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A Study of Methods Used i n

mBaSmmWT m; U U Y 8 1 9 OF Smf MEfT %N ST

Planned and conducted j o i n t l y by

Office of Indian A f f a i r s , Bureau of Ileclarnation

Tennessee Valley A u t h o r i t y , Corpsof Blngineers

Geological Survey, Depastmentof A g r i c u l t u r e

and Iowa I n s t i t u t e of Hydraulic Research

Report Bs. 9 BmSITP OF SmIM&:NT%D m S IN mSERVQ1N E. 8. L m e and Victor A. Roelzer

Published at

S t + Paul U. S. Engineer D i s t r i c t Sub-.Office

W d r a u l i c Laboratory, U n i v e r s i t y of Iowa

Iowa C i t y , Iowa

November 1943

Iri s r a e r t o determine the r a t e at whleh r e s e s v o z r s VIPLI f i l l w i t h

oedlmeri~ x t 1% o f t e n n e c e s s a r ~ to e s ~ l f n a t e the weight, pel urlat volume s f

r,he d e p o s ~~ e d sedlmecit because the q u a n t i t y o f sedlment c a r r i e d by a stream 1s usr*aJ.ly e q r e s s e d i s ; terms 0 % weight r a t h a i tharl volume A t h e t o u g h s L ~ ~ d yof t h i s s u b j e c t h a s never beer1 undertalprer~ arid consequently

thd- esC1mated d e n s l c a e s used cover a wide and i n d i s c r i m a t e range of val

ues All availabke d a t a have beera complied 111 this reporl The r e s u l t s

a.r](i C O ~ I C ~ ~ S L O U SC b r ' a w ~ ~from au a n a l y s ~ s oP the d a t a a r e s

f'o rm 2 p p ~1cab I t to the rleeas sf orgarl a ~ a t i o n s o r individuals i n t e r e s t e d. resarvolr dt?srgi~

Table of' Con tents (^) -- 7

FDU OF CONTEXTS

e^ Bectm-^ ion

f u INTROBUCTIBM I Scope of the project,,,,. , G - , o. ,................................. .1l 2 Purpose of this investigation, , ,.. " , c.............. 12 3 Bcope of this report"... , : ;. 2. , a. , ,.. ,... ,. -........ ,.. 4 Authority and personnel,................................. 14 5 Aehowledgment s.... -... ,,... , , , , " , ~...... , -. ,....... , , 15 11 A r n V I E 1 OF r n L I S r n D L I T g u T m 6 Previously published l i t e r a t u r e , ,. q 1 I I E~mphreysm d A b b ~ t t a. ,.. ,. , , * , 1 7

8 Elephant Butte Reservoir, , ,... I (

9 C o l o r d o River Basin, , , - , 20 10 Texas reservoirs,,, c a. - -. o o , , a , o , , 2 1 k l Mi sssuri Bi ver , ,. , a > 216

12 HiiimS Conservaaey District retarding basins, , , n a o u. 25

1 4 Et~ropea~~investigatioa~s... a c - o n , 2.4 1aaves"cjgat ions of coarse sediments ~n Califsrnia-. , -. 2 8 I? Studies of i n i t i a l density by Trask,. ., -

16 Other investigations, = , , > , a " 3 3 31

111, MSULTS OF STUDY OF A V A I M U DATA 17 Factors influencing sediment density.9o.;. ,.. -. --.. , - ,. ,....... - = 333 I& Analysis of observed densities,,,,. ;. -. a a ~ , 2 ~ ~ ~ : - , ~ ~ , , 9 35 ~. ~ , , , 19 Values of density f o r use in design,. : : , , ,. : ,. , , , , , , , , , , , , , , , (^) *&g

