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Riprap Sizing - Drainage Ditch D -H1 1% Slope Reach <br />D50 = Size of Riprap <br />D50 = ((V X S ^.17)/7.58)) ^2 <br />D50 = Diameter in feet <br />V = Velocity <br />S = Slope <br />D50 = 0.02 feet 0.3 inches <br />None Required <br />Concrete Ditch <br />Flow From 1 -1 and J 4 - 10 Year Event <br />Manning's Equation <br />Flow In a Trapezoidal Channel <br />DEPTH <br />D <br />0.190 <br />FEET <br />WIDTH <br />W <br />1.000 <br />FEET <br />Slope <br />S <br />0.010 <br />EXPRESS AS DECIMAL <br />Mannings "N" <br />N <br />0.015 <br />EXPRESS AS DECIMAL <br />SIDE SLOPE <br />X <br />1.000 <br />SLOPE = X:1 <br />AREA= (W- D) +(X -D ^2)= <br />WETTED PERIMETER= (W) +2 "[((X "D) ^2 +D ^2)^0.5] <br />R= AREAMETTED PERIMETER <br />V= (1.49/N) -(R ^.667) "(S ^.5) = <br />Q =AXV= <br />Q REQUIRED - Peak Discharge <br />0.23 FEET ^2 <br />1.54 FEET <br />0.15 <br />2.77 FT /SEC <br />0.63 CFS <br />0.60 CFS <br />TR -045 Exh -8 - 171 - 04/07 <br />AFPr2ov�b <br />