A rectangular notch weir is $5m$ wide. The base of the notch is $2\mathrm{.}5m$ above

the bed of the channel. If the total depth of water upstream is $3\mathrm{.}5m,$

calculate the flow over the weir using the simpler formula with a coefficient

of discharge of $0\mathrm{.}7.$ Calculate the flow over the weir using the rectangular

weir formula with a coefficient of discharge of $0\mathrm{.}723.$

Rectangular notch $-$ simpler formula: $Q=C_d\frac{2}{3}B\sqrt[\phantom{2}]{2g}{H}^{\frac{3}{2}}$