20 Supplementary B a t a 3 0 ~ ~ , , = ~ L , ~, ~ , o~ , o ~~ ~ o,. ~c o o, 0 3 ~.. , ,. s , ,. 2. 0 52

Section v-. R---. 11

%, 1, Lane and Victor A. Koelzer*

1, --The measurement of the q u a n t i t y m d c h a r a c t e r of sediment t r m s p o r t e d by strerams i s rn important a c t i v i t y common t o r i v e r m i n t e n m c e a d development, stream dischasge m e a s u s e ~ e n t , e r o s i o n c o n t r o l , i r r i g a t i o n a d h y d r o - e l e c t r i c development Considerable work i n sediment measurement and m s L y s i s has been done, but t h e methods and a y p w a t u s used L : ~ Y C v a r i e d nideljr and the q u a l i t y of the r e s u l t s r m g e s from very g09d t o very p o o r , 1x1 an e f f o r t t o improve and t o standardize the methods and equipment a cooperative p r o j e c t h a s 'been undertaken by t h e f e d e r a l agencies having problems i n t h i s f i e l d , S i x r e p o r t s covering t h e r e s u l t s of these s t u d i e s , have been issued as f o l l o w s * Report No l--scField P r a c t i c e and Zquipment used i n Sm- ment and neth hods used^ ed%mentu, i n suspendedis^ a^ d e t a i l e d review of sediment sampling^ the from theequip- e a r l i e s t i n v e s t i g a t i o n t o t h e p r e s e n t with d i s c u s s i o n s of t h e advantages sllu disadvantages of t h e various methods and i n s t r u - ments. The requirements of a samples which would meet a l l f i e l d conditions sat i s f a c l o s i l y a r e s e t f o r t h --93quipment Used f o r S m l i n g Bed-Load anad Bed Material". d e a l s mith equipment f o r s m p l i n g bed-load and

bed m a t e r i a l in a manner s i m < l & t o t h a t i n which Beport No. 1

covers suspended load, Suspended^ B e p o r f l o , Sediments',^ 3--- " M a l y t i c a l. covers an^ Studyi n v e s t i g a t i o n of the^ of^ Methods^ s f accuracy^ S w l i n g of v a r i o u s methods of s m p l i n g suspended sediment i n a v e r t i c a l s e c t i o n sf a s t r e a n , based on the l a t e s t developments i n t h e a p p l i c a t i o n sf t u r b u l e n c e t h e o r i e s t o sediment tsansport-,ation. *Professor of Hydraulic Engineering, S t a t e U n i v e r s i t y of Iowa and

A s s i s t a n t Engineer, U o 3 , Engineer O f f i c e , L s u i s v i l l e , Kentucky, formesly

J u n i o r Engineer, U o %.Geologic& Survey, r e s p e c t i v e l y ,

1" 2 "- - ---- ------ Section 2

---^ Report,.^ Ro^4 l'Me^ l2lods^ of^ Analy^ ~ l n gSediment^ Samplesf',^ de i , r i b e ~dnd c i ~ o c u c n e smaiy netbods developeci f o r determining the s i z e o f small p a r t i c l e s i n sediment a n a l y s e s D e t a i l e d i n

s t r u c t i o n s a r e ga veri f o r many of the cornon methods i n use for

clet,err:iining t h e p a r t i c l e s i z e and the t o t a l coizcentration of sediment 1x3 sLtaLples a s developed by agencies doing e x t e n s i v e work i n t h e s e f i e l d s , tfLabora"cry I n v e s t i g a t i o n s of Suspended Sedi,- r n e n f l w l e r s " , d e s c r i b e s investiga"cons of t h e e f f e e t of vari--

ous intake condi t i o n s 0 x 1 the r e p r e s e n t a t i v e n e s s of sediment s m - -

pbes the f i l l i n g c h a r a c t e r i s t i c s s f slow f i l l i n g samplers utjder v a r i o u s conditions, Report Mo , I - "A Study o f ;tee Methods f a r S i z e Analysis of ~uspend-t Samplesfi g i v e s account of a study t o develop methods of s i z e a n a l y s i s more s u i t a b l e to t h e c o n d i t i o n s usu- a l l y rnet 1x1 suspended s e d i m e n t s t u d i e s , I t d e s c r i b e s a simple

form of a p p a r a t u s developed m d g i v e s d e t a i l e d procedures f o r

i t s u s e , Two addi t ~ o n a lr e p o r t s now i n p r e p a r a t i o n v r i l l be issued s h o r t l y on Lhe f o l l o a z n g s u b j e c t s Report--- 110, 6 "The Design of Improved Types s f Suspended Bob.lm@n"Lmplers~~d e s c r i b e s t h e development of v a r i o u s t y p e s asl" Lrkune integrating smunplers s u i k b l e f o r t a k i n g v e r t i c a l l y i n Legrated sarn,uLes i n f l o a l n g streams and o t h e r s f o r Lakialg time--

