Delineation of flood vulnerable zones using AHP and GIS techniques in climatically vulnerable Sagar Island, Indian Sundarban Delta

Flood vulnerability assessment is crucial in the face of climate change, particularly for climate-vulnerable coastal communities. Rising sea levels, erratic rainfall patterns, and intensified cyclonic activities have exacerbated flood risks, threatening livelihoods, ecosystems, and infrastructure. While various tools and models have been developed for flood prediction and management, the Analytical Hierarchical Process (AHP) emerges as a powerful approach for addressing the complex and multifaceted nature of flood-related issues. This study selected eight components (four physical and four socio-economic) to develop a comprehensive flood vulnerability map. These components were constructed using remotely sensed data (DEM, satellite images) and census data, grouped into five-point vulnerability classes based on their contributions to flood risk. The results reveal that 52.40% of the area, particularly the southern and northeastern coastal mouzas and two western coastal mouzas, fall under ‘exposed zones’ (very high, high, and moderate vulnerability) due to low elevation, mild slopes, proximity to the sea, poor embankment conditions, and inadequate socio-economic structures. The southern and northern zones are identified as the most vulnerable mouzas due to their geomorphological location and poor socio-economic conditions. In contrast, central mouzas exhibit lower vulnerability owing to their distance from the coast and better access to assets and amenities. The vulnerability map provides critical insights for identifying areas of relative risk that support future management and planning efforts. This approach identifies priority areas for intervention and supports the formulation of evidence-based policies for disaster risk reduction (DRR). This model can serve as a replicable framework for other climate-vulnerable coastal communities globally, addressing the specific vulnerabilities of the Sagar Islands in coastal India. Ultimately, integrating AHP with multi-criteria analysis and expert validation offers a robust pathway for mitigating flood risks, safeguarding coastal populations, and promoting long-term resilience in the face of escalating climate challenges.