HYDRAULICS BRANCH OFFICIAL FILE COPY

UNITED STATES · DEPARTMENT OF THE INTERIOR

BUREAU OF RECLAMATION

BUREAU OF RECLAMATION HYDRAULIC LABORATORY

SOME HYDRAULIC ENGINEERING ASPECTS OF

DENSITY CURRENTS

Hydraulic Laborat ory Repor t No . Hyd - 373

ENGINEERING LABORATORIES BRANCH

OFFICE OF THE ASSISTANT COMMISSIONER AND CHIEF ENGINEER DENVER, COLORADO

August 31 , 1954

CONTENTS

Introduction . . . . . . . . . . . . . . . . . . . . . Causes of Density Currents . · • • • . • • • • • • • • • Underflow Turbidity Currents • • • . • . • • • • • . • Interflow and Overflow Turbidity Currents . • • • • Data on Turbidity Currents in Reservoirs. . .. . • • • • Possibility of Decreasing Deposits in Reservoirs

by Venting Turbidity Currents • • • . • . • • • • . . Density Currents Due to Dissolved Solids. • . • • • . • Density Currents Due to Temperature Differences • • • . Mechanics of Density Currents • • . • • . . • • • • • Miscellaneous Facts About Turbidity Currents • .• • • •

APPENDIX I

Data on Turbidity Currents in Reservoirs

Lake Mead Above Hoover Dam • . • . Elephant Butte Reservoir • . • • . • . Lake Texoma, Oklahoma-Texas •..• Conchas Reservoir, New Mexico • • . Turbidity Currents in Lake Issaqueena .

TABLES

• • • • • • 4t •

. . . . . . . . . .. . . . . . . . . . . . . . .

Page

1 1 2 3 4

4 6 7 8 8

10 12 17 18 18

No. i - Density Flows Into Elephant Butte Reservoir. • • 14 No. 2 - Density Flows out of Elephant Butte Reservoir. • 15 No. 3 - Temperatures, Salt, and Sediment Content

Elephant Butte Reservoir, August 9, 1935. . . • • . • 16 No. 4 - Data on Turbidity Current in Lake Texoma . . • 17

FIGURES

Underflow Turbidity Current in a Reservoir- -Plunging Type . . . . . . . . . . . . . . . . .

Underflowing Turbidity Current in a Reservoir--. Settling Type . . . . . . . . . . . . . . . . . . . . Cumulative Curves Showing The Estimated Mean Size

Compositions of Sediments Deposited in Lake Mead Above Hoover· Dam • • . . • . . . · . . • . . . • . •

Longitudinal Section Through the Deposits in Lake Mead Above Hoover Dam . . . . . . . . . • • . . . • ·. .

APPENDIX II

Bibliography

Number

1

2

3

4

. . .. , , U:t;H'~ED _ST A TE~. .· .. , DE.PARTMENT .,OF:.THE INTERIOR

BU-REAU oF· RECLAMATION ..... . . ' '• ' -~ . . .

Office.of the :Asst~ta~t. Cqmm~~sion~r. La.b_oratc>'ryReportNo. Hyd-373 · and Chief Engineer . - ,H;y<Jraulic Laboratory· Engi_n~ering Labor1;1.torie_.s 'G<>mpiled by: ,E ~·· W. Lane . · Denver:~. C,oloradc;> ,Reviewed by:'. _E,.. J,., Carlson,. August_ ~i, 1954,

Subject: Some hydraulic engineering aspects 'of density c·uTrents

INTRODUCTION"

. . . . , . Density. c.urrents have been defined by Belli(4).!/ as "a grav-. _.ity flow of a fluid through, under, or over a flµid oi,appl'oxi~ately

equaJ.density. ''. Such c.ur:r;-ents caus~ a number of effects which are. of impo,rta1;1c.e to t};l.e hydraulic. engineer, and, he should ther~for.e be aware of t.he:m.. It is the purpose of thi~ report to qri1;1g together .. t,rom widely

· scattered sources some of the most important informa~ion pn .th:is sub-jec1: · · ·

. . . . ,. . . _, ; . . _. . . '- .

. . Density currents are very common~ · a~ :many large scale, . movements of air masses in the a~mosphere are i~ this_ class. Cloud

. ·or fog movements and dust storms .are other examp~es. These cur-1'.'ents range in size from actions covering a good fracti<>n of the ear~h's ~tirface to ~in~te movements _of mud in a pudc,Ue ..

Causes of Density Currents

. The density currents.which ar·e of interestto .the. hydra~lic. engineer· a~d are treated in this paper are those. which occur in rivers, res.ervoirs, lakes .or the oceans, and involve flows of water. They may be gro.uped into thre.e classes, 'according tothe causes of t};leir_motion. One class covers currents with movement due to the suspension of sedi­ment in the flowing water, and usually involves the deposition of sedi­ment in reservoirs. This class has been called. turb~dity. currents. A ·second class. cove:rs. those densitY, cp.rrents ~aus·ed by dissolved material ;in.the wat~r. ~pd is import.ant ~rozp. the standpoin.t of t]).e,suita:;bility ot w~ter_ fo;i:-, irrigation or domestic use; . The thir.d class, is· movements due to.djfference in densities set. up by differences in temperature in .the wa­ter, and is .of interest in conn_ection.-with the quality of water ·fr.om res-ervoirs:-used .for publi9 wa.te;r;- supply:, . · ·

Since density currents are due to differences in density of the flltids tnvolfed, tl;l~y_may be due t_q any single .cause!Which sets up dif­ferences of density, or .to any ,coµibinat:Lon of cause-s .. For example, in

1 / 'Numbers refer to ·articles in: -the bibliography ·at the end of , this report.

Lake Mead in the Lower Col9rado ~ive'r·/in southw.estern United States, sediment content, salt c~ntent~ ·and _temperature: 'are all three of im­portance and may ad in·eombination. · · · · · · · · ·

Since density currents are flows of a fluid, through, under, or· over·anoiher flu1d, they :,pay also be classified· according to wh~ther the flow of the one fluid is through, under I or over the other. The den­sity currents which· flow through another fluid are called interflows',, · tho.se,which flow- under another· fluid are underflows and those: which flow over the other fluids are overflows. It is possible to have a combination of these types, for example, a flow may start as an underflow and then become an interflow. · ' · · ·· · ·

Underflow Turbidity Currents

0ne of the· common types of density current is· the underflow­ing turbidity current, Figure 1, which moves down the bottom: of the ·res­ervoir, due to the greater density of the turbid water resuiti.Iig from 'the inclusion of suspended sediment. For example, currents of muddywa:.. ter have·been· observed to flow down the bottom of take Mead for over·a hundred miles, under a quiet body ofclear water the surface of which. was practically level. The force which causes motion is the greater·den­sity of the muddy water, and the magnitude of the force depends on the differ·ence 6f'denslty of the muddy and clear water, the depth of the flo:w, and the longitudinal slope of the reservoir bottom: Because of its greater dlrnsity:, the turbidity current usually follows the low"est path down the' res -ervo-ir. In some: cases it deposits part of its sediment as itfl~ws, ·and in other cases it appears to deposit little if any material. 'Initially ·the flow closely follows the original stream channel down the bottoµi of the_ rese_r­voir, but the inertia effects at bends are more pronounced than in ordi­nary flows, and such currents have been known to rise up and go across a bend,· rather than following the lbwer botto:m ~round. it_. This_. is possi­ble· because th·e ·effective weight of the turbidity current is much less than in ordirtary flows, 'as ·the effective weight is only the difference in weight of"the clear and turbid water, and may be as little as 1/1000 · of the act~al --weight~ · · · . · · . • · . .. . · · .

When such a current reaches a dam in which there are openings · at'· river bed 1eve1, · the turbidity current will flow out in many cases with­out ·mixing with the clear water. If the discharge of the· turbidity current

· is· greater than-the discharge -capacity of -the sluices, · part of- the flow ~ay be, temporarily stored in the bottom ·of-the reservoir, ·like a flood flow in a retarding basin. - If there are no openings·, the 'turbidity current tends to form a lake of muddy water in the :bottom of the reservoir under the clear water.

· · The turbid water 'flowing into a reservoir niay plunge directly under the.clear water in the lake as shown.in Figure L In'this case it sets up an upstream current on the surface of the .clear :wat.er, as indicated ;hyj}:l.e arrows.. Whe:re this upstream _flowing current of clear water meets the downstream flowing muddy water, drift brought down the str.~am may collect on the surface in large quantities.

2

.. · Becau~e of the drift.on .. the·,surfac~.and the sharp line of sep­aration .. of:the muddy and the cle.ar,.water. the formation of a turbidity-, cur.reµt,as just-described is readily.apparent •.. T~ere,is. reason tc;>-be-· · lieve.; • ,howeyep., that in ,many .r,eser.,voirs·: the inflowing water does not , dive :Ul).der tb~. clear. water. but pushes ·it downstream and .·f ortns a, ·con.-. si,c::Jetable pody1of muddy water:.· in which the sediment.is .slowly· settling to t.b..e: l;>ot:tom:~$ shown in!Figure 2 .. ·When.this sediment reaches .the bottom, some of it collects in the .form of a dense .. fluid, which-flows . down the banks to the main channel and then flows down the main chan­~el. in. an undertlowing turbidity ·current. as in the. previqus case. This

-means. of .forllla'tion .of, a density current ·is riot. so -easily detected as the one previo,usly.described and·has not,been directly observed but its ex:-

. istence is inferred from the deep deposits of fine material in the stream bed near the upper ends of some·large reservoirs. These deposits are· much deeper compared with the deposits outside the clia:nne1, than would occur if there were no movement of-the settled sediment after it reached the reseI.'voir bottom ... In the .upper end ·of ~ake Mead,, deposit', except in the s.tream channel, is usually nonexistent, although .muddy water has frequently covered much,of the upper-end'. of the reservoir, and no doubt much of this sediment has settled to the bottom ..• Underflow type of tur­bidity currents sometimes occur as the- result of suspension of sediment caused by wave action on the s.hores of reservoirs. . In this ·case the flow is f~Qm the banks ·at the edge of the res:ervoir to the bottom of the: reser­voir.

