Understanding population movement and the evolution of urban spatial patterns: An empirical study on social network fusion data

Population movement has become one of the main vehicles for information transfer, factor flow, and resource allocation between cities. It is also considered as the main way to form the structure of regional organizational networks. This study analyzes the population movement channels, spatial patterns, and evolutionary mechanisms of the Yangtze River Delta with fused data (i.e., long-scale population migration and short-scale 48-hour population movement.), The results show that the population movement presents multipolar and decentralized evolutionary characteristics, and the population movement network in the Yangtze River Delta region has entered a complex network stage, showing a spider web-like convergent nested structure in terms of the population movement at a long time scale (2009–2017). The gravity model reveals that cost factors such as Spatio-temporal distance of population migration and boundary effects between urban nodes are complementary to the urban environment constituted by economic dynamics and social environment. Cultural exchange and regional integration are also quietly removing the cost-benefit constraints of population migration, thereby changing the mediating and diluting effects of the region. (1) Shanghai has not shown the great advantage of being the first city in the region; strong population movement mostly occurs within the provinces, with less cross-provincial movement; (2) population movement is more likely to occur between large and small cities, rather than between large or small cities, two cities with similar industrial structures are more likely to attract and connect with each other, (3) the institutional adhesion of administrative boundaries may have been diluted by the substitution effect of high housing prices, and (4) the stability of land property rights due to driving the regional integration process. This paper extends the vision and methodological practice of the gravity model to examine the network influence mechanism and analyze the mechanism of daily inter-city movements in two dimensions to provide policy insights for understanding the integration process in the Yangtze River Delta and the optimization strategy of regional metropolitan area integration.