Exploring the Spatiotemporal Integration Evolution of the Urban Agglomeration through City Networks

Regional integration is a global trend and an integrated region consists of different cities of different sizes and functions, against which researching their organized structure is an important issue when discussing regional coordinated development. So, we construct the city networks, among which cities and their linkages are regarded as nodes and connections, to explore the spatial characteristics of a region and evaluate the integration level. The Yangtze River Delta Urban Agglomeration (YRDUA) is taken as the study area. For city nodes, this paper first evaluates the cities’ qualities comprehensively based on the multidimensional indicators during the rapid cities’ developmental period from 2005 to 2019. For city linkages, the interactions between different cities are then assessed by the improved gravity model. Then, the city networks consisting of city nodes and their linkages are constructed and analyzed by the social network analysis to deeply understand the orientations and relationships of cities in an integrated region. The results show that the developmental pace of different cities is imbalanced. The overall network of the YRDUA is relatively compact of the city-pair linkages forming the overlapping structure from primary to secondary axes, and different cities have specific functions. However, some small cities do not reach a mutual connection with big cities and face the risk of social resource outflow. In conclusion, attention to the existence of latent hierarchy should be paid to avoid the marginalization of small cities, especially under administrative intervention. The findings can enrich research on cities′ relationship and integration level of the YRDUA, and the specific characteristics of spatial organization paralleling with the leading development of the YRDUA can provide the reference to other regions under the strategy of national regional coordination.