Groundwater Vulnerability Assessment with DRASTIC Index Method in the Salinity-Affected Southwest Coastal Region of Bangladesh: A Case Study in Bagerhat Sadar, Fakirhat and Rampal

The southwestern coastal region of Bangladesh has a severe problem of extracting groundwater due to salinity intrusion. This study aims at the vulnerability assessment of the shallow aquifer of such a salinity-affected region of coastal Bangladesh. GIS-based DRASTIC Index method has been applied in Bagerhat Sadar, Fakirhat and Rampal Upazila which accounts parameters like Depth to the water table, net Recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone, and hydraulic Conductivity. Finally, the mapping of the DRASTIC Index has been resulted in low-, moderate- and high-vulnerable zones. This study reveals that about 85.43% area which is 656.85 km2 is exposed to moderate vulnerability. Only 7.88% area is under low risk, whereas 6.69% area is highly vulnerable. Fortunately, the southwestern part which is adjacent to the coast has a comparatively low vulnerability. The northeastern region which carries the urban area is characterized by highly vulnerable zones. Moderate- and high-vulnerable zones imply more accessibility of saline surface water to the ground.