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<br />8. Flood.!l.zdrographs - The computed SPF hydro[;raph for the Yam"" RIver
<br />"'as adopted for the 500 year event (see paragraph 7e). The 100 year
<br />hydrograph is considered to be prir~1.d_ly a rainflood and "'3S p3tt:eI'ned
<br />after the April 1974 event at Hayden. TIle SO and 10 year hydrogI'aphs
<br />are primarily snow7.lelt events and ;;ere patterned after typical snc,,-",elt
<br />hydrographs for the Ya8pa River at K1.ybell.
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<br />The 500, lOa, and 50 ye'1r events on the s=ll stre2~-;]S around Cr2ig
<br />are pri=rily cloudburst events. Flood hydroJraphs for these events
<br />are based on the synthetic rain flood corr,,,utations for these areas. TI,e
<br />10 year event is prieaI'ily a snoo,ccelt flood. Hydro[;raphs for the
<br />snq~~elt events ~ere patterned after recorded snc~~clt floods on
<br />Fortification C:reek tzking illto account diffe}:cr~ces in d1\1rn21 v2.ri<1tic'n.
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<br />The 500 2nd 100 year events on Fortific2t:l_on Creek are prL:.erily
<br />cloudburst events. Flood hydro8!"3phs for these events are ba.sed on t1H~
<br />synthetic: rainflood cOl:::;flutations for these <';-':;:.-:1.S. Tn(~ 50 ;J,;:1d 10 Yc'ar
<br />events are priF;Jrily s,lQ1;,r01clt fleads.. Hydro3.r;:::.pl~s fOI~" th,~ s:;,o;,--,'1C'lt
<br />events were pattcl.-ncd after l-('col<ded .s,no\,T,;clt hy:h-ograp~1s on Fort:tfic2tiol~.
<br />Creek.
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<br />TIydrographs are not presented in this repori but arC ~v3il~ibJe.
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<br />9. Cor:c121Tcnt flo-w-g - Concurre:-lt fIo~r;rs '';.,'cX'e est:lj;;atcd fo-'~ sc,:~~'cral
<br />inde;-p-;i-n.t-s-~-~~-Co--:-1-currcnt clout:[)~l-':s t flD-...~s "",'CL'C ::Jcsed on th,,~ r,:~ in! nll-
<br />runoff cOl.:lputations discussed e3::J iC".:..4e Ccncurrp;:lt SI':o-....--;-;:<21t fIo'..'s .r-;c~re
<br />selected on an arbitrary b.:1sis since there j s no data to L;ri~~e ~~ !)jul.-e
<br />precise dctennination. The 10 2nd 50 year concurrent sno~1~lt flous for
<br /><in lnccx poi;l.t \.:cre s21cctcd 38 being c.q'J:Lve.lc:nt to the 2 yc.ar .J.::d
<br />10 year specific sDcT,..:aelt floYJs, r,.,2spectivcly, 2.t th2!: i;vL2X pointe
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<br />The concurrent flows on the Y<~mpa lU.vcr foc use vlJth the 100 2nd
<br />500 year clo'..ldburs.t floods on tortiflcation Creek shGuld :-c,prescnt a
<br />sU-;;:1JcrtiJ:e Yar;;.pa Rivcr- flow since a clouci'Gurst on Fortiiicat ion Creek
<br />".'ould r.ost likely occur in the SU-i:i;JCl'tili1Ce An aJ~3.1)"sis of July 2.l1d
<br />Al..li;ust flm;s at ~faybell \"'.as ffi2dc to detcn:;inc these COl1Cll{rent flCi',';s.
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<br />10. Results ;n'!d C07;'".:TIcnts - F1.m....s for use in csti[j;at:tng fJclod
<br />PJai;1-s--{Or--th-e-v(~~f;1~s-~-;-trc2ms :-At Ci-<:d~' nre listed on L:hle 3~ An
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<br />ev,11u3tion of the r(>~;t11ts of tlds :;tudy ;~'as r:~2de by cO;;:.:).~r-t;':.g 100 year
<br />nnd 500 year pc."}}.: flo\:s \lith the ",';:v'-'lopc C\ll-V~, Chart: I... 'l1ds co:::;:ar["on
<br />indiu:tes the results <ere rensQ;",ble.
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<br />As inoicatcd in p3r;:-j~ra?h S. ice j,-i;;-:S ll::vc c;~t1sed f~ocdinG 1!l CL1.1.g.
<br />^n <'lnnlysis of ice jall1S '",'<~S not p(1.';~:;ible t1\le to .a lack of (~;~t.:1e T\-::e
<br />jz:.i~ ;;.r..:' not b,~llcvCG to be as ~cl.iGtlS no:.' on fGrtific:1\:i_o:1 ,:.s in p:~J'.\l:L-~'J!:;
<br />yc'ars ~i:C<1USC the ch:innC':l h.'1S LCl:n i i.-.pro\.-'c.cl ;;nd .,.; t-ra ig11:.:\'nc0... t:nl.':; i ;ICU:,J:. :lq:
<br />it~ c2.p;1city ,:.fld elil,;i.n<!til~~ Elt:'i1Y :lr('il~; '.--:hprc tee j;l.::!~3 (lcctlJ."rcd in ('h~ p;..~:t.
<br />In ;:ddit:f.cn, c{)J1~~ldcr:lble cffo:.:t l!::; r:,:'.{~(' by th2 City of Cr,Jig to n.-".r:o'/C ice:
<br />ja:i.s l)('.[orc they CfC'ltc flo0J C:oi)rl.{_tL-}i"iS~
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