Assessment of vulnerability to seawater intrusion and potential remediation measures for coastal aquifers: a case study from eastern India

Seawater intrusion is a major threat to the rapidly depleting groundwater resources in the coastal areas of India. Groundwater-based irrigation, significant industrial development and rapid urbanization are some of the key contributors exacerbating the stress on groundwater resources. Vulnerability to seawater intrusion in the Ramanathapuram district of Eastern India is assessed here utilizing the GALDIT method, for a period of 10 years (2001-2010). Results revealed a drastic increase in percent area coverage under moderate vulnerability, from 19.5 to 53.88 %, between the years 2001 and 2010. On the contrary, areas classified as highly vulnerable underwent minor changes over the span of the study. Vulnerability of the study area was also analyzed for the year 2050 considering an average global mean sea level rise of 3.1 mm/year. Results from the analysis for the year 2050 showed that, almost, the entire study area (similar to 97 %) was classified under moderate vulnerability. As a remedial measure to this imminent threat, favorable zones for artificial recharge were delineated on the basis of overlay analysis with weightage values for important controlling factors. Subsequently, the quantity of artificial recharge required to inhibit the intrusion of seawater, at specified favorable zones were estimated to be 674.87, 599.18 and 1,450.66 m(3)/year.