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• METHODOL06Y AND ASSUMPTIONS <br />The required hydrology, sedimentology and pond hydraulic calculations <br />for all proposed drainage and sediment control structures were performed <br />utilizing a combination of hand calculations and the SEDCAD+ computer <br />model developed by Civil Software Design. SEDCAD+ is a third generation <br />hydrologic and hydraulic calculation model designed for use on IBM <br />compatible computers. <br />HYDROLOGY <br />All hydrology for the revision area ponds was calculated by the SEDCAD+ <br />computer model. No hand calculations were performed. <br />SEDCAD+ Hydrology Calculations <br />• The SEDCAD+ model calculates runoff and peak flow via a numerical <br />modeling technique based on user inputs of runoff basin information and <br />design storm. Design storm inputs include rainfall amount and duration, <br />selection of a rainfall distribution, and convolution increment. <br />Hydrographs are developed on a subwatershed basis with the input of <br />area. time of concentration, SCS curve number, and selection of one of <br />three (3) dimensionless double triangle unit hydrograph shapes. This <br />information is further discussed in the SEDCAD+ User's Manual (Schwab <br />and Marner, 1987) and in the SEDCAD+ Inputs section that follows. <br />Routing of hydrographs is accomplished by Muskingum's methods. <br />Specific hydrologic output values calculated by the SEDCAD+ model are as <br />follows: <br />- Peak Flows (cfs) <br />- Storm Runoff (inches) <br />- Runoff Volume (acre-feet) <br />- Total Storm HydrograpA <br />23-61 <br />