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POWDER MAGAZINE EPHEMERAL CHANNELS <br />Calculation Rational and Results Summary <br />Rational: <br />Calculated using Sedcad+ Ver. 4 <br />Areas slopes and flow paths from digital topography (MISC-25). <br />For the drainage areas a CN of 85 was used to represent a D-Soil Group, sage- <br />grass with (poor) 20% cover. <br />10 year 24 hour storm event of 1.4" <br />The ephemeral channels have two contributing flows. One is from the CRDA-2 <br />east upper diversion ditch (6.96 cfs). The other is from the Roadside North west <br />upper diversion ditch (3.33 cfs). <br />Channels: <br />Channels designated by watershed and gradient are shown on MISC-25. Three <br />watersheds were evaluated. Three distinct gradients (12%, 50% & 8%) were <br />used for the channels designed within upper watershed (#1). One gradient (8%) <br />was used for the channel designed within the middle watershed (#2). Two <br />gradients (2% & 13%) were used for the channels designed within and below the <br />lower watershed (#3). <br />Results: <br />See page MISC-24 <br />INEER'S CE <br />The SEDCAD calculations and inform <br />MISC-36 were prepared by me during <br />presented is true and correct to the bE <br /> <br />James E. StoJe'~~.E. <br />Registered Professio`rl <br />State of Colorado No.~ <br />les MISC-24 through <br />2007, and the information <br />id belief. <br /> <br />®e~~~o <br />~® ®o <br />MISC-23 ~ 0/07 <br />