The.velocity of flow in an·underflow type of-turbidity current depeJ:lds on the densit,y of. the turbid water. the depth of the flow, · and the steepness of the channel. The force per unit .volume causing the flow in­creases with .an increase in the difference in density between: the two · · fluids. It increases with an increase in the bottom slope and with·an in.., crease in the thickness of the heavier liquid. Ordinarily the velocity of flow is less than 1 foot per ,second, but some authorities believe that much higher velocities are sometimes attained ... Density currents have ·been used to explain the formation of submarine canyons in the ocean~ .and the presence of sand and gravel on the sea bottom at large distances from the land and a.t great depths. Under such conditions the slopes are steeper·. tha:n -usually found in reservoirs: and the velocities are probably hi,~~er ~

Interflow _a:nd. Overflow Tqrbid:j.ty Currents

. . . . .. : When, the clear water in the different levels of reservoirs has· C011$ide:rapi~ different densities" . interflows· may be formed. , Frequently ~he- water near the surface e>!. a reservoir is much warmer and ther..efor:e lighter than the water near the bottom. If turbid water witha density be.­tween the light surface water and heavier bottom water enters such a res­ervc;>ir it is_ likely to C fqrm an interflow. The turbid: water. flows along the res_e,rvoi~ pottom as an unqerflow. w;itil it reaches a layer of the .colder • botto:¢ water which h~s a,_greate:r ·dep.sity ~ The turb.id·watercthen 'flOWS.: . al()-:r;,.g ~he. top of .. this l~yer •. forming, an iI\terflow between the tw.o layers. of cl_~a.r~ :W~ter •: , · ·

-1 ·• ,_·

3

--; - · · . ·When.the· inflowing turbid wate.r 'has a· d~nsity les·s than the water in the ·re.servoir, it will flow:-out- on top of·the ~enser.water./· · ,._-, .­causing; an o;verflow type of turbidity-,current~ A,common; ease of;thls ·• · type· occ-urs when a. rive-r of turbid wate-r, enters·: -the salt water of' the . · · ocean, and it :flows out into the ocean :on top of the· heavier ;"Salt ,wa:ter,. ' T:he, M-iss~sippi .River·,flows for- ·many miles out -into the Gulf-of Mexic·6-as an' ov.erflow- type ·of density current. · Although it contains :sediment, · it is :leas, dense Jha:n:the sa:lty·ocean water~: · · - . · · , · · · , :

' :- ·. . ': .:· ~ \ :-

: · .. , In any one reservoir, the conditions ·may change so that more than one type of turbidity current is formed. In Lake Mead above Hoover Dam,. u·nderflow, interflow ,· and overflow types have all been· observed~·

: I . •

Data oii ,Tu_rbidity Currents in Reservoirs ·

,: ' · ·_· ' The. most complet.e data on turbidity currents ill reservoirs -deal with _those Which have occurred, in Lake Mead, above· Hoover Dam . on .. the, Lower Colorado River (l. 2, 3) 9, 12C. 36, 41:, andAppendix'l).· C.onsi'dera..ble data are also: available on the Elephant Butte Reservoir-,· . (3; .. 15;; 18,, and·Appendixl),onthe Rio Grande in New-M-exico. -on the .· C'Qnc·has--.Reservoir (11) on the So~th Canadian River in New M·exico;. and ·pn,_Lake Texoma on the .. Red River in'.Texas and Oklahoma~ Some ,obs:er·­.-vations:;,haVe been.made on Lake Issaqueeha (14-) in South 'Carolina a:nd · Lake Lee (16) in North Carolina and Morris Reservoir in California. Density currents have also been observed in Lake Kemp in Texas, Santa Al'li.ta· and ·Morena Reservoirs· in -California; E"cho Reservoir; in Utah, ·Norris ~e.se:rvoir and the. lake above Wilson.Dam in Tennessee, L'oek,·-' Rave,n,.Res.ervoir in Maryland; Zuni Reservoir in New-Mexico, Lak~·-Mu:r-ray in South. Carolina,- As.hokan Reservoir in New York, and··Lake Arthur (5l in.;South Africa-. . · ·

. .

--! . ; ,· ·,Data-on some: density currents·-observed in a few of the reser.:.. voirs :mentioned are· included: as· Appendix I.to this report.: :A rather· ex..; tensi;ve bibliography is included as Appendix IL.. · · ·: · · · '·

of Decreasin (!)sits in Reservoirs -b- ··Turbidit- ·,

The possibility of decrceasi.Ilg thE3. r.ate c;,f- fHµti:lg of -~El-~lYQirs_ ' with sediment by venting the turbidity currents of the underflow type has been widely discussed (2. '3, 5, 6, 7,: 14, 18) and exampl_es- of such cur­rents: being dis charged from. reservoirs are, numerous. . A:rgum:ents. bbtli for and against this pro<::e-ss as a means of :decreasing reservoir dep·osits -have ;been made. · · · · ._. ·

--,- ,'.·: -~, :

, . · · · ' .. · The reduction' of deposits by.this_ method has been used· in the 1,ake: .Arthur Rese.rvoir· in South Africa .for flow-s of flocculated c1ay··with · concentrations between-a lower limit;of 1.:..1/2 percent to,'5 ·percent:and· ,.

=an upper limit of 25 percent. No data from Lake Arthur Reservoir are available on the amount of sediment removed by this process. ·In ·order to save water. the inflowing turbidity current is retained until its sediment

has settled down to near the maxiuium' concentx-ation a:t which-it .will- ·: .. '. flow out through the gates, and this concentrated slurrf'is"then drawn· out. -- .

' . ; . . . ., ·. ... . ~'-· :·.: ' . -} :; ·/l ~

· The experience :with rese.rv.oi:rs in the United States:. ha's'. not :_ be~z:i e:nGpqraging to the venting of density currents as a·means 0of' sub­stantial.ly reducing sediment de-posits .. in.re.servoirs. · .In the early years ·

. of 1.l.$1:l' ot 'the ~lephant · Butte Reservoir on the. Rio Grand.e, these currents brougl\lt ,secUinent-down to the dam and.it ·wa;s;;discharged lhrouglf-tlte ·out;. let in the bottom of the dam. Some irrigators downstream ·often declined to use the water, as it had no fertilizing value, and if used to irrigate ne:wly ,planted -land,_ :kiiled the ·young sprouts~ : Irrigators- whose land was too.sai,.dy, :h(>w.ever; eagerly sought-the water,, as it'improved the texture of their soil .. · E::ven in the early years of Elephant.'Butte.Reservoir, ·where the conditions are especially favorable to the formation of such currents, tb.e:\Se~liment dis.charged:ili this way was less,,than 5 perce-nt of that enter­ing. th.ea -r:eservetr .. In recent years,· -no turbidity currents have r·eached · El,epb.&At: Bµtte Dam .. ·.·

·: • ·: '. ':-: . Tbe frequency of turbidity currents· in :Lake Mead on· the C.olo­ra<Jo:River has _been lower in rece-nt years than s.oon afte·r the ·reservoir was built. The reason for the decreased frequency of flows- in-Lake Mead and Elephant Butte Reservoirs is probably that the deposits on the lake bottoms :formed by tbe turbidity currents are level across the. reservoirs, and_ the. density flows pass over these b0.ttoms in: a ·thin .sheet. A:s· the de­pos~ts fiU the yalley, the width of.these deposits·increases·and.the.depth. of flow of the·currents becomes correspondingly smaller .. As·the depth of a..b1rl>i~ity; cqrrent decreases its. velocity e>f flow also decreases, and mor~ of tq.e. sediment :ls d~posited on the_:bot.tom.,. and, less therefore · reaches th~ dam. ,At one poiµt-inLake -lVIeadt:he- width of the level bot- · tom has_become more t~ 6,090 feet. Measurements in recent years­have shown lower v.elocit_ies than·th~ velocities in the. earlier flows. It · s~e~s iµ,t improbable that in the futu:re th;~se. density cur.rents- may cease to .r~~ch the- dani. in both the Elepq.ant l3utte ,Reser.voir and Lake 'Mead.

- ~ . '

. In the T~xoµia Reserv:oir-.on_the lted River, .the s.edim:ent brought down to the· dam by turbidity currents is probably le.ss .than 10 percent of the total sediment load. Records of 15 to 30 percent of inflowing sediment r~aclrlng. t~e dam was o'btained from the Conchas Reservoironthe·Canadian ~ive.r., .w,here the cpndJtj.;Qlls·are favprable for turbidity currents.· The ~lopes ar~ steep- (8 to 12 feet. per male)-, sediment ·concentrations. of the in­flow~g rive:~·-are high (up to 5.-5 :percent); and the reservoir . .is narrow .. T-hes.e· values onthe.Conchas were for the first 11 years·of operation, and will likely decrease, as- the reservoir fills with sediment~

. F-rom the foregoing discussi.on ·it may be concluded that -in most re,serv:oirs· the sediment that can be remov.ed by -\tenting density currents will not ·be a .large part of the· totalsedim:ent fuflow .. · If .outlets ate plaeed

.. near,:the bottom of the reservoir to discharge water'for 'other purposes, - .· they;may. also ·be-useful to :discharge the turbidity curre·nts -that· occur.

-Where water is valuable., . the· practicability· of the methrid. desc,:ribed,. as used_ in S.outh Afriqa s.hoµld ·be studied. ·

5

Density Currents Due· to Dissolved Solids .,_ ;.:!.

Density currents are frequently caused by dissolved solids in the water. A very striking case of this kind is observed at the mouth of the Mississippi River,.- where the muddy water of the river flows for many miles out into the clear water of the Gulf of Mexico, with a sharp· line of demarcation between the muddy and the clear water. Here the muddy Mississippi water flows on top of the clear Gulf water; the Missis­sippi water in spite of its load of sediment, being less ·dense than the salt water of the Gulf.

An interesting phenomenon .occurs in the Mississippi near the· mouth at times of very low flow. Here the river water flows downstream near the surface and salt water flows upstream near the bottom.

