Spatial Boundary Definition Of Urban

Urban-rural fringe is areas where urban land use changes most intensely. Spatial pattern of urban is expansion; the boundary of urban-rural fringe is changing with remarkable"gradualist"and"dynamic"characteristic. For a long time, there are many severe problems in Urban-rural fringe. For example, land use types are the most mixed, rapid change, weak governance, etc. Defining boundary of Urban-rural fringe is good for urban geography research system; for being targeted planning and management; for helping to promote Beijing's"livable"urban development goals.Based on the analysis of land use characteristics, landscape features and demographic characteristics; select the proportion of agricultural land, the proportion of construction land, landscape diversity, population density as four indicators to build index system for defining urban-rural fringe. Index system has close relationship with land-use classification system. It helps to combine with the statistical data, updates the data, conducive to the promotion index system."Gravity model" which always uses in physics applied to define the border of urban-rural fringe in this article. "Gravity model" that can adequately reflect deferent gravitation between he urban core and its surrounding towns, spatial distribution clearly because of the distance attenuation. With analyzing the gravitational distribution of changes, we can find out the gravity breakpoints; determine the spatial extent of urban-rural fringe.First of all, select the Chaoyang, Shunyi Miyun District as typical bands, based on km grid to analyze. When "Gravity model" and index system are used, the inner boundary of Urban-rural fringe is at a distance of 15 kilometers outside the city center, using the city's road network to measure, that is, along the fouth ring or outside 2-3 kilometers of the fourth ring. Outer boundary of urban-rural fringe is at a distance of 88 kilometers outside the city center, reaching miyun reservoir in the north, almost yanqing and some region huairou. It has beyond the actual administrative boundaries in Beijing in the West, East, south.Second, defining the boundaries of urban-rural fringe of Beijing based on administrative boundaries. When "Gravity model" and index system are used, Urban-rural fringe of the inner boundary is presenting circular distribution with slightly prominent in the eastern Chaoyang District. Outer boundary is alng the administrative boundaries which departure from the city center. Outer boundary along the clockwise included the towns as follows: Xisanqi Street, Laiguangying Township, Wangjing Street, Jiangtai Township, Changying Township, Guanzhuang Township, Fatou Street, Jiugong Township, Hua Township, Lugou Bridge Township, Ancient City street, SijiqingTown, Qinglong Bridge Street,Malianwa Street,Qinghe Street.The Outside urban-rural fringe reaches the Mitian Township in the northern; Shandongzhuang Township, Xiagezhuang Township in the east; all the Daxing District and half fangshan District in the south; wangpin region in the western. The Results are basically consistent with the analysis based on km grid, which can fully illustrate the defining method is feasibility.On this basis, the article has chosen the breaking point method which is widely used, to test the gravity model results. Verification of different spatial scale are consistent with the earlier results based on the gravity model, proving once again that this research method is feasibility.