Research On The Urban Spatial Form And Structure Of Changsha City Based On Multi-source Data

A city is an area where human activities gather.As a place for the close exchange and transformation of material,energy,and information,the city development and expansion have a huge impact on the natural environment and the form of human activities.Therefore,studying the development and expansion process of a city from the perspective of spatial form and structure has great significance for future human production,life and urban planning.At present,most of the research on urban spatial morphology and structure is based on a single traditional data,which leads to the lack of depth and breadth of research in this field.With the advent of the era of big data,more and more types of geographic information data are available.By using these different types of data,we can analyze the changing laws of urban spatial morphology and the hierarchical relationship of urban spatial structure from more perspectives.Based on NPP-VIIRS night light data,cell phone signaling population data,OSM road network data,Amap POI data and other multi-source data,this paper analyzes the urban spatial form and structure of Changsha through different algorithms,and the following main conclusions are drawn:(1)The urban built-up area of Changsha City builds an east-west urban comprehensive development axis with Fenglin Road,Wuyi Avenue and Renmin Road.At the same time,the builtup area is divided into two parts from north to south by the Xiangjiang River.The eastern urban area is obviously larger than that of the western urban area,and the expansion mode is mainly from the eastern urban area to expand outward.The eastern urban area and the western urban area have a large gap in development and expansion intensity.The spatial form of the urban built-up area deviates from the circle,the layout is relatively fragmented,and the outer space of the city is showing obvious fragmented development.(2)Through the local contour tree algorithm based on topographical principles,it successfully identified 21 city nodes and 12 city centers in Changsha,and formed corresponding levels according to the topological relationship between each node,clearly showing the interior of the city structure and level of the space and find out the nested hierarchical relationship between the spaces.Comparing it with the urban spatial structure of “one main center,two sub-center,six clusters” proposed in the general plan,it is found that the 12 identified urban centers are all in the“1+2+6” plan of Changsha City.The centers have obvious characteristics of "multi-center,grouplike" distribution.(3)There are obvious differences in the degree of functional mix between the various urban functional areas in Changsha.The commercial service functional areas are mainly concentrated on the two sides near the Xiangjiang River,showing the characteristics of concentrated and contiguous agglomeration.Among them,Furong District and Tianxin District,as the urban center of Changsha City,have dense commercial service functional areas and strong economic vitality.Moreover,as the main urban area,their plots have a relatively high degree of functional mixing.In the cluster area surrounding the urban center,the function of urban construction land is relatively single and the degree of function mixing is relatively low.The distribution of urban functional areas in Changsha City has a relatively obvious "circle" differentiation feature.