FIGURE $7\mathrm{.}24$ Cross$-$section for Problem $7\mathrm{.}30.$ el$.=$ elevation.

seam is present as shown. This sand has $k=9{10}^{-2}c\frac{m}{s}.$ Compute the water loss from the canal to the river due to seepage through this sand layer and express your answer in acre$-$ft per month.

Note: One acre$-$foot is the amount of water that would cover one acre of ground to a depth of one foot, and thus equals $43,560f{t}^3.$