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<br />e <br /> <br />e <br /> <br />~ <br /> <br />e <br /> <br />( 3) Arraz.I8. the 24-blNr BPS rUD.tall ftlua. datena1M4 1Jl <br />atep (2) 1Jl . aequence tavorable to :prodIlct1em at oritical I'ImDtf .t proJ.d <br />locat10D8 UDder cona1deratiOD, baa.d em a C-nJ. &ppft1iMl of b1dro1.aC1c <br />coDd1ti0D8 1Jl the project b&e1Jl. <br /> <br />( 4) Prepare lID oftrley ot the 180~ .p BhoVll OIl <br />Plate 12, CODvert1.t\g the 1.0h7et val_. to 1zlche. ot ~ SPS ra1Atall <br />bJ" IlII1lt1pl;T1Jlg the peJ'CeDt~e value. em Plate 12 b7 the 8PB 1A4a 1Ia1DtILll <br />ftlue dete:rlllWed ill. atep (1). <br /> <br />(5) Superlmpeae the project b&e1D outl1M over the total- <br />storm 1aohyet&l _p obta1Ded 1D atep (4). &Il4 pl-1-ter to detena1De the <br />average depth 01' tot&l-storaa raiAtalJ. oftr the baa1a 8Il4 each aub-41Tl.a1oD <br />tl1ereot that 1a to 'be coue1dered 1D utiMt1DS tile BPS re.1D1'all-ezce.. 8Il4 <br />runoff ratu. <br /> <br />(6) Subd1vide the total-atom SPS ra1Dh.ll valuu obta1De4 <br />iIl step (5) iIlto 6-hour valuea 1D accord.llDce with criteria pre anted OD <br />Plate 10. The aB1118 aequeDce lIDd 6-hoUr17 peJ'Cntace 41nributlem 01' ra.1J:l- <br />1'&11 ia aaaumed tor each da7 ot the BPS. <br /> <br />(7) It the COlllpllted value ot "tp" tor the clra1.Dege are <br />under study. or 1mportaDt au'bd1 via1OD8 tbereot tor vh1cb SPF 41.charges <br />are des1red, 18 leBS than 16 laura, aubdivide the .....1_ 6-haur SPS ra.1J:l- <br />tall value 01' the may1...". 24-11our raiAtalJ. 1Dto aborter 1ID1t durati0D8 1D <br />accordA:o.ce with criteria preseDted OIl Plate ll. (See p. II ot retereuc. <br />c1ted 1D paragraph 1-01 tor explaDat101l ot "tp. &Il4 ~ ot cOlllpllt&t1em). <br /> <br />(8) Subtract eat1lllated 1DtlltratiOD 10.... trca SPS Jl&1nt&U <br />va.bes obta1Ded in atepa (6) aDd (7) to obta1D ra1Dtall-excea, Q,u&Dtitle. <br />to be used with III11t h7drograpb, 1D cClllpUt1DS SPJ' 41.cbaqe.. <br /> <br />b. Simp11tication at Procedure 1D Special Calle.. It aua.l1n. <br />,,~ re.1A:all and r.mott records 1D tb. project 'baa1D or cOlllpara'ble vater- <br />sheds 1nci1cate that 1DtlltratioD capacitiu over the 'baaiA are relat1Ye17 <br />uniform, and subdivis10D ot tbe dra1.Dllg. baa1D tor hydrologic reasona 18 <br />not otherw1.e required tor proJ.ct study purpose'. the ccanJ. procedure <br />outl1ned above _y be aimplified by OIII1tt1DS preparatlllll ot the i~tal <br />pattem reterred to 1D step (4). '1mplJ' ua1DS the dept.h-azoea CU1'ft value. <br />obta1Ded 1D step (3). wi tbout correctiem tor 'bu1Jl lIbape. <br /> <br />c. Illustrative Exauiple: COIIIpIIt&tlOD ot SPa re.1D1'all tor a <br />s8lllple dra1%Ia6e 'baain tolloviDg the steps outJ.1%led iA ~raph a abaft <br />18 d.monatrated ,Oil. Plat. 14. TIle dra1.Da8. 'bu1Jl lIZId i~ overIa7 <br />(8tep 4) are SbOVD on Plate 13. In this c.... the ex1ltace ot a t1oo4- <br />cODtrol reservoir 1D tbe area 1, aallUllled 1D order to" ,.,-trate the ceD- <br />ter'..ng ot the ,tom over the uncontrolled area SDd the cClllllPltatiem ot ra.1J:l- <br />tall tor the cODtroU.d and uucontrolled are.. aeparatel1. 1l!lcp'....t1OD ot <br />the computat1OD 1, aa tollon: <br /> <br />II <br />