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<br />storm E~vent models such as HEC.-1 and TR-20 do not have <br />this capacity. The s imulat,ed peak flood f lows can be <br />statistically analyzed at the locations of interest <br />within the watershed in a manner similar to the statis- <br />tical methodology used for actual streamflow data. <br /> <br />Design storm Ana,lysis <br /> <br />Rainfall informat:ion that is employed primarily in the <br />Design storm Method of Analysis is readily available <br />from the Western United states Rainfall Atlas (Ref. 1). <br />The cri.tical questions in the application of the design <br />storm method of analysis a,re: <br /> <br />What duration should be used as the design <br />storm? <br /> <br />What temporal pattern or time distribution <br />should be used for the desisrn storm? <br /> <br />What a,ntecedent moist,ure condition should be <br />used to estimate the infiltration rates for <br />the soil within 1:he water:3he,d? <br /> <br />The des:ign storm methodology typically relies upon the <br />use of a storm duration and storm temporal pattern <br />specified by the developers of the methodology. For <br />ex<~mple, the Soil Conservation Service unit: Hydrograph <br />method always makes use of a 24-hour duration storm <br />with a specified temporal pattern. The SCS makes use <br />of a 24-hour Type II or a 24-hour Type IIA Storm de- <br />pending on the location of the watershed. The SCS Design <br />Storms are specified in d:.mensionless form by a series <br />of time ratios and rainfall ratios that allow the <br />develoFment of the 24-ho~r mass rainfall carve. The <br />Urban Dt'ainage and Flood Cont.rol District: has calibrated <br />a Design Storm methodology called the Colorado Urban <br />Hyclrograph Procedure (Cm{p) tha1: has received extensive <br /> <br />g <br />