Integrated Hydrogeological and Hydrochemical Assessment of Basaltic Aquifers in Dhar District, Madhya Pradesh, India

Groundwater forms the primary source of freshwater in the basaltic hard-rock regions of central India; however, rising agricultural demand and increasing dependency on deeper aquifers have resulted in growing stress on groundwater resources in parts of Dhar District, Madhya Pradesh. To address this concern, an integrated hydrogeological and hydrochemical investigation was carried out in the district, underlain predominantly by Deccan Trap basalts. The study identifies a multi-layered aquifer system comprising a shallow weathered zone (5–30 m depth) and deeper vesicular and fractured basalt aquifers (30–150 m depth), where secondary porosity plays a dominant role in groundwater storage and movement in deeper aquifer. Pumping-test results indicate highly variable aquifer productivity, with transmissivity values ranging from 3 to 593 m²/day and yields from 0.10 to 24 L/s, reflecting strong spatial heterogeneity. Seasonal and long-term water-level behavior highlights monsoonal-controlled recharge, with localized decline observed in southern parts of the district due to excessive extraction. Hydrochemical analysis revealed dominant Ca–Na–HCO₃–Cl and Na–HCO₃ facies, with localized fluoride and nitrate contamination. Elevated fluoride (up to 2.5 mg/L) and nitrate (up to 142 mg/L) concentrations in specific pockets pose risks for drinking-water use, while irrigation suitability varies from medium to high salinity hazard. The study recommends a combination of supply-side measures, including artificial recharge structures in fractured zones, and demand-side measures such as water-use efficiency, regulated pumping, and improved fertilizer management. The findings offer a scientific basis for sustainable groundwater development and can serve as a reference for similar basaltic terrains in India.