在遥感技术与GIS技术的支持下,采用分形几何理论对绍兴市城镇体系空间结构特征和形态特征进行分析,探讨城镇体系的演化规律。研究表明,绍兴市城镇体系无论在空间结构上还是在空间形态上都具有分形特征。城镇分布密度由绍兴市区向周围逐渐衰减,且分布不均衡,具有向交通线集中的趋势,形成了优化的空间结构。但1984~1997年间,空间结构的演化趋向于围绕绍兴市在半径方向上均匀分布,分形特性减弱。此外,各城镇基本是以各自的中心逐渐向外扩展,空间关联性大致不变。空间形态则日趋复杂,稳定性越来越低,发展的随意性越来越大。绍兴市区这一特点更明显。
It is useful for the sustainable development of city to analyse spatial characteristics and evolvement of urban system. In this paper, spatial structure and pattern of urban system in Shaoxing based on remote sensing and GIS are analyzed by fractal geometry. The rule of evolvement is discussed by comparing the data in 1997 with that in 1984. Remote sensing techniques can provide the necessary data rapidly and periodically for the spatial characteristics and evolvement study. GIS is an effective tool to analyze the spatial characteristics and evolvement with the strong spatial analysis functions. Firstly,the study area including Shaoxing City and towns is cut from TM images in 1984 and 1997 after geometric correction based on the 1:50,000 topographic map. Secondly, the spectral characteristics of the urban system and background on the TM images are analyzed by samples statistics. Thirdly, a model is established based on the difference of spectral values between them to extract the urban information. Fourthly, the result of extraction is transformed to vector map in order to correct some errors and imported to GIS. Then the aggregation dimension, spatial correlation dimension and fractal dimension of pattern in different times are calculated one by one based on the attribution table of GIS. The results of analysis suggest that both spatial structure and pattern of urban system in Shaoxing are obviously fractured. The aggregation dimension D denotes the aggregation or dispersion state around the centre of the urban. If D<2, the density of towns is attenuating from the centre to the surrounding. If D=2, the towns are distributed evenly around the centre of the city. If D>2, the density of towns is increasing from the centre to the surrounding, which is not natural. The correlation dimension D denotes the uniform extend of the towns aggregation. If D→0, the distribution of towns is centralized. If D→1, the towns are aggregating to a geographic line. If D→2, the towns are distributed evenly around any town. The fractal dimension D of spatial pattern denotes its complexity and stability, which can discover the trend of the urban evolvement. It varies from 1 to 2,and the greater the D, the more complex the distribution of towns. If D<1.5, the shape of the urban system is becoming more simple. If D=1.5, the stability is worse,and the urban system is in the Brown movement. If D > 1.5, the shape is more complex and instable. If D=2, one place on the plane is filled by the graph of the town. According to the results of the calculation, the aggregation dimension of Shaoxing urban system is smaller than 2, which suggests that the density of towns decreases gradually around the centre. The spatial structure is optimized. The correlation dimension is nearly 1, so the distribution of towns is not proportional, which tend to aggregate to the traffic routes at the same time. As far as the evolution of urban system is concerned, from 1984 to 1997, the towns tend to be distributed evenly around the city, and the fractal dimension of the spatial structure is decreased. Every town expands around its center gradually, and the spatial correlation is unchanged on the whole. But the spatial pattern of urban system becomes more complex, unstable and random. Especially, with the increasing of economy in Shaoxing, the city develops more quickly, and the spatial pattern is more complex and instable than other towns. Lastly,some suggestions about the development of Shaoxing are brought forward based on the conclusions.
[1] 张小雷,李春华,宋亚君. 基于可持续发展思想的县域城镇体系规划[J].干旱区地理,1997,20(2):17~19.
[2] 张志斌,张小平. 河西地区城镇体系特征及未来发展构想[J]. 冰川冻土,2002,24(4):463~469.
[3] 刘 明,谢光辉,谢炳庚,等. 环洞庭湖区城镇体系发展研究[J]. 地域研究与开发,2001,20(1):32~37.
[4] 李英豪. 市(县)城城镇体系发展机制研究[J]. 城市规划,2001,25(7):19~24.
