Cross-scale effects and driving mechanisms of spatial structure and functional coupling in coastal city leisure blocks: A case study of the Jiaodong urban agglomeration

As sensitive zones where urban functions and coastal ecosystems intersect, the coupling mismatch between the spatial structure and functions of coastal recreational blocks has become a bottleneck to high-quality urban development; yet, their cross-scale response mechanisms remain underexplored in academia. This study constructs a three-dimensional “scalar nesting − indicator iteration − factor deconstruction” framework, examining 127 coastal city leisure blocks in the Jiaodong urban agglomeration. Utilizing coupling coordination degree and GeoDetector, it reveals cross-scale coupling effects between spatial structure and functionality alongside their driving mechanisms. Key findings include: (1) Block-scale spaces exhibit “morphological regularity yet accessibility stratification,” while urban-scale networks demonstrate “loose connectivity but organized layout”; (2) Cross-scale coupling manifests “structure-function mismatches,” with urban functionality generally outpacing block-scale spatial capacity; (3) Core drivers comprise urban terrain ruggedness, coastline length, and demographic-economic factors, where coastal parameters amplify local terrain influences by 5.3 times through “geographical transducer” effects. The study provides quantitative foundations for optimizing coastal urban leisure space planning.