The Mississippi River reaches the Gulf of Mexico through four principal distributaries, branching off from the main river like toes on the foot of a bird. At the end of each of these channels a bar is formed by a deposit of sediment brought down by the river, over which the depth of water is much less than in the river channel. The depth in the distrib­utaries is somewhat more than that over the bar, and less than the· depth in the main river.

At all discharges of the river the greater density of the water in the· Gulf tends to produce an underflow of salt water upstream _in the Mississippi, . but only in times of low flow does it succeed in producing · . an upstream current. At such times there is an upstream flow of s·alty· water along the river bottom, above which there may be a downstream · current of $alty water· being dragged along by the flow of the river water. For certain flows this condition. extends from the Gulf only part way up ·. the distributaries, and no salt water reaches the main river channel. · Under other conditions it is possible that the salt water does not mix ' with the fresh water, but occupies a wedge shaped space below the fresh water, with the thin edge of the wedge upstream. At high flows the drag of the water flowing downstream is sufficient to prevent any density cur­rent from flowing upstream and the flow of salt water is thus prevented from entering the distributaries. -·

At very low discharges the amount of salt water carried down;.. stream is less than the density current flowing upstream, and part of 'the density· current enten; the deep channel of the main river. Here the ·chan­nel is much deeper and the velocity smaller than in the distributaries. The salty water collects in the bottom of this deeper section of the river, and in -times of protracted low flow it fills up the low portion anct extends upstream many miles, causing bad pollution of the water supply of New Orle~ns, which takes· its water supply from the river about 120 miles above its ~outh. When high enough.flows occur, the salty water is flushed out into the Gulf again. The .salt water, while .collected in the deep part of the river, causes much of the sediment brought down. -by the river to coagulate into athick slurry, which remains in the deep part of the river· until flushed out by the higher flows. While passing out through the dis tributaries, · this slurry has been known to be thick enoughto stop the passage of a large steamship.

6

.· ,W.;t\~ µps.tr~a:m.- flQw.·ing '.!salt water: wedges" ,as the~ are called occur_n~ar the mouths- of ·othe:r ,river_s. ent,e,ring tbe; sea, and. cause. t_rou­ble where. th,e ~resh wat,e_;r-of .the ·:river ,is used ·for. doin.estic :or .irrigation water s.µ,pp.ly. • , _ . . ._ . . , ; - · , ...

. ·:. '. . . .. ~ . . . . ! : ;, .

Another case of trt>uQle froD:1: dens:ity .currents occurs where a navigation lock is placed between a fresh water stream or lake and the oce,ap. .. , Her._e.the •salty;wate;r flows into the lock when:the.downstream ptes .. a.re, ,o~n~ a~d: tben- upstream'. .through the, upper· gates when they are op.~11,ed., .If iUi~ desired to have a fresh,water. condition.in.the ch&Jlnel· above_ ~h:e, loqk, _ the salt: wate:r entering. through the lock may prove to be very undes~rable. This conditio~ has. oc:c-u;fred .at Lake-Washington at · Seattle, Washington.

Daly {44) describes an interesting situation at :the Strait. of· Gibraltar where the top 200 meters of the opening is occupfed by·a cur­rent f~QW:ui,g. into the Med~terranean Sea w:hich n,i.ay reach .·a velocity of 4-5. km p,er hour,., and in the -bot;_tom_,~0Q.-meters .the_ cur.rent is at about the- sain,e' v-efocity t;ow~:fd the Atlantic. : These currents· ar,e caus_ed by dif(e.reiiees. of, dens!ty· of -the. Atlantic a.Ad, ~e<Uterran~an waters that is only 2/1000.of eit~er. ; . · -: . > . · · . . . !_. • • · •

De,~ity ,Currents Due to Temperatur~ Pif~el'.,ences I • • • ' • • '

; . • _..Ari. .int~resting cas~ of a density eurrent due to temper.ature diff~rence~. wl,liob pccurr.ed on a tributary of the: Tennessee River {21,-22, 4.0)- ~-~~ to the- da!Ils, of..the 'rVA: :;ystem, may be0 des.cribed .as -fol'- . lo"'{&: ' .· , . ·r '. ' . ,'' r ••. .,.,.

. . ' . . . , . 'The town of Iulrrunan, Tennessee, .. is located -on the Emory

Rive~ a,~ a distance of 14 miles. above its -junction with·the··Clinch River ... Its waterworks intake is located on the Emory 1-1/2 miles upstream -. from the place where a paper mill discharges its waste into that stream. It is:. ~:ls:o upstream,from .the: point where the sewers of the.town enter the river·.:· T-he ·Watts Bar Dam wa$ constructed on:the ·Tennessee River below the ;mouth. of the Emory River, and backs water t.JPstr:eani above · the Harriman int~ke. · lnthesummer, the-:Emory River .inflow.is small, and its water is warm, but the water coming down the Clinch River from the reservoirs upstream is cold. This cold water sometimes·fJows up~­stream along the bottom of the Em.'ory River as a density current and carr~~~ $,ewag:e. and. pape:r .m.i:U waste up$tream. to the· ;w,aterw.orks intake, thus· pQUl\ting the wate.T s~pJly. :Under ce,rtain conditions -thr~e leViels _ of flowµig: water-were.observed. Water.flowed up~t~ec.im at u~id-d~pth and. downstreEl.m,·at both .tb.e bottom.and top .• -. . · . -. ·

_ . . -]),ensity cur:rents due to, temp.eratur.e differences in lakes have be~,0, kn9wn for :m.a:ny years._ II,l many lakes i11, the·fall of the-,.year; as the sµrface. water, cQpls, . it bec¥)Jnes; :hea v.ieF than _the water be11eath. ,it- and -~iri~~r to· the .pQttom of,tbe-. lake an.~ the bottom water then rises to the top. r-,e~1,1-ltj,ng in a- turning over :of the: wa~er, in th,e rese.~vQir ., ._ Thi_s $ometi:rnes has an important bearing in the quality of water, furnishec;l ;to, city water supply, systems. ·

7 .,

· The water;flowing into lakes is sometimes at a "different temperature than that in the lake and density currents of the under­flow" ·interflow.~ and overflow .types are set up in the :same way as the turbidity currents previously described. Such currents have'· been observed in the Swiss Lakes, (23) and are an important factor in mak­ing them suitable for bathing in the summertime.·

Detailed observations were made by Bell,. (25) where a com­plicated set of currents were produced by a stream of colder water en­tering the lake and· mixing with the. lake water.. It was found that under· favorable.conditions a density current was possible when the specific ' gravity of the mixture varied as little as 0. 01 percent from that of the . lake- water. · ..

Mechanics of Density Currents . .

· · It will be· readily seen that the velocity of flow of density currents w-ill be increased for increasing values of the effective den­sity. of the flow, the·thickness of the layer, ~ the slope of the reser­voir bottom. O'Brien (2: p743) has shown·thatit is.approximately pro-·· portional to the square root of the product of these quantities. · ·

As the layer o~ turbid wat.er. passes µµger; · pver ,' or through· the clear water, it may mix with the clear water or may remain en­tirely separate from. it,, with a sharp surface of separation between them known as an interface. Whether or not·there is mixing at them:... terface can °be established by the analysis used to determine whether . · or not waves at the surface of two fluids moving at different velocites·, such as air and water, will break. The treatment developed by Lamb is given by Knapp (:8). A great deal of work on this subject has been done. by Keulegan at the U. · S. · National Hydraulic Laboratory (28 ;· 29, 30, 32).

. Those who wish to investigate this phase of the subject fur-­ther are referred to the additional information supplied by Monish · (2 p75'2), · Einstein (17), O'Brien and Chern9 (20), Craya (26 and 35), Farmer (32), Hamada (38), and Schijf and Schonfeld (3-9). ·· ...

Miscellaneous Facts About Turbidity Currents

It is p:robable that turbidity currents are prominent in only· a par-t of the reservoirs. Dobson (2 p759) e)tam.ined the results _of sur;.;. veys of 55 re·servoirs and in only two were there decided evidence of such currents, although others showed inconclusive evidence of them.

· Brown (6 p68),has collected· a great deal of information on the velocities and concentrations involved in turbidity currents. The· veloc...; ities range from 3 to 0.1 feet ·per second.· They have occurred on slopes as .low · as l .foot per mile. The sediment concentrations ranged fro~ 7. 8 percent to as low as O. 007 percent and the depths of the currents· from a few inches up to more than 100 feet. ·

8

The sediment carried by Jµ!"pidity currents is very fine, and usually consists almost entirely of silt and clay sizes, ordinarily with the clay sizes predomi.Jlat~g. .,'rhe: compos~tif?.Il p( the, ~epQS'its on the bottom of Lake Mead is shown-in Figure 4., ·-· · ·· · · · ···· · · ··

' ... • '

...... ·_ I

,, ;_·

·.:.

,· ,-~

. ~ ,· '

·; i.

\. ._ : . . ' . . ~

. ,-.'I.'·.

. . .:- --1. ~ . !

9

APPENDIX 'I·

Data;, !an Turbidity Currents -in R es~rvolrs · ·, f, ·'

ake Mead Above Hoover Dam

· The reservoir from which the most data are available re­arding its density currents, is Lake Mead, which is located on the ower Colorado River in Nevada and Arizona. Extensive studies of he flows in this .lake have been reported in detail (2., 9., 12c., 41).

Lake Mead has a maximum length of 120 miles and the orig­al bottom slope of the river bed averaged about 4. 6 feet per mile. uring the early stages of filling of the reservoir I water was dis-harged through sluice gates at the bottom of the reservoir, and the urbidity currents were plainly evident in the turbid water discharged.

hen the lake had filled to the level of the powerhouse intake, about 60 feet above the stream bed, these temporary outlets were perma­ently blocked and since that time no turbid flow has passed out of he reservoir. Samples have been taken at frequent intervals in the eservoir just upstream from the dam, and although all small flows ay not have been detected, it is believed that all large ones have

een determined, since they cause a rise in the level of the interface etween the turbid and clear water stored above the dam. Since this eve! settles very slowly after a turbid inflow, a large flow would be dicated., even though no measurements were taken while it was in

rogress.

