College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing 100871, China.
College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing 100871, China.
Sci Total Environ. 2019 May 10;664:60-71. doi: 10.1016/j.scitotenv.2019.02.008. Epub 2019 Feb 1.
Megacities pose both challenges and opportunities for the transition towards sustainability, and understanding the evolution of urbanization in megacities has profound implications for human societies in an increasingly urbanized world. Here, we mapped and quantified spatiotemporal dynamics of urban expansion in China's six megacities (i.e., Beijing, Chongqing, Guangzhou, Shanghai, Shenzhen and Tianjin) from 1978 to 2015, integrating remote sensing and GIS technology combined with landscape metrics and urban growth type analysis. The results show that six Chinese megacities have all undergone extensive physical expansion over the past four decades, and the magnitude of urban expansion is ranked in the order of Shenzhen, Guangzhou, Chongqing, Shanghai, Tianjin and Beijing, with annual growth rates of 11.02%, 8.07%, 5.80%, 5.37%, 4.56% and 3.46%, respectively. The megacities with smaller initial urban areas were associated with higher urban expansion rates. Differences in the direction, extent and location of expansion for each megacity related largely to the topography, policies and urban master planning. Temporal dynamics of urban growth and landscape metrics suggested that the urbanization processes of Beijing, Shanghai, Shenzhen and Tianjin were basically consistent with urban growth theory, while those of Chongqing and Guangzhou did not match the theory well. Temporal coevolution of the urban area with urban population implied efficiency of urban land use in Shenzhen and Beijing, which are the first special economic zone and the capital of China, respectively. The efficiency of wealth creation in the urbanized area base was observed for all Chinese megacities, signifying the effectiveness of urban expansion as a vehicle to promote economic growth. We face the challenge of managing trade-offs between the benefits and costs of urban agglomeration.
特大城市的可持续发展既面临挑战，也存在机遇，了解特大城市的城市化演变对日益城市化的人类社会具有深远影响。在这里，我们利用遥感和 GIS 技术，结合景观指标和城市增长类型分析，绘制并量化了中国六个特大城市（即北京、重庆、广州、上海、深圳和天津）从 1978 年到 2015 年的城市扩张时空动态。结果表明，过去四十年，中国六个特大城市都经历了广泛的实体扩张，城市扩张的规模排序为深圳、广州、重庆、上海、天津和北京，年增长率分别为 11.02%、8.07%、5.80%、5.37%、4.56%和 3.46%。初始城市面积较小的特大城市与较高的城市扩张率相关。每个特大城市扩张的方向、程度和位置的差异主要与地形、政策和城市总体规划有关。城市增长的时间动态和景观指标表明，北京、上海、深圳和天津的城市化进程基本符合城市增长理论，而重庆和广州的城市化进程则与理论不太吻合。城市面积与城市人口的时间协同演化表明，深圳和北京的城市土地利用效率较高，分别作为中国的第一个经济特区和首都。中国所有特大城市的城市化区域的财富创造效率都有所提高，这表明城市扩张作为促进经济增长的手段是有效的。我们面临着在城市集聚的效益和成本之间进行权衡取舍的挑战。
