water emerges from under a gate into a trapezoidal, concrete channel. the gate opening is 0.55m, and the flow rate is 12.6 m3/s. the entry channel has a 1.5m bottom width, side slopes of 1:1 (h:v), and a bottom slope of 0.015. determine the channel and flow classification (e.g., m-1, s-2) and explain your supporting logic.