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total required volume. Carlson Software or SEDCAD was then used to design ponds in each <br /> location which had the parameters described in the previous section. All ponds were designed to <br /> fully contain the 25-year, 24-hour event. Ponds 015, 016, and 018 are designed to contain the 100- <br /> year, 24-hour event. <br /> Shown on the following two pages are the calculations used by Carlson Software or SEDCAD in <br /> determining typical pond volumes. <br /> Universal Soil Loss Equation: Used by Carlson Software <br /> -------------------------------------------------------------- <br /> Required User Input: <br /> Note: The following values are to be entered by the user for each area in the watershed. The method <br /> 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 /> Area (sq units): Can be entered by the user or the program calculates the area of a user-selected <br /> closed polyline. The user also has the option to enter the area in different units. <br /> Slope, S (%): Can be entered by the user or the program calculates the slope when the user selects <br /> an area from the screen. <br /> Length(L): Can be entered by the user. If the user selects an area from the screen,the length is not <br /> calculated since the Gross Erosion is directly calculated. <br /> Topographical Factor(Ls): Will be calculated from Length(L) and the Slope(S), only when these <br /> values are entered by the user directly, as against calculated by the program from the screen. In <br /> the second case, the value of Ls is calculated for individual grids and not for the 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 /> Section 2.05.3(3) Page 8 July 2020 (TR-99) <br />