Assessment of hydrogeochemical characteristics and potable quality of groundwater around Retteri lake in Thiruvallur district, Tamil Nadu, India

Hydrogeochemical characteristics of groundwater are significantly affected by its interaction with aquifer minerals. This in turn affects the quality of groundwater for its intended usage. The objective of the present research is to identify the processes controlling the hydrogeochemical characteristics of groundwater around Retteri lake and to assess its potable quality. Ground water samples from 26 sites were collected from the study area and physicochemical analysis were performed to evaluate the water quality parameters such as pH, Electrical Conductivity(EC), Total Dissolved Solids(TDS), Total Hardness(TH), Total Alkalinity(TA), Ca2+, Mg2+, Na+, K+, Cl-, SO42-, CO32-, HCO3-and NO3-. Correlation analysis for the water quality parameters was performed to identify the nature and degree of correlation among the various parameters. A strong positive correlation was observed between pH and HCO3-. EC and TDS shows a strong positive correlation with Ca2+, Mg2+, Na+, Cl- and SO42-. TH exhibits a strong positive correlation with Ca2+, Mg2+, Cl- and SO42-. Scatter plots were drawn among major ions to identify the geogenic processes responsible for the hydrogeochemical evolution of groundwater in the study area. The Gibbs plots of the study region indicate that water-rock interaction is the major process that influences the composition of groundwater. The Piper diagram reveals that Na-Cl and mixed Ca-Mg-Cl are the major hydrochemical facies of the groundwater in the study region. The potable quality of groundwater was examined through the evaluation of water quality index (WQI) by weighted arithmetic method. The WQI calculations reveals that 19% samples of groundwater are of excellent quality, 62% samples are of good quality and 19% samples are of poor to very poor quality.