Field Determination of Free Water Content in Wet Snow

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Field Determination of Free Water Content in Wet Snow

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N A T I O N A L R Z S E A R C H C O U N C I L CANADA

A F I E L D D E T E R P I I N A T I O N O F

FREE

WATm C O N T E N T I N

WET

S N O W

AF? A1.Y ZED

% p o r t No,

69

o f the

D i v i s i o n o f B u i l d i n g R e s e a r c h

OTTAWA A u g u 3 t _{1 9 5 s 0}

(3)

T h i s R e p o r t r e c o r d s p r e l i m i n a r y i n v e s t i g a t i o n s by t h e D i v i s i o n i n t h e d e v e l o p m e n t of a s i n p l e f i e l d method f o r m e a s u r i n p t h e f r e e w a t e r c o n t e n t of wet snow. T h i s i s e a s j . 1 ~ a c c o m p l i s h e d i n a l a b o r a t o r y , b u t n o s i m p l e method i s a v a i l a b l e f o r makin,g s u c h d e t e r m i n a t i o n s i n t h e f i e l d . A l t h o u g h some of t h e e q u i p m e n t must b e i m p r o v e d , t h e r e s u l t s o b t a i n e d f r o m t h i s s t u d y a r e e n c o u r a g i n g . W i t h t h e s e i m p r o v e m e n t s a n d a l o n g e r p e r i o d o f s t u d y ( t h e s t u d y r e p o r t e d o n l y s t a r t e d i n Msrch of t h i s y e a r ) i t i s h o p e d t h a t d e f i n i t e r e c o m m e n d a t i o n s c a n be made f o r a s i m p l e , o b j e c t i v e t e s t f o r t h e f i e l d c l a s s i f i c a t i o n of wet snow. O t t a w a A u g u s t

195.5

N , B . H u t c h e o n , A s s i s t a n t D i ~ e c t o r .

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SUMMARY

A f i e l d method of d e t e r m i n i n g t h e f r e e w a t e r c o n t e n t of snow by measuring t h e d e n s i t y t o which wet snow c a n be compacted was i n v e s t i g a t e d , P r e l i m i n a r y r e s u l t s i n d i c a t e t h a t w a t e r c o n t e n t of snow can be e s t i m a t e d w i t h i n

+

3,16 p e r c e n t , 7 0 p e r c e n t of t h e time, once t h e f i n a l compacted d e n s i t y i s known, F u r t h e r e x p e r i a e n t s w i l l be n e c e s s a r y b e f o r e t h i s method can be a c c e p t e d as a simple, o b j e c t i v e t e s t f o r

(5)

A FIELD DETZRMINATION O F FREE WATER L'ONTZNT I N WZT SI\!OW

The amount o f f r e e w a t e r i n snow i s an i m p o r t a n t p r o p e r t y whtch must b e d e t e r m i n e d i n any r e a l i s t i c c l a s s - i f i c a t i o n o f wet snow. It i s a p r o p e r t y which s h o u l d be r e c o r d e d d u r i n g any t e s t u n d e r wet snow c o n d i t i o n s . U n l e s s t h i s b a s i c f a c t o r i s known, s u c h t e s t s c a n n o t be compared o r t h e i r r e s u l t s p r o p e r l y a n a l y s e d , A knowledge o f t h e f r e e w a t e r c o n t e n t o f snow i s o f i m p o r t a n c e i n such e n g i n e e r i n g problems a s snow c o m p a c t i o n , t h e d e t e r m i n a t i o n o f w a t e r h o l d i n g c a p a c i t y o f snow f o r h y d r o l o g i c a l s t u d i e s and f o r e s t i m a t i n g maximum snow l o a d s on r o o f s . It i s t h e r e f o r e i m p o r t a n t t h a t a s i m p l e f i e l d method be a v a i l a b l e f o r i t s measurement.

