长江三角洲地区城镇空间扩展特征及机制

城镇空间扩展是城市化作用于地理空间的直接结果，揭示城镇空间扩展过程、格局及机制已成为识别城镇发展阶段、认知城镇发展规律的有效手段。基于长江三角洲地区多时相卫星遥感影像数据，以城镇用地扩展空间分异与关联特征为切入点，利用间隙度指数、分形维数、扩展强度指数、扩展速度指数和空间关联模型，定量揭示了区域城镇空间扩展特征的多样性、空间组织异质性和“热点区”格局演化。结果表明：20 世纪80 年代以来，长三角洲地区城镇空间扩展在以中心城市集聚为主导的过程中，遵循“小集聚，大分散”的特点，围绕“Z”形区域发展轴线，大致经历了点轴扩展、沾粘式增长和蔓延扩张的过程，区域融合现象凸显；空间扩展的“热点区”格局不断演化，“热点区”的核心集聚作用在减弱，沪宁沿线、沪杭沿线、杭甬沿线和沿江地区成为驱动长三角城镇社会经济发展的核心区；同时，在城镇空间扩展的不同阶段，驱动机制有所差异，经济全球化和区域城市化推动着长三角城镇空间一体化进程。

Urban Spatial Expansion Process, Pattern and Mechanism in Yangtze River Delta

The investigation of the process, pattern and mechanism of urban spatial expansion has become an effective method to recognize the stages of urbanization and explore the laws of urban development as the direct result of urbanization to geographic space is the spatial expansion of cities. Based on the satellite imageries data including Landsat TM or ETM, IRS-P6 of the Yangtze River Delta (YRD) from 1980 to 2007, this article, starting from the characteristics of urban spatial heterogeneity and spatial association, revealed quantificationally the diversity of urban expansion, the heterogeneity of spatial organization and the spatial evolution of "hot spot" areas, with the help of lacunarity index, fractal dimensions, expansion intensity index, expansion speed index as well as spatial association model,. The conclusions can be drawn as follows. (1) Since the 1980s, although central cities have dominated the process of regional expansion, this evolution still follows the law that "small scale agglomeration, large scale dispersion". (2) Along the Z-shaped axes, urban growth has experienced three stages, namely point-axis expansion, adhesions-type growth and spread expansion. In addition, an obvious regional integration was observed. (3) The gathering role of "hot spot" areas has been diminished, and areas along the Shanghai-Nanjing, Shanghai-Hangzhou, Hangzhou-Ningbo highways and the Yangtze River have become core areas that propel regional socio-economic development in YRD. (4) The driven forces varied in different development stages. It is the combination of economic globalization and regional urbanization that dominates the regionalization of the YRD.