Urban expansion modes of major cities in China in the past four decades

摘要

Urban lands of Chinese cities tend to expand in an unreasonable way, which has been a critical problem for China due to its insufficient land resources. As the important carrier loading active social economic activities and dense population, municipalities and provincial capitals are in an important strategic position in the China. In this study, 4 municipalities and 27 provincial capitals are selected as the study objects, and Urban Expansion Type index (UET, hereafter) is employed to quantitatively analyze the spatial-temporal characteristics of the urban expansion mode in these 31 sample cities. Results indicate that (1) in the past four decades, edge-expansion was the primary urban expansion mode in municipalities and provincial capitals, and infilling and leapfrog modes were the secondary and the third modes, they had contribution rates of 73.16%, 24.00% and 2.84 to urban expansion, respectively. (2) 56.86%, 42.69% and 0.45% patches of increased urban lands appeared in edge-expansion, infilling and leapfrog modes, respectively. (3) In six periods, increased urban lands in edge-expansion mode increased dramatically first and then decreased gradually, while presenting a dramatically increasing trend and fluctuated change trend in infilling mode and leapfrog mode, respectively. (4)The area and number of patches converted from non-urban lands to urban lands in three modes all had some close correlation, especially the infilling mode.