Farm-scale recharge pits for improving local groundwater availability: insights from a hardrock watershed in Rajasthan, India

Groundwater depletion is a major challenge in semiarid, hard-rock regions where irrigation demands often exceed natural recharge. This study evaluates the effectiveness of farm-scale recharge pits as a local, supplementary, and community-managed groundwater recharge solution in the Dharta catchment of Rajasthan, India. Alongside check dams and direct well recharge structures, six recharge pits were monitored over three monsoon seasons to assess infiltration performance, water quality effects, and economic viability. In this hardrock setting, recharge occurred through weathered layers and preferential flow paths in deeper fractures. Average infiltration rates ranged from 0.04 to 0.51 m/day. Pits located in permeable soils and with well-matched catchment-to-pit volume ratios (6–35 mm) performed best. Recharge pits were more cost-effective than direct-well recharge structures, with benefit–cost ratios approaching or slightly exceeding 1 when infiltration exceeded 0.2 m/day. Water quality observations showed that recharge water had substantially lower salinity than ambient groundwater. Turbidity in pit water was high, but no corresponding increase was observed in nearby dug wells, suggesting effective natural filtration through the vadose zone during the monitoring period. Although modest compared to natural monsoonal recharge, these pits were associated with localized groundwater level rises and improved well water quality. The study indicates that when carefully sited, sized, and maintained, recharge pits can be viable and relatively safe farm-scale managed aquifer recharge (MAR) options in hardrock areas where large-scale infrastructure is unfeasible. The findings offer practical field-based design insights and highlight the potential of decentralized recharge to enhance local water security. They also support integrating community-led, small-scale recharge approaches into watershed development and groundwater governance policies. Importantly, the study acknowledges the limitations of attributing broader aquifer responses to individual pits in geologically complex settings, underscoring the need for adaptive, location-specific recharge strategies.