Problem $3\mathrm{.}35$

For an unlined open$-$channel cross section with a width of $10$ ft $,$ depth of $3$ ft $,$ and

side slopes of $3$:$1($h$.$v$),$ find the flow rate assuming a slope of $0\mathrm{.}001f\frac{t}{f}t$ and an earthen

surface with short grass and a few weeds. Answer given $172\mathrm{.}5$ft$3/$ sec