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Ditch 7a <br />Manning's Equation <br />Flow In a Triangular Channel <br />Depth D 0.9 Feet <br />Width W 0 Feet <br />Slope S 0.33 Express as Decimal <br />Mannings "N" N 0.04 Express as Decimal <br />Side Slope X 2 Slope = X:1 <br />AREA=(W*D)+(X*D^2)= 1.69 FEET ^2 <br />WETTED PERIMETER=(W)+2*[((X*D)^2+D^2)^0.5] 4.11 FEET <br />R=AREA/WETTED PERIMETER 0.41 <br />V=(1.49/N)*(R^.667)*(S^.5)= <br />=AXV= <br />Q REQUIRED - Peak Discharge <br />Riprap Sizing - Ditch 7a <br />D50 = Size of Riprap <br />D50 = ((V X S^.17)17.5$))^2 <br />D50 = Diameter in feet <br />V = Velocity <br />S =Slope <br />D50 = 1.67 feet <br />11.84 FT/SEC <br />20.04 CFS <br />19.08 CFS <br />20 inches Use 24" Rock <br />TR -98 App. B-36 01/15 <br />