The rich-club phenomenon of China's population flow network during the country's spring festival

This paper provides a structural analysis of the rich-club phenomenon of China's population flow network (PFN) during the country's 2015 Spring Festival. We define the PFN as the weighted network where nodes are cities and links account for the population flows. The global weighted rich-club coefficient, local weighted rich-club coefficient, assortativity and community detection are used to quantitatively characterize the rich-club tendency of the PFN. Results of global rich-club coefficient uncover the existence of a significant rich-club phenomenon in the PFN. Six cities including Beijing, Shanghai, Suzhou, Guangzhou, Shenzhen and Dongguan are identified as rich-club members. And, the value of assortativity (−0.216) shows that the network is a dissortative network. We therefore conclude that the network has typical oligarchy characteristics. Subsequently, our local rich-club coefficient analysis reveals that most (77.66%) of the nodes in the network prefer to connect to rich nodes rather than non-rich nodes. Community detection demonstrates that the network presents obvious geographical agglomeration characteristics and rich-club cities also play a dominant local role in their own “responsible” communities. These findings suggest that China's PFN during the country's Spring Festival is a specific kind of hub-and-spoke network where the rich-club cities are hubs and their interconnections form the backbones. We also identify some specific problems (e.g., the community in southwest China lacks its own rich-club cities resulting in its less integration into the national transportation and migration network). Being the first to discuss rich-club issues of population flow networks in China, findings of this research may be useful for a wide spectrum of applications ranging from population migration, urbanization and traffic infrastructure planning in China.