Compute the flow rate in the channel below with $n_1=0\mathrm{.}04,n_2=0\mathrm{.}014,$

and $n_3=0\mathrm{.}018.$ The flow depth $y=3ft.$ The channel slope $S=0\mathrm{.}01$ as shown in Figure

The side slopes $m_1=2$ and $m_3=0\mathrm{.}5.$ The channel base width $b=10\mathrm{.}0ft.$

Figure $1$: Channel with a complex distribution of roughness.