基于高分辨卫星影像的城市用地不透水率分析

Impervious Surface Coverage in Urban Land Use Based on High Resolution Satellite Images

不透水地面是城市地区的特征，它与总用地的比值～不透水率作为一个重要的城市生态指数常出现于城市水文、城市水质面源污染以度城市植被制图等研究中。本文借助高分辨率卫星影像首次在我国城市中心城区尺度上探索土地利用的不透水性。基于对南京5个典型城市功能区中555个有效用地斑块样本的不透水率数据的分析表明。不同土地利用类型的不透水率在统计上存在显著性差异，建设用地中绿地的不透水率最低（0％～30％），市政设施用地的不透水率最高（80％，100％），居住与道路广场用地的不透水率接近，而工业用地的不透水率相对较低（40％～75％），平均城市建设用地不透水率约69％。该结果填补我国城市用地不透水率研究的空白，为城市水文模拟研究提供下垫面参数。并可望用于城市土地利用的生态规划。

Impervious land cover characterizes urban areas. Its ratio to the total land area has frequently appeared in research reports of urban hydrology, water pollution and urban vegetation mapping, etc. as an important ecological indicator of the city. Based on high-resolution satellite image and RS and GIS technologies, this paper explores imperviousness of land patches at the scale of urban buih-up area in Chinese cities for the first time. Five urban zones related to land use were selected including West Beijing Road zone dominated by institutional land, Nanhu zone dominated by residential land, Yanziji zone dominated by industrial land and Xinjiekou and Fuzimiao zones dominated by commercial-residential land. The average impervious surface coverage of the five sampling zones was calculated. The result shows that two commercial-residential zones hold higher impervious surface coverage and the institutional and industrial zones are with lower impervious surface coverage and the residential zone is in mediacy. 555 patches of land use out of the five zones were examined of impervious surface coverage, which cover six construction land use types including residential, public facility, industrial, municipal utility, road and central square and green space, and three non-construction land uses such as farm, water and unused land. The statistical analysis with the 555 cases notes that the two variables of impervious surface coverage are related, and the impervious surface coverage is significantly varied by land uses. The land used for municipal utility hold the highest impervious surface coverage among 6 urban land uses, 80% ~ 100%; the green space hold the lowest, about 0% - 30% ; the impervious surface cover about 65% ~ 100% of the public facility land, 55 % - 85 % of the road and square, 50 % ~ 95 % of the residential land, and 40% ~ 75% of the industrial land; and the impervious surface coverage is 69% in average for the urban construction land. Compared with US and Australia cities, the impervious surface coverage in Nanjing city is similar to that of them in middle-high density residential land and commercial land, and it is significantly different in low-density residential land and industrial land. Due to the compact form of Chinese cities the low-density residential land use type that frequently occurs in US cities sparsely exists in Chinese cities. The garden factory that holds low impervious surface and usually occurs in Chinese cities can hardly be found in US cities. For the different city form and land use features, some constant parameters in foreign urban hydrology models should be adjusted with the references of Chinese cities when they are adopted in China. The results of this paper can provide local information of imperviousness for modeling researches of urban hydrology in Chinese cities, and facilitate the ecological planning of urban land use.