determine the flow from the soil into a $2$m depth open drain $100$m long when the drains are spaced $50$m apart. the depth of the pervious stratum is $3\mathrm{.}5$ m and the depth of water midway between drains is $1\mathrm{.}5$ m below the ground surface. the average permeability of the previous stratum is $0\mathrm{.}0001$ m$/$s$.$ the depth of water in the drain is $0\mathrm{.}2$ m