The main method u s e d t o d e t e r m i n e f r e e w a t e r i s t h e c a l o r i m e t r i c method, d e s c r i b e d i n d e t a i l by H a l l i d a y ( 1 ) . I n t h i s method a q u a n t i t y o f wet snow i s p l a c e d i n a

c a l o r i m e t e r c o n t a i n i n g h o t w a t e r . The w e i g h t o f snow, t h e w e i p h t o f h o t w a t e r and t h e i n i t i a l and f i n a l t e m p e r a t u r e s of t h e w a t e r a r e measured, The w a t e r e q u i v a l e n t of t h e c a l o r i m e t e r i s p r e v i o u s l y d e t e r m i n e d b y e x p e r i m e n t . A s t h e s p e c i f i c h e a t o f w a t e r and t h e l a t e n t h e a t o f m e l t i n g o f i c e a r e known, t h e w e i g h t of i c e c r y s t a l s i n t h e snow c a n be c a l c u l a t e d u s i n g a s i m p l e h e a t b a l a n c e e q u a t i o n . Once t h e w e i g h t of i c e c r y s t a l s i s known, t h e p e r c e n t f r e e w a t e r i n t h e sample c a n b e c a l c u l a t e d , H a l l i d a y ( 1 ) s u r v e y s t h e a c c u r a c y c l a i m e d by s e v e r a l d i f f e r e n t o b s e r v e r s u s i n g t h i s method: Croce c l a i m e d a c c u r a c y of

5

p e r c e n t of t h e w a t e r c o n t e n t , Y o s i d a c l a i m e d

6-30

p e r c e n t a c c u r a c y , w h i l e De Q u e r v a i n m e n t i o n s

+

1.5

p e r c e n t a c c u r a c y , Oda a n d Kudo ( 2 ) i n d i c a t e t h a t an a c c u r a c y of a b o u t

5

p e r c e n t o f t h e w a t e r c o n t e n t was ob- t a i n e d . T a y l o r

( 3 )

i n d i c a t e s t h a t a c c u r a c y u n d e r f i e l d c o n d i t i o n s was n o t b e t t e r t h a n 1 p e r c e n t f r e e w a t e r . G e r d e l

( 4 )

p r e p a r e d an e x c e l l e n t s e t o f i n s t r u c t i o n s on how t o d e t e r m i n e snow q u a l i t y by t hl s method, b u t gave no

i n d i c a t i o n o f t h e p o s s i b l e a c c u r a c y , Even i f r e a s o n a b l e a c c u r a c y c a n b e o b t a i n e d , t h e c a l o r i m e t e r method i s n o t r e a l l y s a t i s f a c t o r y f o r f i e l d u s e . F o r good r e s u l t s , a c c u r a t e t e m p e r a t u r e and w e i g h t r e a d i n g s a r e n e c e s s a r y . F r e e w a t e r c o n t e n t v a r i e s w i t h snow d e p t h , w i t h l o c a t i o n , and a p p r e c i a b l y w i t h t i m e i n a s i n g l e day. A s u i t a b l e f i e l d method s h o u l d p e r m i t t h e t a k i n g of s e v e r a l r e p r e s e n t a t i v e s a m p l e s o v e r t h e a r e a where t h e wet snow i s b e i n g t e s t e d so t h a t a s t a t i s t i c a l a v e r a g e can b e o b t a i n e d , I n t h e c a l o r i m e t e r method t h e number of s a m p l e s t h a t c a n be t a k e n i s l i m i t e d by t h e number o f .

(6)

c a l o r i m e t e r s a v a i l a b l e , and by t h e s u p p l y of h o t w a t e r , The whole p r o c e d u r e i s q u i t e time-consuming, s u i t a b l e f o r l a b o r a t o r y work b u t n o t s u i t a b l e f o r f i e l d use, e s p e c i a l l y i n i s o l a t e d a r e a s .

