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For the gravel pad: 7 (paved areas). <br />For the tank: 7 (paved areas). <br />3.3 Soil Erodibility Factor (K) <br />This measure of susceptibility of soil particles to detachment and transport by rainfall and runoff has been <br />selected as 0.37 (reference SEDCAD+ guide). <br />4. UNIQUE SEDCAD+ INPUT PARAMETERS <br />SEDCAD+ parameters unique to a situation are introduced as encountered under area specific discussions. <br />4.1 Areas <br />Areas (acres) were measured or calculated as follows: <br />1) cutslope: 0.002 acre. <br />2) tank: 0.140 acre. <br />3) exposed pad: 0.193 acre. <br />4.2 Curve Number (CN) <br />Curve numbers reflect the runoff potential of an area (a value of 100 represents an impervious area where <br />100% of the water would run off), and is a function of soil type (a "D" used in this analysis) and the land use. <br />For these analyses, CN are (reference the SEDCAD+ guide): <br />For undisturbed portions of the watershed, overland flow: 63 (for Arid and Semiarid Rangelands, Oak, <br />fair cover). <br />For the cut slope, overland flow: 94 (Developing Urban Area (No Vegetation), Newly graded area). <br />For the gravel pad: 91 [graveled paved areas (roads)]. <br />For the tank: 93 (impervious area). <br />4.3 Hydrograph Response Shape <br />Hydrograph response shapes reflect the rapidity with which water runs off a watershed, rated in SEDCAD+ <br />as fast, medium, or slow. A slow response shape would correspond to a forested area or an area with a lot <br />of obstructions, while a fast response shape would correspond to an unvegetated or poorly protected area. <br />These ratings are for overland flow. Once overland flow is surpassed, a fast rating is assigned. <br />4.3.1 Overland Flow <br /> <br />Lengths of overland flow (sheet and rill drainage) is a direct input parameter in SEDCAD+ for sedimentology <br />analyses, and has an indirect influences on other parameters, such as LUC. The estimated maximum <br />permissible lengths of overland flow within a woodland (fair cover) for slopes less than 25% is selected as 225 <br />feet. <br />3