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SIZE TRAPEZOIDAL CHANNEL FOR OUTLET PROTECTION <br />• MANNING'S EQUATION <br />FLOW IN A TRAPEZOIDAL CHANNEL <br />ENTER DEPTH IN RANGE D 0.750 FEET <br />ENTER WIDTH IN RANGE D 3.000 FEET <br />ENTER SLOPE IN RANGE D 0.100 EXPRESS AS DECIMAL <br />ENTER "N" IN RANGE D 0.040 EXPRESS AS DECIMAL <br />ENTER SIDE SLOPE X IN D 2.000 SLOPE = X:1 <br />AREA=(W*D)+(X*D)= 3.38 FEET^2 <br />WETTED PERIMETER=(W)+2((XD^ 2+D^2j)^.5 6.35 FEET <br />R=AREA/WETTED PERMITER 0.53 <br />V=(1.49/N)*(R^.667j*(S^.5)= 7.73 FT/SEC <br />Q = A X V = 26.07 CFS <br />Q REQUIRED 23.04 CFS <br />The outlet channel for the 36" portal culvert will be a 4' wide <br />trapezoidal channel with a flow depth of 9 inches and a freeboard <br />of 12 inches. Riprap 6 to 12 inches in diameter will be placed in <br />the outlet channel. <br />D50 = ((V X S^.17)/7.58))^2 <br />D50 = Diameter in feet <br />V = Velocity <br />S = Slope <br />D50 = 0.475 feet 5.698 inches <br />COLLECTION DITCH CD-4 <br />FLAW FROM DRAINAGE AREA NO. 4 <br />FLOW IN A TRIANGULAR CHANNEL <br />DEPTH D 0.510 <br />SLOPE S 0.010 <br />MANNINGS "N" N 0.030 <br />DITCH SIDE SLOPE X 1.500 <br />AREA=(W*D)+(X*D)= <br />WETTED PERIMETER=(W)f2((XD^2+D^2))^.5 <br />R=AREA/WETTED PERMITER <br />V=(1.49/N)*(R^.667)*(S^.5j= <br />Q = A X V = <br />Q REQUIRED <br />FEET <br />EXPRESS AS DECIMAL <br />EXPRESS AS DECIMAL <br />SLOPE = X:1 <br />0.39 FEET^2 <br />1.84 FEET <br />0.21 <br />1.77 FEET/SEC <br />0.69 CFS <br />0.67 <br />. 8-96 <br />