Most of the following information on Lake Mead sediment is uoted from Gould's (12c) very complete report. The overflow type urrents occur in the late spring and early summer. The water in he river has about the same temperature as that in the lake, but is

uch less saline; hence, the river water is less dense and flows on op of the lake water. The overflows seldom travel beyond the Virgin asin, about 25 miles upstream from the dam, and none have reached

he dam. Interflows occur in August and September., when the tem­erature of the inflowing water is about equal to that near the surface f the lake, but has a much higher salinity, which gives it a greater ensity than the surface water of the lake but not a greater density han the cold water near the bottom of the lake.

Underflows are the dominant and most important currents ransporting sediment. In the late spring and summer., overflows

d interflows are periodically replaced by underflows, but during he fall and winter there is a continuous movement of turbid water

ong the lake bottom. From October to April., Colorado River water s colder, more saline., and has more sediment than the deeper trata of water at the upstream part of the lake. All three of these ause the inflowing water to sink beneath the clear water and follow ong the Colorado River channel. During this period, the division

ine between .the turbid water and the clear lake water is sharp and

10

dis:tUJ:ct,. a¢ ~omQionly m.~:k~ byian ar~a-o.f qriftw:QQd;.QoU-ected at the point of conv:eyance by opposiµg cur:rent~ •.. , , . .- ... ,_ ...

, .. : . : . ~P,S~; OJ .t)le -~d~cilOW$. dQ · Q(;)t. ~e~c~·:~h~· ).~~~;: "~~r/ ~f. the · lak~,., ·.Reco~ds s~o,:w: that Qn).yJ2 .con~picµo'l1$ ~d~9WS.;haveitrav~­eled t9 th~. d;µn ... ·. Of the$e, ·U. occu.rr.ed; m. ;the, first ,'7; y;ea:r.s (1935-. 1941) _ when. the. lake. wa$. _.70- to. l. 20 .mil~ l.ong, }l'l}e, only, ~the,r: ,ll'lajor fiow. to ~eac~ the d1;1,rn. W:a.$_· .in the fa.ll <>f.1.9.•7• w~n-Jti~ l~ke .. was,:78;. miles long. In, t;tie,first ;L4 ye~s ot op~:raij.o:p., ·.C.lQs,e,,tq -~j:(),00 .,:rn.il­lion ton.s of sedµJ;J.e:nt a~c~ulated µi the-r~servoir and:,~,upied : .. abo.:ut 0.-42 cubic, miles-or _5 percent o( t~ r.~se:r,-v~4" capa..city. Very close to h~f of the ,tot~-w:eight. and tw~'"'.thi,rd~" of the total: volu.me Qf this sediment .have been tran~ported by turb~dity, currents.. Of thi• . mater!~l, about 80 ,percen~ ~as accu~l;llated :on the Z"eser,yQir floor. . at a-id!st~ce 9f mor~ th~ 43 nu,J.es :frpm tll~ :Qr~~,r:lv~r:~n,tran~e . into t);le ;a:Tes~r:v.oi~, ~ ~};>out 23·,p~:rcent ha$. ac,c.um.~ted ~t -~ .. dis­tanc~~of-'.~or~ than)OQ_Jniles., l3e~ause, of the. forward~µipvemE!nt .of. _ the d-,u~;-the exaet d~t.an(?~.pf_.t:rav~tqf ti$ ~ate:dal in tu;r;b.idlty , currents. c·an,n.e>t· be: ~,et,rIX).iileq. Mo~t._.of t~e .. se<iin;L_ent t~~t.. is- depos~ ited more than lD.O :piil,.es._,fppm th:e, Q;E"!gµuµ h,e~<i_..of the .. dit_lta trav- · .. eled at least 70 miles. By 1948 the maximum depth in the reservoir based on tbe Jnaxim,um.wat~ surface elevation, w.as, .r~uce4•from apprpximatE!ly ij~O,to 47~ .f-ee.t,. and.tl\~,mel;l.n depth,b,s~d.,on. ~h, max­imum. ;wat~J" .suria<?e·; .e~ey;iU.on. ~al:i i:redu~ed ,froQJ.. 209. to- ·?90 .. feet. .. . . Fl'O~.·lS,48 to ~9.53_ th,e· dep.t~_.of s:EKiime.ptJn Jbe rese.rvo~:Xl~ar. the ... dam has consol!date.d,app,:q~im~tely 1? feet •.. Tbei-r~sult;o(tbis ~on-. solida~on of th~ s.~iD.Jie.:nt deposit: pas ;q,ee~ an _4i,crEtas.~;,Ul d~th of,.·· . · wafer: .~t t_~e d_aµJi of:a:pp:r~~atd,y ,l!i-feet s·ince 194~,-i . T~e tJJ.~r.y. . · that -~.·th~ .suJn:g,erged .r~v~~c<[:h~~l fills::witll silt. tllie·wide·r~ow~, :q.o·. lo,nger ,.s.tay ,•vi\~ a. (:h~~l b\lt ::tenq , to spr.ead .qut .ovflf · ,tp~. l~ke; Jlot­tom ~4 dissipate ill ~he,uppe;r p~rtion of:th~:,res.~rv~~:;;;i.ppe~rs.to .. apply: .. at :Laite _Mead. _·: :NQ. major .1.µ1d.erfµ>ws. reacbi,lg the da,J;n. tia,ve been dete_cted ~µ>.cf! 19.,7:~ . . Jf ,th~unqer.fiows .coµtinue .to.~is_,;ipat~ ~e­fore.r;e1:1..c_hip.g_ tpe dalll, the depth-of,tlJ.e.r.:eservoJ,r,.~tJ;l).e dam will riot. change materially for many years to eome. -.A. lopgitudinal s~ction · through the deposits in the channel at Lake Mead are shown in Figure 4. The depth of deposit along the channel is shQwn ,in.li'igure ·.3. .

. . , . The .mate,rial deposi~eq ~t .. the:. upp,er :,end ,of La~_e., .l\llEJad is sand and coarse silt., Th~t peposi~~d -o.:n, the. bQttom :.ls cp.m.po·sed o.f . fine. sUt and clay._ Tll,e,m!:l,tE!r.ial.c~riedJQY th~-tµ~bidity:'.CtU"l'eD:t~ ·· has_ an.:average me~iian diameter.,of 1:.JU$ mic:f.Qns .inJbe.disperse~:l . sbl;te, and ~o~ists ot ,67 p~r~en:t cl!1Y'Size,.· ,;32 .P,~c;EJn.t_.silt, -and.:l.e$s thalil 1 per:c;~nt s~nct -The ~o~sest d~os~~~-- ar~ µearJ:t,.e,.q.ppe~. end. and. ~~e fil;les_t ~e'.ar. th,e low.ep end of: ~he. _res~_r:y.o~ •. FJg~~; 4 ,Sl;l':)WS · ·: th~:dis~rib.u~ion,and the:s~~s; in-~~f;? deposit~ •. t, .. , . , .... ,

• ' ,. : : : ' . : •• ,'. :· '. !. ' • . • l. ..: . : _i , • • • • •.• • ; ·•• .- ·:-: _: •• ·.: • :~. ' • • . • •

. . The mat_eril;l,l .~ .th~ turbi~ity. c,µ:rrents, _wa~ :A99.c,µIat~ •. th~ . . finer-· the.ma~er4a]..the gre~teA the_fl.,occq.la.Uo~~· · .~qe1p,1,egian .d~ai;n- . ete1!5 of.the dis.per,seq.,mate~-ial dec:r~~s~ in·a.downs.t:i;-e~ c;Ur.~ctiop., from·.?: Q to ,o. 9 microns,' ~- ~_he: effetjtiv,e d~et~~;of: ti?-e -flpc9u-._ .- ·;.' lated particles from 13 to 11 microns. .

11

·: - : The·densities Qf the-underflows in most-eases l'f!ached peaks· of 1. 02 or greater. but in the 'first underfiow-it was only l. 012-and the May 1939 peak reached only 1. 006. Some of the turbidity cur­rents ·maintained a -velocity ·of as--high ·as l foot·per second- through practically the whole of -the 115-mile length.of the lake. Bell"(4) es..; timated the velocity of the three underflows reaching the dam· at ·ap-- ' proximately 0;83 foot per second. Similar records:of the Bureau of···· Reclamation (9) show that the average velocities of the later currents were generally less than O. 5 foot-per second and comm.only~ low as O. 3 foot per s-econd. -· ·These record's also indlcate that the under- · flo~s travel much more rapidly over the steeper• upper parts of the delta than' over the flatter; 1-ower portions.. Mean velocities of ·1. O · foot per ·second are common: at the mouth of the river-where the tur..:. bid water plunges beneath the lake, -but by the time these .currents reach the Boulder Basin their velocities are less than o. 25 foot per· second ·and are·often too low for measurement~- ·The depth of flow of the:!tmderfi'owtfis generally only a few feet. Above Iceberg Canyon, about:'14 miles ·below the river entrance, the underflow is·-confined · to the 'd·e·epest part of -the reservoir; · In the November 1948- flow -the dep_th of turbid~ty current~in this section averaged 3 feet.

T-herels evidence from the distri'l)ution of sediment accumu-. lated in Lake Mead that small underflows must takepb.ce. along the·· ·· steep slopes normal to :the deep submerged channel of the Colorado · · River. - If minor-underflows of this type were not active in· Lake Mead, the sediment that is dropped from the overflows" would be expected to-· be found accumulated over a· great part of. the lake bottom~ · Investiga­tions of the distribution of the accuri:uilated sediment :show that essen:.. tial.ly all ·of the sediment_ brought lnto· the lake :t,y 'the Colorado River -turbidity currents is confined to the region of -the submerged Colorado River channel~and-no appreciable sediment from this source has accu·­mulated 'in other· areas· of the lake bottom. It s:eems probable there­fore; that the sediment -dropped from the overflows in the shallow · lake areas must continue to travel along the bottom. ·lllltil $.t 'reaches· the deep submerged channel of the river. · ·

Elephant Butte Reservoir

Elephant Butte Reservoir is located on the Rio Grande in New. Mexico.-·· It is about 40 ,miles long and originally had a storage capac­ity of 2, 6'38, 000, acre feet. . The average stream slope of the reser- , · voir bottom.:originally was 4; 7 feet per mile. - The Rio Grande carries a heavy load of sediment, averaging 1.18 percent concentration, which is probably the largest concentration of any river of' equal discharge · in th·e United States. A short distance upstream from the upper .en,d of this reservoir, the Rio Grande is joined by the Rio Puerco, whlcfr pos­sibly carries the highest (?Oncentrations of sediment in the wo_rld. Samples which contained sediment weighing up to 68 percent of the total sample weight having been obtained (11). It is -probably flows _ from this stream whj.ch were responsible for' most of the density cur­rents observed in the· Elephant Butte Reservoir~ The _composition of

12

the sediment flow from this stre.l$<J$ largely of clay size par-ticles.

