o o d i n g , ( b ) f u r r o w m e t h o d , and ( c ) b o r d e r s t r i p m e t h od. I n t h e e a r l y i r r i g a t i o n o f c e n t u r i e s p a s t , w a t e r was a p p l i e d by " w i l d f l o o d i n g " . I t i s p r a c t i c e d l a r g e l y where i r r i g a t i o n w a t e r i s a b u n d a n t and i n e x p e n s i v e . I t i s an i m p o r t a n t a n d d i f f i c u l t p r o b l e m t o a p p l y w a t e r e f f i c i e n t l y by u n c o n t r o l l e d m e t h o d s . The d i s a d v a n t a g e s o f w i l d f l o o d i n g a r e h i g h i r r i g a t i o n l a b o r r e q u i r e m e n t s , l o w w a t e r a p p l i c a t i o n e f f i c i e n c y , and u n e v e n w a t e r d i s t r i b u t i o n . Where l a n d and w a t e r a r e e x p e n s i v e i t i s n o t g e n e r a l l y e c o n o m i c a l t o u s e u n c o n t r o l l e d i r r i g a t i o n m e t h o d s . I n f u r r o w i r r i g a t i o n w a t e r i s a p p l i e d t h r o u g h n a r r o w c h a n n e l s h a v i n g a c o n t i n u o u s s l o p e i n t h e d i r e c t i o n o f i r r i g a t i o n . The f u r r o w i r r i g a t i o n m e t hod c a n n o t be a p p l i e d on t h e s a n d y s o i l s b e c a u s e o f h i g h w a t e r i n t a k e r a t e . A g a i n h e r e e x t e n s i v e i r r i g a t i o n l a b o r i s r e q u i r e d , some r u n o f f , u s u a l l y i s n e c e s s a r y f o r u n i f o r m w a t e r a p p l i c a t i o n and e r o s i o n h a z a r d s o c c u r on s t e e p s l o p e s ( 2 4 ) . The b o r d e r s t r i p m ethod i s a f o r m o f c o n t r o l l e d s u r f a c e f l o o d i n g ( F i g u r e 1 ) . As B i s h o p e t i a l . ( 2 ) d e s c r i b e i t , a l t h o u g h t h e b o r d e r s t r i p m ethod o f i r r i g a t i o n h a s some F i g u r e 1. . G r a d e d - b o r d e r i r r i g a t i o n . (U.S.D.A. S o i l C o n s e r v a t i o n S e r v i c e ) ( 2 4 ) . l i m i t a t i o n s s u c h as e x t e n s i v e l a n d g r a d i n g a n d e n g i n e e r i n g c o s t , b u t i f t h e s y s t e m i s . p r o p e r l y d e s i g n e d t h e n h i g h w a t e r a p p l i c a t i o n e f f i c i e n c y , and e f f i c i e n t u s e o f i r r i g a t i o n l a b o r i s a c h i e v e d . The b o r d e r s t r i p method i s a p p l i c a b l e on most s o i l t y p e s and i t h a s l o w m a i n t e n a n c e c o s t s , and p o s i t i v e c o n t r o l o v e r i r r i g a t i o n w a t e r w i l l be o b t a i n e d . L a b o r r e q u i r e m e n t s a r e among t h e l o w e s t f o r a l l a p p l i c a t i o n methods ( 2 4 ) . The s t r i p w i d t h c a n be d e s i g n e d t o accommodate t h e f a r m m a c h i n e r y u s e d f o r t i l l a g e , p l a n t i n g and h a r v e s t i n g ( 2 4 ) . I f s u r f a c e d r a i n a g e i s c r i t i c a l t h e method i s an e x c e l l e n t means f o r r a p i d d i s p o s a l o f e x c e s s s u r f a c e w a t e r , b e c a u s e t h e e x c e s s w a t e r c a n be c a r r i e d away i n t h e f o r m o f t a i l w a t e r f r o m t h e e n d o f t h e b o r d e r s t r i p ( i f t h e r e i s no d i k e o r s t o p p a g e o f w a t e r - f l o w a t t h e end o f t h e b o r d e r s t r i p ) . The p u r p o s e o f t h i s s t u d y was t o d e v e l o p an i r r i g a -t i o n s y s t e m f o r a f i e l d i n t h e N i c o l a V a l l e y o f B r i t i s h C o l u m b i a , Canada. C o n s i d e r i n g t h e l i m i t a t i o n s o f e a c h m e t h o d , t h e c o n d i t i o n o f t h e a r e a , f u n d i n g a v a i l a b l e , and c o n s u l t i n g w i t h t h e c o - o p e r a t i v e f a r m e r , i t was f e l t t h a t t h e b o r d e r s t r i p m ethod w o u l d be t h e most s u i t a b l e and e f f i c i e n t one f o r t h e above a r e a . T h e r e f o r e t h i s s t u d y h a s b e e n c a r r i e d o u t t o d e v e l o p a b o r d e r s t r i p i r r i g a t i o n s y s t e m t o d e t e r m i n e : 7 . 1) The amount and d e p t h o f w a t e r r e q u i r e d f o r e a c h s t r i p , t h e r a t e o f f l o w o f w a t e r f o r e a c h s t r i p , t h e i r r i g a t i o n i n t e r v a l s , a n d t h e t i m e o f a p p l i c a t i o n o f i r r i g a t i o n w a t e r t o e a c h s t r i p . 2) The b e s t l e n g t h a n d w i d t h o f e a c h s t r i p . 3) The u n i f o r m i t y o f w a t e r d i s t r i b u t i o n i n b o r d e r s t r i p m e thod a n d compare i t w i t h t h a t o f t h e w i l d f l o o d i n g method. 4) The w a t e r a p p l i c a t i o n e f f i c i e n c y o f t h e b o r d e r s t r i p m e thod and compare i t w i t h t h a t o f t h e w i l d f l o o d i n g , method.. I I . BORDER STRIP METHOD The b o r d e r s t r i p m ethod i s one o f t h e most common t y p e s o f i r r i g a t i o n s y s t e m s and i s among t h e b e s t methods f o r i r r i g a t i n g many c r o p s i n g e n t l e s l o p e s . I t i s s i m p l e , e c o n o m i c a l , a n d an e f f i c i e n t way t o i r r i g a t e ( 6 ) . I n t h e b o r d e r i r r i g a t i o n w a t e r i s a p p l i e d on t h e g r o u n d a t t h e g r o u n d l e v e l and i t f l o w s by g r a v i t y o v e r t h e s u r f a c e o f t h e f i e l d . I t i s a c o n t r o l l e d f l o o d i n g p r o c e s s . The a r e a t o be i r r i g a t e d i s d i v i d e d i n t o s t r i p s by c o n s t r u c t i n g b o r d e r d i k e s o r l e v e e s . The b o r d e r s t r i p s a r e w i d e , s h a l l o w c h a n n e l s i n w h i c h t h e w a t e r f l o w s f r o m t h e h e a d d i t c h t o t h e end o f t h e s t r i p , m o i s t e n i n g t h e s o i l as i t f l o w s down t h e s l o p e . E a c h s t r i p i s i r r i g a t e d by " t u r n i n g i n ' " a s t r e a m o f w a t e r a t t h e u p p e r e n d . The s t r e a m must be l a r g e e nough t o s p r e a d o v e r t h e e n t i r e w i d t h b e t w e e n t h e b o r d e r d i k e s w i t h o u t o v e r t o p p i n g t h e m ( 2 3 ) . The d i k e s r e s t r i c t t h e l a t e r a l movement o f w a t e r , c a u s i n g i t t o f l o w t o t h e end o f t h e f i e l d b e t w e e n t h e d i k e s . The d i k e s must be h i g h e r f o r t h e g e n t l e s l o p e s t h a n f o r t h e s t e e p e r o n e s . The b a s e o f t h e d i k e s s h o u l d a l s o be b r o a d , so t h a t f a r m i n g o p e r a t i o n s c a n be c a r r i e d on a l s o o v e r t h e c o n s t r u c t e d d i k e s ( 2 0 ) . As t h e S o i l C o n s e r v a t i o n S e r v i c e B u l l e t i n (2 4) i n d i c a t e s , t h e b o r d e r s t r i p s s h o u l d h a v e l i t t l e o r no c r o s s s l o p e , b u t s h o u l d h a v e some s l o p e i n t h e d i r e c t i o n o f i r r i g a t i o n . The amount o f s l o p e t h a t i s r e q u i r e d d e p e n d s m a i n l y on t h e a v a i l a b l e w a t e r s u p p l y , t h e s o i l , t h e c l i m a t e , and t h e c r o p s . T h e r e f o r e , t h e b e s t t y p e o f l a n d p r e p a r a t i o n f o r b o r d e r i r r i g a t i o n i s a u n i f o r m s l o p e i n t h e d i r e c t i o n o f i r r i g a t i o n w i t h no c r o s s s l o p e ( 1 ) . The b o r d e r s t r i p m e t hod i s commonly u s e d when s l o p e s i n t h e d i r e c t i o n o f i r r i g a t i o n ( p a r a l l e l t o t h e d i k e s ) r a n g e s f r o m 0.1 t o 1% f o r most c r o p s t o as much as 6% f o r p a s t u r e l a n d s ( 2 ) . T h e r e f o r e , e x t e n s i v e g r a d i n g i s u s u a l l y r e q u i r e d f o r t h e b o r d e r s t r i p m ethod o f i r r i g a t i o n . , The b o r d e r i r r i g a t i o n m ethod i s s u i t a b l e f o r most c l o s e - g r o w i n g c r o p s s u c h as g r a i n and a l f a l f a and some row c r o p s s u c h as c o t t o n a nd some o r c h a r d s ( 6 ) . I t c a n n o t be u s e d on s o i l s t h a t h a v e v e r y l o w o r v e r y h i g h i n t a k e r a t e s . • The l i m i t a t i o n s o f t h e b o r d e r s t r i p m ethod a r e e x t e n s i v e l a n d g r a d i n g , e n g i n e e r i n g d e s i g n s a r e n e c e s s a r y f o r h i g h e f f i c i e n c i e s , r e l a t i v e l a r g e f l o w s a r e r e q u i r e d , s h a l l o w s o i l s c a n n o t be e c o n o m i c a l l y g r a d e d , and d i k e s h i n d e r c u l t i v a t i o n ' and h a r v e s t i n g . W e l l p l a n n e d , a d e q u a t e l y c o n s t r u c t e d , and on a d a p t e d l a n d , t h e b o r d e r s t r i p m e t hod makes p o s s i b l e e f f i c i e n t a n d e c o n o m i c a l i r r i g a t i o n . 10 . I l l ' DESCRIPTION OF THE AREA The N i c o l a V a l l e y a r e a i s l o c a t e d b e t w e e n M e r r i t t and K a m l o o p s i n t h e P r o v i n c e o f B r i t i s h C o l u m b i a . The l a n d r a n g e s i n e l e v a t i o n f r o m 1000 t o 6000 f e e t , c o n s i s t i n g m a i n l y o f p l a t e a u a r e a s i n t e r s e c t e d by s m a l l a l l u v i a l v a l l e y s . . W i l l c o c k s ( 2 6 ) h a s r e v i e w e d and d e t e r m i n e d t h a t most o f t h e a g r i c u l t u r e i s c a r r i e d on b e l o w t h e 2500 f e e t l e v e l . He a l s o h a s i n d i c a t e d t h a t t h e r o c k u n d e r l y i n g t h e l a n d s u r f a c e o f t h e N i c o l a V a l l e y v a r i e s f r o m l i m e s t o n e t o i g n e o u s i n t r u s i o n s o f g r a n i t e . G e n e r a l l y t h e s o i l s a r e c a l c a r e o u s i n n a t u r e . F o r a g r i c u l t u r a l p u r p o s e s t h e y a r e d e f i c i e n t i n N i t r o g e n a n d P h o s p h o r o u s ( 2 6 ) . The N i c o l a V a l l e y a r e a r e c e i v e s 10 i n c h e s o f p r e -c i p i t a t i o n a n n u a l l y ( 4 ) . The c u m u l a t i v e e v a p o t r a n s p i r a t i o n a t M e r r i t t a d j u s t e d f o r t h e l e n g t h o f t h e g r o w i n g s e a s o n i s t a k e n as 31.9" ( 2 6 ) . D u r i n g t h e g r o w i n g s e a s o n t h e a v e r a g e t o t a l p r e c i p i t a t i o n f r o m ' A p r i l t o O c t o b e r i n c l u s i v e , i s 4.7" ( 2 6 ) . T h i s d e c r e a s e s t h e i r r i g a t i o n r e q u i r e m e n t f o r e v a p o t r a n s p i r a t i o n t o 2 7.2". T h e r e f o r e , i t i s o b v i o u s t h a t i r r i g a t i o n i s r e q u i r e d f o