2005～2017年快速城市化背景下洱海流域不透水表面时空格局分析

Temporal and Spatial Pattern Analysis of Impervious Surface in Erhai Lake Basin under the Background of Rapid Urbanization from 2005 to 2017

近年来随着中国经济建设的不断加快以及城市化的快速发展,工业和人口的大规模聚集造成了不透水表面的快速扩张,这对城市生态环境产生了严重的影响。作为城市化水平的关键指示因子,不透水表面已经被广泛应用在城市生态环境评估中。为了定量的分析洱海流域不透水表面拓展的时空动态特征规律,以大理市所在的洱海流域为研究对象,利用2005~2017年的大理市Landsat 5、Landsat 8遥感影像,提取基于改进的归一化水体指数(modified normalized difference water index,MNDWI)和归一化差值不透水表面指数(normalized difference impermeable surface index,NDISI)对洱海流域的城市、道路进行空间分析并提取出不透水表面信息进行空间格局分析。研究结果表明:2005~2017年,随着城市化的快速发展,洱海流域的植被覆盖率和水体等自然地物覆盖率处于下降状态,而不透水覆盖率从11.6%上升到19.8%,呈现快速持续上升趋势。由洱海水质和其流域内不透水覆盖率线性拟合结果可以得到两者具有一定的负相关性。可以预见洱海水质未来发展中随着不透水覆盖率的增长而下降。因此,在城市发展的同时,应该注重对洱海的综合治理,不能任水质自行调节。本研究结果为洱海流域内城市规划管理和流域水环境治理提供参考信息,具有重要的现实意义。

With the continuous acceleration of China's economic construction and the rapid development of urbanization,the large-scale accumulation of industry and population has caused the rapid expansion of the impervious surface,and has also had a serious impact on the urban ecological environment.As a key indicator of urbanization level,impervious surface has been widely used in urban ecological environment assessment.The Erhai river basin where Dali City is located is taken as the research object,and the Landsat 5 and Landsat 8 remote sensing images of Dali City from 2005 to 2017 is used to quantitatively analyze the temporal and spatial dynamic characteristics of the impervious surface expansion in the Erhai basin.The modified normalized difference water index (MNDWI) and the normalized difference impermeable surface index (NDISI) are used to spatially analyses the cities and roads in the Erhai river basin and extracts the impervious surface information for spatial pattern analysis.The results show that with the rapid development of urbanization from 2005 to 2017,the vegetation coverage and water coverage of the Erhai river basin are declining,while the impervious coverage rate rises from 11.6% to 19.8%,showing a rapid and sustained upward trend.From linear fitting results of Erhai water quality and impermeable coverage in the basin,it can be concluded that there is a certain negative correlation between them.It can be predicted that the future development of Erhai water quality will decrease with the increase of impervious coverage.Therefore,at the same time of urban development,we should pay attention to the comprehensive management of Erhai lake and not allow the water quality to adjust itself.The results of this study provide reference information for urban planning management and watershed water environmental management in Erhai watershed,and have important practical significance.