Assessing the relationship between flood risk and its terrain driving factors: an empirical study of the Rupnarayan river basin, West Bengal, India

Krati Bansal, Anindita Nath, Tanupriya Choudhury, Bappaditya Koley

Abstract: In south Asian monsoon region flood is one of the most destructive quasi-natural hazard. In the current research work aim to identify the flood risk zones (FRZ) applying the multi-criteria evaluation method through Geographical Information System (GIS) of Rupnarayan catchment area West Bengal, India. the work developed by the expert based opinion method and surveyed by 35 experts through questionnaire. Seven triggering criteria have been chosen for the flood risk assessment and implement the Analytical Hierarchical Process (AHP) to obtain the weights of each criteria. Digital Elevation Model (DEM) with 30 m resolution and 2020 Landsat 8 satellite image have been used. Here, Drainage Density (DD), Distance to River (DR), Elevation, Slope, Topographic Wetness Index (TWI), Normalized Difference Vegetation Index (NDVI) and Stream Power Index (SPI) have been chosen as criteria layers to generate the final Flood Risk Map (FRM). From AHP vector weights was acquired i.e., DD as 4.77%, DR as 7.43%, TWI as 4.94%, SPI as 14.84%, Slope as 23.36%, Elevation as 26.88% and NDVI weights considered as 17.79% all and final FRM generated (Fig. 1). From the FRM values the map class has been categorized into five distinct risk zone with their area i.e., Very low flood risk zone (6.69% area), Low (22.42% area), Moderate (27.86% area), High (27.12% area) and Very high flood risk zone (15.91% area). The outcome flood risk map was validated with AUC – ROC curve where the obtain ROC value is 0.85. Hence, acquired outcome may have the insightful impact to the flood mitigation management and the risk reduction strategies in chosen catchment area.

External IDs:doi:10.1007/s41324-025-00650-z