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<br /> <br />(Q.'!8.96 <br /> <br />'Zt303 866 H 7.j <br /> <br />CIICB <br /> <br />~002 <br /> <br />1-1: ~8 <br /> <br />MEMORANDUM <br /> <br />COLORADO WATER CONSERVATION BOARl) <br />DA.RIES C LlLE <br />DIRECTOR <br /> <br />DATE: <br /> <br />April 18, 1996 <br /> <br />TO: <br /> <br />CSM Project Team Two <br /> <br />FROM: <br /> <br />Tom Brownmg - CWCB <br /> <br />.RE: <br /> <br />Walsenburg Hydrology Study <br /> <br />In response to a conversation I had with Kcvin, I am providing some information that should be <br />helpful for your study_ Below arc somc regional regression equations that can be used for <br />detennining peak flow values for your srudy _ Try using these equations in addition to using the <br />Rallonal Method, and compare the result~ <br /> <br />usns Regr<;ssion Equations: <br /> <br />QIO = 500(A)89 <br />- 15-0 ^)107 <br />{JlOO = J (.-. <br /> <br />Where: <br />QIO = lO-year peak How (ds) <br />QlOO = 100-year peak How (cfs) <br />A = Drainage Area (square miles) <br /> <br />ewCB Regression Equation: <br /> <br />Q ~ '9'iQ7( ^) 3M <br />Ion _ _~._.... <br /> <br />\\/here: <br /> <br />QlOO = <br />A= <br /> <br />100-year peak flow (cfs) <br />Drainage Area (square nules) <br /> <br />I am proVIding you WIth Time-TnIensity-Frequency CUrves that were developed for the Denver <br />area. These curves will be good enough for use with your study. For the Rational Method, me <br />the curves to estimate the rainfall intensity. Assume a time of concentration (te) of 15 minutes. <br />Then, using the time of concentration and the curves for the IO-year and toO-year events, <br />estimate the rainfall inlensitles. Calculate the lO-year and J OO-year flows using the equation Q = <br />CiA. You'll probably find that the Rational Method gives you higher values than the regre"lon <br />equations. Please call me if you have any questions. <br />