GIS flood susceptibility mapping from Sentinel-1 SAR using Analytical Hierarchy Process (AHP) model: study area Selangor, Malaysia / Nur Aliah Izzah Yaakob

Floods have a lot of negative effects on the environment and society. Overflowing water from floods submerges the landmass, destroying infrastructure, built environments, and agricultural fields. Understanding the contributing elements and developing a precise map for flood susceptibility are the flood susceptibility problems. The aim of this research is to assess the frequent floods event at Selangor, Malaysia using Analytical Hierarchy Process (AHP) model and Sentinel-1 SAR image. Thus, the objectives of this study are to determine flooded area based on flood marks related to Department of Irrigation and Drainage (DID) rainfall volume and water level record (2020-2022), determine flooded area using Sentinel-1 imagery and evaluate the susceptible area of flooded using AHP and Sentinel-1 SAR. About 818 points of floodmarks in 3 years (2020-2022) were used. There were 6 factors affecting flooded area: elevation, slope, rainfall, land use, topographic wetness index (TWI) and flow accumulation. The flood susceptibility was assessed using Geographic Information System (GIS) and assigned parameter’s weights through (AHP). The flood susceptibility map was validated using area under curve (AUC). The result of AUC between AHP and floodmarks was 0.626 that shows satisfactory values for susceptibility area. The AUC value of 0.689 between AHP and Sentinel indicates satisfactory accuracy in identifying flood prone area. The result of this research producing high precise map illustrating susceptibility to flooding for the flood-prone area. This study can be a useful tool for determining flood risk areas and planning flood mitigation and control strategies.