- Urban flooding is an escalating threat in rapidly urbanising regions, particularly in sub-Saharan Africa (SSA), where unregulated expansion and climate change intensify risks. Nature-based Solutions (NbS) are increasingly recognised as cost-effective, sustainable measures for flood mitigation, yet their implementation strategies remain underexplored in SSA. This study assessed the hydrological impacts of water-related ecosystem loss (1986–2023) and evaluated the effectiveness of NbS (floodplain restoration and wetland creation) under various scenarios in the Aboabo catchment within the Greater Kumasi Metropolitan Area (GKMA), Ghana. Using spectral indices and TELEMAC-2D hydrodynamic modelling, we found a 59% decline in wetlands and a 134% increase in built-up areas, resulting in reduced cumulative discharge and intensified, shorter floods. Among NbS scenarios, the combined approach (floodplain restoration and wetland creation) consistently achieved peak flow reductions (16–19%) inUrban flooding is an escalating threat in rapidly urbanising regions, particularly in sub-Saharan Africa (SSA), where unregulated expansion and climate change intensify risks. Nature-based Solutions (NbS) are increasingly recognised as cost-effective, sustainable measures for flood mitigation, yet their implementation strategies remain underexplored in SSA. This study assessed the hydrological impacts of water-related ecosystem loss (1986–2023) and evaluated the effectiveness of NbS (floodplain restoration and wetland creation) under various scenarios in the Aboabo catchment within the Greater Kumasi Metropolitan Area (GKMA), Ghana. Using spectral indices and TELEMAC-2D hydrodynamic modelling, we found a 59% decline in wetlands and a 134% increase in built-up areas, resulting in reduced cumulative discharge and intensified, shorter floods. Among NbS scenarios, the combined approach (floodplain restoration and wetland creation) consistently achieved peak flow reductions (16–19%) in prolonged storms, while the restoration_ambitious scenario (restoring the full floodplain network) delivered the highest reduction (24%) for short-duration storms. In contrast, the landscape scenario (wetland creation in available spaces) achieved limited reductions (1–3%), highlighting the need for spatially targeted interventions. TELEMAC-2D proved highly adaptable for modelling flood resilience in data-scarce environments, making it particularly valuable for SSA. This study provides one of the first quantitative assessments of NbS in SSA using TELEMAC-2D and advocates for hybrid approaches that combine NbS with engineering solutions to enhance both immediate and long-term flood resilience. The findings offer a replicable framework for sustainable urban planning in SSA and similar regions.…
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