Hydrogeochemical Evaluation and Groundwater Quality Assessment for Drinking and Irrigation Purposes of Lokapavani River Basin, Mandya District, Karnataka, India

Abstract

Groundwater is a vital resource for domestic and agricultural use in semi-arid regions such as the Lokapavani River Basin, Mandya District, Karnataka. This study evaluates the hydrogeochemical characteristics and suitability of groundwater collected from 41 locations during the pre-monsoon and post-monsoon seasons of 2023. Physicochemical parameters were analyzed using standard methods and water quality was assessed using the Water Quality Index (WQI) and irrigation indices such as SAR, Na%, PI, RSC and Kelly’s Ratio. The WQI values ranged from 16.79 to 106.16, indicating water quality from excellent to unsuitable for drinking. Most samples fall under good to poor categories, while a few locations showed unsuitable quality due to high salinity and ion concentration. The fluoride (F) concentration ranges from 0.22 to 1.90 mg/L, slightly elevated concentrations in some locations may pose potential health risks if consumed over long periods. Irrigation indices indicate low sodium hazard but moderate salinity hazard. The Piper diagram shows dominance of Ca–Mg–HCO₃ facies, suggesting silicate weathering and rock-water interaction. Seasonal variation indicates improved quality during the post-monsoon due to dilution. The study highlights the need for regular monitoring and sustainable groundwater management.