Comprehensive evaluation of groundwater quality and human health risk assessment in an ecologically sensitive mountainous catchment in Southern Western Ghats, India

The rapid surge in population growth and economic development has imposed immense pressure on groundwater resources in many arid and semi-arid river catchments. Lack of adequate data on groundwater quality and its assessments is a major setback in many densely populated regions of the world. Therefore, this study evaluates groundwater quality in the semi-arid Upper Bhavani river basin of Southern Western Ghats, which forms part of the Attappadi Critical Zone Observatory. A total of 156 groundwater samples from open and bore wells were collected seasonally (pre-monsoon, monsoon, and post-monsoon) and analyzed for physicochemical parameters, including trace metals. Water Quality Index , Heavy Metal Pollution Index, corrosion and scaling indices (LSI, PSI, AI), and human health risk assessments were used to assess water suitability for domestic purposes. Bore well samples showed poor water quality, with high levels of fluoride, calcium, total hardness, and TDS. About 14% of bore wells exceeded the WHO fluoride limits during the pre-monsoon season, posing health risks, particularly to women and children. No critical heavy metal contamination was found, though localized variations of barium and cadmium were noted. These findings highlight the need for regular monitoring, defluoridation and sustainable groundwater management aligned with the objectives of SDG 6 .