HYDROGEOCHEMICAL INDICATORS OF SEAWATER INTRUSION

India has an extensive coastline of about 7517 km. the coastline of Tamil Nadu has a length of 1076 km which constitutes about 15 percent of the total coastal length of India and stretches along the Bay of Bengal the Indian Ocean and the Arabian Sea. About 46 rivers drain into the Bay of Bengal forming several estuaries adjoining coastal lagoons. The International Panel on Climate Change (IPCC) considered seawater intrusion into aquifers an important future impact of climate change and sea-level rise. Understanding the evolution of groundwater chemistry especially the balance between highly saline and fresh groundwater is crucial for proper water management in coastal zones in the face of both climate-driven and anthropogenic changes. Monitoring groundwater salinity can bring awareness to the early signs of migration of the freshwater-saltwater interface and provide information on saltwater encroachment. Understanding the evolution of groundwater hydrochemistry especially the balance between highly saline and fresh groundwater is crucial for proper groundwater management in arid and semi-arid zones.