Geospatial flood risk assessment: multi-criteria approach integrating hydro-climatic hazard, exposure, vulnerability

Floods cause severe losses, impacting communities and ecosystems, while risk assessment aids mitigation. Flood risk in Ardabil's watersheds was assessed using a multi-criteria approach integrating hazard, exposure, and vulnerability. Flood risk was determined by considering hazard, exposure, and vulnerability using 19 criteria that influence flood occurrence. These criteria include max 24-h rainfall, potential runoff generation, frequency of floods, max flood discharge, runoff contribution area, and floodplain extent, average floodplain width, population density, cultural heritage, reservoir storage capacity, flood control, natural lands, flood awareness/preparation, illiteracy rate, emergency services, topography, unemployment rate, housing quality, and infrastructure. Hydro-meteorological data and GIS maps were used to calculate factors via the arithmetic mean of standardized criteria, with risk estimated by multiplying the factors. The hazard factor had the greatest impact on flood risk, with low risk in the Eiril and Namin watersheds and the highest in Mashiran. About 32.52% and 33.81% of the studied watersheds area are assigned as very high and high-risk classes, respectively. As a concluding remark, the presented map can provide managers and planners with a comprehensive view of the risk of flooding, taking into account all the effective factors in different climatic conditions, topography, and diversity of human activities.