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<br />The 2.ycm. S-ye~r. IO.ye~.. 50.}'ear. and 100-ye~r .~infall distributiol1s at t,ve.m;lIule limc
<br />inncm"nls a,c p,ovided by T~ble" I ll1rollgb 6, The 2.llOur. ZDne L Iln~dju.'ted ,tonn event i,
<br />rrovid~d by Table I, The J-hour. Zone I. ,torm ~vcnl for drnina.~c ~reas belween l () 'qllarc milo, ~l1d
<br />20 'qua., mile, i, providud by Table 2. The 6.h,-,ur. 1,0"0 I. sturm e"onl f\!rdmina~o area, belweun
<br />,Osqlla", milcs and 75 .'qua.c m,lcs i, pruvldcd by Table J. fMc !.hour. h>nc iI. Ilnadju'tcd wmn
<br />CV"lll i'provid"d by Table 4, Thc3_hoLLr.Zol1ell. "<lnnCvont fo,draina!!sarea,b.twc~n 10 "luare
<br />m;les ~nd 20 $qlLare miles is p",vided by Tab]e S, Tne 6-hour.Zone 1I. storm c"cnt fo, dmina~e areas
<br />between SO ,quare miles and 7S square miles is provided by Table 6,
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<br />Thcge rainfall distribulions were u,ed in lhe Colorado t;rbon Hydrograph Procedure (ClIH!') model
<br />10 g~"crale hydrogmph, fr"m e'ldl ",b.wat~r>h~d (L;DFCD. 19%).
<br />
<br />c.
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<br />COLOIV\IJO UtBA~ HYIJIWGRAI'H PROO;l>lIRE PARAYlETERS
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<br />fhe CUHl' ~omputer program wa, u,ed to ~ompute 'lOrm runoff hydrog.aphs for the v:..io", ,ub.
<br />\\'~k"hcds The versiol1 Llsed for the studv w~, Cl})WQ8, The ,uh.w~t""hcd inpul pJramders
<br />reqlJir"d I,,, CUH!' arc: 'lLb'wat~,,;hcd Lde~tili"alion numb.r, drainage arc~.le~g~h nt\d c~ntroid.11
<br />let\glh. d,~it\nge"'~y ~Iore. ;mperviou, peree~l~ge. der~:1(ion ~t\d retenti"" slr>mg~ ]o,""s. and
<br />i~tillrati~~ la,s rat~'. A summary ollh,' CUB!' input par~l1lcters used for the analysis ~r~ prc.,cltlcd
<br />in rabies 7thwugh 10, Tabk 7 ptesenLS the l'L'J II' i"put parwnel.rs for the We<< sCdion o[thc stud"
<br />~reJ, LLblc ~ P,C"lCrllJ th~ CL;IlP mpul paramclers for the Soulh~J"1 section ofth" 'lud\' arca, Tablc
<br />(j pre~,'Ill, lhe ('l,H~ "'r"l p:unm,'ref> for the Last ,e"lwn ot rl,e sllJdy ~'ea. 1'.1hl~ III I"e,enl, tile
<br />CUBP ;l1pLJ1 pa'am~terS for lilc off.,ite arco.
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<br />D.
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<br />rbe \\e'>,ht~d c'ltanncl slop"s ""rC adjLl\ted using Figuro 4.1 of the RUl1dfCh~pterofthe \.:SDC).,I
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<br />l~;r .npm in:,. CUI lr, ~;ub_"Jtc",h.:J H"'H1).::ri~., "'.:,.: itK~.<,,'c,l Ji"'~tl:- fr"m ii'" m~ppi;j!i 1';~I,~;'"d
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<br />for this studv u;in~ ARC/lllt'O. \1"p, wc," ",~"ted dclirle"l;n~ the e~"ting and fLllure impe,vioLI,nes,
<br />p",'.;ent.gc ,,'ilhm rl10 ,l\Ld:- ,lrCO ~r"l in the nn~,itc Mc" l>a;ed (lll ,,~i.,!i"g mning. th~ Dl'''gla,
<br />COllrlly Mil;t"r PI:m (DmJglas C"unTy. j')'12\. .,orial phntography.l:SGS quod.~ngle 'MrS. llS(,S
<br />(\""I[C' \bp~. '111d ,itc viSLl', Fl1tm~ ;mpcr"i"u.,t1~~< i8lhe impe."i",,,,,e,, Ihotlsnp<:<:l"J;ll \llt;mate
<br />buiIJ-('ut "fth~ ""(e,,h.d, rhe l'\lIm. ['Cr~c'ru imp.rvi",,,ne<< of Ill" "'>1I<'"h"d (;!U,I> "r":I.lnd off.
