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Universal Soil Loss Equation : Use in Survcadd Program <br />Required User Input: <br />------------------- <br />------------------- <br />Note : The following values are to be entered by the user for each area in the watershed. <br />The method for obtaining these parameters is left to the user. <br />Rainfall Factor (R) : Default = 50; <br />Erodability Factor (K) : Default = 0.37 <br />C Factor (C) : Default = 0.5 <br />P Factor (P) : Default = 1.0 <br />Geometric Information <br />---------------------- <br />---------------------- <br />Area (sq units) : Can be entered by the user or the program calculates the area of a <br />user - selected closed polyline. The user also has the option to enter the area in different <br />units. <br />Slope, S ( %) : Can be entered by the user or the program calculates the slope when the user <br />selects an area from the screen. <br />Length (L) : Can be entered by the user. If the user selects an area from the screen, the <br />length is not calculated since the Gross Erosion is directly calculated. <br />Topographical Factor (Ls) : Will be calculated from Length (L) and the Slope (S), only when <br />these values are entered by the user directly, as against calculatedby the program from the <br />screen. In the second case, the value of Ls is calculated for individual grids and not for the <br />entire area. <br />Ls = (L/72.6) ^m * ((430 *S ^2 + 30 *S + 0.43)/(6.613)) <br />where L and S are defined above and <br />m = 0.5 if S = >5 %; = 0.3 if S <= 3% ; = 0.4 otherwise. <br />(Revised June 2010) 2.05.3(3) -18 <br />