r t h e v a l l e y t o s a t i s f y c r o p r e q u i r e m e n t s . I n t h e N i c o l a V a l l e y a r e a t h e m a i n c r o p s a r e o a t s , a l f a l f a , r e d and a l s i k e c l o v e r , and some g r a s s e s . The m a j o r i t y o f i r r i g a t i o n i n t h e a r e a ( a b o u t 80%) ( 2 6 ) i s c a r r i e d o u t by s u r f a c e methods w h i c h h a v e r e c e i v e d l i t t l e a t t e n t i o n f r o m t h e P r o v i n c i a l G o v e r n m e n t . Most o f t h e a r e a i s i r r i g a t e d by w i l d f l o o d i n g w h i c h h a s p o o r w a t e r a p p l i c a -t i o n e f f i c i e n c y and w a t e r d i s t r i b u t i o n . F o r t h i s s t u d y , a 60 a c r e f i e l d ( F i g u r e 2) was c h o s e n i n t h e V a l l e y and i t was s u r v e y e d by S.R. L e g g e t t a nd A s s o c i a t e s . A d e s i g n o f l a n d l e v e l l i n g was p r e p a r e d and t h e b o r d e r s t r i p s f o r c o n t r o l l e d f l o o d s u r f a c e i r r i g a t i o n w e r e c o n s t r u c t e d by a l o c a l c o n t r a c t o r i n t h e N i c o l a V a l l e y . F i g u r e 2. S i t e o f E x p e r i m e n t 13 I V . ' REVIEW OF LITERATURE On many f a r m s some o f t h e i r r i g a t i o n w a t e r i s w a s t e d To p r e v e n t s u c h w a s t e f i e l d s s h o u l d be p r o p e r l y p r e p a r e d b e f o r e t h e y a r e i r r i g a t e d . The p r e p a r a t i o n o f l a n d f o r i r r i g a t i o n , o r l a n d g r a d i n g as i t i s commonly c a l l e d , i s t h e r e s h a p i n g o f t h e l a n d s u r f a c e t o f a c i l i t a t e o r i m p r o v e t h e d i s t r i b u t i o n o f t h e w a t e r . G i v a n ( 1 2 ) f o u n d t h e a p p l i c a t i o n o f t h e l e a s t s q u a r e s m e thod ( w h i c h i s a s t a t i s t i c a l p r o c e d u r e f o r o b t a i n i n t h e b e s t f i t t o a g r o u p o f p o i n t s ) t o t h e p r o b l e m o f f i t t i n g a p l a n e t o t h e d i f f e r e n t e l e v a t i o n s d e l i n e a t i n g an u n e v e n l a n d s u r f a c e o f a r e c t a n g u l a r t r a c t . Then Chugg ( 8 ) e x t e n d e d t h e a p p l i c a t i o n o f t h e l e a s t s q u a r e s method t o i n c l u d e l a n d a r e a s o f any s h a p e , b u t t h e method does n o t n e c e s s a r i l y p r o v i d e t h e b e s t s l o p e f o r i r r i g a t i o n ( 2 1 ) . M a r r ( 1 8 ) i n d i c a t e d t h a t t h e l e a s t s q u a r e s a n d a v e r a g e p r o f i l e s m e t hod i s a n o t h e r a d a p t a t i o n o f ' t h e same p r i n c i p l e o f t h e l e a s t s q u a r e s method t o t h e p r o b l e m . The method p r o p o s e d by M a r r a p p e a r s t o be s u f f i c i e n t l y e a s y t o f o l l o w , p r a c t i c a l t o u s e and w a r r a n t s w i d e a c c e p t a n c e . The S o i l C o n s e r v a t i o n S e r v i c e ( 2 5 ) s u g g e s t e d t h e p l a n e method f o r l a n d g r a d i n g . The p l a n e method assumes t h a t t h e f i e l d i s t o be g r a d e d t o a t r u e p l a n e . The a v e r a g e e l e v a t i o n o f t h e f i e l d i s d e t e r m i n e d , and t h i s e l e v a t i o n i s a s s i g n e d t o t h e c e n t r o i d i o f t h e a r e a . 14. I n a l l t h e methods m e n t i o n e d a b o v e , t h e s l o p e o f t h e l a n d i s d e p e n d e n t on t h e g e n e r a l t o p o g r a p h y o f t h e l a n d , a nd t h e " c u t - f i l l " r a t i o i s g r e a t e r t h a n one. The " c u t - f i l l " r a t i o i s t h e amount o f c u t d i v i d e d by t h e amount o f f i l l . E x p e r i e n c e h a s shown t h a t t h i s r a t i o s h o u l d be g r e a t e r t h a n one ( 2 1 ) . C o m p a c t i o n f r o m e q u i p m e n t i n t h e c u t a r e a w h i c h r e d u c e s t h e v o l u m e o f c u t and a l s o c o m p a c t i o n i n t h e f i l l a r e a w h i c h i n c r e a s e s t h e f i l l v o l u m e n e e d e d a r e b e l i e v e d t o be t h e p r i n c i p a l r e a s o n s f o r t h i s e f f e c t . I t w o u l d be a s e r i o u s p r o b l e m , as f a r as e r o s i o n i s c o n c e r n e d , i f t h e c a l c u l a t e d s l o p e became more t h a n 2% f o r b o r d e r s t r i p m e t hod. A v a r i a t i o n o f t h e p l a n m e thod i s p r o p o s e d . I n t h e m ethod t h e i r r i g a t o r w i l l c h o o s e t h e s l o p e o f t h e l a n d b o t h G^g* a n d GT7r,** ( F i g u r e 3 ) . B e s i d e s t h e amount o f f i l l i n t h i s m e t hod WE w o u l d be e q u a l t o t h e amount o f c u t . I n t h e b o r d e r i r r i g a t i o n m e t hod an a t t e m p t i s made t o a d j u s t t h e s i z e o f t h e i r r i g a t i o n s t r e a m t o t h e i n t a k 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 , t h e s l o p e o f t h e b o r d e r s t r i p , and t h e a r e a t o be c o v e r e d so as t o p r o v i d e a n e a r l y u n i f o r m t i m e o f w a t e r c o v e r a g e ( i n t a k e o p p o r t u n i t y t i m e ) a t a l l p o i n t s a l o n g t h e l e n g t h o f t h e b o r d e r s t r i p . " ^NS = s-*-°Pe °^ "*-^ e l i n e w h i c h b e s t f i t s t h e p o i n t s w h i c h p r e s e n t t h e a v e r a g e l a n d s l o p e i n a n o r t h t o s o u t h d i r e c t i o n a c r o s s t h e f i e l d . S\JE = s-'- 0P e °^ ^ e l i n e w h i c h b e s t f i t s < t h e p o i n t s w h i c h p r e s e n t t h e a v e r a g e l a n d s l o p e i n ' a w e s t t o e a s t d i r e c t i o n a c r o s s t h e f i e l d . 15. X a x i s - s t a t i o n distances A— P o i n t o f o r i g i n 2L F i e l d boundary O O o o o o o o o H - c e n t r o i d e l m O G r i d corner e v a t i o n D i r e c t i o n o f i r r i g a t i o n O o o F i g u r e 3. An e x a m p l e o f a r e c t a n g u l a r a r e a w h i c h i s t o be g r a d e d . 16. A g e n e r a l k n o w l e d g e o f t h e h y d r a u l i c s o f b o r d e r i r r i g a t i o n s y s t e m i s b a s i c t o b o r d e r s y s t e m p l a n n i n g a nd d e s i g n . T h i s i n c l u d e s t h e d i s c h a r g e , w i d t h o f b o r d e r , l e n g t h o f r u n , s l o p e , w a t e r i n t a k e , d e p t h o f f l o w , t i m e o f i r r i g a -t i o n , t h e t o t a l q u a n t i t y o f w a t e r t o be a p p l i e d , and w a t e r movement i n t o s o i l a n d w a t e r a d v a n c e o v e r t h e l a n d . S i n c e some o f t h e v a r i a b l e s i n v o l v e d i n t h e b o r d e r i r r i g a t i o n s y s t e m h a v e n o t b e e n e v a l u a t e d and t h e i r r e l a t i o n s h i p s h a v e n o t b e e n d e t e r m i n e d , e m p i r i c a l p r o c e d u r e s a r e c u r r e n t l y e m p l o y e d i n t h e d e s i g n o f s u r f a c e i r r i g a t i o n s y s t e m s . S h o c k l e y e t a l . ( 2 2 ) i n d i c a t e t h a t t h e c o m p l e t e l y r a t i o n a l m e thod o f b o r d e r i r r i g a t i o n d e s i g n demands t h a t t h e d e s i g n e r s h o u l d be a b l e t o p r e d i c t t h e i n t a k 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 , t h e r a t e o f a d v a n c e o f t h e water 5' 5 f r o n t m o v i n g down t h e b o r d e r s t r i p , a n d t h e r a t e o f r e c e s s i o n o f w a t e r * * f r o m t h e b o r d e r s t r i p a f t e r t h e i r r i g a t i n g , s t r e a m h a s b e e n t u r n e d o f f . I n t a k e c h a r a c t e r i s t i c s c a n be d e t e r m i n e d f r o m c y l i n d e r i n f i l t r o m e t e r s (13)., a n d a p p r o x i m a t e methods o f p r e d i c t i n g t h e a d v a n c e c u r v e h a v e b e e n p r e p a r e d by H a l l ( 1 4 ) , a nd C h r i s t i a n s e n , B i s h o p a nd Fok ( 7 ) . H o w e v e r , no s a t i s f a c t o r y m ethod h a s b e e n d e v e l o p e d f o r p r e d i c t i n g t h e r a t e o f The r a t e o f a d v a n c e o f w a t e r i s c a l c u l a t e d f r o m t h e t i m e f o r t h e a d v a n c i n g s h e e t t o r e a c h v a r i o u s d i s t a n c e s down t h e f i e l d . The r a t e o f r e c e s s i o n i s c a l c u l a t e d f r o m t h e t i m e t h a t t h e w a t e r r e c e d e s p a s t e a c h s t a t i o n a f t e r t h e w a t e r i s t u r n e d o f f . 1 7 r e c e s s i o n . T h e r e f o r e , S h o c k l e y e t a l . ( 2 2 ) p r o p o s e d a q u a s i -r a t i o n a l m ethod f o r d e s i g n i n g a b o r d e r s t r i p i r r i g a t i o n . They e m p h a s i z e d t h a t i r r i g a t i o n w o u l d be most u n i f o r m i f i n t a k e o p p o r t u n i t y t i m e was t h e same f o r t h e e n t i r e l e n g t h o f t h e b o r d e r . T h e r e a r e a number o f v a r i a b l e s w h i c h s h o u l d be c o n -s i d e r e d when d e s i g n i n g a b o r d e r s t r i p method. T h e s e v a r i a b l e a r e ; s i z e o f s t r e a m , r a t e o f a d v a n c e a nd r e c e s s i o n , l e n g t h o f r u n , b o r d e r w i d t h , d e p t h o f f l o w , i n t a k e r a t e , s l o p e o f l a n d s u r f a c e , e r o s i o n h a z a r d , and d e p t h o f w a t e r t o be a p p l i e d ( 2 1 ) . Among t h e v a r i a b l e s s i z e o f s t r e a m , s l o p e o f l a n d s u r f a c e , l e n g t h o f r u n , b o r d e r w i d t h and i n t a k e r a t e a r e v e r y i m p o r t a n t a n d s h o u l d be c o n s i d e r e d c a r e f u l l y . M a r r ( 1 9 ) has p r o p s o e d a t a b l e w h i c h c a n be u s e d f o r e s t i m a t i o n o f t h e s v a r i a b l e s . 