Urban Expansion Trajectories in China’s 36 Major Cities

As the largest developing country, China has experienced dramatic urban sprawl since the "reform and opening-up" policy started at the end of the 1970s. To find out the laws of the past urbanization in China is of great importance for promoting a sustainable development in the future. In this paper, we monitor three decades of urban expansion in China’s 36 major cities, based on the spectral mixture analysis of remotely sensed satellite images. The results demonstrate that these major cities have expanded by 5.85 times from 1986 to 2015, with 15.51km2 average expansion area per city per year. We find the urban expansion trajectories show three different modes, i.e., exponential, linear and s-shaped, which are closely related to the city development level. In addition, there is an interesting common tendency of the impervious surface first increasing and then decreasing in the old city zones.