The bed width of a trapezoidal channel is 5.0 m, 5,= 0.0004, the side slope is m = 2 horizontal: 1 vertical, and the n value is 0.02: y = 3.0 m is the normal depth of flow. Calculate and plot the resulting gradually varied flow using the direct step method, when the channel flows into a pool at the downstream end and the pool elevation is 1.25 m higher than the channel bed elevation at the downstream end. Estimate the length of the gradually varied flow that the pool elevation produces.

a water resource engineer is in charge of designing atrapezoidal open channel for flood control. Typically, these types of channels are made ofconcrete. Use Manning’s Equation.Flowrate (Qb), channel slope (S0), bottom width (Bw), channel sidewall angle (θ), actual depth(y), and Manning’s coefficient (n) are tabulated below. State all assumptions. * z is the sidewall ratio: for every 1 unit increase in depth, the top width increases by z on eachside of the channel, or 2z total.A) Given the actual depth, y = 1.25 ft, find the discharge Qa.B) Find the Critical Depth, yc, for the discharge Qa found in (a). For a trapezoid,dA/dy =Bw +2 yz .Is the flow sub- or super-critical?C) Determine the uniform flow normal depth (yn) at Qb = 209 cfs.D) If the slope is increased to 0.001, what roughness coefficient would be needed tomaintain the same discharge Qa? What about for Qb? Would it be the same value?

A trapezoidal channel with uniform flow depth 4 m. The base width is 6 m and the side slopes are equal to (1V:1H), Manning's n can be taken as shown in the figure. What is the weighted Manning's coefficient using Horton's equation. n=0.019 n=0.022/|1 n=0.012