Analysis of rainfall-recharge relationships

Abstract

Understanding the recharge process and its relationship with rainfall is of critical importance to the management of groundwater systems and enormous effort has been made to estimate the amount and process of recharge by infiltration using precipitation data. In the present research, in-situ lysimeter experiments and numerical simulations were used to study the relationships between rainfall and recharge by infiltration at different groundwater depths. Four lysimeters, 1.5, 3, 4.5, and 5 m deep, were installed in the field to measure the infiltration recharge rates under conditions of fixed water tables at the bottoms of the soil columns. Annual infiltration recharges at different groundwater depths were obtained through the lysimeter measurements. The effect of rainfall pattern and annual rainfall distribution on infiltration recharge was simulated at various groundwater depths using a numerical model based on soil-water dynamics, and comparisons of the simulated and observed recharges showed very good agreement. Relationships between rainfall and infiltration recharge at different groundwater depths were investigated using the lysimeter measurements and computer simulations. Groundwater systems were classified into three categories, i.e. shallow water table, intermediate water table, and deep water table, based on the relationship between rainfall and infiltration recharge at different groundwater depths.