Geochemical characterization of groundwater and water quality assessment for sustainable management of hard rock aquifer in South India

Abstract Hydrogeochemical investigation was carried out in groundwater of Virudhunagar district, Tamil Nadu, India. Geologically the study area is occupied with Archaean, Charnockite, Unclassified Genesis and Pleistocene Laterite formations. A total of 72 groundwater samples were collected spatially during North East Monsoon (NEM) in 2019 based upon the coverage of geological formations. The collected samples were studied for different physio-chemical parameters like pH, TDS and EC, major cations (Ca, Mg, Na, K) and major anions (Cl, HCO3, SO4, PO4). EC and TDS ranges from 273 to 5869 mg/L and 194 to 4159 mg/L. The ionic dominance of the hydrochemical parameters follows in the order of Na > Ca > Mg > K and Cl > HCO3 > SO3 > PO4. The data represents two major hydrogeochemical facies of Ca-HCO3 and mixed Ca-Mg-Cl in the study region. The USSL classifications of samples signifies low alkali hazard and high to very high salinity hazard. The higher concentration of TDS and EC in the samples reflects the unsuitability of groundwater. According to the WHO drinking water quality standards and the value of SAR, RSC, Na% reflects the groundwater in the study region is more suitable for irrigation than drinking purpose. The statistical method also adopted to understand the major factors influencing the variation in hydrochemistry of the region. Weathering, leaching of salts and anthropogenic activities were identified to be the key governing factor in the varied groundwater chemistry of this region.