O t h e r methods h a v e been s u g g e s t e d by Rader

(5)

b u t s o f a r n o t h i n g d e f i n i t e has been r e p o r t e d . Gerdel

( 6 ) has d e v e l o p e d a m e t e r which measur-es Lrle p e r c e n t a g e of f r e e w a t e r by f i r s t m e a s g r i n g t h e d i e l e c t r i c c o n t e n t of snow which a p p a r e n t l y v a r i e s w i t h f r e e w a t e r , The r e s u l t s of t h i s method v a r y w i t h snow t y p e and r e p o r t s on i t s u s e a r e l i m i t e d . Even though t h e r e has b e e n c o n s i d e r a b l e

i n t e r e s t shown i n t h i a problem, t h e r e i s as y e t no s i m p l e method s u i t a b l e f o r f i e l d u s e ,

F o r t h i s r e a s o n t h e Commission on Snow and I c e of t h e I n t e r n a t i o n a l A s s o c i a t i o n o f Hydrology g i v e o n l y a n a p p r o x i m a t e method f o r c l a s s i f y i n g wet snow

(7

) , Simple o b s e r v a t i o n t e s t s a r e l i s t e d t o d i f f e r e n t i a t e between f o u r c l a s s e s of wet snow, r a n g i n g f r o m m i s t snow t o s l u s h snow, Such a c l a s s i f i c a t i o n , r e l y i n g on t h e judgement of t h e

o b s e r v e r , i s n o t g e n e r a l l y s a t i s f a c t o r y and s u g g e s t s t h e need f o r a s i m p l e o b j e c t i v e method which would d e f i n e more r i g o r o u s l y t h e c l a s s l i m i t s f o r wet snow, I t was t h e r e f o r e d e c i d e d t o i n v e s t i g a t e t h e problem of f i e l d d e t e r m i n a t i o n

of f r e e w a t e r c o n t e n t i n snow i n o r d e r t o s e e i f a r a p i d and r e a s o n a b l y a c c u r a t e method c o u l d b e d e v e l o p e d t h a t would b e s u i t a b l e f o r f i e l d u s e ,

I n s o i l mechanics, P r o c t o r

( 8 )

found t h a t t h e m o i s t u r e c o n t e n t had a n e f f e c t upon t h e d e n s i t y t o which

s o i l c o u l d b e compacted. By u s i n g this dependence he w a s a b l e t o measure t h e a o i s t u r e c o n t e n t of a p a r t i c u l a r s o i l by t h e u s e o f a p l a s t i c i t y n e e d l e , A s s o i l p a r t i c l e s v a r y i n s i z e from - 0 0 1 mrn, o r l e s s f o r c l a y s , t o 2.0 mm, o r l e s s f o r c o a r s e s a n d , and t h e s p e c i f i c g r a v i t i e s a l s o vary, no u n i v e r s a l p r o c e d u r e c o u l d be d e v e l o p e d which would a p p l y t o a l l t y p ~ s of s o i l , It i s common knowledge t h a t i t i s d i f f i c u l t t o compact d r y snow i n t o a snow b a l l a l t h o u g h i t i s e a s y t o compact wet snow i n t o a h a r d mass. T h i s o b s e r v a t i o n

s u g g e s t s t h a t t h e e f f e c t of m o i s t u r e c o n t e n t upon compacted d e n s i t y found by P r o c t o r f o r s o i l s may a l s o h o l d t r u e f o r wet snow, A s t h e s i z e v a r i a t i o n of i c e c r y s t a l s i n snow i s from . 0 1 mm, t o 5 , 0 mm., and a s t h e s p e c i f i c g r a v i t y of i c e i s c o n s t a n t , t h e p o s s i b i l i t y a r i s e s t h a t t h e r e l a t i o n - s h i p P r o c t o r e s t a b l i s h e d f o r s o i l s m i g h t prove t o b e even more a p p l i c a b l e t o wet snow,

(7)

If a sample, of wet snow i s p l a c e d u n d e r a compressive s t r e s s i n s u c h a way t h a t i t s volume i s d e c r e a s e d , t h e r e a r e

