Study On Coordination Of Urban Spatial Interaction And Expansion In Chengdu

As a regional center,the city compensates for the shortcomings in its own development by continuously exchanges resources,information,capital,and population with the surrounding areas.This exchange is called spatial interaction.With the deepening of reform and opening up,and the rapid advancement of industrialization and urbanization,the interaction between cities has continuously increased.At the same time,the imbalance of economic development has led to an increasing gap between cities;urban expansion has been rapid and disorderly,and the “big cake” expansion model has been unsustainable;problems such as low land use efficiency and serious waste of land resources have become increasingly prominent.How to coordinate the inter-city relations within the region and guide the orderly expansion of cities in the context of changing urban spatial interactions is an important issue that needs to be faced in the process of urbanization.As the provincial capital of Sichuan Province,Chengdu's comprehensive quality within the region is constantly increasing.At the same time,regional development imbalances and urban expansion disorder are also severe.Therefore,it is of great significance for optimizing urban layout,guiding rational and orderly urban development,efficiently allocating inter-city resources,and promoting the implementation of the strategy of "balanced development" of chengdu by analyzing the changing status of interaction among cities in chengdu and the characteristics of urban expansion and exploring the internal relationship between them.Taking 15 county-level cities in Chengdu as the research object,this paper constructs an index system composed of 3 first-level indexes including urban radiation force,urban attractiveness and inter-city exchange power,and 16 second-level indexes to evaluate the comprehensive quality of cities in chengdu.Based on the results of comprehensive quality calculation,measure the intensity of interaction between cities and the potential value of each city and analyze it.Then,using urban expansion strength,expansion speed,urban expansion center of gravity movement,and extended azimuth index to measure the urban expansion characteristics.Finally,exploring the intrinsic relationship between urban interaction and expansion by analyzing the coordination of urban potential and comprehensive expansion rate composed of the intensity and speed of urban expansion,and urban synergy and different orientations of different cities from the dimensions of increment and space,which is of great significance to promote regional balanced development and provide a basis for rational planning of urban construction land.(1)From 2001 to 2016,the inter-city interaction power and the potential value of each city in Chengdu are significantly enhanced,and the regional internal imbalance is obvious,and the intensity of inter-city interaction changes from generally weak link to general link.The main city has the highest external contact intensity,followed by the surrounding cities in the main city and the lowest in the regional edge cities.The interaction between the main city and its neighboring cities is strong and the integration trend is obvious.The potential value of each city has been significantly improved,and it has been distributed in a circle-like manner around the main urban area.(2)From 2001 to 2016,the expansion of cities in the Chengdu is rapid.Urban expansion has the characteristics of “large scale,fast speed and medium intensity” in terms of time,and shows the overall expansion from east to south in the space.From 2001 to 2016,the urban built-up area of the whole region increases by 858.817 km2,of which the Shuangliu's expansion area is the largest and the Pujiang is the smallest.The expansion speed of Chengdu urban built-up area is 13.699%.and the period of 2010-2016 is lower than 2001-2010.Shuangliu's expansion speed is much higher than other cities,and the main city is the slowest.The overall expansion intensity of urban built-up areas in Chengdu is 0.472,and the period of 2010-2016 is lower than 2001-2010.The expansion intensity of the three cities of Pidu,Wenjiang and Xinjin have changed greatly in two periods.From the perspective of urban gravity shift and extended azimuth index,most cities in the region expand eastward and southward,and their centers of gravity move to the southeast.Some cities are expanding westward or northward,with the center of gravity moving westward and northward.(3)Urban construction land expansion and urban potential show a significant coordination state.The decoupling status between urban construction land and urban potential in Chengdu is mainly divided into weak decoupling,growth linkage,and growth negative decoupling,and the state of coordination is more significant,that is,the urban construction land is increasing along with the growth of urban potential.With the change of time,the degree of intensive utilization of urban construction land is increasing.(4)During the study period,the 15 cities showes a coordinated state of synergy and urban expansion.In the three periods of 2001-2010,2010-2016 and 2001-2016,the “quantitative association-to-coordination” type of orientation accountes for the largest proportion of the four types,namely 36.67%,41.67% and 39.17%.From 2001-2010 period to 2010-2016 period,the “quantity-to-coordination” orientation and the “quantity loss-to-loss” orientation have increased,and the latter has more increments than the former,which shows that the coordination between urban expansion and joint force is developing in two situations,and the development speed of irrational situation is slightly higher than the reasonable situation.The factors affecting the interaction between cities and the coordination of urban expansion mainly include terrain,urban planning,and administrative divisions.