Acta Geographica Sinica ›› 2020, Vol. 75 ›› Issue (12): 2730-2743.doi: 10.11821/dlxb202012013

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Developing an urban sprawl index for China's mega-cities

YUE Wenze1,2(), WU Tong1, LIU Xue1, ZHANG Linlin3(), WU Cifang1,2, YE Yanmei1,2, ZHENG Guozhou4   

  1. 1. Department of Land Management, Zhejiang University, Hangzhou, 310058, China
    2. Laboratory for Saving and Intensive Utilization of Urban and Rural Construction Land by Ministry of Natural Resources, Beijing 100812, China
    3. Department of Urban-rural Planning, Zhejiang Gongshang University, Hangzhou 310018, China
    4. College of Computer Science and Technology, Zhejiang University, Hangzhou 310007, China
  • Received:2019-08-05 Revised:2020-06-30 Online:2020-12-25 Published:2021-02-25
  • Contact: ZHANG Linlin E-mail:wzyue@zju.edu.cn;zhanglinlin@zju.edu.cn
  • Supported by:
    National Natural Science Foundation of China(41871169);National Natural Science Foundation of China(41671533);Zhejiang Provincial Natural Science Foundation(LQ20D010004)

Abstract:

Urban sprawl has become a global phenomenon. There is, however, no consensus on the connotation of urban sprawl, which still remains subjective to controversy and ambiguity. In this paper, urban sprawl was defined as an inefficient, low-density and disordered mode of urban space development. The definition includes three of the most recognized characteristics of urban sprawl summarized from previous studies. Characterized by the features mentioned above, urban sprawl has been recognized as an important challenge to the high-quality development of cities in China. Therefore, to build an urban sprawl index that can reflect the quality of urbanization is of significance to macro-micro regulation of urban sprawl. Multiple metrics representing the core characteristics of urban sprawl were selected as measuring indexes, based on satellite images and socio-economic statistical data. Furthermore, in order to make the results more objective and comparable, the method of principal component analysis was applied to calculate the comprehensive sprawl index. Finally, 106 of China's mega-cities were chosen as cases, and the degree of urban sprawl of each city was measured for the year 2014. As shown from the results, the first principal component mainly reflected the dimension of economic efficiency, contributing 41.30% to the comprehensive sprawl index. The second principal component mainly represented the dimension of population density, followed by the third principal component that described morphological dimension. It is noteworthy that, because the short board effect of economic efficiency dimension was significant, many less-developed cities were ranked to a high sprawling level. In addition, the spatial distribution of different dimensions of urban sprawl index were distinct. Population density and land use efficiency were generally consistent with each other, while the distributing law of city form showed distinguishing features. Last but not least, the comprehensive sprawl index had a certain negative correlation with city scale, which reminds us to pay more attention to urban sprawl in medium-sized cities in the future.

Key words: urban sprawl index, measurement, spatial morphology, density, efficiency