... . _ .Data.on all the fiows.~ecord.ed for. Elephant. .. Butte Res.er.voir,. .. f;µ°m:,lte.<tbjM~-: w~ -,~'.;B~iGh.,?·~.e.::giv~-'.in Tables 1 and 2. The.:··.:~·;,, first of thes~ tabl~s gives dates of the density current infiow and the av:~ta_g,eji:nd'ima.xwu.m. t.¢ns.··.6t s:e!liment.p~r q,C.r.e. fool of water, ... and the second table g~ves the same data for ~he outflowing curren~ •. 'l'hE! weight per acre fo9t has been based on a unit weighfof;th'e·rlHxture :. ·: of sediment and water of 62. 4 pounds per!cubic foot. weights ob-. served' iri 1931 weli"e 63. 5 a;:ria 65. 3 pounds per cubic foot,:. arid·-ih11933 twelve measurements rang84 from 62. 39 'to 63. 75 pounds per c;:upic foot. The values given are vherefore probably slight1t1too:1ow~· ···

• l

'.:,in practic;any all cases concentr~tions of outflow1.hg cdfrezits'. are le~~ than for the inflow~g currents. :Observations sho_wing ~he rever&i1to be the case are 1very likely due to the variation bf'; 'fil:te·0sed­imen,t flow not being accurately defined,. sediment sa~ple~ no_t beiµg. taken often enough: and/ or the flashy nabirEf of·the inflow·: .. >I_,.._ ...• ·. ·. ;, ·: , ,, ,

! ,. ·=- i ' ~ ·~: ... :· . ' :

Only one ~ensity c_:u:rrent flow in :Elephant Butte R~servoiz: has ocrltirred since 1935. I'n-the first 20 years there were'--'13 flbws~ ,, and in the second 20 years, only 1. This :is probably due Jo a v~_riety of causes, among them beirig the growth Qf vegetation in the upper end of the basin, and the s~l!,1].ow nature of the density -Q,ow~, as p~f:;-:-.. viously·' -'mentioned. ,' '. . d - .. - \. ·: ,:. :- ', '.

• I

'· Little dat~ are available on the qtiantity of ftedinlent ·carried by these currents.: The outfiow of July 1919 was estirr.iate,d to ca;r:-ry _ .. 2,500 acre feet of sediment, 1 Fiock (18) estimated that'),tli~f total-sediment outfio'Y .:UP- to abou~ 1933 was less than 4, 000 acre feet,, 9r _only 2 OI" . 3 percent of the total sediment inflow. Siµce that time•the··pe:rc-enf'-l_ · remov~d has been still less. 1

_ The following inte;resting information is also give~ by ~r. Resch:': ··"It is inte~esting tcFnote on Table; 3 that the silt stratum···was approxi~ately 14 ~eet in depth a thousand 'feet above th~. d~~- During August18 and Augu~t 9 this ·run of silt was· followed through thEfr'es­ervoir and at no place was the layer of silt found to be more than., 2 .. _. feet in thickness until after it had reached the dam, whereupdn1a'-c'U-til­ing effect m.ust·have occurred tha't threw·t:tre ·silt back ·on·-uself·and ··· thus increased the thickness of the stratum. This phenomenon was not understood at that time; had it been, more detailed observations would have been made in the vicinity of the dam to more definitely define the point at which the silt stratum began to deepen as a result of the approach to the face of the dam or as a result of the probable curling effect after impinging against the face of the structure.

•,

"I personally followed this silt flow through Elephant Butte; and during the observation for determination of the thickness of the silt stratum, I was amazed in finding that it never exceeded 2 feet in depth. This definition of the thickness during these observations oc­curred in a distance along the old river bed of the lake of some 16 to

13

Table l_ .

DENSITY CURRENTS FLOWING INTO ELEPHANT BUTTE RESERVOIR

Date · r_ons ,of s,ediment, er. acre-,(qot of Witer -

· 1917 A few d~ys no data ' .

1919 July 5.:22

July 31-A~g •. 9

1921 Jµly 23-29 __

.• _ Augus_t 1 ;.4 ··

19'23 September No detailed data . available·

. . ',

1927 S~pt. ·9

Sept. ·15

1929' Aug. 8-16

Aug. 25-Sept .• · 5

. 1931_ Sept. 19-25 . _

1933; .June 15.-28

1935 July 28

Aug •. 5,-:6

Aug. 18--22

1941 May- ~o data

14

Avera e

88 1,.46 ' I'

84 201

119 153

71 95

139 139

49 49

79 146

58 91

i20 . ' 141

58 124 .

1.6 1. 6

84 96

99 171.

;1:-: DJ!lNSITY C:URRENTS-FLOWING·OU-T-OF: ,·.·:.:: :~ . . ·_' .. ···1 -:ELEPHANT: BUT:TERES.ERVOIR' .'-. :r : .. ·.:-:·

Date Tons of sediment er acre-foot of water !,c, i ·-~ ( . . -~ .. : .

.. ;·-./ !, · .......

·.: f~:1JtA ·_1e~::-~~;s _r1~ data;, ·-:_ -~: :,:_·~_-; : ..., t./ \ .. • •.; . ,'.- ·. . .. .

.. 11rr9 Ju~1--r: 1 n · · · ,. · · ,, ., i"• ! ;, ~ .·

July 15

Ju}y 18-28

1921 A few days no detailed data

::,1923 Sept. ,22-26

1927 Sept. 19-21

· ·1929 Aug. 1;:t-31

Sept.: .a6-0ct. 7

:193_1 Sept •. 22-25

r.}f:>33:-June 23:--30 .... _,_

1835 Aug .. 9-l,1

Aug. 25-26

1941 May 9 A few hours no data

15

Avera e

' ., . ,: ... ;' j. ': .. , 51 - _,,.., . ":, -; ·.

51

87 i:

14

79 ·

32 ,:_··

58 :, :

56

43

28

,21 ..

Maximum

. i J ''. i

··st· ' . ' . t . ·, ;:

. ;, . :51 .. ! •.

_:. J!:2-6

. -'25 '_i t

83

.'64

·' _:·93 ,-· .

·, 71 ' • "; I

i_: . :6:'7

5-0

TEMPERATURES, ·sALT ·AND SEDIMENT'GONTENT, ELEPHANT BUTTE RESERVOm 'AUGUST; 9, 1935

. . •. ·_.'1_·· . • ..

· 'Obs·ervations taken 1; 000 feet above Dam.

Elevation TemperatuD& .: Parts ·uer mill:k>n in Lake Depth of Water Degrees F Salt Silt

i. ·., ,} ''

4335.8 Surface 80 400 0 34.8 1 79 30.8 5 · 78 2.5.8 10 78

,.

" ... ·•

15.8 20 77 05.8 30 76 .. '

.- ·_. !.

4295.8 40 74 85.8 50 · 71 · · 540, ~· 't :; . .··, :60 75.8 60 69 70.8 65 •. 66

... ' •'

65.8 70 65 60.8 75 64 600 ,. . :, -100 55.8 80 64 600 0 54.8 81 64 ... 600 0 . -

54.3 81.5 65 53.8 82 68

. .- .. 700 !' : li 100 •.

52.8 83 69 900 11,000 60. 8 85 71 ,;. 900 ,.· 30,-SOO 45.8 90 72 1,100 41,800 40.8 95 72 1 .. ,000 · 37,000 39.8 96 71 _1, 100 45,300

4239.3 96. 5 (Bottom) I

16

17 miles. Another peculiar condition that_.J:n~t~(J 'du.rbig_:th~s.'e ob~. servations was that the change from clear water to extremely silty. water took-'.pl~ce:withlln ·o .. 8 'or o. 4·,:ot" a.:.f.oot, ·the:_changt?:·b~:lng v._~~Y .. abrupt;b--e~-- the.'~l~r ~d.mu~dy ~a~.~r:.,-'i::, :.: · · ·· , .. :·.· :· ·· ·,

Lake Tex:oma.- Oklahoma.;.Texas ' ' ~ ' .

·. l• . ,; . \ "• -~- . . : .. s'. , .' .· .

I . '

. : "Lake.:Texoma. is on the Re'd River in. ·the -States .of Texas' arid Oklahoma~, . Th'e .only turbidity·current 'which ha:s occurred 'ilr this lake . since operation started in 1945 was during the flood of'May 19:51.· At; · the time the flood started, the storage in the reservoir was 2, 540, 000 acre:fe,et, and the length-:of the·r.eservoir was ·&o miles·~ 'Abolif 4 days after. the muddy :inflow:.reached. the upper end of the reservoir· the tur-;.. bidity, ,e-urreat Started to flow ·at: the low·er· ·end of. the reservoir alitl this flQW lasted 3 days, at -which' time the storage had increased: to 3, 440., 000. a.ore. feet~ ·The peak infiow was ·146., 000 ·cfs, wliicli was · the highest flow since 1908~-; The·daily data on.flow· a.nd·sedtn1:ent·con-· centration.during the .flood are,· given: in Table 4. : ·'.- · ' ·. , .. · · ·

~ : '. I • -• •

Grain-size:- ~alyses. sl:tc,wed· that• of·: the ·sediment· m, the Red' River inflow about 40 percent was finer than O. 004 mm, 40 percent between o. 004 and o. 062 mm, and .20 pereent coarser thmr·o~ 062 mm-..· In the outflow it was found that about 54 percent was"finer 'tha.n··o:"0'04,. . mm, 44-p.er..cent between o. OO4·.mm- and. 0.062 mm,. an,d· only-about 2 percent .:coars-er th~, ·.O•. 062 mm. It· was estimated ,that not :m:ore· than -15 percent. of th-e·inflowing sediment passed· through the·resenoir~ ,

. . . . . . . ~ .. -:··· ·. ; · .. ·:·. _..,. ·. -·

, , : .:.The Bur.ea.u of ,Reclamation •is indebted to ·the United. ·States Corps. of Engine.ers for-,the.data.on ,this ·lurb1.dity flow~= · · '

; ' . ' - L ." . . - . . . :- -. .,. . ·.: .l .• ~ , ~;. .• ~: '

Table 4 - .. ., ..

