Groundwater Recharge Potential Zone Identification and Water Quality Assessment: A Case Study of Rajsamand District in Rajasthan, India

Abstract

Hydrogeochemical evolution was assessed through groundwater recharge potential and water quality assessment in the Rajsamand District representing the sub-humid region of Rajasthan. Three groundwater recharge potential zones (GRPZ) were identified using geology, geomorphology, lineaments density, land cover, soil type, rainfall, slope, drainage density, and topographic wetness index. These thematic layers were given weightage based on their influence using the analytical hierarchy processes (AHP) technique and integrated weighted overlay technique in the ArcGIS platform. Groundwater quality was assessed for eighteen samples by determining pH, electric conductivity (EC), total dissolved solids (TDS), major anions (CO ^2-, HCO ^-, Cl^-, F^-, SO ^2-, NO ^-,) and major cations (Ca²⁺, Mg²⁺, Na⁺, K⁺). These parameters were further used for groundwater suitability tests for drinking by applying the entropy water quality index (EWQI), groundwater pollution index (GPI), and irrigation purpose by Kelly's index. Spatial distribution was achieved using an inverse distance weighted (IDW) interpolation tool. The central part of the district was observed to have moderate (with 65% of the area) type recharge potential, whereas the eastern part was found with high recharge potential. Hydrochemical analysis revealed the sub-standard water quality in the central, eastern, and southeast parts. GPI-endorsed potential contaminants are F^- and NO ^- from natural and anthropogenic sources. A reciprocal relation between recharge potential and water quality was observed. It implies that a shallow aquifer composed of porous Schist in the southeast part allows comparatively more water to percolate and carries acidic leachate from mining, resulting in higher ionic concentration through dissolution.