Groundwater quality and its suitability for drinking and agricultural use in Chithar River Basin, Tamil Nadu, India

Hydrochemistry of groundwater in Chithar Basin, Tamil Nadu, India was used to assess the quality of groundwater for determining its suitability for drinking and agricultural purposes. Physical and chemical parameters of groundwater such as electrical conductivity, pH, total dissolved solids (TDS), Na+, K+, Ca2+, Mg2+, Cl−, HCO −3 , CO 2−3 , SO 2−4 , NO−3, F−, B− and SiO2 were determined. Concentrations of the chemical constituents in groundwater vary spatially and temporarily. Interpretation of analytical data shows that mixed Ca–Mg–Cl, Ca–Cl and Na–Cl are the dominant hydrochemical facies in the study area. Alkali earths (Ca2+, Mg2+) and strong acids (Cl−, SO 2−4 ) are slightly dominating over alkalis (Na+, K+) and weak acids (HCO −3 , CO 2−3 ). The abundance of the major ions is as follows: Na+ ≥ Ca2+ ≥ Mg2+ > K+ = Cl− > HCO −3 > SO 2−4 > NO −3 > CO 2−3 . Groundwater in the area is generally hard, fresh to brackish, high to very high saline and low alkaline in nature. High total hardness and TDS in a few places identify the unsuitability of groundwater for drinking and irrigation. Such areas require special care to provide adequate drainage and introduce alternative salt tolerance cropping. Fluoride and boron are within the permissible limits for human consumption and crops as per the international standards.