A systematic GIS and remote sensing based approach for mapping groundwater recharge zones in Kallakurichi district, Tamil Nadu, India

This study aims to estimate groundwater recharge and delineates groundwater recharge potential zones (GWPRZ) in the Kallakurchi district, Tamil Nadu, covering an area of 2.242.64 km2. Geographic information system (GIS) and Remote Sensing (RS) techniques were employed to integrate and analyse multiple thematic layers, including geology, lineament density, drainage density, land use/land cover (LULC), slope, and soil type, factors that significantly influence recharge, particularly in hard rock terrains. A weighted overlay analysis (WOA) was carried out by assigning scores and weights to these factors to generate a groundwater recharge potential map, categorizing the region into five zones: very high, high, moderate, low, and very low recharge potential. The spatial analysis revealed that very high recharge zones (300.96 km2) are concentrated in the eastern and central parts of the district, while high recharge zones (714.41 km2) are also predominantly located in the eastern region, whereas low (438.07 km2) and very low (97.09 km2) recharge zones are mostly situated in the hilly and less permeable areas. Model validation yielded a coefficient of determination (R2) of 0.86, confirming a strong correlation between the assigned weights and groundwater recharge. The total annual groundwater recharge was estimated at 425.66 × 106 m3, accounting for approximately 16% of the district’s average annual precipitation. These findings provide a valuable basis for groundwater management, offering spatial guidance for sustainable agricultural development, water resource planning, and long-term policy formulation in the region.