<br />,itl');' rdati,dy ie,,, be':au,~ tll" J"vd(\pmot1l il1~l nL~;' ~"~Ll' Lrl Illi, Iv<\t,'"I1"d;; limill'J ~LL~ t,} ll1"
<br />I:\d ot ~v:"I~b!~ II ~IN III SLLrr"" dewlllrllH'11l and oecoLJ'c 0 Io'g~ roMi"" {1f rhe nit 'llc "'''''',<1,,'<1
<br />" ""!,,,tl~i I,c""" li"Ld i .",J 11"~L,'I;)I~ " "H;;~d." I" j,c J,.\ ol"I.,.JI
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<br />Draw;ng? 'hQ'" the existing imperv;ousnes, in tbe study arca. Drawing 10 show, the future
<br />imperviousne'l in the ,(udy ~re~ Dr"wing II ,how,; the cxist;ng imperv;oll'nes~ In rhe off.,ile area.
<br />and Dr"wmg 12 show, th" proweted impervrOll,,,e," in the oit~stte area, For each ,uh-watershed. a
<br />"ompo';le\'alucofthcpercent;mper\'iou,'l1O,sw"scaloulatedu,ingARClInf'>,
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<br />,\ ,oil mal' of th~ SCS hydrologic soil groups Wa'; ~,calcd for the study ",co from information
<br />sllrpli"d by Douglas County, Drawing U is tbe wil map for th~ sludy area, A soi] map was also
<br />~rcal~d fo, the off-,ite orca from IllC SCS Soil Survcy (SCS, 1974) (,ec Drawing i4), mi, map is
<br />based on the SCS soilo"o"i~tion group. Eachsoilas.,ocialiotlgroupiscompriscdofs~ve,aldifTerenl
<br />,oil types tbat may hJ'~ difkr."t hydrologic ,oil group classifications. Compo,ite inliltration
<br />param~krs were then estimated ba,~d Iln hydrol"g;e s"i] grollpS in each soil assc>eiation group, Tabl~
<br />11,,,mmarizc,thisanaly,is,
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<br />Det""tion. rctention and infiltration parameter> were a"igrled to e,,~h hydrologi~ soil group a,
<br />r~cornmcnded in Tablo, :-1 and :-2 L)fth~ RunoffChaplerofthe USDCM. Forca"b sub.water;hed.
<br />""omp",ilc ""Iue c)f(h~ detentioTl. rele:1t'';'Il. ,llld infihmlioJ1 was ~alcubted u,ing ARC/Info,
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<br />~ample CUHP il1mLt t']e~ for the W~'r ,~et;on of the slLLdv ~re~. lhe S""thcast '~~lion "flhe 'ILld"
<br />arC:I.;\T1,1111C East sccrL<mol'tbc >ludy' ",ca "re ",clIlded Lo:\ppcndix A. Tbeoff-,itc"LLb'wal~"hed,
<br />ace ino IlIded in ~he study ~'ca ,,,,,del,,
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<br />STORM WATER .\lA!\'AGF.\IENT \lOUEL (SWMi.~,
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<br />I'h" pcrscln"l ""mput"r "e"'Jr1 of the CDFCD SWMM w", "scd to ",ute lhe CUHP-generaled runoff
<br />hyd.ogr.1pl1" The 1''';,1011 nt"h~ mn<lelll,ed was UDSWM<)~, The mUling c1~mcn' p"r~mClers
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<br />r~qlL;,~d f"r S'-''''~:l~'! ,,,e: "!~~'O~l ~'.ttnb."~. ~'P'~ (q;, "bnn'~!. pir~. etc,). !~~g(h. sl"\,,,. 2"d
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<br />"'1a"t1tn~" "n"' lalue, A sllmmary"ftl,e SWMM input p~ram~ler,usod forlhea".])',i;aropre;enled
<br />i"Tables 12lhr0"gh IS, T"bl.l:pre'e"t;thcS\"~'1Minplllp"t:HnClcrsforlhe\\."e8t,eclionofthe
<br />,1,,,lv,,rea Tallie 13 pre'e1l!> rh" SW'v1'0 "'put I"lrnmcters fL"Ii1eS<JLltlle~;I,"'et;on (lflhe'ILLd,"'
<br />~r~". lable l~ ~""onl, the SW~vtM ;ll~ut pamlllet"r; for the 10",: ,celi,,,, ~fthe study "'OJ, Table 15
<br />prescnt.< the' S\\ "1.\1 inpul p~rametc" t'Jrthc off_,ite "rc~.
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<br />1'1", "!"" ,1f' \\'\1\1 -."";11,' ,,1,,"1<'''''' I,,~,l we'" ha,d ,," the e"istin~ drain~~~\va\ "~"n"ur~t;()n,
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<br />;td ,It"~",, f\'r "'''"l, .ll1d ,t,mn wlle"..l \l'''ltljfl~'' "n"' \'alue ~fO,02Q ,,~,. us"d. F", "X;';('''l'
<br />c1llnn,'I<. rllt' \1"H''''g', "n" 1 "Iue "'3, e<lImatcd u"ng EqUJtHlTl 2 rc<;"~"ne"ded ," 'h," ~Wi\.'1M
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