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SEDCAD+ Sediment Calculations <br />The sedimentology of each watershed was evaluated by SEDCAD+. <br />SEDCAD+ develops a sedimentgraph utilizing the Revised Universal Soil Loss <br />Equation using a new revised representative length-slope factor as follows: <br />Y = 95(V x Q,)°'°K(LS)(CP) <br />Where: Y <br />V <br />Q, <br />K <br />LS <br />CP <br />Sediment yield in tons <br />Runoff volume in acre feet ~~~~ <br />Peak discharge in cfs ~~ <br />Soil erodibility factor ,w~ <br />Representative length-slope factor <br />Control practice factor <br />The new length-slope factor for the RUSLE subroutine is as follows: <br />LS = ~ '" x (slope factor) <br />72.6 <br />Where: ~ = representative slope length (ft) <br />m = 0.6 for Slope > 10% <br />m = 0.5 4%<slope<10% <br />m = 0.4 Slope = 4°,6 <br />m = 0.3 Slope <49'° <br />Slope Factor is a piecewise linear relationship with the slope break point <br />being at 8% as shown on Figure 5.5, Slope Factor for the Revised <br />Universal Soil Loss Equation, contained in the SEDCAD+ Users Manual. <br />The sedimentgraph is then routed to a structure using an exponential decay <br />procedure incorporating deposition of a partite size distribution. The eroded <br />particle size distribution is an input item. <br />9 <br />