Terra/MODIS时间序列数据在湖泊水域面积动态监测中的应用研究——以洞庭湖地区为例

Application of Terra/MODIS Time Series Data in Dynamic Monitoring of Lake Water Area Variations——A Case Study in Dongting Lake Region,China

论文利用2005年Terra/MODIS卫星8天合成的250m地表反射率数据（MODIS Terra Sur-face Reflectance 8-Day L3 Global 250 m：MOD09Q1）构建的时间序列数据集，通过计算NDVI指数，结合典型地物的谱间特征，并借助SRTM数字高程数据，采用多源信息提取的方法对洞庭湖地区2005年水域面积变化进行了动态监测。结合Terra/MODIS数据特点，提出了全年最大淹没时间指数的概念，并通过对该指数的构建，完成了对洞庭湖地区重点水域的淹没风险评价。结果表明：①文中提出的基于Terra/MODIS MOD09Q1数据的多源信息水体提取方法，通过更高空间分辨率ENVISAT/ASAR数据以及水文测站水位数据的检验表明，是切实可行的；②2005年洞庭湖地区水域面积变化特征总体表现为，在11-4月份期间水域面积较小，而在5-10月份期间较大。其中，4月份最小，9月份最大，两者相差了几乎1.5倍，受地区季节性降雨的年内分布规律及长江主汛期的影响显著；③通过全年最大淹没时间指数的计算发现，占研究区总面积84.13%的年内持久陆地和持久水域区域，基本上没有防洪压力，而剩余的15.87%的年内变化水域，由于潜在淹没风险的存在，则需要抗洪防险部门进行重点防控；④文中多源信息水面提取方法的实现以及全年最大淹没时间指数概念的提出，为今后更加深入地探讨三峡工程建成运营对洞庭湖地区水域变化以及江湖关系的影响奠定了基础。

The present research explored the variation of surface water area in Dongting Lake region by utilizing MODIS Terra Surface Reflectance 8-Day L3 Global 250 m （ MOD09Q1 ） dataset in 2005. A multi-source information method was adopted to extract surface water area. This method synthesized several factors such as NDVI, spectrum characters of typical ground objects and the SRTM digital elevation information. In addition, the concept of all-year max-submersion time index was also proposed. The submersion risk evaluation of the major water areas was completed based on this index. The results showed that ： （ 1 ） The validation using ASAR/ENVISAT and site measured water level data indicated that the multi-source information method based on Terra/MODIS MOD09Q1 data was feasible. （2） The main feature of the surface water area was that, the area of the surface water was small from November to April and large from May to October with the area in April the smallest and September the largest. There was an obvious impact from seasonality of precipitation and flood of the Yangtze River. （3） The all-year max-submersion time index indicated that, the persistent land or water bodies took nearly 84.13% of the total area, without the pressure of flood control. But for the rest fluctuating region, measures should be taken for flood control and flood fighting. （4） The method based on multi-source information implementation for water extraction and the concept of all-year max-submersion time index, established a foundation for the further discussion of the impact of Three Gorges Project on Dongting Lake variations and of the relationship between Yangtze River and Dongting Lake.