Flood Risk Analysis: Causes and Landscape-Based Mitigation Strategies in Dire-Dawa City, Ethiopia

In flood prone areas, understanding flood causing factors, assessing the flood induced risks and adopting nature-based mitigation strategies can increase the knowledge andawareness and help  individual communities to protect themselves and their properties using appropriate flood management measures before and during flood events. Dire Dawa city is in the foothills of southern mountains from where rivers crossing the city are originated. The multidimensional causes of flood hazard and limited landscape-based mitigation strategies in the study area have exacerbated the impacts of flooding. This study was conducted with the aim of assessing flood causing factors and to propose landscape-based flood mitigation strategies. Case study data was collected from the Ethiopian Meteorology Agency, land use maps of Dire Dawa city administration and government reports. Findings of the study indicated that flood risk in the study area has resulted from multiple factors such as intense rainfall, topography, encroachment to the riverbanks, institutional problems and aggravating factors resulted from power interruption during heavy rain and regime changes. More importantly, flood risk of the study area was found to be sensitive to hourly variation of rainfall distributions and varies based on the location of the sub-watersheds. Based on the prioritization of sub-watersheds’ susceptibility to flood risk through morphometric analysis, select sub-watersheds are identified as the most flood risk susceptible watersheds demanding urgent landscape-based conservation measures and sustainable water conservation structures are also identified. The overall result of the study shows that managing the root causes of flooding at the upper catchments and adopting recommended proposed water conservation structures at proposed site helps to sustainably curb flood induced risks of Dire Dawa city.