Estimating the rate of aquifer replenishment is probably the most difficult of all measures in the evaluation of ground water resources. The methods available for the estimation of ground water recharge directly from precipitation can be broadly divided into three-inflow, aquifer response and outflow methods according to how the studies are conducted (Kumar C.P, 1977).
The following methods are commonly in use for estimating natural ground water recharge (Sathish Chandra, 1979):