Consider the drainage channel and adjacent floodplains. The manning roughness coefficients are given by
Left Floodplain=.04
Main Channel=.016
Right floodplain= .050
and the longitudinal slope is .5%. Field tests have shown that the Horton equation best describes the composite roughness of the channel. Find the capacity of the main channel and the lateral extent of the floodplains for a 100-year flow of 1590m^3/s.