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<br /> <br /> <br /><..-' SPECIAL STU'CI~ <br /> <br />00 <br />c.n <br />~ ~or predicting more precisely than n~~ possible, the ~neral quality of <br />irrigation ~eturn flow. The me~~c for ~cca~lizhing this will be tr~ough <br />the use of mathematical models and high-speed computers. The ~athematical <br />~el is primarily a mathematical formula ~r expression attemptin~ to <br />duplicate conditions encoQ~tered on ~~ irrigation project. The study <br />Jtilizes data from existing irrir,ntinn projects in oruer to verify the <br />technique. <br /> <br />The objective of the study is to use n model in pr~dictip~ changes <br />in capacity and the associated w~ter ~uality distribution of the aquifer <br />a~d also the quality distribution of the ~~ter as s~face effluents from <br />the system. The prediction of t~c system responses was comp(~ed .Nith the <br />historical data. both quantity and ~uality distributions .I.S a !:1.easure of <br />the reliability of' the rtodel. Data from the Vernal Unit or the Central <br />Utah Project have been used for designin( ."l-'1U testing the model. ?urthcr <br />tests will be made using data from the Grand Valley a:ca in Colorado ~~d <br />the Cedar Rlui"~ Unit in Ka."1sas. <br /> <br />Although model testing and development of' all the math~atical sub- <br />models is not complete, it appears that a satisf'actory m~lel has been <br />designed to predict the mineral quality of return ~low from irrigation <br />projects. Completion of the submodcls will extend capalility to impact <br />analysis, opti.xUzntion, and best plan selection. <br /> <br />The :mr!l~"''!t :O!1 for ''''It.'~r r~ZOur'":e Tro.:ects is ',h<:-L- :'a!"""' of,er.<J.tion <br />('o'll-i bl'> ,'le~ip;:'?'i "'n "lSr.> t!->o:> Ie,,:,,-L- ~'lO:l.~-L- 0-; w~::~r '::..; 1 T"'-!:'l.;.'!":1 the small- <br />est nrooU."1t o~ salt to t.he river ......h:le :)ennit'in,- ':h '~~er ~o obtain <br />'he rre!itest possible ret'..lI;;: from his far:':'!. 'lsi!lf -:h. s model. '.he salt <br />loao. reductions expected f'rorn irri(lltion sche'lul:!"), CUi,j ma:1'l.;:~men~ couli <br />be ',re!'ified on "'-,he Vernal V:1i+ in t.he :.ntah 3::.::. <br /> <br />2. Grand Valley Salinity Control Demcnstration Prociect <br /> <br />This project._ located near Grand .Tunction~ Sol(.. initiated in IT <br />11.9 under a FWW, (no...... EPA' demonGtr9.tion grant, is now nearing comple_ <br />tion. The objective of this project is to demonstrate the salinity <br />control potential of lining irrig!ltion cana.ls and laterals. The ':;rand <br />Valley is underlain by an aquifer containing hi~v saline ground ....-ater. <br />Seepage ~roo canals and laterals contributez to the recharge o~ this <br />aquifer. This recharge displace.::: the saline groUJ1d water into the Colo- <br />rado River, increasing its salt load. Reduction of such recharge by <br />reducing seepage from conveyance syst~~s is thus expec~ed to reduce the <br />salt load discharged to the ri~er, <br /> <br />;. ::!lajor portion of the canals and some of the laterals serving a <br />study area of about 1.0,600 acres ~.ere lined ..o'ith concrete in 1969 and <br />1970. Most oi' tr.e lining ..--as a::complished by :l c:J!"poration of' local <br />irrigation and drainage distri~~s ~~ich direct the de=,onstration project. <br /> <br /> <br />21 <br /> <br />