Research On The Evaluation Of Urban Agglomeration Resilience Of The Three Urban Agglomerations In The Yangtze River Economic Belt

In the process of urban development,cities are often impacted and disturbed by changes in the external environment.The resistance,adaptability and resilience of cities in dealing with such shocks and disturbances are called "urban resilience".In recent years,the evaluation of urban resilience has become a hot topic in urban geography and urban planning.However,the assessment of urban resilience at home and abroad mainly focuses on the resilience level of urban individuals,and seldom considers the resilience of urban agglomerations.Urban agglomeration,as an urban network complex with close connection and compact spatial organization,the risks that need to be dealt with are becoming increasingly complex.Whether individual cities within the urban agglomeration are resistant to external shocks and whether the urban agglomeration network as a whole is anti-interference will affect the resilience of the urban agglomeration.After experiencing rapid urbanization,China is facing tremendous pressure in population,resources and environment,which puts forward higher requirements for urban agglomeration resilience.In the new stage of promoting new urbanization in an all-round way,the state regards urban agglomeration as the main spatial form of new urbanization.Building a resilient urban agglomeration is in line with the concept of "intensive,efficient and sustainable" of new urbanization,and is an important direction for the future development of urban agglomerations.Therefore,a comparative study on the resilience of the three major urban agglomerations can explain and reveal urban agglomeration resilience from various aspects.The Yangtze River Economic Belt connects the urban agglomeration of Yangtze River Delta,the urban agglomeration in the middle reaches of the Yangtze River and the Chengyu urban agglomeration in series.Its size,hierarchical structure and spatial form are significantly different,representing different types,different stages of development and different maturity of urban agglomerations.At the same time,the three major urban agglomerations are located in the eastern,central and western parts of the Yangtze River Economic Belt,in the same basin,which is an important carrier to promote the integrated development of the Yangtze River Economic Belt.Studying the resilience characteristics of the three major urban agglomerations is of great significance in optimizing the spatial structure of the urban agglomerations,promoting coordinated regional development and promoting the high-quality development of the Yangtze River economic belt.Based on the systematic analysis of the resilience theories of cities and urban agglomerations,this paper holds that the resilience of individual cities within urban agglomerations is the comprehensive strength of cities in preventing and resisting external shocks.The resilience of the urban agglomeration network structure is the ability of the urban agglomeration network to restore its original function as soon as possible when it responds to and adapts to external shocks.The comprehensive resilience of urban agglomeration is a comprehensive consideration of the whole urban agglomeration network and individual cities.Its connotation includes the comprehensive resilience level of individual cities within the urban agglomeration and the structural resilience level of the whole urban agglomeration network in terms of hierarchy,matching,agglomeration and transmission.Based on the above considerations,this paper takes the three major urban agglomerations in the Yangtze River Economic Belt as the research object,and conducts an empirical study in the context of "individual city resilience → urban agglomeration network structure resilience → urban agglomeration comprehensive resilience".Firstly,the index system is constructed from four dimensions of economic resilience,social resilience,engineering resilience and ecological resilience to compare the resilience level of individual cities in the three major urban agglomerations;Then,based on the multi-source data such as socio-economic statistics,big data of passenger flights and Baidu search index,the economic,transportation and information contact networks of the three major urban agglomerations are constructed respectively.By using Arc GIS spatial analysis tool and Gephi social network analysis tool,the structural resilience of the economic,transportation and information networks of the three major urban agglomerations are compared and analyzed from the four dimensions of hierarchy,matching,agglomeration and transmission of the network respectively.Finally,from the perspective of the combination of individual cities and urban agglomeration network as a whole,the paper constructs an integrated network of urban agglomerations,makes a comparative study of the comprehensive resilience of the three major urban agglomerations,and puts forward relevant suggestions to enhance urban agglomeration resilience.The main conclusions are as follows:(1)Based on the comparative analysis of resilience levels of individual cities in the three major urban agglomerations,it is found that:(1)The urban agglomeration of Yangtze River Delta is dominated by cities with higher and high resilience levels.The urban agglomeration in the middle Reaches of the Yangtze River and the Chengyu urban agglomeration are still dominated by cities with medium and low resilience levels.There are only 2 cities in the Chengyu urban agglomeration that are located with high resilience.The urban resilience level in the Chengyu urban agglomeration is generally low.(2)From the hierarchical structure of urban resilience of individual cities,according to the comprehensive resilience index from high to low,the urban agglomeration of Yangtze River Delta has a "pyramid" structure,the urban agglomeration in the middle reaches of the Yangtze River has a spindle-shaped structure,and the Chengyu urban agglomeration forms a discrete structure of high resilience cities and medium and low resilience cities.