Reconsider Prob. 13–53. If the maximum flow height the channel can accommodate is 3.2 m, determine the maximum flow rate through the channel.

Data from Problem 13–53

A trapezoidal channel with a bottom width of 6 m, free surface width of 12 m, and flow depth of 2.2 m discharges water at a rate of 120 m³/s. If the surfaces of the channel are lined with asphalt (n = 0.016), determine the elevation drop of the channel per km.

FIGURE P13–53

12 m 2.2 m 6 m