Assessment of Seawater Intrusion in Coastal Aquifers of Puri District, Odisha

Abstract

Seawater intrusion is one of the major threats in coastal areas and subsequently a major concern for the groundwater resource management. Effective planning and management is required for mitigation of this problem in coastal aquifers. The present research is aimed to identify the spatial distribution of seawater intrusion in the coastal aquifers of Puri District in the state of Odisha. In the present study, the vulnerability of aquifers to saltwater intrusion was assessed by GALDIT, an index-based method. To quantify the spatial extent of susceptibility of coastal intrusion, six hydro-geological characteristics were considered in the model such as G: Aquifer type (confined, unconfined & semi-confined), A: Conductivity of aquifer, L: Level of groundwater above MSL, D: Perpendicular distance from the shoreline, I: Cl- /HCO3 -+CO3 2- ratio representing existing effect of the intrusion of saline water and T: Saturated thickness of aquifer. Different weights and ratings were assigned to these layers according to the model and overlay analysis of the layers was done for mapping the seawater intrusion vulnerability map. For the pre-monsoon, susceptibility zones are categorized as low, moderate, and high, with percentages of 75.12 %, 22.84 %, and 2.034 %, respectively. Similarly, for the post-monsoon season, 78.07 %, 21.08 %, and 0.84%, area are categorized under low, moderate and high susceptible zones. The Gop block was found to be the most susceptible area out of the 5 studied blocks. Statistical analysis such as map removal sensitivity analysis showed that the level of groundwater above MSL and perpendicular distance from the shoreline are the most sensitive parameters and thickness of aquifer is the least sensitive parameter for groundwater contamination in the study area. Such modeling studies can help in planning and managing activities for sustainable groundwater resource management