: DATA, 01\l. TURBIDITY CURRENTS IN LAKE TEXOMA

. -Red- Riyer inflow a. C .• .. Outflow from r-eservoir .. ·-

' ; M~. d.aily flow Suspended ··: Mean daily flow. Susp·ended at Gainesville :-sediment· at Oolbert. s:ediment

Date . -Gage·.® :Red .Rivel" · concentration- .. ' ·"Gage ·concentration 1951 ' ; • -~ r --.(cfs) · . {o/o .by weight)- (cfs) (% by weight) .. ..

; : .. .. ... '.

May 18 '\, .. l;-090 ; ,3,49'0 · ·clear· 19 a.s. 800·. ... 1~35 ' 3,320 Clear 20 :84.;500 •.. o.a& 5; 580 . . . · Clear . . ..

21 -1.3.8,,. 0()0 , , ; 0.49 " 11,-300 Clear 22 117,000 •..

22,.500 ·' Clear . •.

23 .. 64. 300 · _ · _: ,0~_45 .. ;;-; 32~4,00 .. 0."39 .. .. ... ·,'. . .

24 ; 34, 000-; -:-- .,. ,· · .. 0.:47 r ·SB,.- 600 o. 86 :·

25. '.22,- -1.00 · 38,, 100 · .. .•

·-·· ' .. .. . .

26 \, .. ·.,:14.,-900 ·•c ·. 39,--600 ,' ·clear 27 11,800 37, 100 Clear 28 11, 100 38, 600 Clear

17

onchas- ReservQ~ .- · N~ Mexico , . ,

·. ·The_,Conch~ 2.es.e~voir (11 )· is lpcated on the S~n1th Gana~. . ian River in New :Mexico, just below its junction.with the Conchas iver, and the dam. backs. water up both streams. The slope in the onchas arm is 12 feet per mile and in the -South Canadian arm-8·

f et per mile. The lengths of the two arm:s are about 12 and 23 miles esp ~Uvely. . Eighty percent ·of the sediment deposited :in the reser­oir :;was in the ·delta at the head- of the reservoir and-2-C> percent on , . ·.

t e r.~servQil" b9tto~. .:. \ .. . . . ·. ' ·,

:-. ••• ·. f -Bet.ween tbe· closure in 1939 and the :1949 ,survey,·, fr.om, 6,-·000 15~ 000 acre feet of sediment are estimated to have passed through ·,

t e outl~t. .co,nd.uUs as -density currents. This repres,e:nts from 15 to 30 perc:ientr·of the.total inflowing s.ediment~ Between .193·9 and. l944, --•

O to 38 .p.ercent"o(the tot;µ inflowing -sediment during. this period had i ..

p ssed through the reservoir. and outlets as density currents.. This.: :: .·, the largest percentage of sediment passing· through-a :reser .. voir, by.:, ' .

d nsity currents of all reservoirs studied. The concentration of the s diment at the. outlet·works·reached.a high of 5.0 percent •

. Lake:Issa.queena (14) is located in the Piedmont r~gion of .. S utb Carolina. ·The streams·of this region·comtnonl-y carry sedi- .

ent, morethan-90 percent of which is_ composed of fine material. I had an original capacity of 1, 836 acre feet and a length of 7, 400 f et. ,The bottom slope was, 24 ·feet per mile •. The. observed rate of f ing was about 1. 6 ,percent .per year.: Considerable data. Oll turbid-· i y currents in this lake were collected by the United States Soil Con­s rvation Service.

Between August 1940 and April 1942 on nine occasions an in­c ease of the concentration of the sediment in the water flowing out of t e reservoir was observed with no increase in sediment concentration o the water at the surface of the lake. Ea.ch of these case·s occurred_. a teriheavy 'rainfalls and a .rise.·in stage of the inflowing itream, -'show- .. · that density currents had occurred. 'In one case the inflowing wa-t r carried l, 071 parts per million of s,ediment and the outflowing wa-- · . t r-~-eached a concentration of 504 parts per million. On a number of ' . o casions the muddy water was observed to form a deep layer at·the b ttom of the lake, which drained out slowly. On one occa.,sion when t e velocity of flow of the turbidity current was estimated, · it was · f nd to be not over O. 1 foot per second. Thick deposits were ob-s rved on the bottom of the lake near the dam, similar to those in Lake Mead. The data taken were not in sufficient detail to indicate · q antitativ·ely what reduction in reservoir deposits would be possible b controlling this reservoir to discharge as much sediment as pos..;. s ble through the outlets. hut enough information was collected to in­d cate. that this would not be a large part of the mflowing material.

18

Delta

~ ; ·' ...

·,;--- floating drift° ...

-

.'Original

Turbidity current,

I ,, ~

.• ·-; . .

Clear water .... .,...#' ,, ,.,

','

,,-Dam

FIGURE .I ··>UNDE·RFLOWJ:NG-· TUR.81.DIT.Y -CU..R.R.E·NT .. I.rt.A .8.ES.,E-RVOIR . . .--~ ·- . . - ~. ' -- .. .

-- : ~ :~ . .: ~~:: ;~·: -> :;',: ',,,_! ~· ,--

P Lu N-~-1 .a.•-G· -·T"' PE;,~- ...J"'. . ;_~ . 1; . . . .

;-~ i,trl

~.. :1 ::c:~ ,-<:111 .• ,o.,

ff"" ~·

;1~- ~)~'

505

L ·: ;';ArS:e;d,t~-ent -~ .. di~tri buted .- _ ~ through the water

:~ :'". ~~·~;;·_;i\\,.~~_:·~~~-- :.~~~t ... : ... ~.---~- ~~ i.;, .. : 'i.- ;:_ ~ 0 "'·011; ··--:·-· .•. ~ .

Delta deposit_:..:.- ·o,w.:_:_-;;,.\\::::-. :::: ~ ·'?-q1,-:.:..,· -~ --- ~­

• o': · o~ -~·-· ··oll\\"• Current forming from · .• ·.-~:qq!i,: . __

sediment settling to bottom __ ., 0•1'\·.~~:-~ ••• _

. . O•lilt•O Ill•

Underflo.wi'ng -·tur-bid:ity · • cu:rrenf.:;~·11r1::.~ --. . .. -~:~:-· ...... --o.u1!,n .. o. -

·Original riyer-·-bottom -..:;;" ""0 ·~.-b~,ii~~_.

... --Dam

FIGURE .g:::- ·tJ·N·O'£::F{E£6·WiN-G--·TuR-Bl·DITY CURRENT· t·N ·A··. RES£-,RVOIR . .. .. ~ ET t (.'i' ~ c{ ,iyp E

L.. ti -~~::.::·. ·=···. tOO[ 1200 · · .···

- iJ ............... •

;90~-~,~. UR Ea? 17 7 I

ZONES I->·'-

MEDIAN DIAMETER MlC.RONS. -->

.... ~ ..

.... ~.-·

.........

.1.-

.f:., ..... ~-~-"'·•·" .. ~- -~4,:

;_}

~- 30 // ····:, . ., ... _ , ·· .. ,:-i· ·-· .. . .. ; ·,

- ' / .:·~ r

-~ ~ ~-·· ·" ·-;, · .. ' - / / .. ;··· ~d- ,.; ~ . 10 ·~ . _; 1 '

a \.I ~ :--~:,_-, - ~ I~; . : . ,, ... ; ;;;; ':' :·' ' •o;' . . 100. .. . .......... ,.,, ; -ilOOO :· ,: · · D I AM c-.. T, ·E- ·R· ·· ·l·N , ,,.i..A. ·J C· n_·O-N S .. : . · ;/"I,.,. .-~.· .. ·,. , ..... ·,: •. ,. ri,:-:,,1.,r;L., "· ,.·, · · • ·

1:;u\ ~-"-0·". ri,,

, -FU3URE 3 - CUMULATIVE CURVES .. SHOWING THE ESTIMATED MEAN SIZE COMPOSITI_ONS OF SEDIMENT IN LAKE MEAD ABOVE HOOVER DAM

;:'.".(~

~ ~ ~=-----------------------~~=-~~=:-~:::~~~~~~~~~~~--==----Jc,m :~"' .....

. (,,I

~:-~,···'

···""

.\.~

12.00 ........ . ._. Approximat., :me.an lgke le-vel -1170 ft.--,

=·.:·:\:\~~;k)4.\M;"i~~f\\ ---Topset and foreset beds 1100

t- . ··:. ·-:-_:_-:_·.-:· ·:.·· · :·. :::_-::. . . . . . . . ·-----------LLI •

~ IOOOr!·· ··

z z 0

~ ~ .J LJ.I

,.so

·,.

«JOO b~d

aoo~· Original·· .. -Colorado · .?

·,. River bed profile_/· .,

'100 1. '·

·,

600.. • . •, .. ·. ·. __ . · ., . 240 260 -... .280 · 300 320 340 D ls TAN ,c.r. t~t. RIVE:R M.ILES

~- FlGURE··4_·-,.-LONGITUDl'NAL::- .. S·E·CTI-ON TH.ROUGH THE\ DE-POSITS . . IN LAKE MEA.D , ABOVE-.. HOO.VE.R. DAM

. . ·, -

:.lJ m

•:O . :.lJ "Tl

•.. "."fG> ' ::C'c; ,<:%1 i qi'." , .'.1-•

:t.,,i'

-~

·. ,. ·,,: \: · ·A~J?:ENOlX· Il: , : · . ·. . t . ';; . ; r.~ r ._

Bibliography . ':.i ·• ·- : '!,' ' .. ·-~ . ' ~ .-· ' ~"."

t".

