Groundwater quality evaluation and its suitability for domestic and irrigation use in the hard rock terrain of Olakkur block, Tamilnadu, India

Abstract

Groundwater is the main source of water for agriculture and domestic use in the study area. This study was aimed to evaluate the groundwater quality for domestic and irrigational purposes. Groundwater samples were collected from twenty-five locations in both pre-monsoon and post-monsoon months and examined for various Physico-chemical parameters such as pH, total dissolved solids, total hardness, calcium, magnesium, sodium, potassium, bicarbonate, sulphate, nitrate and chloride. To assess the domestic suitability of groundwater, all these parameters were compared with the standards of the World Health Organization and Indian standards. Sodium Adsorption Ratio (SAR) and US salinity diagram were used to evaluate the groundwater for irrigation suitability. At some locations, sodium and potassium values were higher than the prescribed limits. The SAR values were less than 10. Based on the United States Salinity Laboratory Staff (USSL) diagram the dominant categories were C2-S1, C3-S1, C2-S1, C3-S1, C3-S2 in both pre and post-monsoon. Groundwater samples were classified as Na-HCO₃ and Na-Cl water type in pre-monsoon and Ca-Na-HCO₃ and Na-Cl types in post-monsoon. The geochemical analysis revealed that the groundwater samples were fit for domestic purposes. The irrigation quality assessment based on the Sodium Adsorption ratio and US Salinity diagram suggested that most of the groundwater samples were fit for irrigational activities except in certain locations where sodium and salinity values were high. Based on Piper water classification, the mixing process and evaporation were the dominant geochemical process in the study area.