Assessing the role of groundwater recharge from tanks in crystalline bedrock aquifers in Karnataka, India, using hydrochemical tracers

The majority of India’s rural drinking water supply is sourced from groundwater, which also plays a critical role in irrigated agriculture, supporting the livelihoods millions users. However, recent high abstractions are threatening sustainable use and action needed to ensure continued supply. Increased managed aquifer recharge (MAR) using > 200,000 existing tanks (artificially created surface bodies) one Indian government’s key initiatives combat declining groundwater levels. few studies have directly examined effectiveness tank recharge, particularly complex fractured hydrogeology Peninsular India. To address this gap, study impact three crystalline bedrock catchments Karnataka, southern India, by analysing isotopic hydrochemical composition waters groundwaters, combined with level observations. results indicate that limited on regional quality areas, where precipitation recycling irrigation dominate signal. In urban setting (Bengaluru), impermeable surfaces increased relative effect point sources such as rivers, but present, pipe leakage public-water-supply accounted for recharge. Shallow levels inner parts city may lead discharge tanks, dry season. We conclude importance compared other highly dependent specific setting. Additional quantify revisions current guidelines national estimations, less generalised approach, recommended avoid over-estimating play