Application of a time-dependent performance-based resilience metric to establish the potential of coupled green-grey infrastructure in urban flood management

Urban flood resilience (UFR) and related facilities for its improvement, such as green and grey infrastructures and their coupled approach have attracted global stakeholders' attention due to successive flooding events worldwide. However, research on quantifying the potential of such measures in UFR enhancement based on system performance and surface inundation is lacking. How these measures act in different stages of system performance reflecting the state of urban functionality has not been addressed. This study investigated the potential of green and grey infrastructures and their coupled approach in enhancing UFR using a time-dependent performance-based metric in the Minzhi region, Shenzhen City. The metric considers water velocity and physical mechanisms of residents and vehicles keeping their stability. Suggestions for UFR enhancement were proposed. The results suggest that the coupled approach performs best. The adopted measures exhibit different impacts during different phases of system performance. Exploring the implementation methods of individual measures, discussing the synergistic integration of individual measures, and implementing targeted approaches to further enhance UFR in vulnerable regions are important. The coupled approach should be prioritized if the grey one is effective in UFR enhancement and preference should be given to the green infrastructure when deciding between green and grey infrastructures.