22. Groundwater Fitness Evaluation in a Hard Rock Terrain: A Case Study from South India

This research work focused at the connections between ground water quality and the healthiness associated with drinking of contaminated water in the Kodavanar River Basin. Totally sixty samples were collected from river basin to know various elements like pH, alkalinity, TH, TDS, EC, Fe, Na, Ca, Mg, K, HCO₃, NO₃, Cl, SO₄², F, etc., to compare with WHO standard to measure the groundwater quality for domestic usage via entropy water quality index (EWQI). Based on EWQI it is observed that 50% of samples fell into the “good” class and 50% of samples fell into the poor class for consumption purpose. The results subjected into piper plot reveals that significant portion of the research field has the mixed Ca²⁺–Mg²⁺–Cl⁻ water type during all seasons. The spatial exposure of nitrate contaminated groundwater in around 1576 km² in all the seasons shows that 1502 and 986 km² fell into the health risk zone for both children and adults correspondingly. Similarly, the spatial analysis of sum of dermal and oral exposure of fluoride-contaminated groundwater zone identified around 1390 km² in all the seasons, which exposes 1401 km² and 744 km² identified health threat region for children and adults, respectively, in all the seasons like winter, summer, post-monsoon, and pre-monsoon. This study reveals the essentials for workable management of underground water in the region under study and advanced treatment methods such as reverse osmosis, membrane filtration techniques to be adopted to remediate the contaminated ground water in this area.