中国大运河沿线城市扩张时空差异研究

Spatiotemporal differences of urban expansion along China’s Grand Canal

自20世纪80年代以来,中国大运河沿线城市建成区规模、空间扩张模式以及空间分布特征都发生了显著变化。虽然当前不缺乏大运河重要河段以及沿线典型城市的研究,但对于大运河沿线城市整体扩张的研究较为少见。论文结合统计数据与遥感数据分析了1984-2016年中国大运河沿线城市建成区扩张速度特征、空间特征以及区域差异。结果显示:①中国大运河沿线城市建成区扩张速度特征可被归纳为4类,不同类别之间差异显著;②基于遥感影像提取的运河沿线城市建成区面积通常为相同城市对应年份的统计年鉴中建成区面积的1~2倍;③运河沿线城市建成区空间分布整体趋于离散、破碎,江浙地区运河沿线城市的建成区空间分布最离散、破碎,且离散度增长最剧烈。

Since the 1980 s, with demands from water conservancy projects, the rise of canal tourism, and the proposal of the national canal cultural development strategy, the China’s Grand Canal has been reviving. At the same time, the size, expansion pattern, and spatial distribution of built-up areas along the Grand Canal have experienced significant changes, with far-reaching effects on city traffic, communication, production, daily life,and public facilities. There have been abundant studies on the key river sections or typical cities. However, there is a general lack of research on the overall expansion of cities along the Grand Canal. In this study, 35 cities along China’s Grand Canal were selected as the research subjects. The research area covered two municipalities and six provinces from north to south. Statistical data and remote sensing data were combined in this study for analyzing urban expansion speed, urban expansion pattern, and regional differences of cities along the Grand Canal during 1984-2016. All statistical data were collected from statistical yearbooks. Landsat images were the main data source for urban land mapping. Dispersion index(DI) was applied in this study. The index is a new landscape metric, which was developed for describing the structures and distributions of geographic elements in a region. The results show that: 1) The cities can be classified into four types according to the characteristics of the speed of expansion. Class one contains Shandong, Anhui, Jiangsu, and Zhejiang Provinces, where urban land expansion speed increased dramatically after 2000 and decreased latter. Class two contains Hebei Province and Tianjin Municipality, where urban land expansion speed increased moderately but decreased dramatically latter.Class three contains Beijing, where the highest expansion speed appeared in 2000 and then changed dramatically. Class four contains Henan Province, where expansion speed of urban land changed moderately before and after 2000. 2) Urban built-up areas extracted from remote sensing images are generally larger than urban built-up areas collected from statistical yearbooks. The former is usually between 1-2 times of the latter,and urban expansion in northern China mainly extended around one center, but urban expansions in southern China gradually became polycentric. 3) The spatial distribution of built-up areas in most cities tends to become dispersed and discontinuous, and cities in Jiangsu and Zhejiang Provinces are more remarkable in this respect.The spatial distribution of built-up areas in Beijing was most integrated and compact. The growth of DI values of built-up areas in Hebei Province was the lowest and urban land expansion there was slow. With the successful application for World Heritage of the Grand Canal and the proposal of the Grand Canal cultural development strategy, the construction of the Grand Canal culture belt and the development of canal tourism will become an important measure for promoting the joint development of different regions.