A compound channel has the cross-section shape shown in Figure 2 below. Figure 2: Engineered channel cross-section The rectangular central channel has n = 0.025, and the two overbanks have n = 0.070. The bed slope is 0.018.   Determine: The total flow rate in cfs for the cross-section for the water surface position shown, considering vertical interfaces between the subsections and including those interfaces in the wetted perimeter.

A rectangular open channel, with a constant discharge of 32m3/s, has a smooth expansion from (1) to (2) as shown in figure Q2 in the flow direction. At (1) the channel is  3.6m wide and the water depth is 2.4m . At (2) the water depth is 0.8m. Determine the channel width at (2), stating any assumptions made.

= [a Q/gb], where Q is the (a) Show that the critical depth for rectangular channels is expressed by y. discharge, b is the channel width, and a is the energy coefficient. (b) A half trapezoid flood drainage channel (Fig. 3b) has a flow of 100 m³/s. If the flow depth upstream of the 0.2 m step-rise is 4 m, what is the depth at an immediately downstream section of the 0.2 m step- rise? Assume there are no losses in the transition. Also compute the flow depth at the a very far downstream end if the flood drainage channel ends in a free overfall. (c) For a symmetrical compound channel section (Fig. 3c), compute the n., α, and S, based on the assumption that the depth of flow in the section is 5 m; the flood plains and the main channel have the same bottom slope of 0.001; and roughness coefficient for the main channel and the flood floodplains are respectively 0.021 and 0.039.

In a 5 m wide rectangular channel, the velocity u distribution in the vertical direction y is given by u= 1.25y¹/6. The distance y is measured from the channel bed. If the flow depth is 2m, the discharge per unit width of the channel is