Research On The Evolution Process And Mechanism Of The Center System Of The Yangtze River Delta Since The Ming And Qing Dynasties

Founded in the early 20th century,the central place theory is one of the most important theories in geography.However,since its advent,its theoretical development and application innovation have developed slowly.This paper takes 16 cities in the Yangtze River Delta as the research object,takes the theory of central place and other spatial structure as the theoretical basis of this paper,and uses many spatial analysis methods,such as literature analysis,historical analysis,principal component analysis,large data capture,GIS spatial analysis and cartographic representation,to analyze the hierarchical scale structure,function combination structure,spatial structure and evolution process of the Yangtze River Delta central area in different periods since Ming and Qing Dynasties.At the same time,it explores the driving factors of the formation of the high-level central terrain in the Yangtze River Delta,divides the evolution stages of the central terrain system.The results show that during the Ming and Qing Dynasties,the highly developed market economy led to the gradual improvement of the urban system in the Yangtze River Delta and the formation of a relatively complete central structure centered on Suzhou.Suzhou,Nanjing and Hangzhou are first-class centers,forming their respective hinterland areas under the market principle.In the late Qing Dynasty,the Opium War led to the opening of Shanghai's trading ports,Shanghai replaced Suzhou as the central city of the region,and formed a central system based on traffic principles.Nanjing and Shanghai have obvious dual-core structure.As a midpoint city,Wuxi has begun to rise.Since the founding of the People's Republic of China,especially since the reform and opening up,the traditional hexagonal central structure is no longer perfect for the development of regional urban system under the background of the new era.Before the reform and opening up,the centrality of Shanghai was much higher than that of other cities in the region,and the polarization effect was further strengthened,and the centrality of Jiangsu was better than that of Zhejiang.Since the reform and opening up,Shanghai has been the highest-ranking city in the Yangtze River Delta urban agglomeration.Its hinterland is the whole Yangtze River Delta region.Its second-tier cities are Nanjing,Hangzhou and Suzhou.There are six third-tier cities,53 fourth-tier cities and the central-tier system of the Yangtze River Delta is 1:3:6:53.The higher the urban density is,the higher the central level is,and the smaller the hinterland scope is.Since the Ming and Qing Dynasties,the evolution of the spatial central structure of the Yangtze River Delta can be divided into the following stages:the formation of the central level system with Suzhou as its core,the dual-core structure and its competition under the central level system,the rise of Shanghai as a portal city in the dual-core structure,and the development of regional integration.With the development of Shanghai to a certain extent,the role of diffusion has been strengthened,other cities in the region have developed rapidly,the network relationship between cities has become increasingly complex,and the trend of regional integration has become more and more obvious.