Integrated hydrogeochemical characterization, water quality index, and human health risk assessment of groundwater in Maharashtra, India

Background Groundwater quality in industrial regions is increasingly threatened by coal-based thermal power plants due to the leaching of fly ash and ash pond effluents. These processes can alter groundwater hydrochemistry and introduce potentially toxic elements, posing risks to human health and water security. Comprehensive evaluation of groundwater quality, seasonal variability, and health risks is therefore essential for sustainable groundwater management. Objectives This study aims to (i) characterize the hydrogeochemical processes governing groundwater chemistry around the Koradi Thermal Power Station (KTPS), Maharashtra; (ii) assess groundwater suitability using Water Quality Index (WQI) modeling; (iii) evaluate seasonal groundwater level fluctuations; (iv) map the spatial distribution of heavy metals; and (v) quantify non-carcinogenic human health risks for adults and children. Methods Groundwater samples were collected from 30 locations surrounding the Koradi Thermal Power Station during the pre- and post-monsoon seasons for hydrogeochemical characterization, water quality assessment, spatial analysis of trace elements, and human health risk evaluation. Physicochemical parameters (pH, EC, TDS, and major ions) and trace elements (As, Cd, Pb, Ni, Fe, Mn, Cu, and Zn) were analyzed following standard APHA methods. Hydrogeochemical facies were identified using Piper diagrams, spatial analysis was performed using GIS, WQI was computed based on BIS drinking water standards, and the USEPA method was used for assessing health risk, hazard quotient, and hazard index models. Key Findings The groundwater exhibited mixed Ca–Mg–HCO₃ and Na–Cl facies, controlled by mineral dissolution, ion exchange, and anthropogenic inputs. The Water Quality Index (WQI) ranged from 69.1 to 197.7 during the pre-monsoon season and 72.8 to 245.3 during the post-monsoon season, indicating groundwater quality varying from good to very poor, with noticeable deterioration after the monsoon. Several heavy metals exceeded BIS drinking water limits, particularly near the ash pond region, and the health risk assessment revealed hazard index values exceeding unity at several locations. Spatial analysis highlighted localized contamination near ash disposal areas. Broader Implications The findings emphasize the need for monitoring of continuous groundwater and improved ash management strategies to mitigate health risks and ensure sustainable groundwater resources in coal-based industrial regions.