3

p o s s i b l e f a c t o r s t o which t h i s d e c r e a s e might be a t t r i b u t e d : 1) compression of d o l i d m a t t e r ( i c e c r y s t a l s ) ; 2 ) compression of w a t e r and a i r i n t h e v o i d s ; o r

3)

c o l l a p s e of t h e snow s t r u c t u ~ ~ e and t h e r e a r r a n g e - n e n t of g r a i n s r e s a l t i n g i n t h e e s c a p e o f a i r from t h e v o i d s and a r e a r r a n g e m e n t of t h e f r e e w a t e r , The f i r s t f a c t o r , t h e compr.essfon of s o l i d m a t t e r o r i c e , would n o t be i m p o r t a n t u n d e r l o a d s which c o u l d b e a p p l i e d by hand p r e s s u r e , The second f a c t o r , t h e compression o f a i r o r w a t e r , would be p o s s i b l e o n l y i n a c o n f i n e d sample, and would a l s o n o t be i m p o r t a n t under l o a d s which c o u l d be a p p l i e d by hand p r e s s u r e , The t h i r d f a c t o r , t h e c o l l a p s e of t h e s t r u c t u r e and t h e r e a r r a n g e m e n t of t h e g r a i n s mast t h e r e f o r e be t h e m a j o r r e a s o n f o r t h e volume d e c r e a s e of wet snow u n d e r a compressive l o a d , I n t h e c a s e of d r y snow, t h e mechanical r e l a t i o n s h i p s between a d j a c e n t c r y s t a l s a f t e r t h e f a i l u r e of i n t e r c o n n e c t - i n g bonds would d e t e r m i n e t h e d e g r e e of c o l l a p s e u n d e r a compressive l o a d . These r e l a t i o n s h i p s may depend on t h e

i n i t i a l s t a t e of t h e snow and on t h e compressive l o a d

( D o

B o R

Report NO,

55)

.

The f a c t o r s i n v o l v e d i n t h e m e c h a n i c a l r e l a t i o n s h i p between g r a i n s may i n c l u d e g r a i n s h a p e , g r a i n

s i z e , g r a i n - s i z e d i s t r i b u t i o n , and t h e i n t e r - g r a n u l a r f r i c t i o n , Once a n i c e c r y s t a l s t a r t s t o m e l t , i t s s u r f a c e

becomes covered w i t h w a t e r , t h e c o r n e r s a r e m e l t e d , and t h e g r a i n s h a p e t e n d s t o become rounded, A l l wet snow t h u s t e n d s t o have a common g r a i n s h a p e , The w a t e r on t h e p a r t i c l e s a c t s a s a l u b r i c a n t and coupled w i t h t h e tendency f o r t h e g r a i n s u r f a c e s t o become smooth due t o m e l t i n g , r e d u c e s t h e f r i c t i o n f a c t o r . The r e s u l t i s t h a t u n d e r compressive l o a d s wet snow w i l l be more e a s i l y compacted t h a n d r y snow.

I n t h e compaction p r o c e s s a i r i s f o r c e d o u t o f t h e sample and t h e , f r e e w a t e r p r e s e n t i s h e l d on t h e g r a i n s u r f a c e s o r f o r c e d i n t o t h e v o i d s , A s t h e - f r e e w a t e r i s

i n c r e a s e d t h e f r i c t i o n f a c t o r i s reduced r e s u l t i n g i n g r e a t e r compaction. The f i n a l d e n s i t y developed i n t h e compaction p r o c e s s , under c o n s t a n t l o a d , s h o u l d t h e r e f o r e i n c r e a s e w i t h i n c r e a s i n g f r e e w a t e r c o n t e n t .

