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<br />IltllltiA'llnN ANllllllAINM;E ~YSTEMS
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<br />AI'I'L1C^NTS AND OIlJECT(IItS
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<br />01 the Iilrms Thomlon's eSlimilHls 01 runoll losses were betwe(!n 10 arid
<br />20%. On 71 % 01 the falms Thornton's estimale 01 deep pcrco1mionlosses''>:
<br />were I....ss Ihan 10%. <f)
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<br />'compfHed ,to the sUII,1CI1 soil tl!1<tures. TllO Irndino 1l"~nstr,11ed 111<11
<br />;urf.~ce s,orl te~t\llo In itsell is no! a good guidr.line lor l'stirniltmg lnta~e
<br />, amI Y, Erghty,oll!! 181101101.... Il'Sts were on loam tYPl! SOils which Ihe SCS
<br />~eported has an inlilkl! fMT ,Iy of 1.0 illches pel hour ril~hl. III only 6 of "tests
<br />,"'IDS tho Intake tilmrly de!(!ffnineelto be 1.0 iph; 12 lesls tH1Ch hnel an Intake
<br />"~mrry greater than 1.5 iph ilnd In the remaining G3 of 81 tests II , 'I
<br />was less Ihan 1.0 iph (in 43 of the 63 thr. family was less th~n ~e 5 al~r r
<br />WIth regmd :0 fUlrow Ilow r,1tes. 64% 01 Ih(! mCil.'iUll'!d flows w~re :::~
<br />than 25 gp":, CO'T'pared!o Thornton's anlllysis where 31 % wCle tess thl.ln
<br />,.~5 ~pm. Wr!h r(!Dard 10 lield length, 28% of the IUffows mOi!sured were
<br />, e!r loen 1,200 <lnd 1,400 fel'll; 82% were less than 1,200 Icel and 110%
<br />re c greafer ~han 1,400 feel. With respet:t to time 01 advance, 50% wele
<br />,ess than 1.:.1, h.olHS and 23% were gleater than 2.5 hours. Tho soi,
<br />mOisture dcllcrl In 1991, 1'1$0 delelmined using a dAily soil moiSlurr. budal't
<br />.varled Irom 0.65 to 7 G inchl's, !he SMO lor 95% 0' 1111' tests was 31n c c
<br />less nnd 73% 1 r. ' . or
<br />, . W(lS .:J Ill. O' less. In SlImrniHy the !reM If'stinO did nnt
<br />suPPOrt 0' valrdi1te Ille i1ss11mptions Thnrnton mi)(le in using till' SCS d I
<br />handbooks. ,.. es un
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<br />Tablo 5. Distrihution 01 ThOrllton's Runoflllnd Deep PClcol:lllon
<br />losses lIS a Percent of Fallll Heildgale Deliveries (FHG)
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<br />% of HIG losl <10 10.20 20.30 30-110 40.50
<br />nunorr 11 18 2 " 6
<br />% of Fauns
<br />D. r~rc, 71 12 17 0 0 0
<br />%01 r",ms
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<br />In 19~O [II") 1~91, NCr,wWW llerlorrned "'~!ensivl! fil!ld invesllg3:
<br />(rOflS on 1holll\On I,,,,,,s 10 m(:iJ"(lIt~ (,,:1<, aplllic~lliofl t~t'lci{!llcll!s, observe
<br />irrigfltiOrl praclices <IntI cropping flf:Il;lices, monitor sorl moisture with'
<br />neutron prohes, SurVIlV field slopes, llleaSure Hlrlo!I, meaSure odv(lncetimes
<br />and applicat,on timr.s and me(lS\Jre soil intilk~ 'amilies, Field lrrigatlo
<br />npplit':nlion ellrdoncios were eSllllloted by mCilsuling tho amount 01 wale
<br />applied,lhon s\Jbtractlng mOilswed SUl'"'CO runo" <lnd deep percoli!tIO.rr
<br />Deep pelcolation and soil moisture delrCi! ilt the time 01 irrigiltion.wcrl)
<br />tlelermined using D daily soil moistule budget. Using the collecfed dala:
<br />WWWwas able 10 determine ,.old application etliciencies, ralios of sullalf
<br />fUnOI! and deep pcrcolation to 'aIm heildgate deliveries, The rllsulls 01}0
<br />Carnplole freld elfir.rency measulemen!s on 13 ThOlrlton farms arc sunirp'
<br />liled in Tilhh! G_ . .,H~
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<br />To illustralO tl,c results showrl in Tilble 6. lhe mcasured llal
<br />clliciencies on 13% of Ihe tests ranued Irom 50 10 60%; in 19% of th
<br />tests runoff tossos r<lngcd Irom 20 10 30 percen! and In 23% ollhe tCSfS
<br />deep percolation losses were grcater Ihan 60%, TIle etliciency, runolfsn
<br />dr.ep pl.m:;oliltion vlHicd by month, a factor Thornton did not consider
<br />NC&WWW mcaslJfcd values 01 ai'Jphcation ellrcicncies arc consistCflt wit
<br />Ihe diSCusSion 0' Merriam. 1977 and moasurements by t/Te SCS~I
<br />Cololado's Grilnd VAlley 1t!{Iion. NC&WWW measured values she
<br />sigm'icanlly lowll' ,!lIicicncios and gfCiltCI losses to dcep percol:Jlion Ih
<br />de
<br />ThOHllon's. The moasured elfrcil!ncy, deep percolalion and 'unol! loss
<br />percentages were the hasis lor lho cllrcief1cics used in WWW farm budge
<br />model. :"',ii
<br />on ~1.
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<br />The collecled dala WilS alSO Ils(!d to check tho validity 'ol't
<br />aSSllmplions used In the Thornton an"lysrs, Using the lield dat" and'\"h
<br />procedure desr.:,ihed by the SCS rn Chapler 5 ISCS, 1984) soil 1,i1:ip'"
<br />lamilies for 109 complele tests was determined. Thl'! Iasultsl,'("C
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<br />Results of NC&WWW Field Measuromnnts (I'efc('nt!
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<br />AVe/age Monthlv hri!)lltlon ^ppticallon Elliclflncy IInd Surface Runoff
<br />and Deep Pc/colation loss. 103 Tests
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<br /> M" June JulV Aug, Sep, AVfJ.
<br /> 33 45 43 2B 14 34
<br /> 26 26 20 ,. 11 20
<br /> 41 2B 37 53 75 46
<br />DlslrilJutlon 0' IrrigatIon Appllcllllon Efficiencies
<br /><20 20-30 30.40 40.50 50.60 60.70 >70
<br />17 14 12 16 13 10 1B
<br />Dislribution 01 Runo" and Deep PNcol:lllon losses
<br /><10 10.20 20-30 30-110 110.50 50-60 >60
<br />24 29 " 14 6 J
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<br />3c\ 12 7 4 9 11
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