Question $2$

$[10$ marks$]$

The cross$-$section of the flow in a river during a flood was as shown in the figure below. Assuming manning's roughness coefficients for the side channels and main channel to be $0\mathrm{.}04$ and $0\mathrm{.}03$ respectively, determine the discharge and the energy coefficient $.$

Bed slope $=0\mathrm{.}005$

Area of main channel $($before the flood$)=280m^2$

Wetted perimeter of main channel $=54m$