|
<br />,.}
<br />
<br /> J
<br /> I
<br /> I::)
<br />.-." I
<br /> ::;)
<br /> j
<br /> 10
<br /> /0
<br /> I
<br /> 0
<br /> ' '.
<br />10
<br />I
<br />'0
<br />10
<br />I
<br />!O
<br />I ')
<br /> :)
<br /> ""
<br /> ,-...
<br /> '.J
<br />
<br />I :)
<br />
<br />,
<br />!)
<br />
<br />1
<br /><J
<br />
<br />-)
<br />
<br />;....'1
<br />, .
<br />
<br />,)
<br />
<br />\
<br />,
<br />,
<br />
<br />The curve on chart 5 "'as prepared from this data ;'Ind used to ,1,:I:.,,,,J.ne
<br />the mean peak snowo.e1t f10\<l at the un)3aged locations. Suff1cic:lt strei'"f1c\t
<br />data is available for both the Ya:opa River at Cra:Lg (:Lndex point 12)
<br />and Fortification Creek (incex point 1) to define the mean peak fIo,",
<br />at these po:Lnts. Adopted standard deviations and skew~, for the
<br />sno'.'2e1t portions of the frequency curves are listed in the prcceeding
<br />table.
<br />
<br />TIle rainflood portion of the flow frequency curves for the Y=pa
<br />River (incex points 11 and 12) are graphical curves that were <1:,a,,'1 by
<br />plotting the COI7'lputed SPF (see paragra.ph 7) at un excc(~dcnce intc:rval
<br />of 500 Y2..<J.rs. 111i5 czceecer.ce interval i.~-; con~;i.stcr:t 1"d.th a plotti.ng
<br />of the SPS storen amount on the Cr.o.ig l-.day preci.pitation frcq"c!cy
<br />curve, chart 6.
<br />
<br />The rainflood portions of the flo;..~--[requency curves ;....t the other
<br />indC'x points 'i-.~e..-e prcp2::-ed fret1 the synthetic cIo~ldbHrst flood
<br />ca:'.lputatioL1s discussed in pal'agr2ph 7. CI0t)c1b1..!t~~ t SPF' s ~:2re pl_otte.d
<br />at 2.n e...xcecdencc intE::1:val or 500 yc.srs to be consistent v:ith 2. ~11otl iug
<br />of the SPS 3-hour storm ;:;"Jount on the Cra:~g 3-hcuc rredpit2tic,,"
<br />frequency curve, chart 7.. The cloudburst ap,d snoy,"'lTiclt frequr::flcy curves
<br />'\i>.{2rc cOJ;:bi~ed statistically to determine the fil~rtl flo'...;--frcqu(~:1cy curves.
<br />
<br />Typical [lo~~~frcqucnc.y curvC's .<Ire ~::;:l(;'_.:i.l on cl1Cirts 8, 9, 10..
<br />
<br />7. "lntl,etic ralnflood 3I:;'.lzsl~ -
<br />
<br />lt4 Sclec~,~?_~.9_f__~)T_~_~,,_~_Lf~~~i_s- A gell.u:-al Tain stom T,.7;J$ selected
<br />for use. in the co:.::put2.ticn of 2. SPF 0:1 the Y,-~I;:.pa River sillce ti:e 1.921
<br />and 1974 floods resulted from sno\-.'i:H_:lt auv::::ented sUDst:2TIti,3.11y by
<br />rainfa1l'- Thi5 i5 consistent with earlier S?F cOlT,pntatiol18 for t!lC Y;:"pa
<br />River at Ste2I~boat Sprin[;s.. A 3-hour dur~:tion cloudbul:st thuIlc1~rstorm
<br />'\.-as selected for the cO;J.puto.tion of rai,nfJ.oods 0:41 Fortific<:lti.on Creek.,
<br />Fine Ridge. Gulch, Cec2r NQuntain Gulch ~~nd t;lC- Oth2'1~ s:J:.:lll trib..;t;::.rics
<br />around Cr~ig.. A cloudburst is ~o~c critical than a general ral,n type
<br />storm on these ~1l!?.1.1er areas..
<br />
<br />b. Stom 2!.:,ounts - A st<l~:d2rc pl-eject gener;:Jl r2:i;.1 s~'onn
<br />(72 hour-d~;.r.:;..t-~(~lD-cqui\!<11cnt to 35 perc<:'.rlr of ?j.~'p 'i),:JS ~--:'\:.l('(~tcc: for t~1(!
<br />Y~..~::pa River b.::.~sine PHI' <ElQtmts 1,..-,.~!..-e fi1:c1.li~:ih('d by the Iijt1roi:;Ci':,:>()("}ogic;11
<br />Brarlch of the I't-,tioi131 ~.ic~t~).cr S~1.-v1 ce for the. --~~o:1ths or Jl~:-:;C. ;Jnd
<br />August. Aver.:q:;e SPS prccipit.:1tion ov.::,r. t;-,e y,::;~,-,pa Riv.::r b;:::.~;i,n .-t:)0Ve
<br />Craig for the Jene a~d Au~ust stor:ns ~~s 5.60 and 4.87 incl1cs, rcs?eclivcly..
<br />A check of the re2scn<:iblcr..css. of tllese SPS .1r:lcunts \..'a.~; li;.,:'Hle by co!:"!p;icing
<br />24 hour dl:r2ticn SPS foint aUOl~nts Jt Cr;~ig with t~c 11!sl(,r1c~1 (laily
<br />prl."cipitat:icn m:,ollnls at Ct",-dg. T11is cO"ip;lrisonl S~:-:C""",'l1 Oil ClL1rt 6,
<br />indiC<Jtcs the c.CO'..lnts .ore rca~ji):ldble..
<br />
<br />1
<br />
|