Flood hazard attribution and uncertainty analysis with climate changes in data scarce watersheds of southeastern Ethiopia

Abstract

The interaction of the atmosphere and the land surface is vital in hydrological processes. In this paper, climate change impacts on streamflow are explored using soil and water assessment tool (SWAT) in one of the tropical watersheds, Wabi Shebele River Basin of Ethiopia. Regional climate model (RCM) from CORDEX-Africa region is used to analyze the basin's hydrological responses to climate forcing in the projected period. The result indicates that the watershed is likely to experience an increase in flood hazard with an increase in precipitation in the future as temperatures increase less than 2 °C. Flood hazard indices showed a larger value downstream of the river station (i.e., Gode) and a smaller value at the upper and middle stations with no change in climate variables (i.e., the baseline scenario, T + 0 °C, P + 0%). Based on separation method analysis, climate change has a greater impact on the streamflow and flood hazards in the region during the last four decades. Model uncertainty analysis reveals that simulated seasonal streamflow using RCMs has similar oscillation patterns to streamflow using observed climate data within uncertainty bands (UBs) in the study area with NSE and R2 values greater than 0.75 and 0.92, respectively. HIGHLIGHTS Regional climate model (RCM) from CORDEX-Africa has the capability to forecast the climate condition of southeastern Ethiopia.; SWAT model has the capability to simulate streamflow and explore climate change impacts in tropical watersheds.; Uncertainty level of climate change impact on flood hazard at present and future is explored.; Climate change is the most driving force for flood hazard in southeastern Ethiopia.;

Keywords

• climate change impact
• flood hazard
• sensitive parameters
• swat model
• uncertainty analysis