'In t h i s t a b l e f o r e a c h s o i l t e x t u r e b e s t l e n g t h , s l o p e , w i d t h and d i s c h a r g e h a v e been s u g g e s t e d . The U n i t e d S t a t e s D e p a r t m e n t o f A g r i c u l t u r e i n L e a f l e t No. 29 7 ( 6 ) s u g g e s t e d a n o t h e r t a b l e f o r e s t i m a t i n g t h e s e v a r i a b l e s . P h e l a n and C r i d d l e - ( 2 0 ) h a v e g i v e n a t a b l e w h i c h g i v e s t h e b o r d e r i r r i g a t i o n r e l a t i o n s h i p s f o r v a r i o u s s o i l s , s l o p e s , and d e p t h o f a p p l i c a t i o n . The t a b l e s d i s c u s s e d a r e t e n t a t i v e f o r e s t i m a t i n g t h e b o r d e r i r r i g a t i o n v a r i a b l e s b e c a u s e t h e y a r e o f a t e m p o r a r y n a t u r e . L e w i s a n d M i l n e ( 1 6 ) d e s c r i b e d t h e a d v a n c i n g f r o n t o f t h e b o r d e r i r r i g a t i o n s t r e a m m a t h e m a t i c a l l y and p o i n t e d 18. o u t t h a t p a r a l l e l a d v a n c e and r e c e s s i o n p r o v i d e s u n i f o r m i n t a k e o p p o r t u n i t y t i m e and may be o b t a i n e d by s t o p p i n g t h e i n f l o w b e f o r e t h e a d v a n c i n g f r o n t r e a c h e s t h e end o f t h e b o r d e r . C r i d d l e and D a v i s ( 1 0 ) p r o p o s e d a method f o r d e s i g n i n g t h e b o r d e r i r r i g a t i o n s y s t e m . They h a v e p r e p a r e d a c h a r t on w h i c h one c o u l d d e s i g n a b o r d e r s t r i p i r r i g a t i o n i f t h e d a t a on i n t a k e r a t e , s o i l , t h e d e p t h o f a p p l i e d w a t e r , and t h e s l o p e a r e a v a i l a b l e . The b o r d e r s t r i p i r r i g a -t i o n h a s b e e n e v a l u a t e d by C r i d d l e e t a l . ( 9 ) and t h e y h a v e p r o p o s e d a method f o r t h i s e v a l u a t i o n . H a l l ( 1 4 ) p r e s e n t e d a p r a c t i c a l m e t hod f o r p r e d i c t i n g t h e r a t e o f w a t e r a d v a n c e m o v i n g down an i r r i g a t i o n b o r d e r w h i c h s i m p l i f i e s t h e d e s i g n o f a b o r d e r s t r i p i r r i g a t i o n s y s t e m . As C r i d d l e e t a l . ( 9 ) i n d i c a t e d , b o r d e r i r r i g a t i o n s h o u l d be e v a l u a t e d a f t e r d e s i g n i n g and c o n s t r u c t i n g i n o r d e r t o o b t a i n h i g h w a t e r a p p l i c a t i o n e f f i c i e n c y and w a t e r d i s t r i b u t i o n . From t h e f o r e g o i n g d i s c u s s i o n , i t i s c o n c l u d e d t h a t f o r d e s i g n i n g a b o r d e r s t r i p i r r i g a t i o n s y s t e m one s h o u l d e s t i m a t e t h e a d v a n c e o f t h e w a t e r f r o n t as a f u n c t i o n o f t i m e , t h e r a t e o f f l o w , t h e s l o p e , t h e d e p t h o f w a t e r i n t h e b o r d e r , t h e i n f i l t r a t i o n c h a r a c t e r i s t i c s o f . t h e s o i l , and t h e d e p t h o f r o o t i n g zone t o be r e p l e n i s h e d , t h a t i s , t h e t o t a l q u a n t i t y o f w a t e r " t o be a p p l i e d . V. INFORMATION REQUIRED F o r d e v e l o p i n g a b o r d e r i r r i g a t i o n s y s t e m some i n f o r m a t i o n on c l i m a t e , s o i l s , c r o p s and o t h e r v a r i a b l e s i r e q u i r e d i n o r d e r t o o b t a i n a w e l l d e s i g n e d s y s t e m . 1) C l i m a t e Some c l i m a t i c v a r i a b l e s s u c h as w i n d , t e m p e r a t u r e r e l a t i v e h u m i d i t y , e t c . d e t e r m i n e t h e e v a p o t r a n s p i r a t i o n w h i c h i s u s e d a l o n g w i t h t h e p r e c i p i t a t i o n , w h i c h i s a l s o c l i m a t i c v a r i a b l e , t o d e t e r m i n e t h e d e p t h o f w a t e r t o be a p p l i e d - t o a c r o p d u r i n g a s e a s o n . T h e r e f o r e , t h e i r r i g a -t i o n r e g i m e i s g o v e r n e d by c l i m a t i c v a r i a b l e s . R a i n a nd snow w h i c h f a l l on i r r i g a t e d l a n d s a r e v a l u a b l e as a s o u r c e o f w a t e r . The d a t a on p r e c i p i t a t i o n w i l l show how much w a t e r m i g h t be a v a i l a b l e d u r i n g an i r r i g a t i o n s e a s o n . .. . Where i r r i g a t i o n w a t e r i s a p p l i e d by f l o o d i n g m e t h o d s , l a r g e amounts o f w a t e r a r e l o s t by d i r e c t e v a p o r a t i o n f r o m t h e s o i l s u r f a c e w i t h o u t h a v i n g p a s s e d t h r o u g h r o o t s , s t e m s , and l e a v e s o f t h e p l a n t s . .When p l a n n i n g i r r i g a t i o n p r o j e c t s d a t a on b o t h e v a p o r a t i o n and t r a n s p i r a t i o n s h o u l d be a v a i l a b l e s o t h a t t h e d e s i g n e r w i l l be a b l e t o p r e d i c t t h e d e p t h o f a p p l i c a t i o n o f w a t e r . S e v e r a l m ethods h a v e b e e n s u g g e s t e d f o r m e a s u r i n g p r e c i p i t a t i o n and e v a p o t r a n s p i r a t i o n . A l l ! f o r m s o f 20 p r e c i p i t a t i o n a r e m e a s u r e d i n t h e b a s i s o f t h e v e r t i c a l d e p t h o f w a t e r t h a t w o u l d a c c u m u l a t e on a l e v e l s u r f a c e i f t h e p r e c i p i t a t i o n r e m a i n e d where i t f e l l ( 2 1 ) . The b e s t r e c o r d s a r e o b t a i n e d a t s t a t i o n s w h i c h a r e e q u i p p e d w i t h c o n t i n u o u s r a i n f a l l r e c o r d s . Mot o n l y t h e t o t a l . a m o u n t o f p r e c i p i t a t i o n i s g i v e n , b u t a l s o t h e i n t e n s i t y o f e a c h s t o r m c a n be r e c o r d e d . U s u a l l y f o r m e a s u r i n g t h e amount o f p r e c i p i t a t i o n and i n t e n s i t y a w e i g h i n g o r t i p p i n g b u c k e t t y p e gauge i s u s e d ( 2 1 ) . I f o n l y t h e amount o f p r e c i p i t a t i o n i s r e q u i r e d , t h e U n i t e d S t a t e s W e a t h e r B u r e a u n o n - r e c o r d i n g ( s t a n d a r d ) r a i n gauge (8 i n c h e s i n d i a m e t e r ) i s u s e d . I n o r d e r t o d e t e r m i n e s e a s o n a l and peak c r o p w a t e r n e e d s , a means o f m e a s u r i n g o r e s t i m a t i n g s e a s o n a l and peak e v a p o t r a n s p i r a t i o n i s n e c e s s a r y . The most d i r e c t method o f measurement o f e v a p o -t r a n s p i r a t i o n . i s by l y s i m e t e r ( 1 5 ) . A l y s i m e t e r i s a c o n -t a i n e r i n w h i c h p l a n t s a r e grown u n d e r s i m u l a t e d n a t u r a l c o n d i t i o n s . The c o n t a i n e r and c o n t e n t s a r e w e i g h e d a t r e g u l a r i n t e r v a l s t o d e t e r m i n e w a t e r l o s s by e v a p o t r a n s p i r a -t i o n . H o w e v e r , c o n d i t i o n s and f a c i l i t i e s w i l l n o t a l w a y s p e r m i t t h e w e i g h i n g o f t h e c o n t a i n e r . A l s o t h e method i s a s l o w and l a b o r i o u s p r o c e s s . Many e m p i r i c a l f o r m u l a s ( 1 5 ) h a v e b e e n d e v e l o p e d f o r e s t i m a t i n g 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 * b a s e d on c l i m a t o l o g i c a l m e a s u r e m e n t s . * 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 i s t h e amount o f w a t e r t h a t c o u l d be e v a p o t r a n s p i r e d i n a u n i t t i m e by a s h o r t g r e e n c r o p o f u n i f o r m h e i g h t c o m p l e t e l y s h a d i n g ! t h e g r o u n d and n e v e r l a c k i n g f o r w a t e r . I f t h e r e a r e no d a t a on w e a t h e r m e a s u r e m e n t s , t h e e v a p o r a t i o n may be o b t a i n e d f r o m an e v a p o r a t i o n p a n . The S t a n d a r d W e a t h e r B u r e a u C l a s s A Pan ( 2 1 ) i s n o r m a l l y u s e d f o r d e t e r m i n i n g e v a p o r a t i o n w h i c h c o u l d be c o n v e r t e d t o e v a p o t r a n s p i r a t i o n by c o n s i d e r i n g a c r o p f a c t o r . T h i s f a c t o r v a r i e s w i t h t h e c r o p v a r i e t y , t h e c r o p ' s s t a g e o f m a t u r i t y , and t h e f r a c t i o n o f s o i l s u r f a c e c o v e r e d by t h e c r o p . 2) S o i l K n o w l e d g e o f s o i l a n d w a t e r r e l a t i o n s h i p s i s v a l u a b l e t o a l l who h a v e t h e o p p o r t u n i t y t o d e v e l o p i r r i g a -t i o n s y s t e m s , t o o b t a i n t h e b e s t u s e o f w a t e r a v a i l a b l e f o r t h e i r l a n d s . S o i l t e x t u r e i s t h e t e r m commonly u s e d t o d e s i g n a t e t h e s i z e o r s i z e s o f t h e m i n e r a l p a r t i c l e s i n a g i v e n s o i l . The r e l a t i v e p r o p o r t i o n s o f s a n d , s i l t , and c l a y d e t e r m i n e t h e s o i l t e x t u r e . T h i s p r o p e r t y o f s o i l c a n p l a y an i m p o r t a n t p a r t i n t h e d e s i g n o f an i r r i g a t i o n s y s t e m . I t a f f e c t s t h e s o i l - w a t e r i n t a k e r a t e , s o i l - w a t e r h o l d i n g c a p a c i t y , and m o i s t u r e c o n t e n t o f t h e s o i l . A l t h o u g h t h e r e a r e s e v e r a l p r i n c i p l e s t h a t c o u l d be e m p l o y e d t o d e t e r m i n e a s o i l ' s t e x t u r e , t h e most w i d e l y u s e d i s b a s e d upon c h a n g e s i n d e n s i t y o f t h e s o i l p a r t i c l e s s u s p e n d e d i n w a t e r w i t h t i m e a t a g i v e n d e p t h . The p i p e t t e and h y d r o m e t e r methods ( 1 1 ) a r e c l a s s i c a l e x a m p l e s o f t h i s p r i n c i p l e . Summation p e r c e n t a g e c u r v e s o f t h e d i f f e r e n t s e p a r a t e s f r o m p a r t i c l e -s i z e a n a l y s e s c a n be p l o t t e d as a c o n t i n u o u s f u n c t i o n o f d i a m e t e r . Then by u s i n g t e x t u r a l c l a s s i f i c a t i o n c h a r t ( 2 1 ) , one c o u l d d e t e r m i n e t h e s o i l t e x t u r e . S o i l s t r u c t u r e i m p l i e s an a r r a n g e m e n t o f t h e p r i m a r y and s e c o n d a r y p a r t i c l e s i n t o c e r t a i n s t r u c t u r a l p a t t e r n s . I t n e c e s s a r i l y f o l l o w s t h a t s u c h p a t t e r n s i n c l u d e t h e a c c o m p a n y i n g p o r e s p a c e . P o r e s p a c e p l a y s an i m p o r t a n t r o l e i n i r r i g a t i o n p r a c t i c e s b e c a u s e i t a f f e c t s w a t e r c o n t e n t o f t h e s o i l . The r a t e o f e n t r y o f w a t e r i n t o t h e s o i l u n d e r f i e l d c o n d i t i o n s i s c a l l e d i n t a k e r a t e ( 1 5 ) . I t v a r i e s w i t h many f a c t o r s i n c l u d i n g d e p t h o f w a t e r on t h e s u r f a c e , s o i l s t r u c -t u r e a n d m o i s t u r e c o n t e n t o f t h e s o i l . S o i l i n t a k e c h a r a c -t e r i s t i c s c a n be d e t e r m i n e d s a t i s f a c t o r i l y f r o m b o r d e r t r i a l s ( 2 2 ) o r f r o m c y l i n d e r i n f i l t r o m e t e r t e s t s ( 1 3 ) . The w a t e r h o l d i n g c a p a c i t y o f t h e s o i l i s t h e amount o f w a t e r i t c a n h o l d . C o a r s e t e x t u r e d s o i l s , . s u c h as s a n d y s o i l s , h o l d l e s s w a t e r t h a n f i n e t e x t u r e d s o i l s s u c h as c l a y s o i l s . T h i s means t h a t i f t h e s o i l i s a c o a r s e t e x t u r e d s o i l t h e i r r i g a t i o n s y s t e m must be d e s i g n e d t o a p p l y w a t e r more f r e q u e n t l y t h a n i f i t i s a f i n e t e x t u r e d s o i l . S o i l m o i s t u r e c o n t e n t i s one o f . t h e . m o s t i m p o r t a n t f a c t o r s t h a t s h o u l d be d e t e r m i n e d b e c a u s e i t a f f e c t s t h e d e p t h o f w a t e r w h i c h s h o u l d be a p p l i e d t o t h e s o i l . T h e r e a r e s e v e r a l m ethods ( 1 5 ) f o r d e t e r m i n i n g t h e s o i l m o i s t u r e . 