"Hierarchy-network" structure of cities in Northeast China based on Baidu migration data
Abstract
Exploring the pattern of population flow will help reveal the law of urban systems and connections between cities. Based on Baidu migration data from March 9 to April 28, 2021, the “ hierarchical-network” structure of cities in Northeast China was studied from the perspective of population migration by using fractal theory, urban scaling law, social network analysis and Self-organizing maps method. The results are as follows: 1) The primacy ratio of urban system based on migration scale is low, and the distribution of high-order cities is concentrated. The scale fractal characteristics of migration routes are concentrated in the high-order and loose in the low order. The relationship between migration scale and urban population is super linear, and Shenyang, Changchun and Harbin are at the first level. 2) In the network based on migration scale, Shenyang, Changchun, Siping, Tieling and Harbin are at the core of the network, while Harbin, Shenyang, Changchun and Dalian are the key hub cities of the network. 3) There are obvious differences in the structure of the network between the directed migration flow and the net migration flow. The migration scale of Shenyang and Changchun is larger, while the net migration volume of Harbin is higher. 4) There is a spatial agglomeration phenomenon of migration behaviors, and the core regions are in the east, central and southern regions. The migration behaviors within the region are mainly intra-provincial migration, which can be divided into four subgroups according to migration preferences. 5) The internal connection of the Harbin-Changchun metropolitan area is weak, and the Central-and-Southern Liaoning Area has shown a trend of agglomeration development. 6) Cities in northeast China can be divided into six types according to their migration scale and network location, such as high-migration core city and high-migration semi-marginal city, which can better reveal the inner characteristics of cities than a single scale hierarchy division.