{! I \ 1 .,,_ .·: •·.··,.:. ·, .. ,,,i -~-.,;· \ •, .'1·;;_:·~', --~. ·:. ,·,t~····,~i .,,·;

1. "Progress 'Report 'or National Research Coun~il lnterdivisional Committee on Density Currents 1 " H. N. Ea~on1 Transactions

. .~ · .,A,~;r:i.c~Jl·.µ.,,9p,y~~C;lal Vnion ,l,9;38, Part .I:,, pp,.:·387.;-302\;;;, · .· ..

2. "The Passage of Turbid Water Throug~ ·· Lak~ M:~~d-1 " ~. C. -··Gr~ver :and C., ·S. Ho'.Wa'.fd·1 /l'.riUI$a,ctiollS- .ASCE1 ·,.vol •. ·1031 ·1938 1

PP• 720-!9790.c '. , ; I , •••• _. a .... ·. . <: • .' :·.· ... : 3. "St:r;-•tified, :Flow ,J.n ·ij;es~r'V'.Q:irEuind·:lts Use; in.Pr:evention i_of Silt;;.'

··mg,·u ~.-, S; BeJl1, -Ultj.t;ed: ~tates Department: ·of Agll'icult~; 1

Miscellaneous Publication No. 491. ····· · ····· ····· ,, ...... . ·' .-; ,---: , ..... -. ~ . . . ( ·- . . . •'; ._ .. ':_ ... ~~;-~;:.:i!:;'t;J

4. "-Density C~rrents as ·Agents f'o~ ·-T.~.~sp~rting Sediments-, 11. H. s. Bell1 Journal of Geology1 Vol. 501 No. 5 July-August 194·2;· P.P,.~12.~~47.-. . ._._ .... . / -.··: _._.,.-. -.,_.·, ''·,_::r.' -P'

-·.:·>.--.~-- ._-if-~ .: .• ;~·:·. ---~-· .. .-- .:: ~ •· ___ 1·-:.·:·::·;.~~-t·Jr: ... ·._::::. 5. "Silting of Four Large Reservoirs in South AfricaJ11·A-~ D~- ·'tewis 1

Se.cQll4_, GQ~gr;~$-~ :011: ~r.ga.~s.,_ 1CQmµiuni.eatio,n'.No:.,,s..- ,:,,': ' ···. --~ ; --~··;·,.·_: .. :;",~· :":. -.. ·:- .:' ,:·:·.:..: -:· .• _·· : .. - . -~--:···'.:::.:·}~· :- ;- ··.-·./·:·~~:.:-·\

6. "The Control of.Reservoir Silting, II C.~ -B~ .Brown; .. Umte.d .States Department of Agriculture1 Miscellaneous Publication No. 521 1

,.,n·p •. ,65°1'74.·., •·: .. ,·>'.,:·_·.-.'-· ··,-: ·,; ,.:.··· .. ·:,}_:'..'::,. c:~•.r;:: :·· ,,1:_r& ... -;;, .,,,<,_,,.·. .• . . ,.

7. "somlEvtdence lteg~rdi~(rihe lGind:~nd~'-Q~a~tit;.oi ,S~diin~it_ ·, Transported by Density Currents," H. S. Bell1 Transactions ~me;r.-ican Qeophyf}.ical:,Uniqn ~9.2.1 Part I., •pp •. JJ.1-:73. ;_:· ,· :-, · . · ·: ·

II ,·.:,.·::·.~:_,_.·:~·;•_ ·. ·,. ::· :· .. ·· : ... ·· .. : . _. -:< ...... : . ·, _- .-· ./::° ·., ; : ·: :,.·.· • 8. Dens_ijy ~urrent._s:: ,'I;~eif l\'.lixi~g;~har~c,terist,j,.c$ -~nd :.l'beir'. Ef­

fects on Turbulence Structure of the Associated Flow 1 " R. T. Knapp.,..,_Proqe,efi!nB~· :S.~_goneil JJyc;lraul,ic. Canfe,r~~ce~, Bulletin ,2.7., V~ver~#y .p.ftlo~:St:µdies.µ,i E.l:lg:il:u~er,i,ng, .pp. ~89'.":305,. i ~ ·: :

'• .. . . .. . '' '· - ' ... ' - .

't.· ··.

9. "Lake Mead Density Current Investigations 1937-19401 " three vol~&a:1 Uajt~.<t~t~te.~ pe~rt~_~nt of.Jnt~ri_ar,: :aureau of.·-Rec.;. ...

. ,~a:t,t.9ll .... · ' .. _ .. , : ;_ ~ . ,._ ·,. . .. : , -.: .. : .. ·. · . , · . ·. .:.·:· . _ _- ·: _. . · ·. ·u "··_ ..

1 O. "Density Currents in the Panama Ca~l1 ·,:, P~ma ·canai/ riepart­me!lt, o!,. ~pe.r~t~o:q..,~~c:J.;·l\l'ta.mte:na,n;91e I,.,C. S,._ MeJill~:ra.z,.du,m._;298: •.. -' ·.

f."'' 1 . ..... _;·" -~-~~ -; ... , .. · ·.-_;: · .. -~ · . .- ~ · _..-__ . , /r..-- .. i:,:. · .:- ·· , _, .· .:. _,:--_~. :_ ~-.. .. ~ .: .. -~- · ·:· -._ .. · ... · :: _.._ · · -=:- _; .. ·:! ".· ·-:~

11. ,. ··;'Sedimentation Studies at Conchas Res·ervoir in New fyl~xico~,! 1• D. C. Bondurant1 Proceedings American Society Civil Engineers1

s,,pa~'-=~~;-~p~- 2,~'i A~gu·stJ)J.qQ_j a.n.d:D. .. 38., .. ·June 196L' ·: .. , .. :..: < ~,.,},'! •• ~-, _:: .: ,;:·, · , ·, <",~ ; :.·:-•II': 1 ·~· ~,,_- .·-}: -~-• ·.,•,•,;\'~ ~-.:• -~ -~ .: • ,: ~.} :.·}.· •• ·; ~ ..... , '

12. "Turbidity Currents and the Transportat'ioi:i" of Coari:ftfS·eaimerits to J?~~P;.W~te~•-''·-~·syi;npo~i.um,., 0 $ppiety.'·o:fi.Econom:te Pale.ontologists· a~q. ldm~r~lpgia~, ~P~~ial -_P1d?i_icat!o11 N.o. :-~:; :~Pf:·_l_~::'.:~:~~::~_; /(

19

a. "Application of Hydraulics=to-the·-stri:dy of Marine Turbidity Currents," H. W. Menard and J~ C. Ludwick, pp. 1-13.

b. "Properties of Turbidity. Cur~~nts· of _High pensi~y, ." H~ . · Kuenen, ;pp.-14-33.- . ·: ·' · ·. -· ·, " . ·-.,·. · -·

, -. t.. • . •. . I , ~ • :·- • .1

C •... ~rs~me- Qwmtitative ~spects-: of Lake Mead. Turbidity Clll're:nts, II

H. R. Gould,_ pp. 34-52. ·, ~ .· -. ; ' • • • i' - -

1 • -''The Futu:tie'of La.ke·M~dand.Elephant·-Butte Reservoir,_-~,·J\:·:-c. Stevens, Transactions .ASCE, Vol. 111, pp. 1231..;.1342:· 'r-.

1 . "Un.derflow:Studies· at Lake Issaqueena/' J. _W. \J:qhns·on~ ;CH,if .. ; .Engineering,· Vol"' t:2) September 1942,;· pp. :513-~5~6._ _ ·_''.·

1 . "Movement of Silt, Elephant Bu~te Reservoir". Reclamation Re~~_ : or.a,· VoL:, 10,. -September 1919, ·p. 41L · · · · ~.. . -~ ... . . ~:.-·J

:,, :' - '} : ,:: . . •I.) ,,. ~ : f. •

1 . "U~derflow in Lake Lee, North Carolina, " J •, L. Hough, Civ1l _ Elljineering, :Vol~ _9, January 193_9, pp:. 36-37. · .. , _: ...

1 • ·j;T~;-:Vi~~;o~·~ty··of:Highly:Con~ent:rated_l.Tt!d~~flb.ws·juid·lt:s·ln~.\ fluence on Mixing," H. A. Einste~, Transactions, A.G. U. _

_..194~·,:Part.III-; pp. 597-603. - · .· ·.· _: 1 • ·' _ • · •• :- • ,'· '·

1 . "Records of Silt Carried by the Rio Grande and Its Accumtilation in Elephant Butte Reservoir," L. R. Fi.ock, Transactions, A •. o .. u. 1934, -·Part II, Pi>~' 468-473. ··:·.···

.· : ,.

1 • "Density Cui-rents,·" R~ T •·· Knapp, -Round.:.Ta:file D'iscussion:·fui· · the Role of Hydraulic Laboratories. in Geophysical Research

atthe·NationaJ:BureatH>f Standards~ September 13, 1·939'. ,-· .. · : . . . ·: . . . ..

2 • "Model Law for Motion of Salt Water Th:rough. ·Fresh,. 1 '. M·.: P·: .·: O'Brien-and J. Cherno; Transactions; ASCE~ Vol. 99, T9'34, pp. 576-609.

'

2 . '·'Effect of Density Currents upon Raw-Water Quality;" M. A~ · . Churchill, Journal, American Water Works Associaticm/'Vdl. 39, Ap~il 19~7, pp. 357-360. . . . _ .. _ ,: .

' . 2 • "Effect of River·system Development on Water-Quality in the ·· ..

