基于可达性的中国城市群空间范围识别研究

作为指示区域间相互作用的重要度量,空间可达性是刻画城市及其腹地间空间关联格局的表达方式,已经成为城市与区域系统发挥集聚与扩散功能的显著表征。考虑空间异质性,本文综合集成自然地表要素和陆地交通网络,构建更为逼近真实场景的可达性分析方法,精确刻画中国城市空间可达性宏观格局,在此基础上,提取中国城市群空间范围。从空间可达性视角,都市区、都市圈、城市区域和城市群等不同尺度城市与区域系统格局凸显,多尺度城市功能地域系统逐步浮现。从空间连续性、关联性和紧凑性出发,基于城市等时圈,以省会城市或区域中心城市为抓手,最终共提取出15个城市群结构。与国家“十三五”规划纲要提出的19个城市群相比,本文共识别出15个城市群,既存在共性,也存在明显的差别。总体上,本文识别出的城市群空间范围要普遍小于国家或各级政府批复的城市群。科学认识“自然生长的”和“规划引导的”城市群之间的差别,对于更好地发挥城市群功能地域作用、推进城市群可持续发展具有重要价值。

Identifying the spatial scope of megaregions in China from the perspective of accessibility

As a fundamental measurement to depict regional interaction, spatial accessibility has been a marked characteristic of the function of agglomeration and diffusion within urban and regional systems. Considering the spatial heterogeneity of land surface, we in this study developed a more comprehensive analytical method and constructed an accessibility analytical algorithm that more closely approximates the real situation, by integrating both land surface conditions and transport networks, to more reliably determine the overall patterns of accessibility of cities in China at the prefecture level and above. This approach provides a basic guarantee for determining the spatial scope of megaregions in China. The results show that the multi-scalar urban functional regions in China have been recognized at both urban and regional levels from the perspective of spatial accessibility. Utilizing the analyses of urban isochrones, we further identified 15 potential megaregions from the perspectives of spatial continuity, correlation, and compactness. They are the megaregions of Yangtze River Delta, Pearl River Delta, Beijing-Tianjin-Hebei, Chengdu-Chongqing, Shandong Peninsula, Central China Plains, Western Taiwan Straits, Central Shaanxi, Changsha-Zhuzhou-Xiangtan, Central and Western Liaoning, Wuhan, Central Anhui, Central Shanxi, Northern Guangxi and Northern Ningxia. Compared with the 19 megaregions proposed by the Outline of the National “Thirteenth Five-Year Plan” (2016-2020), the 15 megaregions identified in this paper have both commonalities and obvious differences. On the whole, the spatial scopes of the megaregions identified in this paper are generally smaller than those approved by the central government or provincial governments. Therefore, to have a scientific understanding of the differences between “naturally-grown” and “administrative-planned” megaregions is of great value for better playing the role of megaregions and promoting sustainable development of megaregions in China.