Exploring Spatial Connection Networks in Metropolitan Areas Led by Megacities: A Case Study of the Shanghai Metropolitan Area

The synergistic development of metropolitan areas led by megacities is considered a driving force in achieving regional coordination and the high-quality development of urban agglomerations. Extant studies have often neglected the spatial structure of metropolitan areas under the guidance of megacities. This study sought to explore the radiation effect of central cities, the development capacity of metropolitan subcentral cities, and the intermediary role of metropolitan hub cities in the metropolitan area. Based on the modified gravitational model and social network analysis, we constructed a spatial connection network of the Shanghai metropolitan area with districts and counties as the basic research units and analyzed the characteristics from two perspectives: network hierarchy and network structure. Our results indicated the following: (1) The connection strength of the metropolitan area decreased from the center of the network to the periphery. (2) The polycentric pattern was gradually forming, but a significant gap remained between the radiation range and capacity of central and subcentral cities. (3) The clustering phenomenon in the metropolitan area was significant, and the degrees of internal connection and external radiation ability of each subgroup differed. (4) The core-edge structure as obvious, but its intermediary role in the network was relatively weak. Our findings revealed the spatial relationship pattern of metropolitan areas led by megacities and have implications for formulating scientific policies to promote the coordinated spatial development of metropolitan areas and the high-quality development of urban agglomerations.