E x p e r i m e n t a l Procedure

F i e l d o b s e r v a t i o n s on f r e e w a t e r c o n t e n t and t h e compacted d e n s i t y of wet snow d i d n o t s t a r t u n t i l l a t e

March 1955, and were t h e r e f o r e n o t a s e x t e n s i v e a s c o u l d be d e s i r e d ,

(8)

I n o r d e r t o o b t a i n d a t a u n d e r a v a r i e t y of c o n d i t i o n s , measurements on f r e e w a t e r c o n t e n t and t h e compacted d e n s i t y

of wet snow were a l s o made on snow which had been s t o r e d i n t h e cold room f o r s e v e r a l weeks, I n o r d e r t o produce a

c o n s i d e r a b l e r a n g e i n c r y s t a l s i z e t h e snow was s c r e e n e d i n t o two d i f f e r e n t s i z e r a n g e s : 4,76 mm. t o 2,38 mm., and 1,154 mm, and l e s s . In a d d i t i o n o b s e r v a t i o n s were made on unscreened, n a t u r a l snow w i t h a n a v e r a g e g r a i n s i z e of 1 mm.

The f r e e w a t e r c o n t e n t of wet snow was determined by t h e c a l o r i m e t r i c method u s i n g two q u a r t - s i z e thermos

b o t t l e s , The p r o c e d u r e used was e s s e n t i a l l y t h e one d e s c r i b e d by Gerdel

( 4 ) .

In o r d e r t o keep e r r o r s t o a m i n i m t h e

r e s u l t s from t e s ts i n two thermos b o t t l e s were always a v e r a g e d , While no d e t a i l e d a n a l y s i s was made of e r r o r s , t e s t s on d r y snow i n d i c a t e d t h a t t h e e r r o r s were p r o b a b l y w i t h i n

-

+

2 p e r c e n t of t h e f r e e w a t e r c o n t e n t .

The wet snow samples were c o l l e c t e d i n a s p e c i a l l y p r e p a r e d c y l i n d e r of 100 c c , volume, w i t h p e r f o r a t e d s i d e s t o f a c i l i t a t e t h e escape of a i r , The wet snow was i n s e r t e d l o o s e l y i n t o t h e sampling c y l i n d e r . A c o n s t a n t l o a d of 1000 gm/cm2 was a p p l i e d by hand u s i n g a n

N o

R O C o h a r d n e s s

gauge, The compressed samples were t h e n p u t i n t o t h e thermos b o t t l e . Gloves were used i n h a n d l i n g and t h e samples were compacted i n t h e shade i n o r d e r t o p r e v e n t a p p r e c i a b l e change i n w a t e r c o n t e n t from t h e time t h e samples were compacted q t i l t h e y were q u i c k l y i n s e r t e d i n t o t h e thermos, The s i m p l e a p p a r a t u s used i s shown on F i g , 1,

A t l e a s t

3

and sometimes

5

samples were compressed and p l a c e d i n each thermos, The weights and volumes of t h e compacted samples were averaged b e f o r e t h e f i n a l d e n s i t y was c a l c u l a t e d . I t was c o n s i d e r e d t h a t a n a v e r a g e of s e v e r a l samples would improve t h e a c c u r a c y of t h e r e s u l t s ,

D i s c u s s i o n of R e s u l t s

F i g u r e 2 shows t h a t f o r t h e samples t e s t e d t h e r e was a d e f i n i t e r e l a t i o n between t h e f i n a l d e n s i t y of a compressed sample and t h e weight of f r e e water i n wet snow, The l i m i t e d d a t a a v a i l a b l e s u g g e s t t h a t d i f f e r e n t c u r v e s

could be drawn f o r f i n e - g r a i n e d , new 3now, and c o a r s e - g r a i n e d , o l d snow. An o b s e r v e r i n t h e f i e l d would be a b l e t o

c l a s s i f y t h e snow type i n t o t h e s e broad l i m i t s b e f o r e a t t e m p t - i n g t o f i n d o u t t h e p e r c e n t f r e e w a t e r from t h e compacted d e n s i t y .

