A canal and a river run parallel for five $(5)$ miles and are separated by an average of $200$ feet of dry ground. The water surface elevation in the canal and river are $656\mathrm{.}0$ and $633\mathrm{.}4$ ft $,$ respectively. A stratum of sand intersects the sides of both the canal and the river below the water level. This sand extends from elevation $620\mathrm{.}5$ to $625\mathrm{.}0$ ft and has a coefficient of permeability of $6\mathrm{.}5{10}^{-2}c\frac{m}{sec}.$ The soils above and below the sand are stiff clays, which are essentially impermeable in comparison to the sand. what is the total head difference between the canal and river