基于分形维度法的都市区城市蔓延分析——以广佛为例

根据1957与1982年两个时期的地形图并结合1995与2008年的遥感卫星影像提取城镇建设用地专题信息,利用ArcGIS建立广佛都市区城镇建设用地数据库,采用分形维度的计算方法,对广佛都市区城市蔓延的情况进行测度和分析。结果表明广佛都市区三个发展阶段城镇建设用地面积增长速度并不均匀,具有加速发展的特点。四个测度年份的分形维数分别为1.645 4,1.628 5,1.558 6和1.527 0,均在1～2之间,分形维数呈递降趋势,总体下降了0.118 4,城市发展模式由紧凑型逐渐向松散型演变,存在城市蔓延情况,而且城市发展模式以年均0.14%的速度从紧凑型向松散型演变。广佛都市区城市蔓延的地域分异较为明显,具有较强的空间集聚性和中心向心性,广州和佛山毗邻地区以及中心城区是城市蔓延的活跃区和集中区,1982-1995年间研究区内蔓延速度比1995-2008年间要快。通过深入分析发现,经济快速发展、城市人口的持续增长、交通道路网络的建设是广佛都市区快速扩张和城市蔓延的基本动力因素之一,开发区土地扩张,进一步加剧了无序扩张和城市蔓延。

The Urban Sprawl Analysis of Guangzhou-Foshan Metropolitan Area Based on Fractal Dimension Method

Based on topographic maps of 1957 and 1982,and remote sensing images acquired in 1995 and 2008,the normalized thematic data of urban construction land were extracted.These construction land data were stored in database which was built up in ArcGIS.By using fractal dimension method,quantitative measure and analysis about the urban sprawl of Guangzhou-Foshan metropolitan area.The results show that: The construction land between 3 developments stages in Guangzhou-Foshan metropolitan area has the characteristics of acceleration development.The fractal dimensions of 4 measure years are 1.6454,1.6285,1.5586 and 1.5270,which present to a decline trend.City’s developing mode is turned into to the lax type gradually by the tightly packed type and exist situation of urban sprawl.The fractal dimensions totally descend 0.1184,and city’s developing mode turn into to the lax type from the tightly packed type at speed of 0.14% per year.Regional differences of urban sprawl in Guangzhou-Foshan metropolitan area are very obvious.Guangzhou-Foshan metropolitan area has a strong tendency of spatial concentration.Adjacent areas between Guangzhou and Foshan and center districts are the active areas and the focus areas of urban sprawling.The rate of spread in study area between 1982 to 1995 is higher than the between 1995 to 2008.Through in-depth analysis,rapid economic development,urban population growth and road network construction are the basic dynamic factors which make the rapid expansion and urban sprawl happen in the Guangzhou-Foshan metropolitan area.Land expansion in development district further exacerbates urban spread and sprawl.