integrated r,anpl e s at a fixed p o i n t , D e t a i l s o f the b e s t forails

developed are g i v e n ---Report No,^ 8-- '~Measuremene^ s f^ Ihe^ Sediment Discharge^ s f Strezmasft, d e s c r i b e s the most e f f i c i e n t methods and equipment t o bo used i n making sediment measurements under various con- d i t i o n s e n c o w t e red i n n a t u r a l s t r e m s The scope of the p r o j e c e h a s been broadened somewhat i n o r d e r t o eanb~aee Che s1Ct~dy of Bedi~exltderisi t y described i n t h i s r e p o r t , as t h e

s u b j e c t covered was o f considerable importance to the agencies involved

aBnd t h e m a t e r i a l w a s a v a i l a b l e without f u r t h e r e f f o r t ,

2 , Purpose of t h i s i n v e s t i g a t i o n - I n aetesmlaling the economic f e a s i b i l i t y of a r e s e r v o i r p r o j e c t i r ~a sedimerlt b e a r i n g stream, one s f

the mast i m p s r t m ~problems is to malee an e s t i m a t e of t h e l i f e of t h e

1 !-I- "* ----------- (^) - Sect i o n 4

t - i ~ioat ~n d e t a i E ax" a l a r g e m o t m t o f h i t h e r t o unpub%ished d a t a (^) an sedi- aunt d e n s i t i e s md s i z e c o q o s i t i o n , vhich should be useful. i n m y f u r. -

t h 2 2 "aLudics which nay be made sf t h i s s u b j e c t ,

A f t e r the o r i g i n a l d r a f t of t h i s study was completed, c o n s i d e r a b l e

aors s r i g i n % % d e t a i l e d d a t a c o l l e c t e d by the So i l Conservation Service

be&?me a v a i l a b l e , but, l a s ~ f o r t m a l e h y ,i t was i n p o s s i b l e t o d i g e s t these

d a t a and co1~1parethem w i t h the conclusions reached from the e x m i n a t i o n o f the e a r l i e r d a t a , In the time a v a i l a b l e i t mas p o s s i b l e o n l y t o pre- ,jarde t hess d a t a i n d e t a i l i n t a b u l a r f o r n , tvherre t h e y w i l l be a v a i l a b l e

1 1 0 ~ ' ~ U L I Z Z - ~st~dies,as given i n Tables 1% a ~ dl 2

A u t h o r i t y =d persomel--The F e d e r d (^) agencies p a r t i c i p a t i n g i n

the geiAtsaa1 s t ~ d yof ftMeLh~ds Used i n Measurement and h d y s i s of Sedi-

nacr:%,f,s&a in S t r e m ~ ,! ~a r e : the Corps of E x i n e s r s , the Geologies% Sur

u s ; y , the Bureau of B e c L m t i o r , , the O f f i c e s f Indian A f f a i r s , the Flood

C su, t-01 Ctssrdinating Cornit t e e of t h e Depatment of A g r i c u l t u r e , the

'Y', X L R O M S ~ ~Vallegr Autk~ority, The work was l a r g e l y c a r r i e d OIL by personnel

i ~~x~i~iskaadby these w e n e f e s under the d i r e c t i o n o f P r o f G I 3 '@' Wme of

l , f ~ e $ 0 ~ ~ 3 I n s t i t u t e of B y d r a d l ~ Research a s s i s t e d by the s t a f f of the l o ~ : , ; ~ @j ty Sub OZffee of "ce Corps of Engineers Among those engaged or^ ~ l l i eworBr were P o C - Benedict, C. be B o y l l , M - D. Dubrow, 6 B..Borne, 'b he Koelzer, P* M e gobhe V , J c Palmer, F. W , Barker, D E R h i n e b r t , ;uad W P , 8 , S t a n l e y o The p r e s e n t r e p o r t was f i r s t assembled as a p e r s o n a l

p z v j e c L b y the a u t h o r s , but as t h e m a t e r i a l w a s of g r e a t i m p o r t a c e t o

