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Page 6d of 9 <br />Ditch 7 (Lower Segment) <br />Manning's Equation <br />Flow In a Trapezoidal Channel <br />Depth D 0.26 Feet <br />Width W 5 Feet <br />Slope S 0.45 Express as Decimal <br />Mannings "N" N 0.035 Express as Decimal <br />Side Slope X 2 Slope = X:1 <br />AREA= (W*D) +(X *D "2)= 1.44 FEET ^2 <br />WETTED PERIMETER= (W) +2 *(((X *D) ^2 +D ^2) "0.5] 6.16 FEET <br />R= AREA/WETTED PERIMETER 0.23 <br />V= (1.49 1N) *(R ^.667) *(S ^.5) = 10.81 FT /SEC <br />Q =AXV= 15.51 CFS <br />Q REQUIRED - Peak Discharge" 15.30 CFS <br />'Volume 6A, Tab Reclaimed Configuration , Point B +C <br />Riprap Sizing - Ditch D -3 <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 = 1.55 feet 19 inches Use 19 -27" Riprap** <br />" D50 =27" for Manning's n of 0.030, therefore an acceptable range of rock size is provided. <br />Vol. 6A TR -54 08/12 <br />