A green infrastructure planning approach for enhanced flood control and resilience in urban areas

Urban flooding presents a growing challenge in metropolitan areas due to climate change and increasing impervious surfaces. This research proposes a Green Infrastructure (GI) planning approach to enhance flood control and resilience in the flood-prone Yeoksam-dong region of Gangnam, Seoul, South Korea. A mixed-method approach was employed, incorporating both residents' preferences and hydrological simulations using the Stormwater Management Model (SWMM) to assess the effectiveness of various GI controls. Key GI co-benefits were identified through importance-performance analysis (IPA) and fuzzy weight rankings. Based on these, three GI scenarios were developed and evaluated for their flood mitigation potential. Scenario 1 (infiltration trench, rain garden, and rain barrel) emerged as the most effective, reducing surface runoff by 18.56 % and achieving the best cost-benefit ratio of 1.01 over a 10-year period. Scenario 2 (bio-retention, pervious pavement, and green roof), while less effective in terms of flood mitigation, may still offer ecological and social co-benefits. The study also conducted a sensitivity analysis, which confirmed Scenario 1's robustness across various levels of imperviousness, making it a highly adaptable solution for urban settings. This research highlights the importance of community engagement in GI planning and demonstrates how integrating hydrological performance with socioeconomic benefits can enhance urban resilience. By aligning with the 4Rs of resilience; robustness, redundancy, resourcefulness, and rapidity, this study provides actionable insights for policymakers and urban planners seeking cost-effective, scalable solutions for flood-prone areas. The findings underscore the value of multifunctional GI controls in not only reducing flood risks but also promoting long-term sustainability and community well-being.