Flood Hazard Area mapping Using GIS and AHP in Awash River Basin (ARB), Ethiopia

Flood is the second major hazard in Ethiopia, next to drought. The reason behind this is the topography of highland mountains and lowland plains with natural drainage networks created by primary river lines. The study area, Awash River Basin nowadays, encounters several environmental challenges such as land degradation, high growth of population density, deterioration of natural water, wetland destruction, desertification, and salinity. Flooding is also the huge problem that can magnify how severe environmental degradation is in the Awash River Basin. Flood hazard mapping is a critical component of flood-prone land use planning and mitigation strategies. Various studies show that GIS-based flood hazard mapping is significant to hinder severe flood hazards. This paper was an attempt to produce a GIS-based flood hazard area map and discuss major causes and impacts of flooding in the Awash River basin. The main parameters used to produce maps were elevation, slope, drainage density, average annual rainfall, proximity to rivers, land use, land cover change, and soil types. Hence, the rasterized and reclassified potential flood-generating factors were weighted, and a pair-wise comparison had been made. As a result, the vast majority of the basin, or 5,855,130.12 ha (51.4%), is susceptible to high flood hazards, while 4,625,378.51 ha (40.6%) and 866,358.09 ha (7.6%) of the area covered are prone to moderate and low flood hazards, respectively. When compared to other factors, the drainage density, elevation, and slope level have a greater impact on the vulnerability to flood hazards. The outcomes of this research contribute to effective flood risk management and environmental planning strategies in the Awash River basin.