Assessing Salinity Intrusion Risk from Coastal Flooding through a Spatial Multi-Criteria Approach in Satkhira District of Bangladesh

Bangladesh's coastal zones face compounding threats from climate change, sea-level rise, and the resulting intensification of salinity intrusion, critically jeopardizing freshwater security, agriculture, and local livelihoods. This study presents a spatial multi-criteria analysis using a Geographic Information System (GIS) integrated with the Analytic Hierarchy Process (AHP) to systematically assess and map the hazard, vulnerability, and exposure dimensions driving flood-induced salinity intrusion risk in Satkhira District. The comprehensive assessment utilized 17 thematic criteria, revealing distinct spatial patterns of susceptibility. The Hazard analysis demonstrated that 35.21% of the total area is classified under the combined High and Very High zones, predominantly concentrated in the south-western and south-eastern coastal areas. The biophysical vulnerability assessment indicated a high degree of intrinsic sensitivity, with 36.59% of the district categorized as very highly vulnerable. Conversely, the Exposure analysis identified a substantial 28.19% of the land as highly and very highly exposed, reflecting the high density of valuable assets even in inland Upazilas. The final composite risk map reveals that 27.95% of the study area is subjected to either high or very high salinity intrusion risk, with the highest risk observed in Satkhira sadar. These empirically derived risk maps and quantitative findings offer crucial, evidence-based insights for policymakers, providing a foundational tool for the design and implementation of targeted adaptation strategies, sustainable land-use planning, and disaster risk reduction programs in vulnerable deltaic environments globally.