Application of the analytical hierarchy process (AHP) for flood susceptibility mapping using GIS techniques in lower reach of Keleghai River Basin, West Bengal, India

Abstract

Flooding is one of the most devastating quasi-natural hazards in Southeast Asian monsoon region. The recent study aims to define the flood risk zones (FRZ) by using the multi criteria evaluation (MCE) method with the help of the Geographical Information System (GIS) of the lower Keleghai River Basin in West Bengal. For this purpose, post-monsoon multi-temporal Landsat-8 satellite imagery, topographical maps and Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) data have been used to identify the severity level of the flood risk area. To perform this study, different thematic raster layers of nine flood-conditioning factors like elevation, slope, rainfall, geomorphology, drainage density, distance from the river, LULC, SPI and TWI integrated to prepare a flood-zoning map using Weighted Overlay Linear Sum Model (WLSM) in GIS environment. The method of training set and validation in different locations in the study area of existing flood and prepared flood-prone zone has been tested to validate the study. The results depicted that in general very low (0.00–0.25), moderate (0.50–0.25), high (0.75–0.50) and severe (1–0.75)) flood risk zones found in the study area and the proposed multi-criteria approach of spatial layers in GIS environs provides a better assessment of flood risk zone. The outcomes of the study guide in developing comprehensive flood management strategies for efficient management on a priority basis of present and future flood hazards in the area.