Flood risk assessment using geospatial data and multi-criteria decision approach: a study from historically active flood-prone region of Himalayan foothill, India

In recent years, floods have acquired global importance due to their devastating nature that can cause massive damage to infrastructure and society. The Himalayan foothill is very susceptible to flood since time immemorial, and therefore, the present study tries to assess the flood risk of the sub-Himalayan Jalpaiguri region using a multi-criteria decision approach. Hitherto, a detailed assessment of flood in the Himalayan foothill region is not carried due to a comprehensive database limitation. However, for the first time, a multi-source data of about seventeen parameters including, flood conditioning factors (viz. altitude, distance from rivers, slope, drainage density, geomorphology, flow accumulation, rainfall, topographic wetness index, geology, and soil) and socio-economic and infrastructural indicators (viz. population density, household density, Landcover, road distance, proximity to flood shelter, proximity to hospital and literacy) were used to prepare the flood susceptibility, vulnerability, and flood risk map for the study area. Furthermore, an administrative-wise microlevel risk assessment was also carried out in the present study. The result indicates that about 38% of the area is susceptible to high and very high flood zones, while about 58% of the area is covered under high to very high vulnerability zone. In the final flood risk map, about 29% of the area is under a high threat level that seeks immediate consideration. Furthermore, the reliability of this work can be assessed by validating the model using AUC, which gives an accuracy of 0.862 or 86.2%. Thus, the overall approach of this study can be applied for mitigation strategy and to prepare a policy framework to alleviate future flood incidences. © 2021, Saudi Society for Geosciences.