Problem $1)(10$ points$)$

Determine the flow rate of water in a trapezoidal concrete channel with a width of $10m,$ side walls measuring $z=1\mathrm{.}5,$ and a bed slope of $0\mathrm{.}0003,$ assuming a normal water depth of $3m.$ Employ the Manning equation with a roughness coefficient $(n)$ of $0\mathrm{.}012.$