Flood risk using GIS-based MCDA approach for a case study

ABSTRACT Flood hazard assessment was done by integrating the analytic hierarchy process (AHP) and fuzzy analytic hierarchy process (F-AHP). Flood hazard index is estimated using elevation, slope, distance to a stream, normalized difference vegetation index (NDVI), curve number, topographic wetness factor, hydrological soil group, stream power index, curvature, and aspect. The slope in the middle and lower regions ranges between 1 and 15% and NDVI values vary from −0.14 to 0.74. The flood vulnerability index is estimated using eight vulnerability factors of the society flood risk maps with five risk zones generated by combining the hazard and vulnerability index. DEM is the highest sensitive parameter for hazard factors, but the build-up area is the highest sensitive factor for flood vulnerability. The area with high infrastructure development has more chances of flooding. The flood hazard map was generated using F-AHP-based weightage and was grouped into five classes with percentage of catchment area: very low (11.75%), low (13.32%), medium (36.82%), high (32.36%), and very high (5.75%). There is a very high risk for urban areas of Muzaffarpur and Motihari districts. Statistical error analysis demonstrates similar findings for both the AHP and F-AHP approaches. The F-AHP approach is reliable and accurate. Study elucidates a comprehensive and reliable framework for flood management and mitigation strategies to improve decision-making processes in developing flood mitigation.