Calculate the approximate specific energy of a trapezoidal channel having a bottom width of 5m, ratio of side slope is 1:1 and the depth of flow at a discharge speed of 15 m³/ sec is 2.0m A 2.6 m B 2.06 m C 3.6m D 1.6 m

= [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

b4

A triangular channel has a vertex angle of 90o and carries a flow at critical depth of 0.3m. The discharge in the channel is? (a) 0.11 m3/s (b) 0.21 m3/s (c) 0.31 m3/s (d) 0.41 m3/s