Evolution And Optimization Of Spatial Structure Of Urban System In Nanchang Metropolitan Area Based On Fractal Theory

As the result ofrapid development of urbanization,cities are gathering gradually,more and more metropolitan and city circle have appeared in developing countries.The “One belt and one road” policy and the government‘s determination of constructing “Yangtze river economic belt” and “urban agglomeration in the middle reach of Yangtze river”,has provided Jiangxi an opportunity to integrated into the “Yangtze river economic belt” and build up a construction of nanchang metropolitan area.Therefore,itis of great necessivity to carry out an research about the level of urban system and in nanchang city circle size and space structure of Nanchang city circle,which also has certain reference significance.Based on theresearch object,Naanchang metropolitan area,this paper refining the research unit to the level of a town.By the means of ArcGis,SPSS and Excel.And the city's first degrees and fractal methods measured the 2000,2010,2013 level fractal dimension,spatial structure of urban system and evolution of apatial structure characteristics of Nanchang metropolitan area.Analyed the natural geographical conditions,industry conditions,traffic conditions,policy system and so on of Nanchang urban system spatial structure of metropolitan area,then put out some pointed suggestions to the optimization of nanchang urban system spatial layout of metropolitan area,in the aim of promoting the urban system spatial structure of metropolitan area of Nanchang in a coordinated way and the optimization of the central city of social and economic development.The main conclusions are as follows:(1)The metropolitan area development level of urban system structure of Nanchang are inbalanced.The urban system first degree is too high,the level size difference is too big and the structure is imperfect.In 2013,Nanchang,as the central city,is reached to a popullation of 2.2374 minllion,which is in a dominat position.In 2000 and 2010,results show no center towns.In 2013,the only central city Fuzhou own a popullation of 506900;Middle city is in the secondary place,have 22 key towns in 2013,the resident population,1.4087 million,36.13% of Nanchang resident;Small towns developed rapidly;Results show no center towns in 2000,2010,one in 2013;The number of key town was 9,which increased to 22 in 2013.(2)The D values of metropolitan area urban system scale fractal dimension were 1.3403 in 2000,1.2517 in 2010,1.2998 in 2013,which indicates that metropolitan area level of urban scale structure of Nanchang is relatively concentrated,the first city monopoly level is higher,polarization effect in the process of evolution is obvious;The D values of metropolitan area urban system scale fractal dimension is decresed,which shows that the nuclear structure of Nanchang metropolitan area less aggregated and radiated;To measure the nanchang as the center of assembled dimension,got a D values of 0.7395,less than 2,and 1,shows an uneven developing condition of the changes of spatial structure;Nanchang metropolitan area urban system capacity and information dimension were 1.5653,1.5055,determination coefficient were 0.9914,0.9978,Capacity dimension and information dimension are 1<D<2,Spatial distribution balance has improved,but still in a low standard.Nanchang urban system spatial structure of metropolitan area in the correlation dimension is 0.2778 tend to be 0,metropolitan area in the development of core group degree is high,and the peripheral area correlation is low.(3)The influence factors of urban system spatial structure evolution of Nanchang metropolitan area: the central region is flat,water system developed well,urban distribution is well concentrated,which is oppsite in the northwest and the northeast.The distribution of railway and highway are uneven.Main network are spread in the south.Nanchang has the best traffic condition and the least pressure than other palce.The connection between the small towns are decreasing;The ranking of three major industries of Nanchang during 2012-2015 is : secondary industry,tertiary industry,primary industry.secondary industry,tertiary industry are developing in a parallel rate,which will affect the economic benefits of nanchang metropolitan area as a whole and a negative influence in the development of urban spatial structure;For the seek of maximum benefit,the local government tend to ignore the specialization of work,which turned out bad in the industrial construction.(4)The problems in the urban system spatial structure evolution of Nanchang metropolitan area:one polarization of first city,urban system spatial structure presenting the tuberculosis structure,imbalance and loose of urban system structure;Key towns are of great strength,but of less connection;Metropolitan area are in the stage of primary development of Nuclear development,and its attraction is decreaing distinctly.(5)Countermeasures and suggestions: Accelerating the development of core city,promote the city circle of urbanization;Cultivating potential secondary center city,developing the new growth pole;Optimizing the industrial structure,promoting the economic integration;Establishing and improving the transport infrastructure,strengthening the construction of regional transportation system of the network.Strengthening the forming of network and the polarization vision space structure of common development.