Hydrochemical characteristics and salinity of groundwater in parts of Nagapattinam district of Tamil Nadu and the Union Territory of Puducherry, India

An attempt has been made in Nagapattinam and Karaikal Coastal aquifers to explain hydrochemical characteristics and salinization sources. A total of 122 groundwater samples were collected during southwest monsoon and summer seasons and analyzed for major and minor ions. Groundwater samples represents alkaline nature irrespective of seasons. Larger variations in conductivity might be due to multiple geochemical processes. Hill piper plot suggests evolution of groundwater from fresh to saline facies during both the seasons. The multi-rectangular facies evolution diagram identifies saline intrusion dominant during summer and freshening of waters during southwest monsoon. The Ionic ratio plot suggests saline intrusion, cation exchange and anthropogenic sources controlling the groundwater chemistry. Correlation and factor analysis suggests additional sources of salinization from salt pan and agricultural influences. The spatial distribution map suggests larger area influenced by saline water intrusion when compared with other sources.