Mapping hierarchical urban boundaries for global urban settlements

International Journal of Applied Earth Observations and Geoinformation

Gang Xu¹  Zhengzi Zhou²  Ting Lan³  Hao Cui⁴  Chengpeng Li⁵  Zhibang Xu⁵  Limin Jiao⁵  Yaolin Liu⁶ 

[1] Centre for Advanced Spatial Analysis (CASA), University College London, London W1T4TJ, UK;Corresponding author at: School of Resource and Environmental Sciences, Wuhan University, Wuhan 430079, China.;Key Laboratory of Geographic Information System, Ministry of Education, Wuhan University, Wuhan 430079, China;Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China;School of Resource and Environmental Sciences, Wuhan University, Wuhan 430079, China;State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079, China;

关键词: Urban mapping;    Urban settlements;    Urban boundary layer;    Urbanization;    Global map;    Hierarchical data;   

DOI  :  

来源: DOAJ

【 摘 要 】

Urban boundary is the spatial basis for urban statistics and urban planning. However, the city definition by which the urban boundary is determined is not comparable among different countries. A globally consistent delimitation of hierarchical urban boundaries (HUBs) is rare but urgently needed. In this research, we proposed a model to consistently identify HUBs according to physical urban entity. The main quantitative basis of our model is the density, size and spatial relationship of the artificial impervious surface. We produced a vector dataset of global HUBs (named GHUB) based on 30-meter resolution remote sensing products. Cross-product comparison shows the effectiveness and advantages of our model. We furtherly, for the first time, investigated and compared the physical form and spatial characteristics of global urban settlements through the same lens supported by GHUB. We have identified 10,242 urban settlements with an area above five square kilometers, 39.18% of them are located within 100 km of the coastline. Urban settlements are not the “reinforced concrete forest” as commonly thought. The global average proportion of open space within urban settlements is 41.51%. The total area of urban open space in the world is 279.47 thousand square kilometers. Notably, we verified the Rank-size rule of urban settlement is universal, meanwhile, the verification results of different urban systems in 47 countries show that the Zipf’s exponent varies from country to country. Our work can help to consistently investigate global urban settlements without being affected by various definitions of cities. The GHUB can not only be applied to various urban studies but also can support global affairs such as the Sustainable Development Goal 11 due to its international comparability.

【 授权许可】

Unknown