GIS and AHP Based Flood Susceptibility Mapping: A Case Study of Chalakudy River Basin, Kerala, India

Abstract

The present study employs a GIS-AHP (Geographic Information System-Analytical Hierarchy Process) approach to assess flood susceptibility in the Chalakudy River Basin, Kerala, India. Twelve key factors influencing flooding were identified and categorized into hydrological (precipitation, river network density), morphometric (elevation, slope, distance from rivers), land cover dynamics (LULC, NDVI, NDWI, SAVI), and anthropogenic parameters (distance from roads, settlements). Using AHP, weights were assigned to these factors based on available literature, and a flood susceptibility map was generated through a weighted linear combination. The results classify 7.41% of the basin as very highly susceptible to flooding, with validation using Sentinel-1 SAR imagery confirming the model’s accuracy. The Consistency Ratio (CR) of 4.8% ensured the reliability of the AHP-derived weights. The study highlights the interplay of natural and anthropogenic factors, such as monsoonal rainfall, terrain slope, and sedimentation, in exacerbating flood risks. While AHP-GIS proved effective for regional assessments, the study acknowledges its subjectivity and suggests integrating advanced machine learning techniques for improved precision. The findings underscore the utility of flood susceptibility maps for risk management and mitigation strategies, particularly in data-scarce regions.