Research On The Evolution And Mechanism Of The Spatial Structure Of Urban Agglomerations In The Yangtze River Delta From The Perspective Of Coordination

Urbanization and urban agglomeration are important phenomena in the development of human society.The process of urbanization promotes the agglomeration of population,land,economy and other factors.Urban agglomeration is the main form of urbanization when it reaches a certain level.The interaction between them promotes the colorful and unprecedented spatial changes in more than half a century.At present,Chinese urbanization is transforming from focusing on "quantity growth and scale expansion" to focusing on "quality improvement,efficiency improvement and function improvement".Urban agglomeration is gradually becoming a new carrier to promote regional integration and urbanization development in China.Urban agglomeration is urban spatial organization form in the advanced stage of urbanization.Therefore,it is urgent to explain the logical relationship between the development of urbanization and the formation of urban agglomeration.that is,to re understand the spatial structure of urban agglomeration from the perspective of the coordination of the elements of urbanization,to provide practical reference for optimizing the spatial structure of urban agglomeration and realizing the development of regional integration,and to provide a new theoretical paradigm for the formation of the theory of urban agglomeration with Chinese characteristic.Chinese urbanization has entered the era of urban agglomeration.The government is actively promoting the development strategy of urban agglomeration,taking urban agglomeration as the carrier to participate in international competition and cooperation,support national economic growth,and promote regional coordinated development.The Yangtze River Delta is one of the regions with the most active economic development,the highest degree of openness and the strongest ability of innovation in China.On the basis of the State's adoption of the Yangtze River Delta Urban Agglomeration Development Plan in 2016,The Outline of Development Planning of Yangtze River Delta Regional Integration was adopted in 2019,which aims to strengthen regional coordination capabilities and promote high-quality development of the Yangtze River Delta urban agglomeration.Taking the Yangtze River Delta Urban Agglomeration as an example,based on the combing the historical process of urbanization and the evolution of regional spatial organizations and considering the theory of system theory,synergy,and unbalanced development,this paper selects three core indicators of population,land,and economic urbanization and innovatively proposes the research paradigm of “coordination level measurement? coordination relationship analysis ? spatial structure identification ? evolution mechanism discovery”,explores the spatial structure of urban agglomerations from a coordination perspective by using mathematical statistics,GIS spatial analysis,social network analysis,and spatial measurement.The research content of this paper mainly includes four aspects.The measurement of urbanization coordination level in the Yangtze River Delta.With the remarkable improvement of population,land and economic urbanization level in the region,the evolution of the overall and the coupling coordination of population-land urbanization,land-economy urbanization and population-economy urbanization degree shows a steady convergence phenomenon.On the regional scale,there are some differences in the coordination level of urbanization among the three provinces and cities of Shanghai,Jiangsu,Zhejiang and Anhui,but the differences are gradually weakening and the balance is increasing.On the city scale,the high-level coordination zone has gradually developed along the Shanghai-Nanjing He and Shanghai-Hangzhou-Ningbo trunk routes,and the provincial,city,and economic center cities such as Shanghai,Suzhou,Nanjing,Hangzhou,Hefei,and Ningbo have gradually improved their coordination types.The cities with low coordination levels are mostly prefecture-level cities in northern Anhui and southern Zhejiang.Furthermore,from the perspective of spatial relationship,the geometric center of coordination of urbanization over the years is relatively stable,close to the regional geometric center(located in Lishui District,Nanjing);the coordination level pattern of urbanization has little change in the northwest southeast direction,and relatively high degree of dispersion in the Northeast southwest direction.The spatial-temporal pattern of urbanization coordination level in the Yangtze River Delta.From the perspective of global spatial correlation,the "overall" coordination degree in the Yangtze River Delta has significant positive spatial autocorrelation.The high value clusters are mainly distributed in the core areas of the economically developed Yangtze River Delta city clusters such as southern Jiangsu,Northern Zhejiang and Shanghai,while the low value clusters are mainly distributed in the peripheral areas of the economically underdeveloped Yangtze River Delta such as northern Anhui,Southern Anhui and southern Zhejiang;the degree of spatial agglomeration characteristics of the coupling coordination of population-land urbanization,land-economy urbanization and population-economy urbanization have similar characteristics,and they all have a distribution pattern of high in the south,low in the north,and low in the east.From the perspective of local spatial correlation,the characteristics of high-high agglomeration and low-low agglomeration are the most significant in the urbanization coordination of Yangtze River Delta.The high-high agglomeration