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SEDIMENTOLOGY <br />Sediment yield was calculated by SEDCAD+ for single storm events and <br />converted to annual yields by the following equation: <br />V= .R8„~Ue, x (Storm sediment yield)x(~ x 2 Ib~to n <br />Rstorm SW 43~56D ft /acre <br />Where: V =Annual Sediment Volume (acre ft/year) <br />Refni81 =Annual Rainfall Factor <br />R5t„m =Single Storm Rainfall Factor <br />SW =Sediment Specific Weight (Ibs/ft3) <br />Annual and storm rainfall factors and sediment specific weight are explained in <br />detail under SEDCAD+ Sedimentology Inputs. The storm sediment yield (tons) <br />is a SEDCAD+ output, calculated as described below. <br />• SEDCAD+ Sediment Calculations <br />The Sedimentology of each watershed was evaluated by SEDCAD+. SEDCAD+ <br />develops a sedimentgraph utilizing the Revised Universal Soil Loss Equation <br />(RUBLE) using a new revised representative length-slope factor as follows: <br />Y = 95(V x QP)' <br />Where: Y <br />V <br />QP <br />K <br />LS <br />CP <br />~ ~K(LS)(CP) <br />= Sediment yield in tons <br />= Runoff volume in acre feet <br />= Peak discharge in cfs <br />= Soil erodibility factor <br />= Representative length-slope factor <br />= Control practice factor <br />The new length-slope factor for the RUBLE subroutine is as follows: <br />LS = ~- m x (slope factor) <br />72.6 <br /> <br />6 <br />