23 . Among them, t h e n e u t r o n m o i s t u r e m e t e r i s much u s e d i n t h e f i e l d f o r m e a s u r i n g w a t e r c o n t e n t . I t i s a n o n - d e s t r u c t i v e m e t hod and i n t h i s m e t hod m o i s t u r e c o n t e n t on a v o l u m e b a s i s c a n be d e t e r m i n e d i n t h e f i e l d . When w o r k i n g w i t h i r r i g a t e d s o i l s , i t i s n e c e s s a r y t o know t h e i r a p p a r e n t s p e c i f i c g r a v i t y ( 1 5 ) -- o r s o m e t i m e s c a l l e d " b u l k d e n s i t y " -- i n o r d e r t o a c c o u n t f o r t h e w a t e r a p p l i e d i n i r r i g a t i o n . The b u l k d e n s i t y o f t h e s o i l i s i n f l u e n c e d by s t r u c t u r e , t e x t u r e , and c o m p a c t n e s s o f t h e s o i l p a r t i c l e s . The u s u a l method f o r d e t e r m i n i n g t h i s p r o p e r t y o f t h e s o i l i s t o o b t a i n an u n c o m p a c t e d and u n d i s -t u r b e d s o i l s a m p l e u s i n g 7.3 cm ( d i a m e t e r ) c o r e s . A n o t h e r method f o r m e a s u r i n g b u l k d e n s i t y i s by t h e gamma-ray a b s o r p t i o n t e c h n i q u e ( 1 5 ) . T h i s i s a measurement o f b u l k d e n s i t y i n t h e f i e l d . O t h e r i n f o r m a t i o n s u c h as g e o g r a p h i c a l l o c a t i o n , s i z e a n d a r e a o f t h e f i e l d , c r o p s t o be grown on t h e f i e l d , s l o p e , a v a i l a b l e s u r f a c e 1 and s u b - s u r f a c e d r a i n a g e s y s t e m s , s o u r c e o f w a t e r , a n d t h e d e p t h o f r o o t i n g o f t h e c r o p s h o u l d be a v a i l a b l e i n o r d e r t o . o b t a i n a more e f f i c i e n t a n d e c o n o m i c a l b o r d e r i r r i g a t i o n s y s t e m . VI. DEVELOPING A BORDER STRIP IRRIGATION SYSTEM F o r d e v e l o p i n g a b o r d e r s t r i p i r r i g a t i o n s y s t e m f o u r f a c t o r s s h o u l d be c o n s i d e r e d . . T h e s e f a c t o r s a r e : ( a ) s l o p e , (b) s t r e a m s i z e , ( c ) b o r d e r w i d t h , and ( d ) l e n g t h o f r u n . B e c a u s e t h e w a t e r i s r e q u i r e d t o f l o w t h e l e n g t h o f t h e b o r d e r , some g r a d e i s u s u a l l y p r o v i d e d i n t h e d i r e c t i o n o f i r r i g a t i o n f l o w . T h i s s l o p e i s commonly u n d e r s t o o d t o be t h e amount o f f a l l p e r u n i t o f l e n g t h o f t h e s t r i p , e x p r e s s e i n f e e t ' o f f a l l p e r 100 f e e t o f l e n g t h o r i n p e r c e n t . B e f o r e c o n s t r u c t i n g t h e b o r d e r s t r i p s , t h e l a n d s h o u l d be g r a d e d i n o r d e r t o o b t a i n a u n i f o r m s l o p e . A c c o r d i n g t o t h e l e a s t s q u a r e s and a v e r a g e p r o f i l e s method ( 1 8 ) , t h e s t a k e s a r e s e t . and e l e v a t i o n s a r e o b t a i n e d a t 100 f o o t i n t e r v a l s , 50 f e e t i n f r o m .the p r o p e r t y l i n e s , t h u s f o r m i n g a g r i d w i t h t h e e l e v a t i o n known a t e a c h g r i d c o r n e r . F o r g r a d e c a l c u l a t i o n p u r p o s e s , t h e g r i d c o r n e r s a r e l o c a t e d by a s y s t e m o f c o o r d i n a t e s . I n t h i s c a s e , t h e p o i n t o f o r i g i n "A" i s l o c a t e d 50 f e e t n o r t h and 50 f e e t w e s t o f t h e n o r t h - w e s t c o r n e r o f t h e f i e l d . The l o c a t i o n s o f t h e g r i d c o r n e r s a r e d e s i g n a t e d i n s t a t i o n s (number o f 100 f o o t i n t e r v a l s ) s o u t h w a r d a l o n g t h e Y - a x i s and e a s t w a r d a l o n g t h e X - a x i s f r o m "A" ( F i g u r e 3 ) . The f i r s t s t e p i n t h e c a l c u l a t i o n ' s c o n s i s t s o f a d d i n g t h e e l e v a t i o n s a l o n g e a c h l i n e and i n e a c h c o l u m n and c o m p u t i n g t h e a v e r a g e e l e v a t i o n o f e a c h l i n e and c o l u m n . 25 . The s e c o n d s t e p c o n s i s t s o f l o c a t i n g t h e c e n t r o i d and d e t e r m i n i n g i t s e l e v a t i o n , "H ". The l o c a t i o n o f t h e m c e n t r o i d i s g i v e n by t h e a v e r a g e s t a t i o n d i s t a n c e s f r o m "A" on t h e X and Y a x e s , o r X and Y , s o : m m • X _ sum o f s t a t i o n d i s t a n c e s i n X d i r e c t i o n m number o f s t a t i o n s i n X d i r e c t i o n Y - sum o f s t a t i o n d i s t a n c e s i n Y d i r e c t i o n m number o f s t a t i o n s i n Y d i r e c t i o n The t h i r d s t e p c o n s i s t s o f d e t e r m i n i n g s l o p e s o f t h e l i n e s w h i c h most n e a r l y f i t t h e a v e r a g e p r o f i l e s i n t h e two c o o r d i n a t e d i r e c t i o n s . A c c o r d i n g t o t h e l e a s t s q u a r e s m e t h o d , t h e s l o p e o f t h e l i n e w h i c h b e s t f i t s t h e p o i n t s on e a c h o f t h e s e two p r o f i l e s i s : n n n ( E S ) ( E H.) £ (S._ H ) - i = l y i i = l 1 G N S - n : : n—— (1) £ ( S ) - ( £ S ) Z i = l y i i = l y i n and n n n £ ( S H ) - ' ( E S ) (E H.) i = l i i i = l x i i = l 1 G . = — ^ ( 2 ) WE n 9 n „ E (s ) Z - (E s -r . , x. . , x. X = 1 1 1 = 1 1 n w here G ^ = s l o p e o f t h e l i n e w h i c h b e s t f i t s t h e p o i n t s w h i c h r e p r e s e n t t h e a v e r a g e l a n d s l o p e i n a n o r t h t o s o u t h d i r e c t i o n a c r o s s t h e f i e l d . 26 G r ] T - s l o p e o f t h e l i n e w h i c h b e s t f i t s t h e p o i n t s w h i c h r e p r e s e n t t h e a v e r a g e l a n d s l o p e i n a w e s t t o e a s t d i r e c t i o n a c r o s s t h e f i e l d . n E = sum o f n v a l u e s i = l t h e sum o f t h e p r o d u c t o f t h e s t a t i o n , i H i ~ d i s t a n c e a n d e l e v a t i o n o f e a c h o f t h e i = l p l o t t e d p o i n t s n n i = l " i = l The p r o d u c t o f t h e sums o f t h e s t a t i o n E S ) ( E H ) " d i s t a n c e s and t h e e l e v a t i o n o f e a c h o f t h e p l o t t e d p o i n t s . n = t h e number o f p l o t t e d p o i n t s . n 9 E ( S . ) = t h e sum o f s q u a r e s o f t h e s t a t i o n d i s t a n c e s i = l 1 o f e a c h o f t h e p l o t t e d p o i n t s . ( E S.) = t h e s q u a r e o f t h e sum o f t h e s t a t i o n i = l 1 d i s t a n c e o f e a c h o f t h e p l o t t e d p o i n t s The f o u r t h s t e p c o n s i s t s o f u s i n g s l o p e s G N g and G77T. and t h e e l e v a t i o n o f t h e c e n t r o i d t o d e l i n e a t e t h e p l a n e WE w h i c h b e s t f i t s a l l o f t h e g r i d c o r n e r e l e v a t i o n s . The e l e v a t i o n o f t h e p o i n t "A", a , i s f o u n d b y : a = H - ( G n r ) ( X ) - ( G M Q ) ( Y ) ( 3 ) m WE m Nb . m I n t h i s e q u a t i o n t h e o n l y unknown e l e m e n t i s " a " w h i c h c o u l d be d e t e r m i n e d . The new e l e v a t i o n s w h i c h w o u l d 2 7 c o r r e s p o n d w i t h t h e o l d e l e v a t i o n s w o u l d be f o u n d f r o m : H 7 = a + ( G . . r ) ( X ) + ( G M C J ( Y ) . (4) new Wt No Then- t h e amount o f c u t o r f i l l w o u l d be d e t e r m i n e d f o r e a c h g r i d c o r n e r . An e x a m p l e o f t h i s m ethod i s r e p r e s e n t e d i n A p p e n d i x I . I n t h i s e q u a t i o n , G T 1„ and G.TO a r e d e p e n d e n t on t h e g e n e r a l t o p o g r a p h y o f t h e l a n d and t h e amount o f c u t i s n o t u s u a l l y e q u a l t o t h e amount o f f i l l . I t w i l l be f o u n d i n some i n s t a n c e s t h a t s l o p e s c a l c u l a t e d by t h i s m e t hod a r e e i t h e r t o o f l a t o r t o o s t e e p t o s u i t t h e c r o p o r p r e f e r r e d m ethod ,of i r r i g a t i o n . T h i s d i f f i c u l t y c o u l d be s o l v e d i f G^g and G ^ a r e g i v e n . I t i s r e p r e s e n t e d i n t h e A p p e n d i x I I , The most d e s i r a b l e s i z e o f s t r e a m c a n be d e t e r m i n e d by a s e r i e s o f c u r v e s ( 9 ) . T h e s e c u r v e s a r e u s e d i n e s t i m a -t i o n o f t h e u n i t s t r e a m s i z e as a f u n c t i o n o f b a s i c i n t a k e r a t e , s l o p e , and d e p t h o f w a t e r t o be a p p l i e d . The d e p t h o f w a t e r t o be a p p l i e d i s d e t e r m i n e d b y : P X B . D . X D P X D " W o r d = (5) where 100 • 100 d = d e p t h o f w a t e r t o be a p p l i e d (cm) P = a v a i l a b l e w a t e r s t o r a g e c a p a c i t y o f t h e s o i l on d r y w e i g h t b a s i s ( p e r c e n t a g e ) B.D. = b u l k d e n s i t y o f t h e s o i l D = d e p t h o f t h e r o o t i n g zone w h i c h i s i r r i g a t e d i P v =" a v a i l a b l e w a t e r s t o r a g e c a p a c i t y o f t h e s o i l i n v o l u m e b a s i s ( p e r c e n t a g e ) . 28 . The a c t u a l i r r i g a t i o n s t r e a m n e e d e d f o r any g i v e n b o r d e r s t r i p i r r i g a t i o n c a n be d e t e r m i n e d by ( 1 0 ) : Q = q X W ( 6 ) where Q = r e q u i r e d i r r i g a t i n g s t r e a m ( c f s ) q = u n i t s t r e a m s i z e * ( c f s ) L = l e n g t h o f r u n ( f t ) W = w i d t h o f b o r d e r s t r i p ( f t ) The above f o r m u l a c a n be t r a n s p o s e d t o p r o v i d e a d i r e c t s o l u t i o n f o r t h e l e n g t h o f r u n ( L ) and t h e w i d t h o f t h e b o r d e r s t r i p (W) by: L = ( 7 ) q x W and W = ^ (8) q x L S ometimes t h e s i z e o f t h e f i e l d d i c t a t e s t h e d e s i r e d l e n g t h o f r u n and w i d t h o f a b o r d e r s t r i p . I n s u c h a c a s e , t h e e x i s t i n g s i z e o f t h e f i e l d must be c o n s i d e r e d t o m e a s u r e t h e d i s c h a r g e and- t h e t i m e o f a p p l i c a t i o n * * . A f t e r d e s i g n i n g t h e b o r d e r s t r i p i r r i g a t i o n s y s t e m , i t s h o u l d be e v a l u a t e d i n o r d e r t o o b t a i n maximum e f f i c i e n c y . The e v a l u a t i o n p r o c e s s h a s been p r o p o s e d by C r i d d l e e t a l . ( 9 ) , * The u n i t s t r e a m s i z e i s d e f i n e d as t h e s t r e a m i n f t / s e c r e q u i r e d f o r e a c h 100 f o o t l e n g t h o f b o r d e r s t r i p one f o o t w i d e . ** Time o f a p p l i c a t i o n = t i m e o f s p r e a d o f w a t e r + t i m e r e q u i r e d t o f i l l t h e r o o t zone o f t h e s o i l t o f i e l d c a p a c i t y f r o m t h e i n i t i a l m o i s t u r e c o n t e n t . 