A rectangular concrete channel (n = 0.020) changes from a mild slope to a steep slope. The...

A rectangular concrete channel (n = 0.020) changes from a mild slope to a steep slope. The channel is 20 m wide throughout, and the rate of flow is 180 m3/s. If the slope of the mild portion of the channel is 0.0006 m/m, determine the distance upstream from the slope change to the point where y = 3.0 m. (Hint: Use the same step method as in Example 7-5, with y intervals of 0.1 m.)