武汉城市圈城镇用地扩展的时空格局与规模等级模式分异研究

在国家大力推进新型城镇化和优化国土空间开发格局战略背景下，都市圈成为区际竞争的核心载体，定量认知基于长时间序列的都市圈城镇扩展时空格局与不同规模等级城市的模式分异规律，对提升城市空间治理能力与制定因地制宜的空间管控策略具有重要意义。基于1990～2015年4个阶段（1990～2000、2000～2005、2005～2010、2010～2015年）的武汉城市圈土地利用现状数据，用城镇用地来源、城镇扩展速率、城镇用地扩展差异指数、重心坐标、分维数以及扩展强度指数的等扇分析等指标对武汉城市圈城镇扩展的时空格局以及规模等级模式分异进行研究。结果表明：武汉城市圈城镇用地扩展的主要来源是耕地，其次是水域、林地、其他建设用地和农村居民点，来源由单一趋向多元化；城镇用地扩展速率具有明显的波动性和阶段性特征，以及扩展具有空间分异性和空间集聚性；不同时期的中快高速扩展区域呈现出不同的形状，比如扇形、”U”型；根据雷达图把城镇用地的扩展模式划分成单翼、多翼和扇形扩展3种模式，各城市主要扩展方向没有一致性，呈现出小城市扩展方向大城市聚拢的特征；武汉城市圈城市形态较为规则平整，分维数具有波动性特征；武汉、黄石、咸宁的重心往西南方向迁移，鄂州、黄冈、孝感的重心往西北方向迁移；不同等级城市的扩展格局以及模式具有差异性，中小城市的扩展速度大于大城市，城市形态都趋于稳定。 关键词： 土地利用变化；城市扩展；时空格局；模式分异；武汉城市圈

Study on the Spatio-temporal Pattern and Differentiation of Rank-size Distribution of Urban Land Expansion in Wuhan Urban Agglomeration

Under the background that Central Government vigorously promotes the new type urbanization and optimizes the strategic pattern of territorial development,urban agglomeration area has become the core carrier of interregional competition.Quantitative cognition of the long-term spatio-temporal pattern of urban expansion of urban agglomeration area and the pattern variation law of cities at different scales is of important significance for improving the urban governance capacity and formulating appropriate spatial control strategy.Based on the land use data in four stages (1990-2000、2000-2005、2005-2010 and 2010-2015) of Wuhan Urban agglomeration during 1990-2015,this research on spatio-temporal pattern of urban expansion of Wuhan Urban agglomeration and pattern variation law of cities at different scales could be conducted by indexes including the urban land sources,urban expansion rate,urban expansion index,center of gravity coordinates,fractal dimension and expansion intensity equal fan analysis.Results show:the main source of urban land expansion in Wuhan urban agglomeration is farmland,followed by water,woodland,other construction land and rural settlements,which tends to change from a single source to diverse sources.Urban land expansion rate shows obvious characteristics of fluctuation and stage;the expansion appears spatial heterogeneity and spatial agglomeration.Regions with medium and fast expansion speed in different periods exhibit different shapes,such as a fan or "U" type.According to the radar chart,expansion pattern of urban land use could be summarized into three modes,one-wing mode,multi-wing mode and fan-shaped mode.The main expansion directions of each cities show no uniformity and emerge a feature that small cities gather towards big cities.The shape of Wuhan urban agglomeration is regular,the fractal dimension appears a characteristic of fluctuation.The barycentric coordinates of Wuhan,Huangshi and Xianning develop towards the southwest;that of Ezhou,Huanggang and Xiaogan develop towards the northwest.There are differences among the urban expansion patterns and modes at different scales.The expansion speeds of the small and medium-sized cities are larger than that of the big cities,and the urban morphology tends to be stable.