29 . E x p e r i m e n t F o r d e v e l o p i n g a b o r d e r s t r i p i r r i g a t i o n s y s t e m , a 60 a c r e f i e l d i n t h e N i c o l a V a l l e y a r e a was c h o s e n . The f i e l d was s u r v e y e d w i t h a 100 f o o t g r i d s y s t e m o f l e v e l s . The l e a s t s q u a r e s a n d a v e r a g e p r o f i l e s method was u s e d f o r c a l c u l a t i n g t h e l a n d g r a d i n g . The p r o c e d u r e f o r l a n d g r a d i n g h a s b e e n d e s c r i b e d i n C h a p t e r V I . T h e r e a r e two d i t c h e s i n t h e f i e l d ( F i g u r e 4) s e p a r a t i n g i t i n t o t h r e e d i f f e r e n t s e c t i o n s ; t h e r e f o r e t h e 60 a c r e s o f l a n d was d i v i d e d i n t o t h r e e s e c t i o n s f o r l a n d g r a d i n g . E a c h s e c t i o n was g r a d e d i n d e p e n d e n t l y . F o r e a c h s e c t i o n G..„ and G.„ and & , NS WE t h e amount o f c u t and f i l l w ere c a l c u l a t e d . The l e f t t o p s e c t i o n o f t h e f i e l d was c h o s e n f o r t h e c o n s t r u c t i o n o f b o r d e r s t r i p s . T h r e e b o r d e r s t r i p s e a c h h a v i n g a l e n g t h o f 600 f e e t were c o n s t r u c t e d w i t h d i f f e r e n t w i d t h s ( t w o s t r i p s h a v i n g t h e w i d t h o f 25 and one o f 50 f e e t ) . The r e a s o n s f o r t h i s s e l e c t i o n were due t o t h e l i m i t a t i o n s o f t h e f i e l d and f a r m e r ' s p r e f e r e n c e s . I n e a c h b o r d e r s t r i p 3 a l u m i n u m t u b e s ( 2 " d i a m e t e r ) w e re i n s t a l l e d i n t o t h e s o i l i n o r d e r t o m e a s u r e t h e s o i l m o i s t u r e c o n t e n t and b u l k d e n s i t y o f t h e d i f f e r e n t d e p t h s o f t h e s o i l by means o f n u c l e a r p r o b e s . The f i r s t s t e p i n d e v e l o p i n g a b o r d e r s t r i p i r r i g a -t i o n i s t o d e t e r m i n e t h e b a s i c i n t a k e r a t e o f t h e s o i l . The d o u b l e r i n g i n f i l t r o m e t e r was u s e d t o ( m e a s u r e t h e b a s i c i n t a k e r a t e . D o u b l e r i n g s c o n s i s t o f two m e t a l c y l i n d e r s , Creek 30 l o c a t i o n 1 loc a t i o n - 2 l o c a t i o n 3 I r r i g a t i o n D i t c h (1) UPPER TOP SECTION I r r i g a t i o n D i t c h (2) LOWER BOTTOM SECTION NICOLA LAKE Scale: 1" - 400' Figure 4. I r r i g a t i o n d i t c h e s 1 and 2 d i v i d e the f i e l d i n t o 3 s e c t i o n s . The l o c a t i o n s o f holes f o r s o i l sampling are i n d i c a t e d i n each border s t r i p . 31. one s l i g h t l y l a r g e r t h a n t h e o t h e r . The d i a m e t e r s o f t h e c y l i n d e r s w e r e 10 and 8 i n c h e s r e s p e c t i v e l y . The l e n g t h o f each, c y l i n d e r was 18 i n c h e s i n w h i c h 4 i n c h e s o f e a c h c y l i n d e r was d r i v e n i n t o t h e s o i l . W a t e r was a d d e d t o t h e s e c y l i n d e r s and t h e r a t e o f w h i c h i t was a b s o r b e d d u r i n g r e c o r d e d t i m e p e r i o d s was d e t e r m i n e d . Two i n f i l t r o m e t e r s w e r e i n s t a l l e d i n t h e s o i l , b o t h i n t h e m i d d l e s t r i p , one 100 f e e t f r o m t h e u p p e r end and t h e o t h e r 100 f e e t f r o m t h e l o w e r end o f t h e s t r i p . The b a s i c i n t a k e r a t e ( w h i c h i s t h e r a t e a t w h i c h w a t e r w o u l d e n t e r t h e s o i l a f t e r a p e r i o d o f s e v e r a l h o u r s , when t h e c h a n g e i n t h e r a t e becomes v e r y s l o w ) was d e t e r m i n e d . C o r e s a m p l e s as w e l l as b u l k s o i l s a m p l e s were t a k e n a t 3 l o c a t i o n s ( F i g u r e 4, l o c a t i o n 1, 2 and 3 ) . B o t h c o r e and b u l k s a m p l e s were t a k e n a t a p p r o x i m a t e l y t h e same d e p t h a t w h i c h s o i l m o i s t u r e m e a s u r e m e n t s were e s t i m a t e d , t o a d e p t h o f 36 i n c h e s ( t h e a v e r a g e r o o t i n g zone o f a l f a l f a , c l o v e r and o a t s i s 36 i n c h e s ) . I n o r d e r - t o m e a s u r e t h e s o i l t e x t u r e , t h e b u l k s a m p l e s f r o m d i f f e r e n t d e p t h s ( 0 - 6 " , 6"-12", 1 2 " - 1 8 " , 1 8 " - 2 4 " , 2 i 4 " - 3 0 " , and 30"-36") were t a k e n a t t h e 3 l o c a t i o n s . A l l o f the 18 samples were s i e v e d t h r o u g h a 2 mm s i e v e t o s e p a r a t e t h e g r a v e l f r o m t h e " f i n e e a r t h " . A p p r o x i m a t e l y 40 grams o f e a c h s a m p l e was m i x e d w i t h 30 m l o f w a t e r and 100 m l o f 6% o f H 9 0 Q ( H 9 0 9 i s u s e d t o remove t h e o r g a n i c 32 . m a t t e r i n t h e s a m p l e ) . E a c h m i x t u r e was h e a t e d on a h o t p l a t e a n d 5 m l o f 30% was a d d e d t o remove a l l o r g a n i c m a t t e r . E a c h m i x t u r e was t r a n s f e r r e d t o an a g i t a t o r and a g i t a t e d f o r 15 m i n u t e s . Then e a c h m i x t u r e was t r a n s f e r r e d t o a one l i t e r c y l i n d e r . W a t e r was a d d e d t o make t h e v o l u m e up t o one l i t e r a n d i t was k e p t a t 20°C f o r 24 h o u r s . U s i n g t h e h y d r o m e t e r method ( 1 1 ) t h e c h a n g e i n t h e d e n s i t y o f t h e s o l u t i o n w i t h t i m e a t a d i f f e r e n t d e p t h was m e a s u r e d . Summation p e r c e n t a g e c u r v e s o f t h e d i f f e r e n t s e p a r a t e s f r o m p a r t i c l e s i z e a n a l y s i s were p l o t t e d as a c o n t i n u o u s f u n c t i o n o f d i a m e t e r . T h e n , t h e t e x t u r e o f t h e s o i l was d e t e r m i n e d by t e x t u r a l c l a s s i f i c a t i o n c h a r t ( 2 1 ) . L a b o r a t o r y e x p e r i m e n t s w e re c a r r i e d o u t on t h e c o r e s a m p l e s and b u l k s a m p l e s t o d e t e r m i n e t h e s o i l w a t e r c h a r a c t e r i s t i c s a t t h e d i f f e r e n t d e p t h s ( 0 - 6 " , 6"-12", 1 2 " - 1 8 " , 1 8 " - 2 4 " , 214"-30" , and 3 0 " - 3 6 " ) , s o i l b u l k d e n s i t y , a v a i l a b l e w a t e r s t o r a g e c a p a c i t y , and p o r o s i t y f o r t h e 3 l o c a t i o n s . The s o i l w a t e r t e n s i o n , t h e t e n a c i t y w i t h w h i c h t h e s o i l h o l d s w a t e r a g a i n s t a p u l l , as a f u n c t i o n o f v o l u m e t r i c w a t e r c o n t e n t was d e f i n e d f o r t h e s o i l s f r o m t h e v a r i o u s d e p t h s o v e r a r a n g e o f z e r o t o 15 a t m o s p h e r e s . T h i s was a c c o m p l i s h e d i n t h r e e s t a g e s ( 3 ) . From z e r o t o 100 cm H^O t e n s i o n , a h a n g i n g c o l u m n w a t e r manometer was u s e d . From 100 t o 1000 cm H O t e n s i o n , t h e p r e s s u r e p l a t e w i t h t h e h a n g i n g c o l u m n m e r c u r y manometer e q u i p m e n t and f o r t e n s i o n s r a n g i n g f r o m one a t m o s p h e r e t o 15 a t m o s p h e r e s , t h e h i g h p r e s s u r e membrane a p p a r a t u s were u s e d . A f t e r t h e f i r s t s t a g e , c o r e s a m p l e s were p u t i n t h e o v e n and k e p t a t 10 5°C f o r 2 4 h o u r s . The b u l k d e n s i t y a t e a c h d e p t h was d e t e r m i n e d by ( 1 5 ) : g D - w e i g h t o f d r y s o i l t o t a l v o l u m e o f s o i l * Two p a r a m e t e r s , f i e l d c a p a c i t y and t h e p e r m a n e n t w i l t i n g p o i n t ( 5 ) a r e i m p o r t a n t i n t e r m s o f a v a i l a b l e w a t e r h o l d i n g c a p a c i t y . " F i e l d c a p a c i t y " i s t h e s o i l w a t e r c o n -t e n t r e t a i n e d by t h e s o i l f o l l o w i n g an i r r i g a t i o n o r h e a v y r a i n , a f t e r downward movement o f w a t e r has m a t e r i a l l y d e c r e a s e d . I t i s t h e u p p e r l i m i t o f s o i l w a t e r a v a i l a b l e f o r p l a n t u s e . I t u s u a l l y o c c u r s a t a b o u t 0.3 b a r s o f s o i l m o i s t u r e t e n s i o n . " P e r m a n e n t w i l t i n g p o i n t " i s t h e w a t e r c o n t e n t o f t h e s o i l when p l a n t s g r o w i n g i n i t a r e w i l t e d t o t h e p o i n t where t h e y , w i l l n o t r e c o v e r when p l a c e d i n a h u m i d c a b i n e t f o r 12 h o u r s i n an a t m o s p h e r e o f 10 0% r e l a t i v e h u m i d i t y . I t u s u a l l y o c c u r s a t a b o u t 15 b a r s o f s o i l m o i s t u r e t e n s i o n . The a v a i l a b l e w a t e r s t o r a g e c a p a c i t y i s t h e r a n g e i n t h e s o i l w a t e r b e t w e e n f i e l d c a p a c i t y and p e r m a n e n t w i l t i n g p o i n t and i t i s f o u n d f r o m t h e s o i l m o i s t u r e c h a r a c t e r i s t i c s c u r v e s by d e t e r m i n i n g t h e f i e l d c a p a c i t y w h i c h i s s e l e c t e d a t 0.3 b a r s and p e r m a n e n t w i l t i n g " T o t a l v olume o f t h e s o i l i s e q u a l t o t h e v o l u m e o f t h e c o r e . The d i a m e t e r a nd t h e l e n g t h o f t h e c o r e a r e 7.3 and 7.6 cm r e s p e c t i v e l y . 3 4 . p o i n t w h i c h i s s e l e c t e d a t 15 b a r s . From t h e s e c u r v e s t h e p o r o s i t y o f t h e s o i l a t e a c h d e p t h f o r t h e 3 l o c a t i o n s were a l s o ' d e t e r m i n e d . V I I . RESULTS AND DISCUSSION 1. L a n d G r a d i n g The G,TO and Gr,„ f o r e a c h s e c t i o n o f t h e f i e l d w e r e NS WE . c a l c u l a t e d a n d a r e shown i n T a b l e s 1, 2, and 3. S i n c e t h e l e f t t o p s e c t i o n o f t h e f i e l d was c h o s e n f o r t h e c o n s t r u c t i o n o f t h e b o r d e r s t r i p s . The l a n d g r a d i n g o f t h i s s e c t i o n o f t h e f i e l d w i l l be d i s c u s s e d h e r e ( T a b l e 1 ) . A c c o r d i n g t o t h e l e a s t s q u a r e s a nd a v e r a g e p r o f i l e s m e t h o d , t h e l a n d g r a d i n g c a l c u l a t i o n s f o r t h e l e f t t o p s e c t i o n a r e as f o l l o w s : H = e l e v a t i o n o f t h e c e n t r o i d = 9 2.53 m v _ 1 + 2 + 3 + 4 + 5 _ . A - p - o m 5 1 + 2 + 3 + 4 + 5 + 6 - o n - r - 0 . 