申論題

4. Water flows in an open channel of a trapezoidal shape at a normal depth of 1.6 m. The bottom width is 3.2 m and the sides slope at 1:1 (45°). The flow rate is 8.2 m³/sec. The channel wall is smooth, uniform earth with a Manning roughness coefficient (n) of 0.022. Find the bed slope. (12%)