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Ditch F21-1 <br />Manning's Equation <br />Flow In a Triangular Channel <br />Depth D 0.8 Feet <br />Width W 0 Feet <br />Slope S 0.3 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)= 1.16 FEET ^2 <br />WETTED PERIMETER=(W)+2*[((X*D)^2+D^2)^0.5] 3.40 FEET <br />R=AREA/WETTED PERIMETER 0.34 <br />V=(1.49/N)*(R^.667)*(S^.5)= <br />IQ=AXV= <br />REQUIRED - Peak Discharge <br />lRiprap Sizing - Ditch F-21-1 <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 = 1.14 feet <br />9.94 FT/SEC <br />11.48 CFS <br />11.09 CFS <br />14 inches Use 12" Rock <br />TR -81 App. B-54 09/13 <br />