Integrated Framework for Detecting the Areas Prone to Flooding Using AHP in Bihar District, India

Abstract

This study presents a comprehensive flood risk assessment framework that integrates physical hazard indicators with socio-economic vulnerability factors using the Analytical Hierarchy Process (AHP). Biophysical parameters such as elevation, slope, distance from rivers, rainfall, topographic wetness index (TWI), modified normalized difference water index (MNDWI), and normalized difference vegetation index (NDVI) were used to construct the Flood Hazard Zonation (FHZ), while demographic, land use/land cover (LULC), accessibility to essential services, and illiteracy rates informed the Flood Vulnerability Zonation (FVZ). AHP-derived weights ensured methodological rigor, with consistency ratio (CR) values of 0.0607 (FHZ) and 0.0329 (FVZ), both within acceptable limits (CR ≤ 0.1). The resultant Flood Risk Zonation (FRZ), derived from FHZ and FVZ integration, revealed significant spatial disparities: 8.30% of the area was classified as very low risk, 24.96% low, 31.00% moderate, 25.17% high, and 10.57% very high risk across a total area of 94,229.96 km². FHZ alone identified 31.05% of the region as very high hazard, while FVZ showed 33.04% of the area under moderate vulnerability. Urban zones exhibited elevated vulnerability due to population density and service dependency, whereas rural areas were more susceptible due to limited infrastructure and literacy. This multidimensional approach underscores the intricate interplay of environmental and human systems in shaping flood risks and offers a robust decision-support tool for spatial planning and disaster preparedness.