长江中游城市网络结构韧性评估及其优化策略

城市网络结构韧性是国际上区域韧性（regional resilience,也译作区域弹性）研究领域正在兴起的概念,着眼于城市网络结构对区域应对冲击并恢复、保持或改善原有系统特征和关键功能的影响力,对区域空间的健康发展意义重大。以长江中游城市群为研究对象,在构建经济、信息、交通三类联系网络的基础上,借助于Gephi社会网络分析工具,尝试评估城市群城市网络的结构韧性能力及其空间特征。结果表明：长江中游城市群网络具有一定韧性能力,结构韧性的层级性和匹配性差异较大,传输性和集聚性差距不明显;在空间上呈现出总体形态模式差异化、分区形态模式错位化、网络联系特征多样化的特征。进而,对城市群空间结构在总体结构、片区结构和要素流动等方面的优化提出建议。

Evaluation and optimization strategy of city network structural resilience in the middle reaches of Yangtze River

The structural resilience of a city network is a rising concept in the field of regional resilience; it focuses on how structural properties affect a region responding to external shocks, as well as recovering, maintaining, or improving the characteristics and key functions of the original system, which is of great significance to the healthy development of regional space. With the help of the Gephi social network analysis tool, this article takes the urban agglomeration in the middle reaches of the Yangtze River as the example and constructs three kinds of networks of economy, information, and transportation, and attempts to measure the structural resilience of the network and spatial characteristics of urban agglomerations. The results show that the structure of the urban agglomeration in the middle reaches of the Yangtze River has a certain resilience. Specifically, the study includes four distinct dimensions: (1) Hierarchy. Economy and information networks have higher levels of hierarchy, and regional locking is more prominent. (2) Assortativity. The disassortativity of information and transportation networks is evident, and they have heterogeneous and diverse contact paths. The economy network has weak disassortativity, leading to an inhibited structural resilience. (3) Transmission. The average path length of the above three networks is generally long and the diffusion efficiency of the material flow is satisfactory. (4) Clustering. Although the spatial clustering of the three network types is different, the aggregation degree is high and the level is equivalent. In a word, the aggregation effect of the three networks is obvious. From the perspective of spatial structure, the structural resilience presents three characteristics. (1) Disparity of the overall morphological patterns. The economy network mainly presents the structural model of "broken core-heterogeneous nested triangle". The information network mainly presents the structural model of "core triangle-star radiation". The transportation network mainly presents the structural model of "core triangle + heterogeneous star radiation". (2) Dislocation of the classified central cities. Wuhan urban agglomeration shows a unique network structure characteristic, which will be summarized as "a single core + edge cities". The Changsha-Zhuzhou-Xiangtan city group exhibits a local network of the city's balanced trend, the performance of "core group + edge city". The comprehensive level of the Poyang Lake urban agglomeration is low, and is mainly based on the isolated structure model of the "single core" of Nanchang. (3) Diversification of the network connection characteristics. The measure of structural toughness is not dependent on the single index value—it should be combined with hierarchy, match, transmission, and clustering. Furthermore, some suggestions are put forward to optimize the spatial structure of urban agglomeration in the aspects of general structure, area structure, and element flow.