Q$4)$ Design a vertical drop structure in a lined canal carrying a discharge to lower the canal bed by $2\mathrm{.}3m.$ The canal sections in the reaches $\frac{U}{S}$ and $\frac{D}{S}$ of structure are the same and the details are given below:

discharge $=5\mathrm{.}4m\frac{3}{s},$ bed width $=2\mathrm{.}7m,$ Longitudinal slope $=17\mathrm{.}7c\frac{m}{k}m,$ Side slope $=1\mathrm{.}5H$:$1V,$ Manning's coefficient $(n)=0\mathrm{.}015,\frac{U}{S}$ and $\frac{D}{S}$ depth of flow are the same. Also design this drop structure as a USBR impact block type basin. Compare the results of the two designs.