TR-31 : Estimation of ground water recharge due to rainfall by statistical method

Abstract

Direct ground water recharge from rainfall depends on the intensity duration of rainfall, the evaporative demand, soil moisture deficiency, the sorptivity, depth of unsaturated zone etc. Given all these parameters, it is possible to predict the groundwater recharge at a site due to rainfall. Rainfall recharge would result in rise of water table. There have been attempts to predict rainfall recharge by statistical methods using only the point rainfall data and point water table fluctuation neglecting the fact that water table fluctuation may be caused by recharge at some other point with varied conditions. In the present report an attempt has been made to check the validity of statistical approach. Using Green and Ampt infiltration equation and sorptivity of a known soil, the recharge due to rainfall has been predicted. The consequent water fluctuations have been determined using Hantush solution for water table rise due to recharge. Using these synthetic data of water table fluctuation and rainfall values the rainfall recharge has been estimated statistically and compared with true but synthetic recharge values.