耦合网络视角下长三角地区紧凑性的演化特征

Evolution characteristics of compactness in the Yangtze River Delta from the perspective of coupled network

区域紧凑作为紧凑城市理念在更大空间尺度的扩展,指通过城市间有效的相互作用,实现区域一体化发展的地理空间模式。论文以长三角地区为实证对象,基于高铁和城际大巴2种交通出行方式构建区域耦合网络,选取最短出行时间和出行路径评估城市间作用关系的紧凑程度,从全局网络复杂性、核心—边缘结构演化、局部模体结构等层面系统考察长三角地区紧凑性的演化特征。研究发现,长三角地区城市紧凑性在全局层面存在明显的分异特征,随着时间推移,紧凑性分布的不均衡现象逐步突出,空间上的集聚特征趋于显著;局部层面上,紧凑性处于从集聚向均衡的成长阶段,稳定状态下易形成低成本的局部高聚类特征,就城市个体而言,由局部结构涌现的角色类别表现出多样性选择机制。与已有研究相比,论文将紧凑性与出行网络有机衔接,从关系视角为区域紧凑性探索提供了有益尝试。

Regional compactness refers to the urban form of synergistic integration through effective interactions.In essence,it is the reallocation process of factors of production,affected comprehensively by many factors,such as spatial-temporal distance,economic scale,market competition,and policy cooperation.The Yangtze River Delta,one of the regions with the highest level of urbanization in China,has produced many practical problems that affected the coordinated development of the region towards the goal of integration and high quality development.Regional compactness is an expansion of the compact city concept in a larger space,which is considered a better geospatial model to achieve regional integration.Therefore,analyzing the evolution characteristics of compactness of the Yangtze River Delta is helpful for identifying the real stage of the Yangtze River Delta's integrated development and the key pathways of regional compactness construction and governance.This study evaluated the relationship of cities by variables of spatial-temporal distance.In the Yangtze River Delta region,intercity traffic characterizes multi-modal transportation,forming a coupled nested network composed of high-speed railways and highways.This study evaluated city compactness by the shortest travel time and travel path provided by the coupled network and constructed a compact network map.Furthermore,from the macro to the micro scales,it analyzed the spatial distribution and evolution of compactness characteristics from four aspects:The global spatial distribution,structure,the local node organization and location.The study found that the urban compactness of the Yangtze River Delta has obvious global differentiation characteristics.As time goes on,its uneven compactness distribution gradually became obvious,and its spatial agglomeration tends to be significant.At the local scale,city compactness is in the transitional period from agglomeration to equilibrium,and it tends to have the local high-clustering features at low cost in a stable state.With regard to the cities themselves,the role categories emerging from the local structure show a diversified selection mechanism.