浙西低山丘陵区城镇用地扩展研究——以桐庐县为例

Built-up Area Expansion in Hilly Area of Western Zhejiang Province—A Case Study in Tonglu County

以1978—2002年6个时相Landsat影像为数据源,将谱间特征分析与监督分类相结合,提取了桐庐县城镇用地信息。在此基础上,结合土地利用数据,通过分析桐庐县城镇用地扩展的规模和强度、城镇空间格局及空间形态的变化,揭示了浙西低山丘陵区城镇用地扩展的特征,并从自然、经济、交通、社会等方面研究了城镇用地扩展的驱动力。研究表明:①城镇用地扩展呈现出明显的3个阶段:1980年代低速扩展,1990年代加速扩展,1999年后高速扩展,1999年是城镇由低速扩展进入高速扩展的转折点;②以中心城区为核心,富春江、分水江为发展轴线的“T”字形城镇空间格局日益明显;③城镇用地扩展以“轴线式”和“跳跃式”两种模式为主,城镇空间形态趋于复杂;④经济发展是城镇用地扩展的主要推动力,地形、交通等因素影响着城镇的空间布局和空间形态。

Urbanization and industrialization have been developing rapidly since the enforcement of the reform and the opening-up policy.Consequently,the built-up area keeps expanding, and it gradually becomes a threat to national food security.Based on the literature review, researches on built-up area expansion of city and town using RS and GIS have become a hot pot in Geography in recent years.However,most of them focus on developed area and plain area,such as Yangtze Deha,Zhujiang River Delta and Bohai Rim,but pay little attention to hilly area.This study selects Tonglu County as a representative case in which about 79% of land is mountain,9% is farmland and 12% is water area.Supervised classification combined with spectral signature analysis is used to extract town land information in Tonglu County from serials of Landsat images acquired in six different years （1978-2002）.Next,the town land information and land use data are used to measure the area and intensity of built-up area expansion,spatial pattern and morphology of towns in Tonglu County.Based on which,the characteristics of town land expansion in hilly area of western Zhejiang province are identified.The driving force of town land expansion is stated with different views of aspects,such as physical condition,social-economy,transportation,etc. The result indicates four phenomena as following： ①Town land expansion is shown in three obvious phases：low expansion in the 1980s,speeding up expansion in the 1990s and rapid expansion after 1999.And the year 1999 is the milestone at which towns began to expand rapidly.Central district entered this stage prior to other towns,and most ordinary towns haven＇t been in this stage.②General spatial frame of towns presents a ＂T shaped＂ pattern,and it became more and more salient.Fuchun River and Fenshui River are two development axes of it.Central district is located in the center of the ＂T shaped＇pattern,and Fenshui Town is its western center. ③ ＂Axes Mode＂ and ＂Skip Mode＂ are the underlying modes of built-up area expansion.As a result,spatial morphology of towns becomes more and more complex.④Buih-up area expansion is influenced by many factors.The hilly area of terrain determines general pattern of towns.Growth of economy is the internal driving force of buih-up area expansion.Adjustment of regionalism, town planning and policy have instructional influence on town land expansion.And the improvement of transportation speeds up town land expansion.