Study On The Evolution Of Urban Spatial Structure In Lanzhou New Area

Based on Landsat remote sensing images of Lanzhou New Area from 2010 to 2020 and POI data obtained from Gaode Map from 2012 to 2020,this paper analyzes the evolution of the urban spatial structure of Lanzhou New Area from two aspects:construction land expansion and urban functional center evolution.With the help of Google Earth Engine(GEE)cloud platform,the expansion process and spatial pattern evolution of construction land in Lanzhou New Area in various periods are extracted,and their temporal and spatial latitudes are analyzed,And summarize the expansion characteristics of construction land at different stages;The identification of urban functional centers uses nuclear density analysis and exploratory spatial data analysis to identify and analyze the evolution process of urban functional centers in Lanzhou New Area on different functional types,and summarizes the characteristics of the evolution of different urban functional centers and structures in Lanzhou New Area;Based on the two,identify the existing urban spatial structure pattern of Lanzhou New Area,and through comparative analysis with the current urban master plan,explore the development mode of urban spatial structure of Lanzhou New Area from a holistic perspective,analyze the differences between the existing urban spatial structure and the planned urban spatial structure,and analyze the internal reasons for the evolution of its urban spatial structure from four aspects: nature,government,economy,and transportation,Summarize the relevant issues that need urgent attention in the development of urban spatial structure,and propose specific optimization strategies in the future development process.The conclusion is as follows:(1)Since the establishment of the Lanzhou New Area,the overall urban spatial expansion has shown a trend of rapid speed and high intensity,with low urban compactness,irregular external contours,and high complexity.However,in recent years,there has been a gradual trend towards compact and regular development.From the perspective of urban spatial expansion types,the marginal expansion type occupies the main position,showing a gradual downward trend;The type of enclave expansion and the type of infill expansion have shown a trend of ebb and flow,with infill expansion gradually surpassing the type of enclave expansion,and connotation development gradually gaining attention.(2)From the perspective of the expansion stage of construction land,the urban spatial expansion of Lanzhou New Area has experienced five stages: initial expansion,axis north extension,point axis north leap,circle filling stage,and comprehensive expansion stage.The first three stages quickly constructed the main urban framework,and the fourth stage entered a new outward expansion stage after completing the filling of the framework.In addition,subject to the characteristics of the Qinwangchuan Basin,which is long from north to south and narrow from east to west,The main direction of urban expansion in Lanzhou New Area is a north orientation,followed by a south orientation.(3)From the perspective of urban spatial expansion coordination,the spatial expansion of Lanzhou New Area took the lead in the initial stage of development,with population attraction and economic output lagging,and the coordination of urban spatial expansion was poor;however,with the overall rapid pace of spatial expansion,the growth rate of population and economy gradually caught up with or even exceeded that of spatial expansion in just four years,and the coordination of urban spatial expansion has greatly improved.It shows that only with the expansion of space can it become a carrier of population and economy,gradually bringing its spatial expansion,population attraction,and economic output into a coordinated and sustainable spatial economic orbit,displaying strong development vitality.(4)Lanzhou New Area presents a relatively obvious spatial structure of "multicenter and cluster".Zhongchuan Airport is surrounded by comprehensive industrial clusters and comprehensive protection industrial clusters,which are the absolute main center of the city,with a development degree far exceeding that of various sub-centers such as Qinchuan Town and key clusters of teaching and vocational parks;Under different functions,the development of public services,life services,and business centers is relatively mature,presenting a multicenter development trend.The development of leisure and residential centers is relatively slow,mainly focusing on the single-center aggregation of Zhongchuan Airport,and the multi-center structure is not obvious.(5)The development model of the urban "multi-center and cluster" spatial structure in Lanzhou New Area is different from the traditional atypical theoretical model under the guidance of planning.Starting with Zhongchuan Airport as the core,it spreads northward to expand the axis of large-scale urban road network and other infrastructure,and then,based on the planned spatial structure,it performs leapfrog expansion in large-scale space,relying on the extension of urban roads,A number of the embedded island like enclaves serving as "high low" and "high high" aggregation growth cores are connected in series to form several agglomeration growth points connected by the road network for circle level expansion,and a development model of the urban spatial structure that synchronously performs infill expansion within different functional clusters is formed.(6)In terms of the mechanism of urban spatial structure evolution,the guidance of policy planning is the most important driving force for the early development of urban spatial structure in Lanzhou New Area;Economic development and population aggregation are the sustained driving forces behind the evolution of urban spatial structure in Lanzhou New Area after the urban infrastructure reaches a certain level;The construction of infrastructure such as transportation network plays a supporting role in the construction of urban spatial structure;As a congenital constraint,natural conditions have established the pattern and direction of urban spatial development from the beginning.On this basis,various factors are interconnected and interact with each other,jointly promoting the evolution of urban spatial structure.