0 m 6 C o m p u t a t i o n f o r G^g: ES = 21 ( E S ) 2 = 441 E ( S ) 2 = 91 ' (EH) = 555.18 (ESH) = 1921.74 (ES) (EH) G E(SH) - n N S E ( S ) 2 - ( E S ) 2 n 21 X 555.18 G N S. = 1 9 2 1 ' 9 1 I 441 6 - - 1 ' 2 2 f t / 1 ° ° f t 6 ( M i n u s s i g n i n d i c a t e s s l o p e i s s o u t h w a r d f r o m "A") TABLE 1 LEFT TOP SECTION - ORIGINAL ELEVATIONS Line Line Totals Average 481.50 96.30 471.30 94.26 462.40 92.48 457.20 91.44 452.40 90.48 451.10 90.22 2775.90 92.54 + Elevation of Centroid (Hm) NEW ELEVATIONS/CUTS AND FILLS FOR LEFT TOP SECTION Positive numbers Negative numbers .signify f i l l s signify cuts 96.882 96. 234 95. 585 94 .937 94 .289 (-0.818) ( 0. 034) (-0. 815) (-9 .563) (-1 .411) 95.660 95. 011 94. 363 93 .715 93 .067 ( 0.160) (-0. 089) ( 0. 263) ( 0 .415) (-0 .233) 94.437 93. .789 93. 141 92 .493 91 .845 ( 0.937) ( 0. 989) ( 0. 741) ( 0 .593) ( 0 .045) 93.215 92. ,567 91. 919 91 .271 90 .622 ( 0.815) ( 0. ,267) ( 0. 619) ( 0 .571) ( 0 .122) 91.993 91. ,345 90. 697 90 .048 89 .400 ( 0.293) (-0. ,255) ( 0. 498). < 0 .448) ( 0 .100) 90.771 ' 90. ,123 89. 474 88 .826 88 .178 (-1.529C (-1. .877) (-0. 426) ( 0 .126) (-0 .022) Column Totals Column Average G^ g = -1.2222' PER 100 FEET G^ = -0.6482' PER 100 FEET 97. ,70 96 .20 96. 40 95. 50 95. 70 95. ,50 95 .10 94. 10 93. 30 93. 30 93. ,50 92 .80 92. 40 91. 90 91. 80 92. .40 92 .30 91. 30 90. 70 90. 50 91, .70 91 .60 90. 20 89. 60 89. 30 92, .30 92 .00 89. 90 88. 70 88. 20 563, .10 560 .00 554. 30 549. 70 548. 80 93, .85 93 .33 92. 38 91. 62 91. 47 TABLE 2. TOP SECTION - ORIGINAL ELEVATIONS Line Line T o t a l s Average Column T o t a l s Column Average 94.80 92.70 90.80 90.30 89.20 87.90 86.90 86.40 85.70 83.30 82.60 82.90 83.50 1137.00 87.46 94.30 92.50 91.20 90.30 89.10 88.10 86.60 86.20 85.60 84.60 83.80 82.20 82.70 1137.20 76.48 . 93.70 92.40 91.00 90.30 88.80 88.00 87.00 86.70 85.10 84.10 83.20 81.90 79.10 1131.30 87.02 94.00 91.80 90.60 89.80 89.20 88.30 87.50 86 .90 85.60 ' 83.80 82.60 81.40 78.30 1129.80 86.91 94.40 91.60 90.30 89.50 88.30 87.30 87.90 86.90 86.40 84.30 81.90 81.60 79.60 1130.00 86.92 - 93.20 91.30 87.60 86.30 85.90 85.70 87.30 86.90 86.10 84.89 83.10 82.40 76.50 1117.10 85.93 92.50 91.60 87.60 89.80 86.00 84.60 87.00 85.40 82.10 84.30 83.00 81.90 78.30 1114.10 85.70 91.90 89.20 89.20 89.80 88.10 85.40 83.50 82.80 82.10 80.80 79.80 79.60 78.70 1100.90 . 84.68 748.80 733.10 718.30 716.10 704.60 695.30 693.70 688.20 678.70 670.00 660.00 653.90 636.70 8997.38 93.60 91.64 89.79 89.51 88.07 86.91 86.71 86.02 84.84 83.75 82.50, 81.74 79.59 86.51 t Ss -1.0295' PER 100 FEET -0.3759' PER 100 FEET E l e v a t i o n o f Ce n t r o i d (Hm) CO TABLE 2 (Continued) NEW ELEVATIONS/ CUTS AND FILL FOR TOP SECTION POSITIVE NUMBERS SIGNIFY FILLS NEGATIVE NUMBERS SIGNIFY CUTS 94.006 93.630 93.254 92.878 (-0.794) (-0.670) (-0.446) (-1.122) 92.977 92.601 92.225 91.849 ( 0.277) ( 0.101) (-0.175) ( 0.049) 91.947 91.571 91.195 90.819 ( 1.147) ( 0.371) ( 0.195) ( 0.219) 90.918 90.542 90.166 89.790 ( 0.618) ( 0.242) (-0.134) (-0.010) 89.888 89.512 89.136 88.760 ( 0.688) ( 0.412) ( 0.336) (-0.440) 88.859 88.483 88.107 87.731 ( 0.959) ( 0.383) ( 0.107) 0 (-0.569) 87.829 87.453 87.077 86.701 ( 0.929) ( 0.853) ( 0.077) (-0.799) 86.800 86.424 86.048 85.672 ( 0.400) ( 0.224) (-0.652). (-1.228) 85.770 85.394 85.018 84.642 ( 0.070) (-0.206) (-0.082) (-0.958) 84.741 84.365 83.989 83.613 ( 1.441) (-0.235) (-0.111) (-0.187) 83.711 83.335 82.959 82.583 ( 1.111) (-0.465) (-0.241) (-0.017) 82.682 82.306 81.930 81.554 (-0.218) ( 0.106) ( 0.030) ( 0.154) 81.652 81.276 80.900 80.524 (-1.848) (-1.424) ( 1.800) ( 2.224) 92.502 (-1.898) 92.126 (-1.074) 91.750 . (-0.750) 91.375 (-0.525) 91.473 (-0.127) 91.097 (-0.203) 90.721 (-0.879) 90.345 ( 1.145) 90.443 ( 0,143) 90.067 ( 2.467) 89.691 ( 2.091) 89.315 ( 0.115) 89.414 (-0.086) 89.038 ( 2.738) 88.662 (-1.138) 88.286 (-1.514) 88.384 ( 0.084) 88.008 ( 2.108) 87.632 ( 1.632) 87.256 (-0.844) 87.355 ( 0.055) 86.979 ( 1 . 2 7 9 ( 86.603 (. 2.003) 86.227 ( 0.827) 86.325 (-1.575) 85.949 (-1.351) 85.573 (-1.427) 85.197 ( 1.697) 85.296 (-1.604) 84.920 (-1.980) 84.544 (-0;856) 84.168 ( 1.368) 84.266 (-2.134) 83.890 (-2.210) 83.514 ( 1.414) 83.138 ( 1.038) 83.237 (-1.063) 82.861 (-1.939) 82.485 (-1.815) 82.109 ( 1.309) 82.207 ( 0.307) 81.831 (-1.269) 81.455 (-1.545) 81.079 ( 1.279) 81.178 (-0.422) 80.802 (-1.598) 80.426 (-1.474) 80.050 ( 0.450) 80.148 ( 0.548) 79.772 ( 3.272) 79.396 ( 1.096) 79.020 ( 0.320) TABLE 3. BOTTOM SECTION - ORIGINAL ELEVATIONS Column T o t a l s Column Average 82.50 82.00 80.50 80.20 77.40 76.90 75.00 74.10 73.90 72.40 71.70 68.50 69.70 984.80 75.75 82.20 81.40 80.70 80.00 76.90 76.10 75.20 74.30 73.30 72.50 72.10 68.80 68.80 982.30 75.56 82.50 80.50 80.10 80.60 77.70 . 76.80 75.90 74.60 73.30 72.30 71.70 68.90 68.30 983.20 75.63 82.00 80.10 78.80 79.50 77.30 77.00 75.70 74.50 73.40 72.00 70.70 71.50 68.20 980.70 75.44 80.60 .79.40 77.10 77.40 75.40 76.50 73.40 73.10 73.80 71.30 71.00 69.20 69.50 967.70 74.44 Lin e Line •  T o t a l s Average 80.40 77.20 80.80 648.20 81.20 78.60 73.50 79.40 634.90 79.36 76.80 78.40 78.40 630.80 78.85 78.90 74.30 74.90 625.80 78.22 75.30 74.30 73.00 608.30 76.04 76.50 73.50 73.30 606.60 75.82 75.50 75.40 72.50 598.60 74.82 73.70 75.20 72.70 592.20 74.02 72.30 74.30 74.90 589.20 73.65 71.60 72.80 69.80 574.70 71.84 70.00 70.30 69.50 567.00 70.87 69.00 68.50 68.00 552.40 69.05 . 69.90 70.10 70.30 '554.80 69.35 969.50 957.80 957.50 7783.48 74.84 74.58 73.68 73.65 E l e v a t i o n o f Ce n t r o i d (Hm) G = 0.9849' PER 100 FEET SJE = 0.3367' PER 100 FEET CO CO TABLE 3 (Continued) NEW ELEVATIONS/ CUT AND FILL FOR BOTTOM SECTION POSITIVE NUMBERS SIGNIFY FILLS NEGATIVE NUMBERS SIGNIFY CUTS 81 .929 .81 .592 (-0 .571) (-0 .608) 80 .944 80 .607 (-1 .056) (-0 .793) 79 .959 79 .622 (-0 .541) (-1 .078) 78 .974 78 .638 (-1 .226) (-1 .362) 77 .989 77 .653 ( 0 .589) ( 0 .753) 77 .004 76 .668 ( 0 .104) ( 0 .568) 76 .020 75 .683 ( 1 .020) ( 0 .483) 75 .035 74 .069 ( 0 .935) ( 0 .398) 74 .050 73 .713 ( 0 .150) ( 0 .413) 73 .065 72 .728 ( 0 .665) ( 0 .228) 72 .080 71 .743 ( 0 .380) (-0 .357) 71 .095 70 .758 ( 2 .595) ( 1 .958) 70 .110 69 .774 ( 0 .410) ( 0 .974) 81 .256 80 .919 (-1 .244) (-1 .081) 80 .271 79 .934 (-0 .229) (-0 .166) 79 .286 78 .949 (-0 .814) ( 0 .149) 78 .301 77 .964 (-2 .299) (-1 .536) 77 .316 76 .979 (-0 .384) (-0 .321) 76 .331 75 .994 (-0 .469) (-1 .006) 75 .346 75 .010 (-0 .554) (-0 .690) 74 .361 74 .025 (-0 .239) (-0 .475) 73 .376 73 .040 ( 0 .076) " (-0 .360) 72 .392 72 .055 ( 0 .092) ( 0 .055) 71 .407 71 .070 (-0 .293) ( 0 .370) 70 .422 .70 .085 ( 1 .522) (-1 .415) 69 .437 69 .100 ( 1 .137) ( 0 .900) 80 .582 80.246 (-0 .018) (-0.154) 79 .597 79.261 ( 0 .197) ( 0.661) 78' .612 78.276 ( 1 .512) ( 1.476) 77 .628 77.291 ( 0 .228) (-1.609) 76 .643 76.306 ( 1 .243) ( 0.006) 75 .658 75.321 (-0 .842) (-1.179) 74 .673 74.336 ( 1 .273) (-1.164) 73 .688 73.351 ( 0 .588) (-0.349) 72 .703 72.366 (-1 .097) ( 0.066) 71 .718 71.382 ( 0 .418) (-0.219) 70 .733 70.397 (-0 .267) ( 0.397) 69 .748 69.412 ( 0 .548) ( 0.412) 68 .764 69.427 (-0 .736) (-1.473) 79.909 - 79 .572 ( 2.709) (-1 .228) 78.924 78 .587 ( 5.424) (-0 .813) 77.939 77 .602 (-0.461) (-0 .798) 76.954 76 .618 ( 2.654) ( 1 .718) 75.969 75 .633 ( 1.669) ( 2 .633) 74.984 74 .648 ( 1.484) ( 1 .348) 73.999 73 .663 (-1.400) ( 1 .163) 73.015 72 .678 (-2.185) (-0 .022) 72.030 71 .693 (-2.270) (-3 .207) 71.045 70 .708 (-1.755) ( 0 .908) 70.060 69 .723 (-0.240) ( 0 .223) 69.075 68 .738 ( 0.575) ( o .738) 68.090 67 .753 (-2.010) (-2 .547) 4 1 . C o m p u t a t i o n f o r G ^ : (ES) = 15 ( E S ) 2 = 225 E ( S ) 2 = 5 5 (EH) = 462.5 E(SH) = 1381.48 15 X 462.65 r _ 1381.48 - 5 _ bWE 55 - 22_5 " U - b t 3 5 ( M i n u s s i g n i n d i c a t e s s l o p e i s e a s t w a r d f r o m " A " ) . H = a + (G„„) (X ) + (G. T C) (Y ) m , WE m NS m 92.53 = a + (-0 . 65 X 3) + (-1.22X 3.5) a = 98.75 The new e l e v a t i o n s t h a t w o u l d c o r r e s p o n d w i t h t h e o r i g i n a l e l e v a t i o n s w o u l d be f o u n d f r o m : H = a + ( G T 7 T J ( X ) + ( G M C X Y ) . new WE No •• • F o r e x a m p l e , t h e new e l e v a t i o n f o r t h e s t a t i o n 1.1 w i l l b e : H = 98 . 75 + (-0 . 6 5 X 1) + (-1.22X 1) new H = 96.88 new The amount o f c u t o r f i l l w i l l be c a l c u l a t e d f r o m s u b s t r a c t i n g t h e o r i g i n a l e l e v a t i o n f r o m t h e new e l e v a t i o n . F o r e x a m p l e , f o r t h e s t a t i o n . ( l , l ) t h e amount o f c u t w i l l be H - H . . = 96.88 - 97.70 = - 0 . 8 2 . I n T a b l e 1, t h e new o r i g i n a l ' p o s i t i v e a n d n e g a t i v e numbers d e s i g n a t e f i l l s a nd c u t s r e s p e c -t i v e l y . T h i s was g i v e n as an e x a m p l e o f t h e d a t a shown i n 42 . T a b l e 1. O t h e r d a t a i n t h i s t a b l e were c a l c u l a t e d i n t h e same manner. T h e s e a r e c a l c u l a t e d v a l u e s w h i c h a r e c a r r i e d i n 3 s i g n i f i c a n t f i g u r e s , b u t t h e p r a c t i c a l v a l u e s s h o u l d be c o n -s i d e r e d i n one s i g n i f i c a n t f i g u r e . The " c u t - f u l l " r a t i o o f . t h i s s e c t i o n i s a p p r o x i m a t e l y one. I t means t h a t t h e amount o f c u t i s e q u a l t o t h e amount o f f i l l . B e c a u s e t h e b o r d e r s t r i p s s h o u l d h a v e no c r o s s s l o p e s , t h e f o r e a c h s t r i p was a d j u s t e d . 