continues to expand along the Yangtze River from Nanjing to Shanghai,while the low-low agglomeration has been distributed in the edge of Yangtze River Delta.In terms of spatial form,with the continuous expansion of the scope of spatial correlation of urbanization coordination,basically forming a spatial pattern of "one pole alone,triangle core,peripheral low-level".In terms of spatial change,the spatial pattern of urbanization coordination remains stable,and the overall coupling coordination degree has obvious path dependence and space locking characteristics.The evolution of the spatial structure of the Yangtze River Delta urban agglomeration from the perspective of coordination.With the expansion of the spatial scope of the Yangtze River Delta urban agglomeration from 15 + 1 to 26 cities,the regional difference of the coordination level of urbanization also increases,and the spatial distribution pattern of the high coordination cities still shows a Z-shaped distribution with Shanghai as the core,and the low coordination cities were stably distributed in Anhui Province,which is in the expanded area of the urban agglomeration.According to the urbanization coordination relationship,the Yangtze River Delta urban agglomeration is divided into two levels of cohesive subgroups.The spatial structure of the four subgroups on the second level is relatively stable;the connection density and weighted centrality of the eight subgroups on the third level follow urbanization.As the correlation level of coordination level increases,the spatial structure of the subgroups changes significantly,and the polarization effect in Shanghai is prominent,while the marginalization trend of the Yancheng subgroup,Yangtai subgroup,and Tongling-Anqing-Chizhou subgroup is obvious.The coordination structure of theurban agglomeration was identified from two dimensions of space and time.The Yangtze River Delta Urban Agglomeration has transformed from the "circle layer" structure centered on the provincial capital cities under the influence of spatial distance into the structure of "coreperiphery" under the influence of temporal distance.The evolution mechanism and optimization suggestions of spatial structure of urban agglomeration in the Yangtze River Delta.Starting from the internal relationship,external dvring force and the space-time interaction process of the coordinated development of urbanization,this paper analyzes the evolution mechanism of spatial structure of urban agglomeration in the Yangtze River Delta.In terms of internal relations,population,land,and economic urbanization have different effects on the evolution of the urbanization coordination level of the Yangtze River Delta urban agglomeration.When the level of urbanization coordination is low,population urbanization has a greater degree of impact.The influence of the improvement of the level of urban coordination has gradually increased,and economic urbanization,characterized by changes in the industrial structure,has played a stable role in promoting the degree of urbanization coordination.In terms of external dynamics,the urbanization coordination relationship itself has a significant spatial spillover effect,and the total external dynamic factor effect that affects the level of urbanization coordination in the Yangtze River Delta is from economic development level in order from high to small> government macro-control> location traffic conditions> technology Development level> population agglomeration effect.Based on the analysis of the internal mechanism and external influence factors,four suggestions for optimizing the spatial structure of the Yangtze River Delta urban agglomeration are put forward,and the comparative advantages of Jiangsu,Zhejiang,and Anhui with lower levels of urbanization will be brought into full play,which will help promote the overall balance of the Yangtze River Delta urban agglomeration development;Based on the impact of land resource constraints on land and space planning,optimizing the industrial structure is an important measure to further enhance the level of urbanization coordination in the Yangtze River Delta region.Relative to the movement of population and economic factors,it promotes the rational flow of land resources and greatly promotes the inter-city intercity within the urban agglomeration.Synergy effect;expand the spatial correlation scope of urbanization coordination,build a reasonable networked spatial structure,integrate urban circles,strengthen regional integrated development,and form a Yangtze River Delta city group with global competitiveness.According to the research ideas,paradigms,methods and contents,the innovation points of the paper are as follows:(1)Based on the logical relationship between urbanization and urban agglomeration,starting from the coordination of urbanization,the interaction process of population,land and economy and the formation of spatial structure of urban agglomerations are closely combined,which breaks through the existing research paradigm of spatial structure of urban agglomeration,and provides a new path for scientific understanding of urbanization development law and spatial form of urban agglomeration.(2)Spatial connection and coordinated development are two major characteristics of urban agglomerations.According to the urbanization coordination relationship of each city,the agglomeration subgroups are divided,and the spatial structure of the Yangtze River Delta urban agglomeration is identified in the time and space dimensions,which provides a scientific basis for the construction of the inner urban circle,the urban cooperation relationship and the optimization of the spatial structure of urban agglomerations.