基于MODIS数据的洞庭湖水面面积估算方法

MODIS-based water surface area estimation method of the Dongting Lake

利用美国Terra卫星上MODIS传感器提供的NDVI数据产品，采用两种方法分别在年和月时间尺度上对2000～2007年间洞庭湖的水面面积进行了估算。在年尺度上，采用ISODATA方法对NDVI时间序列进行非监督分类，区分水面及各种湿地类型，并分析了各类湿地的面积变化趋势。在月尺度上，采用16d平均NDVI数据，通过NDVI阈值提取水面，在不同的季节选取不同的闽值，并将基于NDVI数据得到的水面面积与基于水位一面积曲线得到的水面面积进行了对比分析。在此基础上，探讨了两类不同尺度上分类方法的优点、缺点及适用范围。

Two methods for different timescales based on the NDVI data provided by MODIS/Terra are used for estimating the water surface area of the Lake Dongting from 2000 to 2007.At the annual timescale,the unsupervised classification method of ISODATA is applied to the NDVI time series.Based on the result of classification water surface and various wetland types can be distinguished,and then the changes of the wetlands′ area are analyzed.At the monthly timescale,the 16-day average of NDVI data is used for identifying water surface,and different NDVI threshold is selected for different seasons.The difference of water surface area obtained from monthly timescale NDVI data is compared with the water surface area derived from the water level-area curve.Finally,we discussed the advantage and disadvantage of the two classification methods at annual and monthly timescales.