Groundwater quality assessment in selected polluted hotspots of Tamil Nadu, India using geospatial and statistical approaches

This study assessed groundwater quality in the Erode and Namakkal districts of Tamil Nadu, India, areas undergoing rapid urbanization and industrialization. Water quality parameters, including pH, Electrical Conductivity (EC), Calcium (Ca²⁺), Magnesium (Mg²⁺), Sodium (Na⁺), Potassium (K⁺), Carbonate (CO₃²⁻), Bicarbonate (HCO₃⁻), Chloride (Cl⁻), and Sulfate (SO₄²⁻), were analyzed for 113 samples to determine their suitability for drinking and irrigation based on BIS (2012) standards. Geospatial mapping visualized parameter variations, while statistical techniques, including the Water Quality Index (WQI), correlation analysis, Piper plot, and Gibbs plot, were employed for risk assessment. Results revealed that 82, 100, 78, 51, 6, 91, 86, 85, 1, and 112 sites exceeded permissible limits for pH, EC, Ca²⁺, Mg²⁺, Na⁺, K⁺, CO₃²⁻, HCO₃⁻, Cl⁻, and SO₄²⁻, respectively. Additionally, limits for RSC, RSBC, SAR, Na ratio, Permeability Index, SSP, TSS, Magnesium Adsorption Ratio, and Potential Salinity were exceeded at 5, 5, 1, 0, 11, 33, 0, 13, 71, and 68 sites, respectively. The Piper plot indicated that sulfate and sodium were dominant ions, underscoring significant salinity and hardness issues. The findings highlight the critical need for comprehensive water treatment strategies, such as targeted filtration and chemical neutralization, to ensure safe drinking water and sustainable irrigation practices. Local policymakers could use these insights to implement stricter industrial wastewater discharge regulations, encourage eco-friendly practices, and prioritize vulnerable zones for immediate intervention. By informing sustainable groundwater management policies, the study underscores the urgency of addressing pollution hotspots in the context of continued urban and industrial development. • Geospatial Mapping to visualize and analyze groundwater quality spatially. • Statistical Analysis to identify trends and factors affecting water quality. • Links groundwater degradation to sources like industrial activities and waste disposal. • The estimation of Suitability of water for Drinking and Irrigation purposes.