sustainability Article Spatial Evolution of Urban Expansion in the Beijing–Tianjin–Hebei Coordinated Development Region Zhanzhong Tang 1,2,3,4 , Zengxiang Zhang 1, Lijun Zuo 1,*, Xiao Wang 1 , Xiaoli Zhao 1, Fang Liu 1, Shunguang Hu 1, Ling Yi 1 and Jinyong Xu 1 1 Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China;
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[email protected] (J.X.) 2 University of Chinese Academy of Sciences, Beijing 100049, China 3 College of Resources and Environment, Xingtai University, Xingtai 054001, China 4 Regional Planning Research Centre, Xingtai University, Xingtai 054001, China * Correspondence:
[email protected]; Tel.: +86-10-6488-9202 Abstract: Against the background of coordinated development of the Beijing–Tianjin–Hebei region (BTH), it is of great significance to quantitatively reveal spatiotemporal dynamics of urban expansion for optimizing the layout of urban land across regions. However, the urban expansion characteristics, types and trends, and spatial coevolution (including urban land, GDP, and population) have not been well investigated in the existing research studies. This study presents a new spatial measure that describes the difference of the main trend direction. In addition, we also introduce a new method to classify an urban expansion type based on other scholars. The results show the following: (1) The annual urban expansion area (UEA) in Beijing and Tianjin has been ahead of that in Hebei; the annual urban expansion rate (UER) gradually shifted from the highest in megacities to the highest in counties; the high–high clusters of the UEA presented an evolution from a “seesaw” pattern to Citation: Tang, Z.; Zhang, Z.; Zuo, L.; a “dumbbell” pattern, while that of the UER moved first from Beijing to Tianjin and eventually Wang, X.; Zhao, X.; Liu, F.; Hu, S.; Yi, L.; Xu, J.