Flood susceptibility mapping of Kathmandu metropolitan city using GIS-based multi-criteria decision analysis

Abstract

Floods are among the most severe hazards around the world triggered by climate change, threatening environmental sustainability, economies, and ecological cycles and damaging infrastructure and causing loss of lives. We aimed to prepare a flood susceptibility map of Kathmandu metropolitan city (KMC) and identify the most flood-susceptible local administrative unit using a multi-criteria decision analysis model, including the analytical hierarchical process and weighted linear combination in geographic information system. Six flood hazard criteria—slope, elevation, drainage density, rainfall, land use and cover, and distance from river—were proposed to produce a flood susceptibility map. Among them, distance from river was the most significant criterion followed by rainfall and land use and land cover. The results showed that a large proportion (56%) of KMC is in moderate flood potential zone, while 32% and 11% proportions of KMC are in high and low flood potential zones, respectively. Wards 4 and 14 of KMC are the highest and lowest flood prone zones, respectively. The accuracy of the obtained map by multicriteria decision model is 81.2%, which was validated through observation of the significant flood events and flood location. These findings are useful for flood risk mitigation and logical allocation of programme budget to the local units. The procedures applied in this study are helpful for hydrologists, urban planners, policymakers, and professionals in hydrology.