Gully Control and Drop Spillways

The discharge capacity of a straight drop spillway weir is given by $Q = C L H^{3/2}$. For discharge coefficient $C = 1.7$, weir length $L = 4.0\text{ m}$, and head $H = 0.8\text{ m}$ ($0.8^{1.5} \approx 0.7155$), the discharge capacity $Q$ in $\text{m}^3/\text{s}$ is (rounded off to two decimal places):