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<br />Septcmber 1993 CYVCC -Sediment Yield Demonstration - Block C ~ 6 <br />Peak Discharge, QP. Peak discharge is calculated internally within the SEDCAD+ program <br />az previously described and is considered to he an internal input. <br />Soil Etodibility Fattor, K. The K factor for Block C wu determined using a weighted average <br />of the predisturbance soil types found in Block C and adjacen[ area. Bazed on Routt County <br />SCS designations, pre-disturbance soil types have the following K factors: <br />Winevada-Splitro Complex K - 0.20 <br />Aaberg Silty Clay K - 0.32 <br />Cochetopa Loam K - 0.28 <br />The weighted average K factors is 0.22. K factor calculations can be found in Appendix A. As <br />previously staled the soils found in Block C are similar to the soil found in adjacent paztureland <br />areas, therefore, the K factor for areaz should not vary significan[ly when compared to the K <br />factor for Block C. <br />Representative Slope Length. The slope length is representative of the typical slope length <br />over the subwatershed and wu determined u the distance from the point of origin of overland <br />flow [o the point where the slope decreues such that significan[ deposition occurs or un[il flow <br />enters a defined channel. <br />Average S1oRe. The average slope is entered in percent and is the typial or representative slope <br />for overland flow for each subwatershed. Average slope wu also meuured directly from the <br />1"=500' scale figures for both areaz. As previously mentioned, for [his s[udy the same <br />topography is used for both areas. <br />Control Practice Factor, CP. The control practice factor is defined az the ratio of sediment <br />loss from an area with a given cover and conservation practice to that of a field in continuous <br />fallow. <br />Using Table S.Sc CP in [he SEDCAD+ Users Manual: <br />Block C <br />Type and Height of Raised Canopy: No Canopy <br />Canopy Cover: 0 °~ <br />Percent Ground Cover: 92.5 9f. (Percen[ cover includes litter and rocks) <br />CP:.0047 <br />Adjusted CP:.0024 or .003 <br />Paztureland Reference Area x ~ ~ ' <br />Type and Height of Raised Canopy: No Canopy <br />Canopy Cover: 0 °k <br />Percent Ground Cover: 97 % ,otg .oosU <br />CP:.003 <br />The CP factor for Block C waz adjusted to account for surface roughness. As shown at the <br />bottom of Table 5.A.2 found in Applied Hydrology and Sedimentology for Disturbed Areas <br />(1981), the following multiplier should be used to account for surface roughness: <br />TERRAMATRIX • P.O. Box 774018 'Steamboat Spnngr, Colorado 80477' (303J 879.6260 <br />