长江三角洲地区城市用地增长的时空特征分析

以Landsat MSS、TM、ETM卫星影像为主要数据源,利用遥感和GIS手段,提取了长江三角洲地区5个时相(1979年、1990年、1995年、2000年、2005年)城市用地信息,分析了城市用地扩展速度、扩展强度、空间结构的变化特征,进而探讨了长江三角洲1979年以来的城市空间生长过程.结果表明:①1979年以来,长江三角洲城市用地增长呈明显的加快趋势-城市用地总体扩展强度也表现为不断提高.不同行政等级城市用地的扩展强度表现为直辖市＞地级市＞副省级市＞县(县级市).②长江三角洲城市用地空间结构的分维和稳定性特征具有一定的波动性.城市用地的空间结构特征与城市用地增长过程和发展阶段具有一定的联系.③长江三角洲城市生长表现出"一核二带"、"二核三带"、"四核四带"和"五核五带"的空间轨迹.

Spatio-temporal Characteristics of Urbanization Area Growth in the Yangtze River Delta

The Yangtze River Delta is one of the economically developed coastal areas. From the late 1970s, its urbanization process has been quickened greatly, which resulted in the number increase and the spatial expansion of urban areas. The Landsat MSS, TM/ETM satellite images, which were respectively acquired in 5 periods of 1979, 1990, 1995, 2000 and 2005, were used to extract urban land information and analyze urban growth data with the help of remote sensing and GIS softwares. We analyzed the spatio-temporal characteristics including urban growth speed, growth intensity, fractal dimension and urban growth pattern. Additionally, dynamics of urban expansion in the Yangtze River Delta were also analyzed. The results are drawn as follows: (1) From 1979 to 2005, the growth speed of urbanization area was accelerating obviously. The quantities of increasing area of urbanized land were 37.66 km2, 112.43 km2, 274.86 km2 and 421.73 km2 in the past four periods (1979-1990, 1990-1995, 1995-2000 and 2000-2005), respectively. Meanwhlie, the growth intensities of urbanized land enhanced gradually. From 1979 to 1990, the growth intensity was only 0.03, then reaching 0.10, 0.24 and 0.37 in the following three periods. (2) The spatial structure of urbanization area in the Yangtze River Delta was fractal. The fractal dimension and stability coefficient of urbanized land structure fluctuated to a certain extent. From 1979 to 2000, the fractal dimension of urbanized land structure decreased yearly. The shape of urbanized land tended to be regular. After 2000, the area increase of urbanized land on a large scale led to more complicated shape of urbanized land. The stability coefficient also had similar characteristics to that of fractal dimension. So the change of urbanized land in spatial structure was relating to the growth process of urbanized land. (3) The growth process of urban agglomeration in the Yangtze River Delta was from one pole and two belts to five poles and five belts. From 1979 to 1990, Shanghai was the only first-grade growth pole of urbanized land and Shanghai-Nanjing railway and Shanghai-Hangzhou railway were the two first-grade growth belts of urbanized land in the Yangtze River Delta. At the latest period (from 2000 to 2005), the first-grade growth poles included 5 cities, i.e., Shanghai, Nanjing, Hangzhou, Suzhou and Ningbo. Besides Shanghai-Nanjing railway and Shanghai-Hangzhou railway, Shanghai-Jingjiang railway, Hangzhou-Ningbo railway and the highway linking Nanjing to Gaochun also became growth belts of urbanized land in the Yangtze River Delta in that period.