AHP-Based Flood Risk, Vulnerability, and Public Health Assessment in Chattogram, Bangladesh: Mitigation and Future Perspectives

Abstract

Chattogram City Corporation (CCC), the principal port city and second largest urban economy in Bangladesh, is increasingly vulnerable to monsoon flooding, tidal backwater from the Karnaphuli River and Bay of Bengal, unplanned urbanization, and deterioration of natural drainage canals (khals). This study develops an integrated Geographic Information System (GIS) and Analytical Hierarchy Process (AHP) framework to assess flood risk across the 41 wards of CCC and examine its association with household level vulnerability and public health outcomes. Seven biophysical and anthropogenic criteria: elevation, proximity to rivers/khals, drainage congestion, rainfall intensity, land use/imperviousness, slope, and population density were standardized, weighted using Saaty’s 1–9 scale, and integrated through weighted linear overlay. The resulting pairwise comparison matrix produced a principal eigenvalue (λmax) of 7.130 and a consistency ratio (CR) of 0.016, indicating acceptable weighting consistency. Approximately 43.6% of CCC was clas-sified as having High or Very High flood risk, concentrated mainly in low lying wards of the central and southwestern areas. Questionnaire data from 360 households indicated significantly higher prevalence of waterborne diarrheal disease, skin infections, and psychological distress in Very High risk wards than in Low risk wards. The July 2026 record rainfall event, which af-fected approximately 450,000 people in the greater Chattogram area, further demonstrated the practical   relevance of the risk map, with reported waterlogging hotspots broadly corresponding to High and Very High risk zones. The findings support integrated structural, non structural, and building scale interventions, alongside policy measures and future applications of remote sensing, machine   learning, and participatory governance to strengthen urban flood resilience.