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CYCC -.Sediment Yreld Demnnsrrnrion Eckman Park Area 4/ <br />~~ <br />HYDROLOGIC SOIL GROUP AREA• (area) PERCENT OF TOTAL <br />A 1.97 0.08 <br />B 1597.22 66.86 <br />C 404.26 16.92 <br />D 302.82 12.68 <br />Rock 82_62 3.46 <br />TOTAL 2388.89 100 <br />Areas measured with digitizer on 1:500 scale mapping, <br />Ground cover values for Area 4l, and the Pastureland Reference Area were obtained from the 1998 vegetation <br />surveys. Curve numbers were obtained from the SEDCAD+ selection tables based on soil type and vegetative <br />condition. Curve numbers were determined for the following conditions: <br />Area 41 <br />Hydrologic Soil Group: Predominantly B <br />Land Use Description: Pasture <br />Condition: Good <br />Cover Type: Grass <br />CN: 61 <br /> <br />Pastureland Reference Area <br />Hydrologic Soil Group: D <br />Land Use Description: Pastureland <br />Condition: Good <br />Cover Type: Grass <br />CN: 80 <br />2.2 SEDIMENTOLOGY <br />Sediment yield was calculated by SEDCAD+ far single storm events for Area 41, and the Pastureland Reference <br />Area. SEDCAD+ develops a sediment graph utilizing the Revised Universal Soil Loss Equation (RUSLE) using a <br />revised representative length-slope factor as follows: <br />Y = 95(Y x Oo)°SbK(LS)(CP) <br /> <br />Where: Y <br />V <br />QP <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 <br />Representative length-slope factor <br />Control practice factor <br />The new Icng[h-slope factor for the RUSLE subroutine is as follows: <br />.~ <br />LS = -) x(slopr fctclor) <br />72.6 <br />• i ~.•norm'unnnxnml~cVdii~ndrel~~r<aJl doc <br />