2. S o i l P r o p e r t i e s A l l d a t a on s o i l p r o p e r t i e s i s shown i n T a b l e 4. The a v e r a g e s o i l t e x t u r e o f t h e s o i l i s l o a m a n d t h e b u l k d e n s i t y 3 v a r i e s f r o m 1.27 t o 1.40 gm/cm . The f i e l d c a p a c i t y , p e r m a n e n t w i l t i n g p o i n t , and a v a i l a b l e w a t e r s t o r a g e c a p a c i t y f o r e a c h d e p t h a r e d e r i v e d f r o m t h e s o i l m o i s t u r e r e t e n t i o n c u r v e s w h i c h a r e shown i n t h e A p p e n d i x I I I . The a v e r a g e a v a i l a b l e w a t e r s t o r a g e c a p a c i t y f o r t h e f i e l d i s t h e sum o f t h e f i e l d c a p a c i t y v a l u e s o f t h e d i f f e r e n t d e p t h o f t h e s o i l m i n u s t h e a v e r a g e p e r m a n e n t w i l t i n g p o i n t s . T h i s v a l u e i s e q u a l ' t o : A.W.S.C. = 5 , 5 8 + 1 ' 3 1 2 + 7 , 9 1 4 = 7.08 i n c h / 3 f t 3. I r r i g a t i o n D e s i g n W a t e r i s n o t e q u a l l y a v a i l a b l e t o p l a n t s o v e r t h e a v a i l a b l e w a t e r c o n t e n t r a n g e ( 5 ) . The a v a i l a b i l i t y c o e f f i c i e n t , w h i c h i s t h e maximum f r a c t i o n o f a v a i l a b l e w a t e r s t o r a g e c a p a c i t y t o be re m o v e d b e f o r e i r r i g a t i o n i s r e q u i r e d , i s 0.5 TABLE 4. DATA ON SOIL PROPERTIES Lo c a t i o n Depth Bulk No. Inches Density gr/cm^ T e x t u r a l P o r o s i t y C l a s s Moisture Content cm^/cm^ at t e n s i o n o f AWSC 0 cm 25 cm 50 cm 75 cm 0.3 3 15 3 3 Bars Bars Bars cm /cm Average AWSC i n c h / 3 f t 0- 6 1 35 Loam 0 .49 0 .45 0 .434 0 :4i5 0 .398 0 .232 0 .128 0 .121 0 .111 6-12 1. 36 Loam 0 .49 0 .45 0 .439 0 .426 0 .419 0 .2435 0 .145 0 .137 0 .1065 12-18 1 38 Sandy loam 0 .48 0 .45 0 .43 0 .424 0 .413 0 .185 0 .1090 0 .1035 0 .0815 18-24 1. 38 Sandy loam 0 .48 0 .45 0 .43 0 .424 0 .413 0 .181 0 .1085 0 .1009 0 .0801 24-30 1. 40 Loamy sand 0 .47 0 .44 0 .425 0 .404 0 .375 0 .135 0 .097 0 .0897 0 .0453 30-36 1. 40 Loamy sand 0 .47 0 .44 0 .425 0 .404 0 .375 0 .138 0 .1010 0 .097 0 .041 0- 6 1. 27 S i l t loam 0 .52 0 .48 0 .463 0 .449 0 .439 0 .2822 0 .1590 0 .1463 0 .136 6-12 1. 29 S i l t loam 0 .51 0 .47 0 .431 0 .420 0 .412 0 .2739 0 .151 0 .1404 0 .1335 12-18 1. 30 Loam 0 .51 0 .47 , 0 .45 0 .442 0 .431 0 .234 0 .131 0 .121 0 .113 18-24 1. 30 Loam 0 .51 0 .47 0 .45 0 .492 0 .431 0 .2475 0 .156 0 .142 0 .1055 24-30 1. 32 Sandy loam 0 .50 0 .45 0 .434 0 ,41 0 .392 0 .169 0 .095 0 .0899 0 .0791 30-36 1. 40 Sandy loam 0 .47 0 .44 0.425 0 .404 0 .375 0 .165 0 .0976 0 .089 0 .076 0- 6 1. 30 Loam 0 .51 0 .47 0 .43 0 .425 0 .418 0 .245 0 .136. 0 .122 0 .123 6-12 1. 30 Loam 0 .51 0 .47 0 .458 0 .453 0 .447 0 .236 0 .129 0 .117 0 .119 12-18 1. 35 Loam 0 .49 - •' 0 .45 0 .443 0 .432 0 .417 0 .235 0 .134 0 .122 0 .113 18-24 1. 38 Loam 0 .48 0 .45 0 .93 0 .424 0 .413 0 .234 0 .130 0 .119 0 .115 24-30 1. 38 Loam 0 .47 0 .45 0 .43 0 .424 0 .413 0 .2375 0 .139 0 .124 0 .1135 "30-36 1. 40 Sandy loam 0 .47 0 .44 0 .418 0 .415 0 .393 0 .170 0 .1010 0 .0915 0 .0785 5 . 5 S 7.72 7.94 CO 44. f o r a l f a l f a ( 5 ) . T h e r e f o r e , t h e a v a i l a b l e w a t e r s t o r a g e c a p a c i t y w o u l d be e q u a l t o 0 . 5 X 7 . 0 8 = 3 . 5 4 i n c h e s p e r 3 f e e t o f t h e - s o i l . The peak e v a p o t r a n s p i r a t i o n r a t e f o r t h e N i c o l a V a l l e y i s a b o u t 0 . 2 5 i n c h e s p e r day ( 5 ) a t t h e s e a s o n ' s peak and t h e r e f o r e t h e i r r i g a t i o n i n t e r v a l s a r e e q u a l t o : 3 5 4 Q ' 2 5 ~ 1 4 . 1 6 d a y s ( u s e 1 4 d a y s ) . T a k i n g t h e i r r i g a t i o n e f f i c i e n c y a t a b o u t 7 0 p e r c e n t ( 2 2 ) , t h e n t h e d e p t h o f a p p l i e d w a t e r w o u l d be c a l c u l a t e d a s : 1 4 X 0 2 5 D e p t h o f a p p l i e d w a t e r = — - — ^ Q 1 = 6 . 0 0 i n c h e s . The a v e r a g e b a s i c i n t a k e r a t e f o r t h e s o i l i s a b o u t 0 . 7 5 i n c h e s p e r h o u r as shown i n F i g u r e 5 and 6. C o n s i d e r i n g F i g u r e 7 ( 1 0 ) , t h e u n i t s t r e a m s i z e ( 1 0 ) w o u l d be c a l c u l a t e d by k n o w i n g t h e d e p t h o f a p p l i e d w a t e r and b a s i c i n t a k e r a t e . T h e r e f o r e , t h e u n i t s t r e a m s i z e ( q ) w i l l 3 be e q u a l t o 0 . 0 0 4 2 f t / s e c . H o w e v e r , t h e s l o p e o f t h e s t r i p i s 1 . 2 2 p e r c e n t , t h e r e f o r e , r e f e r r i n g t o T a b l e 5 ( 2 1 ) , t h e s l o p e f a c t o r f o r 1.2 2 p e r c e n t w o u l d be c a l c u l a t e d as 0 . 8 2 . T h u s , t h e a c t u a l u n i t s t r e a m s i z e w o u l d be as f o l l o w s : q = 0 . 8 2 X 0 . 0 0 4 2 = 0 . 0 0 3 4 4 4 c f s / f t o f w i d t h . T a b l e 6 shows t h e summary o f t h e a bove d i s c u s s i o n and a l s o t h e a c t u a l d i s c h a r g e , Q, t h e t o t a l v o l u m e o f w a t e r , and t h e t i m e o f a p p l i c a t i o n f o r 2 d i f f e r e n t s t r i p s . A c c o r d i n g t o t h e l a n d g r a d i n g c a l c u l a t i o n s , G^g i f o r t h e l e f t t o p s e c t i o n , w h ere t h e b o r d e r s t r i p s w e r e F i g u r e 5. I n t a k e r a t e c u r v e d e v e l o p e d f r o m i n f i l t r o m e t e r d a t a . 46 . F i g u r e 6. I n t a k e r a t e c u r v e d e v e l o p e d f r o m i n f i l t r o m e t e r d a t a . .10 .09 .08 .07 .06 .05 ' I I ' i ^ i i NOTE! Streams suggested ore (or slopes ol approximately 0.5% . For sleeper slopes the unit streoms should be decreased approximately 10% for each percent increase in slope. For slopes less than 0.5 %unit streoms will need to be increosed. 1 2 3 4 5 DEPTH OF WATER REQUIRED TO FILL ROOT ZONE OF CROP t INCHES ) F i g u r e 7. C u r v e s f o r d e t e r m i n i n g d e s i r a b l e , s i z e o f s t r e a m s t o u s e on a b o r d e r s t r i p 1' w i d e and 100' l o n g f o r s o i l s h a v i n g d i f f e r e n t b a s i c i n t a k e r a t e s ( I . R . ) . T a k e n f r o m r e f e r e n c e ( 1 0 ) . 48. TABLE 5. FACTORS FOR USE I N ADJUSTING UNIT STREAMS FROM FIGURE 7 FOR SLOPES OTHER THAN 0.5 PERCENT.. T a k e n f r o m r e f e r e n c e ( 2 1 ) . S l o p e S l o p e S l o p e a F a c t o r 0, F a c t o r L e v e l 2 .00 2 .5 0 . 70 0 . 1 1.43 3.0 0 .67 0 . 2 1.23 4.0 0.63 0.3 1.13 5.0 0 .60 0.4 1.04 6.0 0.58 0.5 1.00 7.0 0 .56 0 . 6 0.95 8.0 • 0 .54 0.7 0.93 9.0 0.53 0 . 8 0.90 10 .0 0.52 0 . 9 0.88 11. 0 0.51 1.0 0 . 85 12 .0 0.50 1.5 0 . 78 2.0 0 . 74 TABLE 6 . SUMMARY OF BORDER IRRIGATION RELATIONSHIPS Depth o f A p p l i e d Water Peak Evapo-t r a n s p i r a -t i o n B a s i c Intake Rate U n i t Stream S i z e Width Length o f o f run Discharge Volume o f Water Time of A p p l i c a -t i o n I r r i g a t i o n I n t e r v a l (Inch) (inch/day) ( i n c h / h r ) ( f t 3 / s e c ) ( f t ) ( f t ) ( f t 3 / s e c ) f t 3 h r s davs ^ _ . _ — . 5.00 0.25 • 0.75 0.003444 50 600 0.003444X600X50 50X600X5 12500 14 100 12 t" 1.03X3600 = 1.03 = 12500 = 3.37 5.00 0.25 0.75 0.003444 25 600 0.52 6250 t=3.34 14 50. c o n s t r u c t e d , i s e q u a l t o 1.22 p e r c e n t . T h i s l a n d i s s u p p o s e d t o be u s e d f o r c u l t i v a t i o n o f a l f a l f a . The s l o p e l i m i t a t i o n s f o r b o r d e r i r r i g a t e d a l f a l f a a r e 0.15 p e r c e n t minimum and a p p r o x i m a t e l y 1.5 p e r c e n t maximum, .but a u n i f o r m s l o p e r a n g i n g f r o m 0.2 t o 0.3 p e r c e n t i s u s u a l l y i d e a l f o r a l f a l f a ( 1 9 ) . T h e r e f o r e , i t i s o b v i o u s t h a t 1.22 p e r c e n t i s n o t s a t i s f a c t o r y f o r a l f a l f a b u t i t i s p o s s i b l e . The f o l l o w i n g s t e p s t r a c e t h e p r o c e d u r e s f o l l o w e d and i n d i c a t e t h e c o n d i t i o n s w h i c h i m p e d e d c o m p l e t i o n o f p l a n n e d r e s e a r c h . 1) The' l a n d l o a n e d f o r t h i s p r o j e c t was l e v e l l e d c r o s s w i s e by a l o c a l c o n t r a c t o r . 2) T h r e e c o n t r o l l e d f l o o d i n g s t r i p s were c o n s t r u c t e d and a c o r r e s p o n d i n g u n c o n t r o l l e d f l o o d i n g a r e a was s e t a s i d e t o be u s e d f o r c o m p a r i s o n . 3) A t l e n g t h w i s e i n t e r v a l s o f 50 f e e t , t h e c r o s s s l o p e o f e a c h s t r i p was c h e c k e d t r a n s v e r s l e y . E a c h • s t r i p was f o u n d t o h a v e a v a r i a t i o n f r o m s i d e t o s i d e o f l e s s t h a n one i n c h p e r 25 f e e t . 4) W a t e r was r e l e a s e d t o e a c h s t r i p by r e c t a n g u l a r w e i r s . 5) A t t h i s s t a g e , c o n t r a r y t o e x p e c t a t i o n s , t h e w a t e r d i d n o t f l o w e v e n l y t o t h e end o f e a c h s t r i p . I n s t e a d , i n b o t h 25 a n d 50 f o o t w i d t h s a b o u t 2/5 h a d f u l l f l o w o f w a t e r b u t 3/5 o f e a c h s t r i p r e m a i n e d d r y . 6) S i n c e t h e u n e v e n f l o w c o n d i t i o n was n o t s a t i s f a c t o r y f o r c o n t i n u i n g r e s e a r c h as p l a n n e d , t h e w a t e r was t u r n e d o f f . 51. 7) On e a c h s t r i p t h e c r o s s s l o p e was now r e c h e c k e d and r e v e a l e d t h a t t h e l a n d l e v e l l i n g ( o f s t e p 1) h a d n o t b e e n m a i n t a i n e d . I n s t e a d , t h e l a n d s e t t l i n g p r o c e s s h a d r e s u l t e d i n as much as one f o o t v a r i a -t i o n i n s t e a d o f t h e maximum 1 o r 2 i n c h e s p e r 25 f e e t o f v a r i a t i o n a l l o w a b l e f o r p r o p e r e x p e r i m e n t . T h i s e x t r e m e v a r i a t i o n o f c r o s s s l o p e a c r o s s t h e w i d t h o f e a c h s t r i p t h u s made i t i m p o s s i b l e t o i r r i g a t e t h e s t r i p s t o e s t a b l i s h p r o p e r b o r d e r s t r i p p a r a m e t e r s . 52 . CONCLUSIONS T h i s s t u d y h a s b e e n c a r r i e d o u t t o d e v e l o p a b o r d e r s t r i p i r r i g a t i o n s y s t e m i n a f i e l d i n t h e N i c o l a V a l l e y i n B r i t i s h C o l u m b i a . From t h e f o r e g o i n g r e s u l t s and d i s c u s s i o n , t h e f o l l o w i n g c o n c l u s i o n s a r e made: 1) The d e p t h o f w a t e r r e q u i r e d f o r r e p l e n i s h m e n t o f t h e s o i l m o i s t u r e i s 5 i n c h e s p e r i r r i g a t i o n . 2) The 500 X 50 f o o t s t r i p s h o u l d be i r r i g a t e d e v e r y 14 d a y s 3 w i t h t h e d i s c h a r g e o f 1.0 3 f t / s e c . The t i m e o f - a p p l i c a t i o n w o u l d be 3.37 h o u r s . 3) The 600 X 25 f o o t s t r i p s h o u l d a l s o be i r r i g a t e d e v e r y 3 14 d a y s w i t h t h e d i s c h a r g e 0.52 f t / s e c . The t i m e o f a p p l i c a t i o n w o u l d be 3.34 h o u r s . 