Assessment of hydrogeochemical status of groundwater in a coastal region of Southeast coast of India

A study was conducted in a coastal region of Cuddalore district of Tamil Nadu, India, to identify the hydrogeochemical processes controlling the groundwater chemistry. The major geological units of the study area are sandstone, clay, alluvium, and laterite soils of Tertiary and Quaternary age. A total of 64 groundwater samples were measured for major ions and stable isotopes. Higher electrical conductivity values indicate the poor quality groundwater along the coastal region. Saline water intrusion mainly affects the hydrochemical composition of the aquifer water reflected by Na–Cl-type waters. Cl−/(Cl− + HCO3−) ratio also indicates the mixing of fresh groundwater with saline water. The results of δD and δ18O analyses show that isotopic compositions of groundwater ranges from − 7.7 to − 2.1‰ for δ18O and from − 55.6 to − 18.5‰ for δD. Correlation and factor analysis were carried out to find the association of ions and to determine the major factors controlling the groundwater chemistry of the region. The study indicates that ion exchange, weathering, salt water intrusion along the coast, and anthropogenic impacts are the major controlling factors for the groundwater chemistry of the region.