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<br />a transposal of the eastern Colorado storm of 30 and 31 May 1935, over the Cherry <br />Creek basin. The peak discharge of this flood was 113,000 c. f. s, and the volume <br />..as 98,800 acre-feet. <br /> <br />INFLOW DESIGN FLOOD <br /> <br />The PMF, which is the current hydrologIc standard for the Inflow Design <br /> <br />Flood at the Cherry Creek Dam, was incr..",se,d when the Probable Maximum <br /> <br />Precipitation (PMP) values for the Cherry Creek basi.n were modified by the <br /> <br />publication of HMR 55 and revised in HMR 55A. <br /> <br />!'REVIOUS INFLOW DESIGN FLOODS <br /> <br /> <br />The Inflow Design Flood developed for the "Definite Project Report for <br /> <br />Cherry Creek Dam and Reservoir" was derived fr,om the storm of 30 to 31 May 1935. <br /> <br /> <br />The depth-area duration curve for this storm was incre.:lsed by a factor of 25 <br /> <br />percent and the resulting runoff estimated using infiltr"tion rates of 0,6 inch <br /> <br />per hour for the first 3 hours and 0.3 inch per hour for .the last 6 hours of the <br /> <br />storm. The peak discharge of the computed Inflow Design Flood ..as 180,700 c.f.s. <br /> <br />..ith a volume of 166,740 acre-feet. <br /> <br />Later, this PMF hydro graph was updat,.d wi th rainfall values tak.lD from the <br /> <br />U. S, Weather Bureau's "Hydrometeorologic"l R,eport No. 44" dat:ed January 1969. <br /> <br /> <br />In this derivation of the PMF for Cherry Cre..k basin, the Pattern "A" rainfall <br /> <br /> <br />values given in the report for the high plains area lyin!\ between Chatfield and <br /> <br /> <br />t:he Front Range were used after applyi.ng a small drainage area Bldjustment. <br /> <br />Losses of 0.5 inch per hour were applied to the rainfall values to obt..in the PMF <br /> <br /> <br />runoff. This resulted in 9,7 inches of runoff from a 96-hour storm with a total <br /> <br />of 23.9 inches of rainfall, This runoff, when applied to the uni t hydrograph for <br /> <br />t:he Cherry Creek basin, produced a hydrograph with a peak discharge of 376,000 <br /> <br /> <br />c,f.s. and a volume of 207,000 acre-feet including a 1,000 c.f,s, baseflow, <br /> <br />!::URRENT INFLOW DESIGN FLOOD <br /> <br /> <br />The PMP values were taken from HMR 55, The 1.., 6-, 24-, and n.hour index <br /> <br /> <br />PMP estimates were determined for the Cherry Creek dr"inage basin a,nd for the <br /> <br /> <br />areas upstream and downstream of the Cast1.ewood Darn site individually. Based on <br /> <br />17 <br />