4) F u r t h e r d e v e l o p m e n t o f a b o r d e r s t r i p i r r i g a t i o n s y s t e m s u c h as d e s i g n e d by t h i s s t u d y r e q u i r e s t h e s e s u p p l e -m e n t a r y s t e p s : a) F i r s t - f o c u s f u r t h e r e x p e r i m e n t on e s t a b l i s h i n g s t a b l e m a i n t e n a n c e o f c r o s s s l o p e o f l e s s t h a n one i n c h p e r 25 f e e t . b) N e x t - p r o c e e d w i t h t h e c o m p a r i s o n b e t w e e n t h e w a t e r a p p l i c a t i o n e f f i c i e n c y o f b o r d e r s t r i p i r r i g a t i o n a n d u n c o n t r o l l e d f l o o d i n g . c) S i m i l a r l y - p r o c e e d w i t h t h e c o m p a r i s o n b e t w e e n t h e u n i f o r m i t y o f w a t e r d i s t r i b u t i o n o f b o r d e r s t r i p i r r i g a t i o n and o f u n c o n t r o l l e d f l o o d i n g . T h i s s t u d y i s a b e g i n n i n g e f f o r t t o f a c e t h e c h a l l e n g e o f d e v e l o p i n g a v i a b l e a l t e r n a t i v e i r r i g a t i o n n e e d s o f a r e a s s u c h as t h e N i c o l a V a l l e y . The u n a v a i l a b i l i t y o f f u n d s f o r r e s e a r c h a b o r t e d t h e t h o r o u g h i m p l e m e n t a t i o n o f p l a n n e d d e v e l o p ment o f b o r d e r s t r i p i r r i g a t i o n u n d e r optimum c o n d i t i o n s o f t i m e , m a t e r i a l s and c o - o p e r a t i o n . N e v e r t h e l e s s , t h e r e v i e w o f l i t e r a t u r e a n d t h e r e s u l t i n g r e s e a r c h d e s i g n o u t l i n e d i n t h i s s t u d y and c o n c l u s i o n s 1, 2 and 3 a b o v e a r e o f f e r e d as a b a s i c f r a m e o f r e f e r e n c e f o r f u r t h e r s t u d y w h e n e v e r f u n d s become a v a i l a b l e . 54 . LITERATURE CITED B a m s b e r g e r , J.C. 1955. P r e p a r a t i o n o f L a n d f o r E f f i c i e n t I r r i g a t i o n . I n W a t e r , U.S.D.A. Y e a r b o o k o f A g r i c u l -t u r e , pp. 279-285. B i s h o p , A.A., M.E. J e n s e n a nd W.A. H a l l . 1967. S u r f a c e I r r i g a t i o n S y s t e m s . I n : I r r i g a t i o n • o f A g r i c u l t u r a l L a n d s , A m e r i c a n S o c i e t y o f Agronomy. M o n o g r a p h N o . 1 1 , pp. 865-884. B l a c k , C A . , D.D. E v a n s , J . L . W h i t e , L.E. E n s m i n g e r , a n d F.E. C l a r k . 1965. Methods o f S o i l A n a l y s i s , A m e r i c a n S o c i e t y o f Agronomy. Monograph No. 9, P a r t 1, pp. 131-137. B r i t i s h C o l u m b i a D e p a r t m e n t o f A g r i c u l t u r e . C l i m a t e s o f . B r i t i s h C o l u m b i a . C l i m a t i c N o r m a l s 1 9 4 1 - 1 9 7 0 . B r i t i s h C o l u m b i a I r r i g a t i o n C o m m i t t e e . B r i t i s h C o l u m b i a I r r i g a t i o n G u i d e . C o r e , E . J . 1 9 5 1 . B o r d e r I r r i g a t i o n . U.S.D.A. L e a f l e t No. 297. C h r i s t i a n s e n , J . E . , A.A. B i s h o p a nd Y.S. Fok. 1959. The I n t a k e R a t e as R e l a t e d t o t h e A d v a n c e o f W a t e r i n S u r f a c e I r r i g a t i o n . ASAE P a p e r No. 5 9 - 7 1 3 . Chugg, G.E. 1947. C a l c u l a t i o n s f o r . L a n d Gradation, Agr.Eng. 28 pp. 4 6 1 - 4 6 3 . C r i d d l e , W.D., S. D a v i s , C.H. P a i r , a n d D.G. S h o c k l e y . 1956. M e t h o d s o f E v a l u a t i n g I r r i g a t i o n S y s t e m s . A g r i c u l t u r a l Handbook No. 82, U.S. Government P r i n t i n g O f f i c e , W a s h i n g t o n , D.C. pp. 11-16. C r i d d l e , W.D. and S. D a v i s . 1 9 5 1. A Met h o d f o r E v a l u a t i n g B o r d e r I r r i g a t i o n L a y o u t s . U.S.D.A. S o i l C o n s e r v a -t i o n S e r v i c e . Day, P.R. 1965. P a r t i c l e F r a c t i o n a t i o n and P a r t i c l e S i z e A n a l y s i s . I n : M e t h o d o f S o i l A n a l y s i s . Agronomy Monograph No. 9, P a r t 1, pp. 545-567. G i v a n , C B . 1940. L a n d G r a d i n g C a l c u l a t i o n s . A g r . Eng. 21: pp. 11-12.' 55. 13. H a i s e , H.R., W.W. Donnan, J.T. P h e l a n , L.E. Lawhon, a nd D.G. S h o c k l e y . 1956. Use o f C y l i n d e r I n f i l t r o m e t e r t o D e t e r m i n e I n t a k e C h a r a c t e r i s t i c s o f I r r i g a t e d S o i l s . U.S.D.A. S o i l C o n s e r v a t i o n S e r v i c e P u b l i c a -t i o n ARS 41-7. 14. H a l l , W.A. 1956.. E s t i m a t i n g I r r i g a t i o n B o r d e r F l o w . A g r . E ng. 37: ( 4 ) pp. 263-265. 15. I s r a e l s e n , O.W. and V.E. H a n s e n . 1962. I r r i g a t i o n P r i n c i p l e s a n d P r a c t i c e s ( 3 r d E d . ) , J o h n W i l e y , New Y o r k . 16. L e w i s , M.R. and W.E. M i l n e . 1938. A n a l y s i s o f B o r d e r I r r i g a t i o n . A g r . E n g . 19: (6) pp. 267-272. 17. M a c D o n a l d , J . 1975. D e s i g n a n d C o s t i n g o f S u r f a c e a n d S p r i n k l e r I r r i g a t i o n . U n p u b l . B.Sc. T h e s i s , 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 . 18. M a r r , J.C. 1957. G r a d i n g L a n d f o r S u r f a c e I r r i g a t i o n . C a l i f . A g r . E x p t . S t a . C i r . 438. 19. M a r r , J.C. 1952. The B o r d e r M e t h o d o f I r r i g a t i o n . C a l i f . A g r . E x p t . S t a . C i r . 408. 20. P h e l a n , J.T. and W.D. C r i d d l e . 1955. S u r f a c e I r r i g a t i o n M e t h o d s . I n W a t e r U.S.D.A. Y e a r b o o k o f A g r i c u l -. t u r e pp. 258-266. 2 1 . Schwab, G.O., R.K. F r e v e r , W. E d m i n s t e r and K.K. B a r n e s . 1966. S o i l a n d W a t e r C o n s e r v a t i o n E n g i n e e r i n g . 2nd E d . J o h n W i l e y , New Y o r k . 22. S h o c k l e y , D.G., J.H. Woodward and J.T. P h e l a n . 1964. A Q u a s i - R a t i o n a l M e t h o d o f B o r d e r I r r i g a t i o n D e s i g n . T r a n s . ASAE 7 ( 3 ) , pp. 420-423 and 426. 23. U.S. S o i l C o n s e r v a t i o n S e r v i c e . 1959. I r r i g a t i o n . N a t l . E n g . Hbk., S e c t i o n 1 5 , C h a p t e r 4, B o r d e r I r r i g a t i o n , W a s h i n g t o n , D.C. 24. U.S. S o i l C o n s e r v a t i o n S e r v i c e . 1 967. I r r i g a t i o n , N a t l . E n g . Hbk., S e c t i o n 1 5 , C h a p t e r 3, P l a n n i n g Farm I r r i g a t i o n S y s t e m s , W a s h i n g t o n , D.C. 25. U.S. S o i l C o n s e r v a t i o n S e r v i c e . 1959. I r r i g a t i o n . N a t l . E ng. Hbk., S e c t i o n 1 5 , C h a p t e r 1 2 , L a n d L e v e l i n g , W a s h i n g t o n , D.C. i 26. W i l l c o c k s , T . J . 1970. I r r i g a t i o n R e q u i r e m e n t s f o r A l f a l f a i n t h e N i c o l a V a l l e y . U n p u b l . M.Sc. T h e s i s , 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 . 56 APPENDIX I . An e x a m p l e f o r t h e l e a s t s q u a r e s and a v e r a g e p r o -f i l e s method. F i e l d s i z e = 132m X 99m. S t a t i o n d i s t a n c e = 3 3m c o r n e r s t a t i o n s . L o c a t e d 33/2 = 16.5m i n s i d e S t a t i o n e l e v a t i o n a l o n g a x i s = 1 0 , 9 , 7 , 8 , f o r Y^. and 9,8,8,9, f o r Y ? and 9 , 1 0 , 9 , 1 0 , f o r Y 3 . A S t a t i o n d i s t a n c e CD O w • H ' O 6 • H Id •P CO Column T o t a l s Column Average 1 2 3 1 2 3 4 10 9 7 8 o o O o 9 8 8 9 o o o O 9 lo 9 lo o o o o » 28 27 24 27. . 9.33 9 8 9 L i n e L i n e T o t a l s Average 36 8.5 34 38 106 8.5 9.5 H m 8.83 X m 1 + 2 + 3 + 4 2.5 Y m 1 + 2 + 3 2 . 0 H m 3WE 10 + 9 + 9 + 1 0 E(SH) -12 ( E S ) ( E ) • n E ( S ) 2 - ( E S ) 2 n 8.3 3m 87.33 - ( 10 X 35 .33) 30 - 100 •0 .199 57 . B e c a u s e : B e c a u s e : £(SH) = C l X 9.33) + (2 X 9) + (3 X 8) + (4 X 9) = 87.33 ES = 1 + 2 + 3 + 4 .. = 10 EH = 9.33 + 9 + 8 + 9 = 35.33 ECS) (E S ) n 'NS E(SH) ES. E ( S ) 2 ( E S ) 2 EH H m H 2 2 2 2 1 + 2 + 3 + 4 100 4 54. - ( 6 X 26.5 ) 30 14 - 36 0.5 ( 1 + 8.5) + (2 X 8.5) + (3 X 9.5) 1 + 2 + 3 = 6 54 2 2 2 1 + 2 + 3 36 5 + 8.5 + 9.5 14 26.5 = a + (G T 7„)(X ) + ( G X T C ) ( Y ) WE m NS m m 8.83, X_ 2.5, Y m m a = 8.83 - (-0.199 X 2.5) - (0.5 X 2) = 8.33 a i s t h e e l e v a t i o n o f t h e p o i n t o f o r i g i n i n t h e p l a n e and t h e new e l e v a t i o n , H, o f e a c h g r i d p o i n t c o r r e s -p o n d i n g t o t h e o l d e l e v a t i o n i s f o u n d b y : i H = a + ( G ^ X X ) + ( G ^ X Y ) 10 9 7 8 o G o o 8.63 8.43 8.23 8.03 % <? 8 o % 9.13 8.93 8.73 8.53 % <? 1 0c 9.63 9.43 9.23 9.03 The f i g u r e s above t h e p o i n t s show t h e o r i g i n a l e l e v a t i o n s , w h e r e a s t h e f i g u r e s b e l o w t h e p o i n t s a r e new e l e v a t i o n s w h i c h a r e f o u n d by t h e a b o v e e q u a t i o n . I f . t h e f i g u r e s a b o v e t h e p o i n t s a r e l e s s t h a n t h e f i g u r e s b e l o w t h e p o i n t s , t h e r e s t i s f i l l . O t h e r w i s e - i t s h o u l d be c u t . I n t h i s e x a m p l e t h e " c u t - f i l l " r a t i o i s 1.08. 59 APPENDIX I I A V a r i a t i o n o f P l a n e M e t h o d A s s u m p t i o n The e q u a t i o n , i f t h e p l a n e i s H = a + ( G W E ) ( n ) + ( G ^ ) y G N S and G W E : a r e g i v e n C u t = f i l l V a r i a t i o n b e t w e e n t h e p o i n t s i s l i n e a r H" = o r i g i n a l e l e v a t i o n H = new e l e v a t i o n n E ( H . * i = l 1 - H.) 1 n • E (H . * i = l X - ( G . T C ) ( Y . ) - ( G u r ) ( X . ) - a) = 0 NS l WE x n n n E H. * - G M C E Y. - G n p E X - ma =• 0 NS . , x WE . x - x = l x - 1 i = l 1 n n •E H.ft - G.TC E Y. - G u r E X. . - x NS . N I WE _. _ n x 1 = 1 1 = 1  n n i = l I n t h e e q u a t i o n o f t h e p l a n e G^ and G^g a r e g i v e n , " a " w i l l be f o u n d f r o m t h e above e q u a t i o n and X and Y a r e t h e s t a t i o n n u m b e rs. T h e r e f o r e , t h e new e l e v a t i o n o f e a c h p o i n t w i l l be d e t e r m i n e d . I n t h i s method G.,„ and G.TO a r e n o t d e p e n d e n t on WE NS • t h e g e n e r a l t o p o g r a p h y o f t h e a r e a and c o n s e q u e n t l y t h e r e w i l l be no p r o b l e m as f a r as s l o p e i s c o n c e r n e d . 60 . The p r o b l e m w i t h t h i s method i s t h a t t h e amount o f e a r t h movement may be t o o g r e a t . APPENDIX I I I SOIL MOISTURE RETENTION CURVES FOR 18 SAMPLES. 62. 6'-l. 70. 73. 7 5 . 76. 

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