$3\mathrm{.}3$ Water flows in a compound channel whose bed slope is $0\mathrm{.}002$ and whose cross section is as shown in Fig. $3\mathrm{.}2$ below. The Manning's coefficient for the concrete chansel section, $n=0\mathrm{.}015$ while that for the floodway section is $n-0\mathrm{.}040.$ The dimensions of different subsections of thip fompoand channel are also given in the figure. Assuming steady uniform flow, detem$$ne the flow rate through the whole channel.

$(16)$

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$3$