~iaeagencies involved and, s i n c e p u b l i c a t i o n w i t h t h e s e s t u d i e s v o d d preserve a great p a r t of t h e value of the r e p o r t b y e n a b l i n g "ee d e t a i l e d

Section-- 5 - - - ---- -----

d a t a "e be p ~ ~ b l i s h e dI n fuJ 1, i t was decided t o i n c o r p o r a t e t h i s s t u d y as

a p a r t a f t h e major i n v e s t i g a t i o n ,

-^ s--Mu~kl.^ of^ the^ q u m t^ i t a t i v e^ d a t a^ on^ d e p o s i t e d^ sedi-

mentvahich have been used ixa t h i s r e p o r t s e r e obtained from m p u b l i s h e d

records of the W e S , Geological Survey, c o n s i s t i n g of t h e r e s u l t s of wit

weighto m d p a r t i e b s s i z e malysss of numeroue s a a p l e s taken from d e p o s i t s along the Colorado River its trlbuCLaries;4 by T, D, C o l l i n s , C. 9. Ilsward, and S , M e Love, Considerable d a t a v e r e f u r n i s h e d a l s o by the

Missouri Rives D i v i s i o n o f eke Corps of Bngineers v ~ h i c h had been eonpiled

by nf. L. 6. Straub. An^ a r t i c l e^ by^ 0exls(2~),^ t r a n s l a t e d f o r^ t h i s^ study

by t h e U , 8 , Bsterways Xxpsriment S t a t i o n Research C e n t e r s , gave a g r e a t

deal o f da"c from European s t u d i e s on t h i s s u b j e c t. A n m b e r o f sampler:

w e r e c a % l e c l e d from t h e Iowa m d Cedar R i v e r s by t h e Iowa I n s t i t u t e o f Xtydraulic Wesearch, These vmro analyzed by 5 , C. Kennedy, of the U. 3 ,

Xngbnwof Dspartrraealt, who also ~mdf;a preliminary review o f t h e p r e v i o u s

1 i t e r a t u r s on t h i s aubjecL SmpLes sf t h e d e p o s i t s i n t h e 3ngLersood mi$

Bermax1town retarding "basins sf t h e %imi Conservmcy D i s t r i c h n e r e f u r -

nished by C o H, E i f f s r t , Chief Engineer, ,and C. 3. B e m e t t , E n g i ~ e e r , of that o r g a n i z a t i o n , A barge c o l l e c t i o n of ~mpu'blishedd a t a was a l s o f u r - nished by the S o i l Conservation Service o f the U. S. Departmerbt of Agri-

c u l t u r e. Q t h e r d a t a were obtained from t h e p u b l i c a t i o n s of the $ o i l Con-

s e r v a t i o n Berviee, and " c h e U , 5. h r e a u o f R e e l m a t i o n , and from M s. A. D * Lewis, D i r e c t o r of I r r i g a t i o n , Union of South A f r i c a. Many v a l u a b l e sug- g e s t i o n s mere made by C a r l B , Brow.., % $ e d of the R e s e r v o i r S e c t i o n , Sedi-

mentation D i v i s i o ~ bof t h e S o i l Conservation S e r v i c e , 9k1e geneyous cooper-

6 , Previously published li terature--The f i r s t phase i n the study consisted of a thorough review of the previously published information

dealing with t h i s subject, Beferences %.rerefound scattered i n engineer-

ing L i t e r a t u r e , and t o a i d fukure i n v e s t i g a t o r s a bibliography i s added

at the end s f t h i s r e p o r t , I t was found t h a t unit veights varying from

3Q to 125 l b s , p e r cu. f t , have been used by various engineers i n e s t i - -

mating r a t e s of reservoir f i l l i n g. En the foSlowing paragraphs the im.- portant information from these a r t i c l e s i s summarized,

7. % 3 u ~ h r e y sand^ Abbott--The*^ e a r l i e s t record^ found^ of^ any estimate

of the d e n s i t y of deposited sediment was made i n 1861 by H ~ p l l r e y sand

Abbott who, used a value of 120 Lbs, p e r cu, f t , f o r the unit weight of

material deposited by the Mississippi River.