F i g u r e

3

shows t h a t t h e f i n a l d e n s i t y of t h e

compressed sample f o r any p a r t i c u l a r w a t e r c o n t e n t i s a b o u t t h e same f o r a l l t h r e e s e t s of l a b o r a t o r y samples, There i s some tendency f o r t h e f i n e - g r a i n e d t y p e t o compress t o a h i g h e r d e n s i t y , b u t t h e v a r i a t i o n i s n o t a s g r e a t a s m i & t

(9)

The samples approached s l u s h c o n d i t i o n 8 b e f o r e f r e e w a t e r could be squeezed o u t by a compaction of 1000 gm/cm2. I h e c o a r s e - g r a i n e d samples had measurable w a t e r squeezed o u t a t 1 7 , 6 p e r c e n t , t h e f i n e - g r a i n e d a t 30.3 p e r c e n t of f r e e water.

The w a t e r c o n t e n t a t which f r e e w a t e r i s f o r c e d o u t of a sample u n d e r c o n s t a n t l o a d could be t e r q e d t h e " s l u s h " l i m i t . This l i m i t c o u l d a s s i s t i n c l a s s i f y i n g wet snow n o t u n l i k e t h e way i n which t h e term l i q u i d l i m i t i s used t o d e f i n e a c r i t i c a l m o i s t u r e l i m i t I n d i f f e r e n t t y p e s of s o i l . The g r e a t e r s c a t t e r of p o i n t s on F i g , 2 can be a t t r i b u t e d t o a t l e a s t t h r e e f a c t o r s : a ) The f a c t o r of g r a i n shape i s a p p a r e n t l y s i g n i f i c a n t i n t h e f i e l d samples, a l t h o u g h i t d i d n o t v a r y much i n t h e l a b o r a t o r y ; b ) The v a r i a t i o n i n g r a i n s i z e was g r e a t e r i n t h e f i e l d t h a n i n t h e l a b o r a t o r y ; and

c ) F r e e w a t e r c o n t e n t of wet snow was o b t a i n e d more a c c u r a t e l y i n t h e l a b o r a t o r y t h a n i n

t h e f i e l d ,

The r e s u l t s of t h e f i e l d o b s e r v a t i o n s were combined with t h e r e s u l t s from t h e unscreened snow i n t h e l a b o r a t o r y and p l o t t e d on F i g .

4,

A s t a t i s t i c a l a n a l y s i s of t h e s e d a t a produced t h e f o l l o w i n g r e s u l t s ,

The a d j u s t e d c o e f f i c i e n t of c o r r e l a t i o n , which i n d i c a t e s t h e d e g r e e of c o r r e l a t i o n between t h e f i n a l

compacted d e n s i t y and t h e p e r c e n t f r e e w a t e r , was found t o be 0 0 9 4 5 e A p e r f e c t c o r r e l a t i o n w u l d g i v e 1 , 0 ,

The s t a n d a r d e r r o r of e s t i m a t e , Syx which i n d i c a t e s how c l o s e l y Y can be e s t i m a t e d once X i s known, was

c a l c u l a t e d a s 3.16 p e r c e n t . T h i s means t h a t f o r 70 p e r c e n t of t h e o b s e r v a t i o n s , t h e water c o n t e n t c o u l d be

e s t i m a t e d w i t h i n

+

3 , l b p e r c e n t once t h e compacted f i n a l d e n s i t y i s known,

When i t i s c o n s i d e r e d t h a t no allowance i s made f o r snow type, o r f o r t h e u n c e r t a i n e r r o r of t h e c a l o r i - m e t r i c method, t h e r e s u l t s a r e c e r t a i n l y encouraging,

Improved s a m p l i n g equipment, a method of v a r y i n g t h e compressive l o a d , and a more a c c u r a t e c a l o r i m e t e r would h e l p t o c o n t r o l t h e experiments and s h o u l d produce more r e l i a b l e r e s u l t s . The improved a p p a r a t u s would have t o be used f o r a wide v a r i e t y of snow t y p e s and f i e l d c o n d i t i o n s b e f o r e more d e f i n i t e c o n c l u s i o n s c a n be reached.

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Acknowledgements

The a u t h o r wishes t o e x p r e s s h i s a p p r e c i a t i o n t o L.

W.