[5] 李春华,刘月兰. 哈密地区城镇体系发展与布局研究[J]. 干旱区地理,2001,24(1):57~61.
[6] 李忆春,黄炳康. 成渝地区城镇体系结构研究[J].经济地理,1999,19(2):55~59.
[7] 王心源,范湘涛.邵 芸,等. 基于雷达卫星图像的黄淮海平原城镇体系空间结构研究[J]. 地理科学,2001,21(1):57~63.
[8] 吴 兵,葛昭攀. 分形理论在地理信息科学研究中的应用 [J]. 地理学与国土研究,2002,18(3):23~26.
[9] 刘继生,陈彦光. 城市地理分形研究的回顾与前瞻[J]. 地理科学,2000,20(2):166~171.
[10] Arlinghaus S. Fractals take a central place[J]. Geografiska Annaler, 1985,67B(2):83-88.
[11] Batty M, Longley P. Fractal Cities: A Geometry of Form and Fu- nction[M]. London:Academic Press,1994.
[12] Frankhauser P. La Fractalit? Des Structures Urbaines[M]. Paris: Economics,1994.
[13] Benguigui L, Daoud M. Is the suburban railway system a fractal? [J]. Geographical Analysis,1991,23(4):362-368.
[14] White R, Engelen G. Cellular automata and fractal urban form: A cellular modeling approach to the evolution of urban land use patterns[J]. Environment and Planning A,1993,25:1175-1199.
[15] 陈 勇,艾南山. 城市结构的分形研究[J]. 地理学与国土研究,1994,10(4):35~41.
[16] Tian Guangjin, Liu Jiyuan, Zhang Zengxiang. Dynamic change of land use structure in Haikou by remote sensing and GIS[Z]. http://www.crisp.nus.edu.sg/~acrs2001/pdf/326tian.pdf. 2001.1-5.
[17] 蒋雪中,杨 山,沈 婕,等. 云南漾弓江流域城乡聚落形态信息提取与分形分析[J]. 遥感学报,2002,6(4):294~298.
[18] 陈 涛. 城镇体系随机聚集的分形研究[J]. 科技通报,1995,11(2):98~101.
[19] 刘继生,陈 涛. 东北地区城市体系空间结构的分形研究[J].地理科学,1995,15(2):136~143.
[20] 刘继生,陈彦光. 城镇体系空间结构的分形维数及其测算方法[J]. 地理研究,1999,12(2):171~178.
[21] 刘继生,陈彦光. 东北地区城市体系分形结构的地理空间图式——对东北地区城市体系空间结构分形的再探讨[J]. 人文地理,2000,15(6):9~16.
[22] 单纬东,陈彦光. 信阳地区城乡聚落体系的分形几何特征[J]. 地域研究与开发,1998,17(3):48~64.
[23] 蒲欣冬,陈怀录,徐中民,等. 基于分形理论的西部干旱区县域城镇体系研究——以定西县为例[J]. 中国沙漠,2002,22(2):177~183.
[24] 刘继生,陈彦光. 分形城市引力模型的一般形式和应用方法——关于城市体系空间作用的引力理论探讨[J]. 地理科学,2000,20(6):528~533.
[25] 陈彦光,刘继生. 区域交通网络分形的DBM特征——交通网络Laplacian分形性质的实证研究[J]. 地理科学,1999,19(2):114~118.
[26] 刘继生,陈彦光.交通网络空间结构的分形维效及其测算方法探讨[J]. 地理学报,1999,54(5):471~478.
[27] 刘继生,陈彦光,余 斌. 区位选择与人文地理系统的分形优化关于城市区位分形理论一般原理与方法的初步探讨[J]. 地理科学,1998,18(4):328~334.
[28] 叶 俊,陈秉钊. 分形理论在城市研究中的应用[J]. 城市规划汇刊,2001,(4):38~42.
[29] 姚士谋,帅江平. 城市用地与城市生长——以东南沿海城市扩展为例[M]. 合肥:中国科学技术大学出版社, 1995.
[30] 董连科. 分形理论及应用[M]. 沈阳:辽宁科学出版社,1991.
[31] 王东升,曹 磊. 混沌、分形及其应用[M]. 北京:中国科学技术出版社,1995.
