基于分形理论的江苏省南通市城镇体系空间结构研究

基于非线性科学分形理论以及运用GIS相关软件,通过计算南通城镇体系的首位指数、中心城市吸引力以及城镇交通网络长度-半径维数、网络分枝维数,探讨了南通城镇体系等级规模结构分形、城镇体系空间关联性分形以及南通城镇交通网络分形特征,从描述城镇等级体系、城镇交通网络分布入手,通过对南通城镇具体区域指标的分析和处理,并以分形理论中的二城市指数、三城市指数、四城市指数和十一城市指数为定量依据,将分形理论引入城镇体系研究的实践中,结果表明:南通城镇体系空间结构呈现分形特征,从而有效验证了分形特征不仅存在于大城市空间结构,中等城市的城镇体系依然存在,进而为指导南通城镇体系空间上合理布局提供定量依据与决策参考,并据此提出了南通城镇体系空间结构合理化的建议。

A FRACTAL STUDY ON THE URBAN SPATIAL STRUCTURE OF NANTONG CITY IN JIANGSU PROVICE

This paper provide a research on the structural fractal features, the fractal features of urban spatial relationship and the fractal features of urban transportation network of Nantong city. The research is based on fractal theory by using the GIS software. The authors analyze the first index of urban system of Nantong, the gravitation of central city as well as the length of the transport network including radium dimension and network branches dimension. Firstly, the authors review the theoretical development of fractal geometry. The concept of fractal is defined as a rough or fragmented geometric shape that can be split into parts, each of which is (at least approximately) a reduced-size copy of the whole. The authors point out that the definition is too limited because in some cases, there are no similarities between parts and the whole but it could be regarded as fractal. It is necessary to develop fractal theory in geography studies. Secondly, the authors analyze the fractal distribution characteristics of Nantong city. The result shows that the urban scale structure is not reasonable. So, the urban system of Nantong blocks the development of the city's functions. The industry structure is mainly built up by upstream industries including textile, raw materials, heavy and chemical industries, as well as transport and simple service which limited the improvement of urban system. Thirdly, the spatial structure in urban system can be analyzed with the fractal theory including the urban hierarchy of fractal characteristics of urban system, spatial association of fractal analysis, the fractal analysis of spatial distribution of urban transport network. Finally, the authors point out that the analysis could provide policy basis for the development of urban system of Nantong.