Analyzing and Planning Urban Flood Resilience and Mitigation Strategies: The Case of Adama City, Ethiopia
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Date
2024-07-01
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Addis Ababa University
Abstract
surrounded by mountains, where frequent flash floods have had a detrimental impact on the local community's well-being. Consequently, this study sought to evaluate the extent of flood vulnerability and devise effective strategies for flood prevention. To achieve this, a Geographic Information System (GIS) approach incorporating multicriteria decision-making (MCDM) and the analytical hierarchy process (AHP) was utilized to identify and map areas prone to flooding. Various factors, including proximity to drains, topographic wetness index (TWI), elevation, slope, precipitation, land use, normalized difference vegetation index (NDVI), distance from the river and road, drainage density, and soil composition, were Combined and analyzed. The results indicated that 98.69% of the study area faces a moderate to very high risk of flooding, with only 1.31% classified as low risk. The flood susceptibility map produced by the model aligned closely with data gathered from ground control points (GCPs), onsite field observations, Google Earth Satellite Imagery, expert insights, and local community reports. In addition, to characterize flood vulnerability, a Socio-EcologicalTechnological Systems (SETS) framework was utilized. Where, each SETS domain identified clusters of flood-prone areas, highlighting the need for urgent adaptive measures to address flood vulnerability in the study area implying adopting holistic approaches to promote sustainable cities. Furthermore, to investigate flood-resistant neighborhoods, a comprehensive analysis of morphological analysis, local community
responses, and expert insights was conducted. By considering the current spatial layout and morphology with urban flooding, the city can enhance its flood management strategies for the future. These findings have implications for other flood-prone neigh borhoods in similar urban areas, highlighting the importance of spatial arrangement in mitigating urban flood vulnerability. Finally, to quantify and implement strategies for mitigating floods, researchers utilized the Integrated Valuation of Ecosystem Services and Tradeoffs Urban Flood Risk Mitigation (InVEST-UFRM) model as a tool to develop adaptation plans for addressing urban flooding. The InVEST-UFRM model offered a thorough insight into the city's flood situation by effectively analyzing urban watersheds and accurately representing flood risk. Running VI the model four times with different rainfall scenarios based on an Intensity-DurationFrequency curve specific to Adama revealed the impact of varying rainfall depths. In the first scenario, there is a moderate retention capacity of 10.76 m3 and a flood volume of 3.34 m3
. In the second scenario, the retention capacity improved to 11.63 m3 with a flood volume of 4.15 m3. In the third scenario, there is a further enhancement in
retention capacity to 12.21 m3 , along with a flood volume of 4.76 m3 . Finally, in the fourth scenario, the retention capacity continues to increase to 12.78 m3
, with a flood volume of 5.40 m3 These simulations produced significant results on runoff retention and flood volume, highlighting the diverse capacities of micro-catchments in the study area to retain runoff and generate floods. The study also emphasized the InVESTUFRM model's effectiveness in assessing the trade-offs linked to both structural and non-structural flood mitigation strategies. It underscored the significance of incorporating disciplines such as hydrology, remote sensing, geographic information systems, and natural capital assessment tools into urban planning strategies to enhance flood resilience and support sustainable urban development.
Key:words: Adama, Flooding, Modeling flood, InVEST-UFRM model, Resilience, Social-ecological-technological Systems, Vulnerability