8, E l e p h a t Butte Reservoir--The Elephant Butte Reservoir,which w a s constructed between 1910 anti 1916 on the Rio Orande River in New ldexico , probably has r e c e i ved more study from the standpoint of sedimen- t a t i o n t h w m y other r e s e r v o i r , Because the sediment Load of t h i s

e t r s m i s extremely heavy, amounting t o as much as 22 per cent by weight,

i h w a s recognized e a r l y t h a t e x t e n s i v e deposition would occur i n the r e s e r v o i r , and s t u d i e s of sedimentation mere therefore p a r t of the in-. v e s t i g a t i o n m d design of the p r o j e c t. The f i r s t study seems t o have been made by T?. II. F o l l e t t of the U. 3. Geological $urvey(5).- On the b a s i s of a single s q l e consisting o f a g - i n , cube taken under c a r e f u l l y

selected conditions, he c o n c l d e d that the u n i t meight of deposited ma-

• 1. 8 ..~ Section PI

tepi;zi_ J L L the proposed Elephant Butte Reservoir would be 53 l b s , p e r cu. f ' c - a~d. that an average of 19,739a c r e f t , of sediment would be deposited & k ~ i. u c i 1 1 y lt, i s i n t e r e s t i n g t o note t h a t a Eater survey of the s i l t i n g of the ilicphnrit DutLe Reservoir indicated(') t h a t it was f i l l i n g at the r a t e of 20,000 acre f t. p e r y e a r , Concerning these r e s u l t s , Hemphill ('1 s a y s ,

J'YooXIett made no e s l i m t e of the silt r o l l e d abomg the bottom of the

stream, but s t a t e d h i s b e l i e f t h a t it might p o s s i b l y mount t o as much as

25 per cent of t h a t suspended, Accepting t h i s r a t i o as a maximum, the L ~ J S U L L ~o f the survey gave aurait value of 65 l b s , of d r y silt p e r cu,

f t , sf d e p o s i t , It i s believed t h a t they ( t h e 3 i o Grmde sediment reo-

o r a d s ) ware accurate enough t o i n d i c a t e f a i r l y that suspended s i l t i n the kliblo Gcande rvibk form d e p o s i t s containing from 55 t o 65 bbs, p e r c u e f t.

O T o i a t f t

w aCutXy o f the sediment deposited i n %he b a s i n was made by R. R ,

g d 3. i n ~ 9 1 6 ,who measured the d e n s i t y of three

~ ~ t ~ a ~ ~ p l c sof sediauaent and f o m d d r y weights of 88 t o L O 1 Iba. p e r cu. f t ,

I ~"r,ll311. average o f 92 I b s , per CU, f t , Sieve m a l y s e s o f t h e s e s m p l e s

~ h , + ~s i z e s ranging f r o m 76 t o 88 per cent (average 8 1 p e r c e n t ) p a s s i n g Cne ;)03 mesh s f e v e md p ~ a c t i e a l l ya l l passing t h e LBO-mesh s i e v e , The water inflow i n t o the Elephant Butte Reservoir has been measured

aC Sari Marsial, a s h o r t d i s t a n c e above the r e s e r v o i r s i n c e before storage

nas s t a r t e d in the b a s i n , Continuous sediment observations were made i n

1913 a d from 1925 t o d a t e , Based on the inflow and sedimene records,

esttmaates of the d e n s i t y of t h e sediment mere made by t h e I n t e r n a t i o n a l Boundary Comission from 1925 t o 1935 and by the Sedimentation Division

(^20) ---- "- - -- --- Section 9

t l i l i d - osraissicara is pl~obablyvalid, The International ]e3oundary Csm-

v a :;b9 0x1 e s t imata neglects the storage sf sediment above spillway level,

cl;L tirzstecl by "Lie $oil Conservation Service at 14,323 acre ft. This is

j ( 5 p t r cent sf the storage used for the total period and l1,8 per cent

r3i" the storage used f o r the 1925 to 1935 p e r ~ o d ~The error is therefore

betryrcen 3,8 and lL 8 per cent It is reasonable to assume that most sf

L!w, sct%inaen"cabove spillway level was deposited in the latter part of the

p d " i. ; d , since during anuch of the early part of the period the reservoir

was S'EIling up, and bklerefsre at a low level Assuming that 18,000 sf

L L I ) $ , 32 j acre fL, were deposited in the 1925 to 1935 period, the in-

c i ~ ~ s i o r ~of t h i s volume in the 1925 to 1935 estimate would lower the sedi-

man% d e n s i t y f r o m 70,2 Lo &4*5I b s , per cu, P t , h o t h e r part of the d4f-

