Coordination Dynamics between Population Change and Built-Up Land Expansion in Mainland China during 2000-2020

Coordination between population growth and built-up land expansion is a major challenge for regional sustainable development. This paper proposed a dual indicator approach, which consists of the ratio of the built-up land expansion rate to population growth rate (HLEC) and the change rate of the built-up area per capita (BPR), and explored the dynamics of the human-land coordination relationship in mainland China using gridded population data and remotely sensed land-cover data. Four gridded population datasets (GPWv4, LandScan, WorldPop, and China gridded population datasets) were evaluated using county-level census data from 2000 and 2010, which showed that WorldPop had the highest correlation with the census data, CASpop had the smallest RMSE, and LandScan had the worst performance. The population of mainland China continued to rise from 2000 to 2020, but the average annual growth rate declined significantly. The built-up land expanded across China, with northwestern China experiencing the fastest growth and the eastern coastal regions experiencing a slower rate of expansion. The HLEC was 5.83, and the BPR increased by approximately 50%, indicating that the rate of population growth is lagging behind the rate of built-up land expansion in most regions, with the exception of Beijing, Tianjin, and Shanghai. Topographical and socio-economic factors have nonlinear effects on the coordination state of the human-land relationship. This approach can be used in areas with no change in population and can better characterize the human-land relationship and its coordination dynamics.