Sea Water Intrusion (SWI) occurs by reverse hydraulic gradient and mainly on account of Salt Water transport by advection and hydro-dynamic dispersion. The Ground Water quality in coastal tracts is determined by the analysis of a large number of chemical and isotopic parameters. Thus, it is imperative to analyze the chemistry of sea water and fresh water for the detection of SWI and to distinguish the origin of salinity. Accordingly, 50 ground water samples were collected in dug and bore wells of different places in East and West coasts of Andaman island in two successive years 2013 and 2014 peak summer season where there was no absolutely recharge.
The samples were analyzed for major chemical parameters such as TDS, EC, Cl, Ca, Mg, Na, HCO3, K, Sr and B. The samples were also subjected to ionic ratio analysis such as rNa/rCl, rCl/rSO4, rCa/rHCO3+ rSO4 etc. The rNa/rCl analysis reveal that most of the ground water samples collected at Mithakari, Ograbraj, Port Mout, Shippighat, Tirur, North Wandoor, Manjery, Saithankari, Namunaghar were showing the ratio less than one indicating the ingression of Sea Water. Similarly, the rCa/rHCO3+ rSO4 indicate that most of the ground water samples collected at viz at Mithakari, Ograbraj, Port Mout, Shippighat, Tirur, North Wandoor, Manjery, Saithankari, Namunaghar show more than one confirming the salinity problem. The piper analysis of ground water samples of these places indicated that the samples landed near the sea label in the upper diamond of the piper diagram. In addition, the high TDS and EC values of these water samples beyond the BSI drinking water standard were corroborating with the ionic ratio analysis results. As a sequel to identifying the SWI in ground water samples, suitable mitigation measures such as artificial recharge, subsurface barrier at appropriate places were suggested.