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SEDIMENT YIELD <br />Tn/Ac.[ Tons/ <br />Area R K LS CP Dr* Yr. Acres Year <br />16 0.24 0.17 0.9 0.15 0.09 5.21 4.689 <br />Sediment Volume = 2K x 1 Acre 4.7 <br />1.25 62.4 43,560 <br />Sediment Volume = 0.0028 <br />* - Sediment trap <br />II. SEDIMENTATION RESERVOIR EMERGENCY SPILLWAY DESIGN <br />Problem: Determine hydraulic data of a Trapezoidal shaped outlet <br />ditch, depth of flow at the design storm, and high waterline <br />elevation of the reservoir. <br />Solution: Maximum allowable velocity, Vmax - 3fps <br />q25 = 4.33 cfs (from Peak Discharge Calculations) <br />n = 0.03 (Manning coefficient for riprap) <br />sideslope = 2:1 (horizontal to vertical) <br />slope(s) = 0.01 feet/feet <br />w = 1 foot <br />Manning Equation: <br />q25 = 1.49 AR'/s S ~_ <br />n <br />Hydraulic Data: <br />Q = 4.33 cfs <br />D = 0.82 feet <br />A = 2.165 feet <br />R = 0.463 feet <br />s = 0.01 feet/feet <br />n = 0.03 <br />V = 2.0 fps <br />Assume reservoir high waterline to discharge the design storm is <br />equal to the spillway invert elevation plus the depth of flow in <br />the outlet channel: <br />H.W.L. 25 year = 4321 + 0.82 = 4321.8 <br />