A discharge of 2,200 cfs (ft3/sec) flows in a trapezoidal channel at a normal depth of 8.0

Question:

A discharge of 2,200 cfs (ft3/sec) flows in a trapezoidal channel at a normal depth of 8.0 ft. The channel has a slope of 0.01, a 12-ft bottom width, and side slopes of l : l (H: V). Detennine the Manning coefficient of channel roughness. Also determine the sensitivity range of the roughness coefficient estimate if the flow rate can only be estimated to within ±200 cfs.