:s:ionbc ill tila densities computed by the two organizations is probably

UP: I(:, Lhe shrir~k~agei r b the sediment ~ i t htime, The assumption is made

i,i~,:C "tit? 0 CPero~rce in "che sedimen"c~rcsJ.tame in 1925 m d 1935 is "che space

'st,$ 1ci.~;-d ibg i,he sediment which cans in during this period" Actually the;

&, d ~ , i l ~ n Cr c e ~ ~ p f s erketoovlly this space but also the space made available

) 1 a g e o f the sedineb%%deposited before 1925 which took place dur

i r l g Ghe 192"30 1935 period. The true volume of the 1925 to l935 sedi-

I t s therefore greater than that estimated md the true density is

Cl~crc Pace Lees khan estlmted, Knowledge sf the rate sf compaction in

r o t,e: ("voi rs f s i l l sxrf f f cient to estimate closely how much difference in

c? e l \ b i t y the csqact5on vouXd make, but it might m o ~ m tto several Lbs,

1 ) 9 1 eu, Et,

.$,L&$ River Basin Considerable data have been collected in

Sset ion 10 2 1

the v a l l e y of the C o l o r d o River i n Arizona a d California. The U. S.

Bureau of RccLwnation used(7) a u n i t weight of 100 l b s. p e r ou. f t. i n

studying the deposited material i n the I n p e r i a l Canals, F o r t i e r and

s l a n s y i 6 ) thought t h i s value was too high f o r material c a r r i e d i n sus-

pension as the material sampled and analyzed i n determining t h i s f i g u r e

was l w g e l y t r m s p o r t e d a s bed-lo&.

Table l i s a s (^) r y proposed by Stevens (16) of a number of samples

of sediment deposits %&en i n the region s f %he GsLor&o River by F o r t i e r

aBlmey,

TUU %

DIHSITY OF Sm$UMS% DBPOSITS FROM VICINITY OF C O L Q W Q RImR

Bed Silts, I q e r i a l Canals, 1925

Bsd Sf lLs, Imperial CmaEs , k9%7-%g

OiPa River s i l t bare;

S e t t l i n g b a s i n s sf fallowing I m e r i a l

Valley m n i c i p a l water systems :

EL Gentro , Calif o r n i a

Imperial, C a l i f o r n i a

Calexieo , C a l i f o r n i a

Iqerimen"e1 basin at R a k e r City

Density l b s ,

p e r cu. f t.

A large number of s m p l e s have been taken from the Colorado River region

by the U. S Q GeoEogicd Survey, the d a t a f o r which a r e given i n Tables 8

and 9.

$ 8 , Texas resewoirs--Table 2 gives d a t a taken. from surveys of

naaeraezs r e s e r v o i r s i n Texas ( b y ' ) i n 1929 by the U. S. Department of

k r i c u l t u r e. This t a b l e gives the dry u n i t weight of the deposited sedi-

ment m d a l e s Lhs p e r c e n t w e of moisture i n the s ~ b e aa s taken. The

Section 10 2 3

report sn t h i s study gives a g r e a t deal of valuable d a t a , of which the

fo l l o ~ i n gparagraphs swvmari ze the rno re i q o r t a n. t finding s o

''It should be kept i n mind tha, the average ultimate

weight of the d r y material per cubic foot of deposit depends

on the function m d operation of the r e s e r v o i r , In a reser--

v o i r used f o r flood c o n t r o l s n l y , the water i s stored tempo-

sari12 , m d the deposited ~ n a t e r i a l, subJected to shrinkage during long periods of time, (^) has , r a v e r w e ultimate weiglit s f d r y i n thernaterjal average r e s e r v o i r f o r storage of water^ per cubic foot^ of^ deposit approximating f o r f u t u r e u s e ,^90 I b s , ;

