亚、非城市地表覆盖时空演变及对比研究—以武汉、喀土穆为例

The Spatial-Temporal Evolution and Comparative Study of Urban Land Cover of Asian and African Cities—The Case of Wuhan, Khartoum

城市地表覆盖类型的转化揭示了人类活动对城市空间形态及生态环境改变的强度特征,对人居环境质量有重要影响。亚、非两洲最重要的河流长江与尼罗河及其支流的交汇将中国城市(武汉)与非洲城市(喀土穆)分割为三部分,但两者在人造覆盖扩张的过程中地表覆盖时空演变及格局存在明显差异。本文基于“全球30米地表覆盖数据”得到武汉与喀土穆2000、2010年地表覆盖信息,结合高分辨率遥感影像,对城市内地表覆盖类型的时空扩展变化、格局演变及差异进行定量对比,并分析造成这种变化差异的驱动机制。结果表明:1) 十年间武汉高容积率的扩张较为缓慢,呈现边缘式扩张,而喀土穆则是高密度、低层数、低容积率的飞地式高速扩张模式;2) 武汉地表覆盖结构相对合理,但随时间变化人造覆盖扩张开始有占用耕地的现象。喀土穆周边有大面积荒地,新增人造覆盖90%来源于荒地,河流水体与植被所占比重较小,城市生态质量较差。3) 两城市人造扩张受到城市人口数量的直接影响,经济政策因素主要影响其空间扩张方向。

The conversions of urban land cover types reveal human activities on urban spatial morphology and strength characteristics of change of ecological environment, and have a major impact on the quality of living environment. Wuhan and Khartoum, are divided by Yangtze River and Nile—two most important rivers of Asia and Africa, into three parts. There are significant differences in the structure of spatial-temporal evolution and the pattern of land cover in the process of urban expanding. The study based on “the GlobeLand30 Datasets” obtained land cover information of Wuhan and Khartoum in 2000, 2010, combined with high-resolution remote sensing images, compared with the evolution of spatial-temporal expansion and pattern in quantitative, then analyzed this variation of driving mechanism. The results show that: 1) In the decade Wuhan expanded with high volume rate but relatively slow, in an edge expansion model, while Khartoum is showing a high-speed, high-density, low-rise, low-volume ratio in enclave expansion;2) Wuhan land cover structure is relatively reasonable, but farmland is occupied by artificial land expansion as time goes on. Khartoum is surrounded by a large area of wasteland, 90% the new artificial covering comes from the wasteland, and river and vegetation have a poor proportion. 3) Artificial cover expansion of two cities is directly affected by the population, while factors of economy and policy impact on main direction expanded.