Estimating Present-Day Groundwater Recharge Rates in India

Abstract

Large number of people in the globe depends on groundwater as a major source of freshwater. Here, we provide present-day regional-scale groundwater recharge rates in a major part of the Indian subcontinent. We have used a combination of ground-based observed water level data obtained from an intense network of observational wells, along with satellite and global land-surface model-based outputs to calculate our estimates. Large variations were observed in the spatial groundwater recharge rates over the region based on geology and climate. High groundwater recharge rates (>300 mm/year) are observed over the highly fertile alluvial plains of Indus–Ganges–Brahmaputra (IGB) system. Comparatively higher rate of precipitation, high porosity and permeability of the unconsolidated fluvial deposits and rapid groundwater withdrawal (>90% of groundwater withdrawal are associated with irrigation) synergistically influence high recharge rates. Most of the regions on the central and southern study areas exhibit lower recharge rates (<200 mm/year). Magnitude of estimated recharge rates was quite similar from different approaches of groundwater recharge calculation; however, inconsistency in the output of different approaches over some of the regions is discussed herein.