中文摘要：

以多时相Landsat MSS、TM和ETM卫星影像为数据源，提取宁波城市各组团（三江片、镇海片和北仑片）多时相的用地信息，分析了港口城市用地扩展的时空特征及外部形态演变过程。结果表明：（1）1979年以来，宁波城市用地面积扩展速度和扩展强度不断提高，但各个组团的表现有较大的差异。（2）各组团城市用地空间结构分维数的波动与城市用地的空间扩展模式表现出明显的相关性。（3）3个组团的城市用地扩展强度指数峰区相对城市质心有不断外移趋势，但扩展强度指数峰值的变化在各个片区有一定差异。（4）3个组团城市用地外部形态演变在不同方向上的差异性与宁波港口迁移及港口经济的发展密切相关。（5）随着宁波港口从内河港向河口港、海岸港的迁移，宁波城市外部形态演变经历块状单一集中型内河港城市、“一城一镇”飞地式群组河口港城市、“一城二镇”飞地式群组海港城市和“一城多镇”不连续带状群组海港城市发展阶段，最后将形成“T”型带状群组现代化国际港口城市。

英文摘要：

Ningbo, classic group city, is the central city of the south Yangtze River Delta and is one of the economically developed coastal areas. Since the late 1970s, its urbanization process has been quickened greatly, which resulted in substantial increase in both urban areas and urbanization intensity. The landsat MSS, TM/ETM satellite images, which were respectively acquired in five 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 software. We analyzed the spatio-temporal characteristics including urban growth speed, growth intensity and fractal dimension. Additionally, outer spatial form of urban expansion in Ningbo city was also analyzed. The results are as follows. （1） From 1979 to 2005, the growth speed and the growth intensities of urbanized area in Ningbo city were accelerating obviously. To the three districts, there are some differences in the growth speeds and intensities. （2） The fractal dimensions of urbanized land structure were fluctuant and relating to the growth process of urbanized land. When the shape of urbanized land tends to be regular, the fractal dimension will decrease. （3） The mode position of index of the growth intensities related to shape centre of the urbanized land tends moving toward the outside. But the change of the mode value differs from each other in the three districts. （4） The direction of spatial expansion of urbanized land was obviously related to transplanting of port and the development of port economy. （5） With the transplanting of Ningbo port from river port, estuary port to coastal port, the evolvement of outer spatial form of Ningbo city was from the type of single central city with river port, enclave group city of estuary port with ＂ one city and one town＂, enclave group city of coastal port with ＂one city and two towns＂ and discontinuity zonal city of coastal port with ＂one city and many towns＂. Finally, the ＂T-shaped＂ outer spat