Integrated field-based and geospatial evaluation of river bank erosion susceptibility mapping using AHP and BEHI: Insights from the lower Kangsabati Basin, West Bengal, India

Abstract

Riverbank erosion represents a major fluvio-hydrological hazard that threatens the socio-economic wellbeing and environmental integrity of floodplain communities. This study assesses riverbank erosion susceptibility in the lower Kangsabati River Basin, West Bengal, India, using an integrated geospatial framework that combines the Analytic Hierarchy Process (AHP) and the Bank Erosion Hazard Index (BEHI). Thirteen physiographic and anthropogenic factors—including slope, geology, drainage density, soil characteristics, land use, and vegetation indices—were incorporated to construct an AHP-based susceptibility model, while BEHI scores were calculated from field investigations at 27 streambank sites based on bank height ratio, root depth and density, surface protection, and bank angle. The results indicate that 20 villages fall within high to extreme erosion-susceptibility zones according to the AHP model, whereas 19 villages are classified similarly using BEHI, with locations such as Kuchiar Mahar, Bhatpara, and Hatihalka identified as particularly vulnerable. The findings demonstrate the effectiveness of integrating AHP and BEHI for delineating erosion-prone areas and provide valuable insights for decision-makers to prioritize mitigation measures, policy interventions, and sustainable riverbank management strategies. Overall, the proposed framework underscores the importance of integrating remote sensing, GIS, and field-based assessments to enhance erosion hazard mitigation and inform future research on the socio-environmental consequences of riverbank instability.