Tennessee River," Journal, American Water VV.orks Assoctation, . Vol. 41,· ~p. 7'85.:. -· · - · · ·. · - ' ::- · ·. · · · ,, · '. ·.: · · .... . . . .:

2 • "Flow of Water Through ·Alpine Lakes~: -"-Ph~:· Foi-chheim:e:r·;, a:y'.:. draulic Laboratory Practice, Fr_e~m~, pp. 322'."'32.~ ... ·, ...

• . ;: • • • •- ; • ·. ' '. .,, I .' . ' . . • : ~· . :·• ; ' , • ·: .•~· • • • ' , I • • • .• , • . .

2 • : ''Problems at,.Mouth of the Mississippi·,':' :C·. McD. To~ns~Iid, .· Military- Engiaeer, v oL i:a·, :March.-April 192 6 ;, -pp. -gg .;;1. 06 ·. ·

20

25. IIIDbe, Effect· of .Entrance".Mixillg on tbel Siz·e.\ of, Density·. Currents : , .. ,.Jin:~haverrJ.ake,'. 1~ ·Hugm ·Stevens:Bell, 'Transl:Letions~ ,A,O. 'U ••

V 1 28N c· r,t·t··b ····1n.A·7.:,• ·•·,,l!l''°,li\ /7.n1•:.! ·. ·>,,·: .,.,.,.; i'·, o • o. ,,1,,. """c: o er.., .,~ • -pp .•. -,,~l\11,...1,'.:.Q· • ·· •.. , ..... , · · .•

26 .... 1,'·!J."h-eoretic.al:R-esearch on 'thie: l1}low1 <i>f··N0n--homoge:t101i1s 1lrltlids ~··· . ··(in: French); A. Craya; dia: ,H.ouille,.B'.tarrehe. ·., J'an.uar.y~February

1949/l>t>~-:·44_5~-... ,. ., ·, .; -~-.-~.· i ·:·,_· ;.<.·:·J .. · .. ·.

27. ~'Expe:rimenta.l.Resea.relr.-on: th:e,Fl~ ·:ofNon ... homogenous Fluids,"· :~.i; , .·c • .1 (jaF.renQht, PauLGarie1,··:Lai·Botiille:~~neh~.(·,~~nuary.,;Feb-

ruary 1949, pp. 56-64. · i ,,,. · . f . <· ,:, .. : · .. ·

28.:·. ;.Na:.tional .· &reeau. of Stand~rds Progr·ess 1Reports on 1VI&i.e1 :,1.a ws' for'' Density Currents. .. :·, i .·:·:,:\:.· .. t .. :::- .. ·:.~<."'·: .... ::.:.

•. ) . · .. a.: •. ;· ''First ·il?rogress· ,Repo:bt, on .Model :Laws f:oD D:ensit;t: Ourt'~tits • \., •. ;~,: ._: : ., ~i •. ,• f,or Chief .. :of ·Engrs.~E'!J~. ·~~-'.-~~y._ ':'·A'p:r.ll 9i, U~4~6:,· by.~arbis

H. Keulegan. ' ', ~ :.r •, . 1.: /.. .. ,~ • • : .• ·..,

·:b/:·. "Second Progress--. Report :¢,111.Model Laws. tor. 'llensity ,Cur,r~rits ·;' .. : .. · ·· Ch. of Engrs.. u .. :si Anny P,roject 48; ''A:u~!.J?::~~~46,

by Garbis H. Keulegan. . • . t .: .- • i.. i' • •.• ••. ,. ' ,1 ·.~ ··,·· , • :. , ·:. '. ·.~ ••• ·,. -.'L .. . ':'~\.-·:;- '') --.. ~·. . ·-..._,'. ' _ _, .. :} -. ... . - . . ' .

· ·c:. ""'1Third Progress Report on :ModeFLaws ,for De:nsi!tyl c~~~nts for Ch. of Engrs., U. S. Army Project 48," December .. 6,

·1~-, .:::i,_.f.J .~,_;_,.l,1,946;:.-_! .-· }' ... _: -~- ~ .·._,. _,- _,•.:- ~-;··.; :_ .r. l' _ ... -...--,-;1;•, :;: ·,. '':· ~:; ..-i:~_:;,;·,·.-·,-1/··~'

• ;"·4,• ~ .· • ., : . '• •.. _' ' • ·_-. ;" ;·• ~- • ~. _) ·:: • , ; • ·- , ; •. l J '·f • •: .,,~· • • I -~ _:: •. :, : ";"' • }. • ,' I •'

d. "Fourth Progr'ess Report on Model Laws for Density· Currents for Ch. of Engrs. • U. S. Army Project 48. 11 October 10.

::., ... ~ '·.:·l.9~.:.-.'. .. ' .-::,',!'.'}'." .. , · .. , ... ·. ·;· ·, ,·: .. ; , · '··:···;·. ,·:·,• ·.,t·: • ,, i:, . r -. ' . -~ ' .... : ·c:~ .=; ./ .- ·-;..:: •. j ,, -,:· .. - : ' : _. •.. ,. ?~. • I,) •:;, ~ ; L :: .. J ·. ~ _, r: :-' :· '·~ -~. •

e:.·. ··i1Fifth;:Prog.res*3,:· a~pont o.tl:··M6del; Lawa, for ·oensityi Currents-­Distorted Models in Density Current Phenomena, II for Wa-

. ·.,,.,, :.t.~:rw.ays ff.,cpe,ritne.nt Statida~ ,No~ :1-188-~i Qc:tober:10, 1<9.i-1~-. p ...... -·oy .. Gairbis H. Keulegan. <:·, . · > . .. ..- · :: ·· ,

f. }!a.d.&th.Prog:r:es.:S :R.epo,rt.son:.Model;.Laws- for;.Density·Ourrents. "'" \,'.,:.· :Etf~diverxess of:Sa.ltd3a:rrier.s µi,River,s,·''·.fo,LWat-erways

· · ... Experiment Station, No . .11.00~r J~: 2 .• · .. -1952,· 1by Gar.bis H. Keulegan. - · ,,.

,.· .. ::.. -._ .. , .- . _' .. :-:·~·-· ,._, :, .. : ,_;·~·-::.·_'.;"; ·,,. -~- .... ·. ;:_,'~. ;:_: : _; :':.:.·:,:.::. ;···.-., -<·1. :·• :' 29. ~'·X.ot~:rfadal Iln$tabi~tyiand.,Mhdng, m,, ·Stratified., Elowsr'':-:Resea:rch

. Paper RP2040, ·1our:naf"ol''Research, National Burea:u ·of Stand­ards, Vol. 43, November l949.

30 .. 11urlifuat.Fiow·:~t~h-e:·~t~~tJ~';\)~' ~~~-:ii~u~~~\· ~.i;-,;~11 · :~~~~~1 of Research, National Bureau of Standards~· ·.tune :U)44·: '6y Garbis H. Keiilegan.

31.. "An Experimental Study of Salt Wedges, 11 by Harlow G. Farmer, Woods Hole Oceanographic Institution Reports, Reference No. 51-99.

21 =:··

, ·~ . . . ~ . ·: .. -· .

32. IISteady State Obaracteristics -.of Subsurface Flow. 1-1· m· '·'Gravity _ Waves.'.' .Circular,521, National Bure:au'Of Standardsi ,;(Supt.

of Documents. Washington 25, :D! .C. $1 .. 75. f- ,. ' .:.·

33. "-Etud~ Statistique de.s ·Ar.ports ·Solide.s et de Leur Excavation''Pa.r . -Gout:ants:de .Densite, '·_, H. -Duqliemiois.,, .Transactions, Fourth

Cong\-ess on Large Dams~1951,"Vol. 4, pp,. 119-1~5.· · ·

3 . ll~tude des -Courants D'Eau Boueus.e Dans Les Retenues,·" .J • .- P • .. , ,:Eta.yna:ud.;,· Tr~nsactions, F.ourth Congress on .Large· Dams; 1951,

Vol. ·4. pp. 137-161. . . . -· ... · . · - ·' -· ..

35.. "C:t"itical~egimes of. Flows with Density Stratification.,: 11 A. :Cr:aya/ Sartryck ur Tellus, Vol. 3, nr. 1, 1951. , : ·· ;1,

36. {'S~dtment· Problems in· Lake Mead and,.Downstream· on: the Colorado .· .. _,Riv.er,/~ C. P.· Vetter, Transactions, ,American Geophysical Union,

Vol. 34, No. 2, April 1953. · · . ·. · ·

3 . _)',The, :Soi,e· of-Density Cu:rrents·.in. Estuaries, 11 H. Strommel; Prb­i' ·C,eedings;.,IAHR, 195~, pp. 305-312 .

.. "Density Current Problems in an Estuary." T. Hamada, Proceed-

ings,. ~-HR, 1953, pp .. 313-320. . . . '.· .. .--- _,• .

"Theoretical Considerations on the Motion of Salt and Fresh Water," J. B. Schijf and J. C. Schonfeld, Pr_oceed~Ss, IA~R. 1953, pp.

· .. ,321-:333.:, · .· · . . . · · · ·' · ,. · • .. . . . . . . . . .· . . ..

"Significant Effects on Density Currents in TV A's Integrated Res­ervoir and River System." A. S. Fry. M. A. Churchill, and

' R. A. Elder, Pro·ceed.ings, IAHRJ 1953, pp~ 335~354. •

41. "Density Curx,ents in Lake.Mead. ·11 C. S. Howard~ Proceedings. !AHR. 1953, pp. 355-368. · · ' ..

110bservati-pns Syslematiques d·e Courantsde Densite' dans ;tin'.e . ··._ .· Retentie Hydtroelectrique. 11 A. Nizery<arid J~ Boruun. Proceed­

.. ings, -IAHR. 1953, pp.,· 369-386.

"Some Observations on Density Currents in the Labe>ratory and in .. ~~;-~i~~~·-u~. Gezaek Bogicll, Pro~ee~inSs, IAH~. · 1953,_ pp.

l. ~- .~ • • • . ' ·". , ' •

"Origin of Submarine Canyons," Reginald A. Daly, American Journal of Science. Fifth Series, Vol.· XXXI; June l 9S6.

22

Interior - Reclamation - Denver, Colo,