城市不透水面信息提取及水环境效应分析——以武汉市江南三区为例

利用ETM~+和Landsat8数据,以武汉市江南三区为研究对象,采用光谱混合分解模型估算不透水面信息在空间和时间上的变化情况,并分析其水环境效应.通过MNF变换和PPI指数运算,确定高、低反照率、植被及土壤4类光谱端元,利用Landsat8新增的卷云波段去除云、土壤、沙地等噪声,利用MNDWI指数去除水体,修正后的高、低反照率组分之和即为不透水面分布估计值.结果表明:研究区14年间不透水面总体随着围湖垦殖呈放射状扩张,面积增加了52.6km2;从短期和长期两个层面,不透水面深刻地影响了城市地区的水文环境,包括地表径流的时空模式、水文循环过程,以及局部小气候;不透水面对城市地区非点源污染也具有较大影响.

Urban Impervious Surface Extraction and Its Effect on Water Environment---A case study in three districts of Wuhan city

Using ETM+and Landsat8 data,three south districts in Wuhan city were chosen as the research area.The impervious surface changes on the space and time was estimated using the decomposition model of mixed pixels,and the related effect on water environment was analyzed.Through the MNF transform and PPI index calculation,four kinds of spectral endmembers including high and low albedo ground,vegetation and soil were identified.The new band of Landsat8:the Cirrus was used to remove the "noise"such as cloud,soil,sand,and MNDWI index was used to remove water area.Through the addition of high and low albedo components,the distribution of impervious surface could be gotten.The result showed that in the past 14 years,the coverage of impervious surface appeared as radial expansion with development of urbanization due to filling in the lake and reclamation.Area increased 52.6km2;no matter from the perspective of short-term or long-term,impervious surface deeply affected the hydrological environment of urban areas,including surface runoff mode,water cycle process,and the local microclimate;in addition,impervious surface also had a great influence on non-point source pollution in urban areas.