ANALYSIS. OF SOIL MOISTURE DYNAMICS AND ASSESSMENT OF RECHARGE

Abstract

To meet ever increasing water demands, reliance on groundwater has been rapidly increasing, especially in the arid and semi-arid regions. Imprudent exploitation of the resource may result in undesirable consequences. Quantitative knowledge of recharge rates forms the basis for the assessment, development and optimal utilization of groundwater resources, and prevention of their excessive contamination. To assess the recharge it is important to know the flow through the unsaturated zone. Flow through unsaturated zone is usually analyzed by solving Richard's equation. The present study involves development of a numerical model for simulating one-dimensional vertical unsteady flow through unsaturated zone. The model essentially comprises a numerical solution of mixed form of Richard's equation by finite difference method. The boundary conditions assigned are evaporation, gravity drainage and infiltration. The model is used to estimate the recharge to groundwater for a period of one month. Sensitivity analysis is also carried out to study the effect of unsaturated soil parameters on the recharge. It is observed that unsaturated soil parameters play an important in the recharge process and the model can be used for predicting the recharge, given the soil parameters and the meteorological data.