Quantifying flood risk using InVEST-UFRM model and mitigation strategies: the case of Adama City, Ethiopia

Adama, the second largest city in Ethiopia, faces regular flash floods. These floods severely impact the city dwellers' livelihoods due to unplanned urbanization in flood-prone low-lying areas surrounding deforested mountains and ridges. To address this issue, the current study employed the Integrated Valuation of Ecosystem Services and Tradeoffs-Urban Flood Risk Mitigation (InVEST-UFRM) model as a tool to quantify adaptation-planning strategies for the study area. The InVEST-UFRM model effectively analyzed urban watersheds and spatially represented flooding, providing a comprehensive understanding of the flood risk scenario in the city. The model was run four times with different rainfall scenarios based on an intensity-duration-frequency curve specific to the study area to assess the impact of varying rainfall depths. These scenarios produced significant findings in terms of increased runoff retention and highlighting the varying capacities of micro-catchments in the study area for retaining runoff and generating floods. The study also emphasized the suitability of the InVEST-UFRM model in quantifying trade-offs associated with structural and non-structural flood mitigation measures. It underscored the importance of integrating multidisciplinary fields such as hydrology, remote sensing, geographic information systems, and natural capital assessment tools in urban planning strategies to achieve flood resilience and sustainable urban development. Overall, the InVEST-UFRM model proved to be a valuable tool for urban planners and policymakers for adaptive strategies to cope with urban flood events.