Assessment of Groundwater Vulnerability in Barisal District of Bangladesh Using GIS-Based Drastic Model

Groundwater vulnerability is a serious issue at the coastal region of Bangladesh because of the extraction of groundwater and increasing contamination due to salinity intrusion. This study aims to assess the vulnerability of the shallow aquifer of Barisal, one of the severely salinity-affected coastal districts of Bangladesh. In this study, a vulnerability map for Barisal was developed using DRASTIC vulnerability index method in GIS environment. In this method, seven parameters such as water table depth, recharge, aquifer media, soil media, topography, impact of the vadose zone and hydraulic conductivity of the study area were considered for the analysis. From this study, the DRASTIC index value range was found 138–171 for Barisal which indicates that Barisal is moderately to highly vulnerable to contamination. From the analysis, it is seen that 56.73% of the total area of Barisal district lies under moderate vulnerability and 43.27% area under high vulnerability. Muladi, Hizla and Mehendiganj upazillas share major parts of the highly vulnerable zone while other places of this district fall mostly under moderate vulnerability. The result of the study will be helpful to the concerned authority to understand the groundwater vulnerability of identified vulnerable locations of Barisal district and take necessary steps accordingly.