MODELING FLOOD HAZARD UNDER CLIMATE CHANGE SCENARIOS IN GENFEL RIVER CATCHEMENT, TEKEZE BASIN, ETHIOPIA

Abstract

Nowadays, Flooding is one of the most natural disasters, significantly affecting livelihoods, infrastructures, and ecosystems worldwide. Genfel River Catchment, located within the Tekeze Basin in Ethiopia, is particularly vulnerable to flood hazard due to its topography, climatic conditions, and hydrological characteristics. Therefore, this study aims to analyze the climate change scenarios as well as flood inundate map and identify flood hazards area. Methodology integrates field-measured elevation cross-section data with a best fitted DEM to improve the river channel representation. The accuracy of digital elevation model (DEM) in representing the river terrain channel was improved by integrating, the field data and FABDEM 30 m resolution. The hydrological process of the catchment was simulated using the HEC-HMS model, which was calibrated and validated with the historical streamflow data. Then a combined 1D/2D HEC-RAS hydrodynamic model has been employed to assess flood hazards under different climate change scenarios, specifically, Shared Socioeconomic Pathways (SSP) 4.5 and 8.5. The results highlight significant change in flood extent, depth, and velocity under future climate conditions, with the worst scenario (SSP 8.5) indicating an increased flood risk. The findings provide valuable insights for flood mitigation planning, emergency response, and climate adaptation strategies in the area. To establish hazard management measures, it is critical to map flood inundation for possible climate change scenarios. The entire area flooded by a baseline period under 200 return period will possibly 243.5 ha, while a future period SSP8.5 scenario will possibly 282.7 ha of the study area. Thus, this study suggests an emergency action plan should be implemented for better hazard management practices to ensure public safety and protect economic interests in the flood prone area.