上海近十年来城市化及其生态环境变化的评估研究

摘要

In this paper, some change detection methods were used for assessment of urbanization and ecosystem changes. The urbanization area index (UAI) derived from land cover was used to reflect the speed of urban expansion, while the fraction of vegetation cover ( FVC ) retrieved from NDVI was used to represent the status of urban ecologic environment. The NDVI time series were derived from MOD13Q1 by using an annual stacking approach. Land cover maps were retrieved from annual NDVI time series from 2000 to 2009. This paper focused on the assessment study of urbanization level and ecologic environment changes in Shanghai. The results indicate that:(1) the urban area of Shanghai increased continuously in the past 10 years; (2) the UAI increased by an annual average rate of more than 1.73％, with its peak value being 4.36％ during 2008 -2009; (3) on the whole, FVC decreased continuously over the past decade, while the FVC of the urban area increased slightly and the FVC of some islands and outer suburbs increased slightly too; (4) the urban ecologic environment of Shanghai became more and more “green” at the cost of decreased cropland and natural vegetation cover. The assessment of urbanization and ecosystem changes suggests that suburban ecosystem protection is an important and urgent problem and the government should implement more effective environmental management policies.%为了了解上海近十年来的变化,应用遥感变化检测方法来评估研究近十年来上海的城市范围及城市生态方面的扩展和变化,即一方面利用从土地覆盖衍生出的城市化面积指数(UAI)来反映城市扩展的速度,另一方面应用植被覆盖率(FVC)变化来评估城市生态环境的演变.研究中,首先对2000～2009年的MOD13Q1影像按照年叠加反演出.NDVI时间序列,然后分析得到每年土地覆盖图和植被覆盖率图,最后逐年进行变化分析.研究表明,近十年来,上海发生以下变化:①城市化范围持续扩展;②城市化面积指数年均增长率在1.73%以上,2008～2009年度最高达4.36%;③植被覆盖率总体上持续降低,但在建成区、远郊和岛屿区域植被覆盖率略有上升;④建成区的"变绿"是建立在耕地、植被减少为代价的基础上.