How to achieve coordinated and sustainable development between urban flood resilience and ecosystem services at the urban agglomeration scale.

Urban flood resilience (UFR) and ecosystem services are crucial concepts and methods for mitigating flood risks and boosting the coordinated and sustainable development in urban agglomerations. While most studies assess UFR or ecosystem services from a single perspective, the interaction between the two remains insufficiently explored. Here, an integrated analytical framework was established to examine the relationship between the two. Taking the Yangtze River Delta Urban Agglomeration as a sample region, the research first constructed an assessment index system for evaluating UFR levels. Then four ecosystem services covering water conservation, soil conservation, water purification, and climate regulation, were quantified. Finally, Pearson correlation coefficient, coupling coordination degree (CCD) model, and geo-detector model were comprehensively utilized to investigate the relationship and underlying diving factors. The findings reveal significant positive correlations between UFR and ecosystem services, with particularly strong correlations observed between each ecosystem service and natural resilience. Spatial heterogeneities in CCDs between UFR and ecosystem services were prominent, with southern cities demonstrating higher coordination levels than northern cities. Moreover, the CCDs exhibited an improvement trend over the research period. Factor analysis identified both ecological environmental conditions and human socio-economic activities as significant determinants of these patterns, with technological investment emerging as the dominant driver in interactive detection. Accordingly, differentiated spatial governance strategies that leverage technological innovation to balance ecological conservation with economic growth, such as cultivating eco-economic industries, delineating ecologically vulnerable areas, and developing localized ecological engineering methods, were proposed to facilitate the coordinated and sustainable urban development. The methodological framework and management insights proposed can be also applicable to other regions.