Assessment of urban flood resilience and obstacle factors identification: A case study of three major urban agglomerations in China

Urban flooding has emerged as a structural challenge that hinders the resilient transformation of cities in the context of intensifying global climate change and frequent extreme weather events. However, comprehensive and systematic comparative analyses at the urban agglomeration scale are relatively scarce. To address this gap, this study developed a multidimensional evaluation framework (EEISI) that integrates economic, ecological, infrastructural, social, and institutional resilience. Based on the CRITIC-TOPSIS weighted evaluation model and the Coupling Coordination Degree (CCD) model, this study measures urban flood resilience and the interactions among resilience subsystems in China’s three major urban agglomerations. Furthermore, this study employs the Standard Deviational Ellipse (SDE) model to explore their spatial–temporal evolution patterns and identify key constraints to resilience enhancement through an obstacle degree model. Key findings indicate: (1) UFR exhibits phased fluctuations with an upward trend, yet significant developmental disparities persist between core and peripheral cities, with the Pearl River Delta demonstrates systemic advantages through subsystem optimization; (2) Subsystem coordination has gradually improved but remains at a primary coordination level, reflecting imperfect cross-system governance mechanisms; (3) Structural fiscal allocation imbalances and fragmented institutional supply constitute the primary obstacles, manifested in constraints such as governmental governance capacity, municipal maintenance funding, and the adequacy of the social security system; This study enriches and refines the existing research indicator system, providing theoretical references for flood resilience capacity building and the practice of resilient city development in urban agglomerations.