Assessment of groundwater quality in hard rock terrain of Mandavi River basin, Rayalaseema region, Andhra Pradesh, India

Hygienic drinking water is limited, not only in India, but also worldwide. Groundwater is a major source for domestic and irrigation use in the area of the Mandvi River basin, Andhra Pradesh, India. Therefore, this paper is mainly focused on it. In this study, 55 groundwater samples were collected and various geochemical parameters were analyzed, such as pH, electrical conductivity (EC), total dissolved solids (TDS), carbonates, bicarbonates, chlorides, sulfates, hardness, alkalinity, fluoride, magnesium, calcium, sodium, potassium, and nitrate. From the analysis, results are interpreted with various geochemical indices such as sodium absorption ratio (SAR), potential salinity (Ps), residual sodium carbonate (RSC), non-carbonate hardness (NCH), permeability index (PI), Kelly’s ratio (KR), magnesium ratio (MR) and percent sodium (PS). From Chadha’s geochemical classification, most of the sample’s hydrochemical facies were Na–Cl (66%) and Ca–Mg–Cl (20%). The results of the study showed that 12.5% and 51.7% of the groundwater samples exceeded the permissible limits for fluoride and nitrate, respectively. Hence, all these interpretations indicated that most of the groundwater samples are not suitable for domestic and irrigation use. Rainwater harvesting, water quality improvement plans, regular monitoring of water quality, and multidisciplinary water research programs are recommended as measures for sustainable groundwater management in the study area.