Groundwater potential zone mapping in the coastal Bagerhat district of Bangladesh using GIS and remote sensing techniques

The increasing global pressure on groundwater resources underscores the need for accurate identification of groundwater potential zones (GWPZs. This study identifies GWPZs in the coastal district of Bagerhat, Bangladesh, using an integrated geospatial method, along with the Analytical Hierarchy Process (AHP). Fourteen hydrogeological, geomorphological, land-surface, soil and climate factors including lineament density, drainage density, land use/land cover (LULC), slope, curvature, topographic position index (TPI), topographic wetness index (TWI), rainfall, geology, roughness, fractional impervious surface (FIS), topsoil texture, soil permeability and general soil types were weighted using AHP according to their relative importance. After assigning AHP derived weights to the thematic layers, the reclassified parameters were integrated through a weighted overlay based multi-criteria decision analysis to generate the groundwater potential index. The index was categorized into four groundwater potential classes utilizing the natural breaks classification method. Results show that the district is dominated by moderate groundwater potential (2431.79 km²; 84.91%), followed by high (339.51 km²; 11.86%) and low (92.42 km²; 3.23%) potential zones, whereas the very high class was negligible (0.10 km²; 0.0036%). Sensitivity analysis indicated that the geology had the most significant influence on the final GWPZ map, while roughness was found to have the least considerable influence. Overall, the study presents a robust, spatially explicit framework for assessing groundwater in Bangladesh’s coastal region. The findings offer valuable insights for formulating strategies to ensure the long-term sustainable management of groundwater resources in this environmentally sensitive area.