dry periods m d increased demand f o r water result, la lowering

of the water surface and the exposure of the s i l t deposit f o r

periods of time r e s u l t i n g i n an average ultimate weight of d r y

m a t e r i a l per cubic f o o t of deposit qproximatjng 70 l b s , ; and

i n a power reser-voir, where the head. is maintained p r a c t i c a l l y

consLmt, e q o s u r e m d the r e s u l t i n g s h r i n k ~ edo not take p l a c e , cubic f o o tm d theo f depositaverage iLpproxInaatesultimate weight 38 (^) l b s ,of the dry m a t e r i a l per

weight^ "The r a t i o s^ wrieer, of^ s i l ta f t e r samples^ c a r e t u ~ l y and the measurements of^ considering^ the^ volume-exposed md sdmerged d e p o s i t s i n r e s e r v o i r s , has s e l e c t e d 70 I b s , as the a v e r w e ultimate weighs sf d r y material per cubic f o o t of d e p o s i t , f o r cora~rertiu~gu n i t s by weight i n t o u n i t s by volume,

This s e l e c t i o n was made with a knowledge of the indeterminable

v o l m e of vegetable m a h e r i u : %lac form of logs and brush which moves d o m the s t r e m a during r i s i n g stages. Since much of t h i e material is waterlogged m d t r a v e l s unobserved dovmstream

below the water s w f a c e , i t i s impossible Go estimate the

voltme, Such material w i l l be deposited where it v ~ i l lbe pre-

served i n d e f i n i t e l y if kept submerged wftb w a t e r o n Regarding the results of these s t u d i e s on Terns r e s e r v o i r s , Hemp-

head sf^ !!Exposed r e s e r v o i r s ,^ b a r s^ ofaverwed^ coarse 9 2s i l t , I b s ,^ ofsuch dry^ a s materialis^ found t o at 1 cu.the

f t , of d e p o s i t , while f i n e r s i l t i n mush the same Location

averaged 82 l b s , S m p l e s Prom "ce surface o f d e p o s i t s near the middle of r e s e r v o i r s averaged 55 Zbs. of d r y m a t e r i a l t o each suUb%ilergsd cu, f t .deposits Smp1es i n ofo l d the f i n e s t materialr i v e s c h w e l s i n r e s e r v o i a * ~talcen from theaver- w e b g l l b s , of dry material t o 1 cu, f t o i s i n t e r e s t i u g t o note t h a t if the average s i l t y i e l d , i n tons per &;quare mile, from "ce a r e a a'b0ve t h i s r e s e r v o i r (C&e Worth) i s c o q s a b l e t o t h a t of the nearby

9 r! i a o s drainage, as shown by the records at Glenrose, the de- p o t ~i Q 'in I h e reservoPr eonlains l e s s than 60 l b s p e r cu, f t. s t

i f 3 .6. ~ i c i r l e ' " ) s t a t e s t h a t the d e n s i t y of d e p o s i t s i n the gedina

f i c s e i v o l r a f t e r I j years o f operation averaged 30 kbx p e r cu, f t , , but 5

, y c t t ~ ~l e t t e r , owing t o exposure t o the suaz and a'ccnosphere i n t h i s period,

had increased to 6 ~ I b s~ 6 p e r cu f t , IIe e s t i m a t e s t h a t .an average vaP-

~ic-:o f / O I b s , per cu fL, shou.ld be used i n r e s e r v o i r s i n which the s e d i -

IXIO~ILJ~positsare subject to a l t e r s a l e webting and drying

L L & r i Dr, % , C , Straub w l e a thorough study sf the i i c ~ ~ $ i i t jo f sediment carried. by the Missouri River f o r t h e Missouri River 3 i v 2 sioa of the U, S o Engineer Departmeu~t A combination of' smples; gaL1iared i n the course of f i e l d operations were separated i n t o various

t , r ; , r C e k i ranging from clw t o pebble gravel and each grade was aIloned to

& r : C b l c i n still water wader i d e a l i z e d conditions, The fol%ov~ing t a b l e

d j s i 1 , vs3r; t h e wait msights and other p e r t i n e n t d a t a from these studies;,

4 n ~ m ~ b e sof samples ere taken fron the s e t t l i n g basins; o f the Em-

W ~ W C i t y , K;insas, waterworks and analyzed f o r u n i t weights; m-d p e r cent

of arside, The wa"cr was p q e d from the Missouri River and hence the

serilrnen t was d e f i n i t e l y suspended, The r e s u l t s a r e given i n the %oL%ow