Gold f o r h i s c o n s t a n t encouragement and h e l p f u l c r i t i c i s m , and t o R. Amour f o r h i s h e l p i n t a k i n g t h e f i e l d o b s e r v a t i o n s .

References

1. H a l l i d a y , I. G o ?he l i q u i d w a t e r c o n t e n t of snow

measurement i n t h e f i e l d . The J o u r n a l of Glaciology, v o l ,

7,

March 1950, ~ ~ 3 5 7 - 3 6 1 .

2. Oda, Toshio and Kiyoshi Kudoo P r o p e r t i e s of snow and i t s d e n s i t y , SIPRE A b s t r a c t S I P 3I+4Z0 Novernber 1954.

3.

Taylor, Major Andrew, dnow compaction. SIPRE Report

13,

J a n u a r y 1953.

4.

Gerdel, Robert

W.

I n s t r u c t i o n s f o r t h e d e t e r m i n a t i o n of snow q u a l i t y . Technical Memorandum No, 1,

Technical Advisory Committee of t h e Co-operative Snow I n v e s t i g a t i o n Program. J a n u a r y 1945.

5*

Bader, Henri. Theory of n o n - c a l o r i m e t r i c methods f o r t h e d e t e r m i n a t i o n of t h e l i q u i d w a t e r c o n t e n t of wet snow. Schweizerische Mineralogis che und P e t r o g r a p h i s c h e M i t t e i l u n g e n , ~ 0 1 ~ 2 8 , 1948, p.355- 361

6. Gerdel, R m W o and A o R e Codd, Snow s t u d i e s a t Soda S p r i n g s , C a l i f . , p.15-16, Annual Report, Co-

o p e r a t i v e Snow I n v e s t i g a t i o n s , U,$. Weather Bureau

and U n i v e r s i t y of Nevada, 1944-1945.

7. The I n t e r n a t i o n a l C l a s s i f i c a t i o n f o r Snow (With s p e c i a l r e f e r e n c e t o snow on t h e g r o u n d ) , I s s u e d by The Commission on Snow and I c e of t h e I n t e r n a t i o n a l

A s s o c i a t i o n of Hydrology, N a t i o n a l Research Council of Canada, A s s o c i a t e Committee on d o i l and dnow

Mechanics, Technical Memorandum NO,

31,

August 195k9 1 6 p.

8

P r o c t o r , R o

R e

Design and c o n s t r u c t i o n of r o l l e d e a r t h

d a m . Bngineering News -Record, vol. 111, 1933, p.245-248, 286-289,

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F i g .

P

-

Shewing simple a p l a r a t x s used in Experimant:

a e s l e s , t h e r w s a f l a s k s , BT.F , C . h s ~ d n e s s gauge, sample 0

c u t t e , S . 3 , S . g ~ a % n sf-ze G U P e

(12)

040

-50

-60

-70

-80

₉₀

X = FINAL DENSITY OF COMPRESSED SAMPLE. COMPRESS I VE LOAD

=

1 0 0 0 ~ m . / c m . ~

O NEW SNOW-VERY F I N E 1mm.-AND LESS. 0 _{OLD SNOW-MEDIUM 1 m m . - 3 m m .}

Field Determination of Free Water Content in Wet Snow

NRC Publications Archive

Archives des publications du CNRC

FREE

WET

69

195.5

+

5

6-30

+

1.5

5

( 3 )

( 4 )

(5)

(7

( 8 )

3

3)

( D o

55)

.

( 4 ) .

-

+

N o

3

5

3

4,

+

W.

7,

3.

13,

4.

W.

5*

31,

8

R e

P

-

-50

-60

-70

-80

=

-

.

FIGURE: 2

F I E L D RESULTS

F I N A L DENSITY OF COMPRESSED SAMPLE

S.

PERCENT

BY WEIGHT

FREE WATER OF WET

-50

60

*70

-80

090

+k

FIGURE

3 LAB RESULTS

FINAL

OF COMPRESSED SAMPLE

S.

I

I

I

I

I

-

y

=

-

38.9

+

_.90