(3)From the contribution rate of urban resilience components,the contribution of economic,social,engineering and ecological factors to urban comprehensive resilience in the urban agglomeration of Yangtze River Delta is relatively balanced,while the contribution of urban engineering resilience in the urban agglomeration in the middle reaches of the Yangtze River is relatively low,while the contribution of urban economic resilience and engineering resilience in Chengyu urban agglomeration is insufficient.(4)From the perspective of spatial distribution,the urban resilience of the central cities in the urban agglomeration of Yangtze River Delta is higher than that of the north and south wings in the urban agglomeration.Cities located at the border of the urban agglomeration of Yangtze River Delta and the urban agglomeration in the middle reaches of the Yangtze River,such as Anqing and Chizhou,have low resilience.In the urban agglomeration in the middle reaches of the Yangtze River,there are high resilience areas centered on Wuhan,Changsha,and Nanchang.The resilience of cities around Wuhan is generally "black under the lights".Within the Chengyu urban agglomeration,there are areas with high resilience centered on Chengdu and Chongqing.Eight cities,including Dazhou and Guang’an,located in the Sichuan-Chongqing junction area,have low resilience levels and appear "central collapse".(2)Based on the comparative analysis of the network structure resilience of the three major urban agglomerations,it is found that:(1)From the perspective of economic network structure resilience,the network of the urban agglomeration in the middle reaches of the Yangtze River is a "low-level,high-concentration,strong-transmission" heterogeneous network with high network structure resilience;The network of the urban agglomeration of Yangtze River Delta has the characteristics of "low level,high concentration and strong transmission",but the network does not have the heterogeneity,the contact path is relatively solidified,and the network structure is not flexible enough;Although the network of Chengyu urban agglomeration has the characteristics of "high distribution and high concentration",the network has high hierarchy and weak transmission,and the phenomenon of "polarization" is obvious,which is not conducive to the diffusion of innovative elements in the urban agglomeration.Therefore,the network structure resilience of Chengyu urban agglomeration is low.(2)From the perspective of transportation network structure resilience,the network of the urban agglomeration of Yangtze River Delta has the characteristics of "low level,high distribution and high concentration",but the low transmission of the network has a certain impact on the overall network structure resilience;Although the network of the urban agglomeration in the middle reaches of the Yangtze River has a low hierarchy and a balanced spatial structure,it is insufficient in terms of heterogeneity,agglomeration and transmission,and the network structure resilience is low.The network of Chengyu urban agglomeration appears high hierarchy,low agglomeration and weak transmission.Although it is a heterogeneous network,the network structure is also less resilient.(3)From the perspective of information network structure resilience,the network of the urban agglomeration of Yangtze River Delta is a "low-level,high-concentration,strong transmission" heterogeneous network with high network structure resilience;The network of the urban agglomeration in the middle reaches of the Yangtze River is of "high concentration and strong transmission" type,but the degree of heterogeneity is low and the network hierarchy is high.Therefore,the phenomenon of "regional lock-in" caused by high network hierarchy should be warned.The network of Chengdu-Chongqing urban agglomeration is a highly heterogeneous network,but the network appears high hierarchy,low agglomeration and weak transmission,which indicates that different levels of cities are not closely connected and the interaction and communication between urban nodes are weak,so the network structure resilience is low.(3)Based on the comparative analysis of the comprehensive resilience of the three major urban agglomerations,it is found that:(1)From the perspective of the comprehensive resilience level of individual cities,the urban agglomeration of Yangtze River Delta,the urban agglomeration in middle reaches of the Yangtze River and Chengyu urban agglomeration account for 31%,10% and 13%,respectively,and the urban agglomeration of Yangtze River Delta has an absolute advantage.(2)From the comprehensive connection network structure resilience of urban agglomeration,the comprehensive connection network of the urban agglomeration of Yangtze River Delta has obvious advantages in hierarchy and matching,the core cities(groups)of urban agglomeration are relatively stable,and the nodes have strong radiation ability and intermediary function;The comprehensive connection network of the urban agglomeration in the middle reaches of the Yangtze River has strong agglomeration and transmission,and the radiation function and intermediary function of nodes are highly complementary,but the phenomenon of "agglomeration" is obvious in the core group of urban agglomerations,and there are scattered connection "weak areas" in Jiangxi Province;The comprehensive connection network of Chengyu urban agglomeration is at a disadvantage in hierarchy,agglomeration and transmission.The interaction between the core cities and the marginal cities in the urban agglomeration is weak,and there is a connection "fault" between the cities located at the junction of Sichuan and Chongqing in the urban agglomeration,which is weak in resisting external shocks.(3)On the basis of considering the urban resilience of individual cities and the network structure resilience of urban agglomeration,it can be concluded that among the three major urban agglomerations in the Yangtze River Economic Belt,the urban agglomeration of Yangtze River Delta has the highest resilience,followed by the urban agglomeration in middle reaches of the Yangtze River,and the Chengyu urban agglomeration has the lowest resilience.It should be noted that the resilience evaluation of urban agglomeration has the characteristics of multi-scale and multi-dimension,which does not depend on the evaluation of urban resilience of individual city level.It should be comprehensively evaluated from the local and global level in combination with the overall network structure resilience of urban agglomeration.