西北地区城市网络结构韧性测度及其优化策略

Evaluation and optimization strategy of resilience of urban network structures in northwest China

【目的】城市网络结构韧性是城市空间组织恢复力与稳定性的重要保障,当前研究多采用单一要素流且聚焦发达地区,而结合多维要素流同时关注欠发达地区网络结构韧性的成果相对较少,因此,本文以欠发达的西北地区为研究对象,并基于多维要素流探究其网络结构韧性,以期弥补相关研究在地域上的留白,并丰富多维要素流视角下网络韧性的实证分析。【方法】以西北地区51个地级行政单元为研究对象,从经济、交通、信息3个视角入手探究2022年西北城市网络的结构特征,定量测度其层级性、匹配性、传输性和集聚性,进而利用计算机仿真模拟研究中断场景下西北城市网络结构韧性,据此提出优化策略。【结果】①西北51个地级行政单元的经济、交通、信息网络总体呈“东密西疏”的分布格局,网络具有“核心-边缘”特点,但3类网络结构存在明显差异。经济网络密度较小、核心节点间的粘性较大,呈现出“以强带弱”与“强强联合”共存的特征、“多组团”格局和“片态化”发展态势;交通网络联系较为紧密,城际联系惯性较强,呈现出“小世界”效应、“纺锤型”格局和“紊态化”发展态势;信息网络具有广覆盖性和强渗透性,呈现出协调性特征、“条带状”格局和“湍态化”发展态势。②3类网络的层级性和匹配性差异较大,传输性和集聚性差异较小。经济网络“马太效应”明显,呈现出核心强同配性和边缘弱异配性特征;交通网络趋于立体化发展,表现出小范围“健壮性”和大面积“脆弱性”;信息网络具有高异配韧性,表现出网络结构扁平化和联系路径多元化特征。③蓄意攻击对网络韧性的破坏力显著高于随机攻击,对比脆弱节点,核心节点遭受打击对网络运转效率具有更大影响。【结论】区域发展不均衡的问题在欠发达地区尤为明显,核心城市“权力”集中但辐射半径较短,位于边缘的城市发展动力不足。3类网络之间的韧性特征同中存异,不同攻击模式下网络韧性具有阶段性变化特征。为促进区域可持续发展,应针对区域特性制定应对政策。

[Objective]The resilience of urban network structures is a crucial guarantee for the recovery and stability of urban spatial organization.Current research predominantly employs individual flows and focuses on developed regions,and there is relatively little research that combines multidimensional factor flows while also focusing on the resilience of network structures in underdeveloped regions.Therefore,this study took the underdeveloped Northwest China as the research object and explored its network structural resilience based on multidimensional factor flow, in order to fill the gap of related research and enrich the empirical analysis of network resilience from the perspective of multidimensional factor flow. [Methods] This study focused on 51 prefecture-level administrative units in Northwest China for the year 2022. It investigated the structural characteristics of urban networks from three perspectives: economic, transportation, and information, quantitatively measured their hierarchy, matching, transmission, and agglomeration,and examined the structural resilience of Northwest China’s urban networks under various disruption scenarios by using the method of computer simulation and proposed optimization strategies from different perspectives. [Results] (1) The economic, transportation, and information networks across the 51 prefecture-level administrative units in Northwest China are generally distributed in a pattern of dense in the east and sparse in the west, showing core-periphery characteristics, but there are significant differences in the structure of the three types of networks. The economic network density is low and the stickiness between the core nodes is large, showing the characteristics of coexistence of “strong assisting weak” and “strong alliances”, with multi-group pattern and fragmented development trend. The traffic network is more closely linked, with stronger inertia in intercity links, showing a “small world” effect, a spindle-shaped pattern, and a turbulent development trend. The information network has wide coverage and strong permeability, showing coordinated characteristics, a strip-like pattern, and a turbulent development trend. (2) The three types of networks differ greatly in terms of hierarchy and matching, and less in terms of transmission and agglomeration. The Matthew effect of the economic network is obvious, characterized by strong homophily at the core and weak heterophily at the periphery;the traffic network tends to experience three-dimensional development, showing local robustness and regional vulnerability;and the information network has highly heterogeneous resilience, showing the characteristics of flattened network structure and diversified connection paths, with a high level of resilience. (3) Deliberate attacks are significantly more damaging to network resilience than random attacks, and a hit on a core node has a greater impact on network operational efficiency than on a vulnerable node. [Conclusion] The problem of uneven regional development is particularly obvious in less developed regions, where the core city has concentrated power but a shorter radius of radiation, and cities on the periphery are not sufficiently motivated to develop. There are both similarities and differences in resilience characteristics between the three types of networks, and network resilience under different attack modes is characterized by phased changes. In order to promote the sustainable development of the region, response policies should be formulated according to regional characteristics.