Keywords: infiltration rates, natural recharge, vertical hydraulic conductivity, artificial recharge structures, semi–arid areas, India, hydrology, granitic aquifers, groundwater levels, water table, defunct wells, aquifer revival
Relevance of hydrological parameters in artificial recharge sites selection and assessment in a granitic aquifer
Due to increasing demand of groundwater and indiscriminant pumping, groundwater levels have been declined beyond economic levels and the natural recharge is not enough. Thus enhancing recharge to the groundwater system through artificial means has been evident. Depending on the situation, a variety of methods have been in practice but assessing their efficacy as well as optimal site selection has been lacking. In this study, it has been decided to use relevant hydrological parameters for an effective artificial recharge experiment using defunct dug–wells. A small watershed in a granitic terrene heavily exploited for irrigation, has been hydrologically investigated, monitored and characterised for flow parameters. The indiscriminant pumping (from about 700 bore–wells in an area of 55 Km²) has resulted in lowering of the water table and making all the 160 dug–wells in the area, perennially dry and defunct. Out of this one defunct dug–well having considerable catchment area in its vicinity was selected for demonstration of the experiment and monitoring the processes. It has been proved that the artificial recharge through defunct dug–wells are the best method to revive the aquifers and at almost no cost.