鄱阳湖天然湖面遥感监测及其与水位关系研究

以1989—2010年鄱阳湖100期(景)Landsat TM/ETM+影像为数据源,对比分析了水体指数法和谱间关系法两种主要的水体提取方法,利用水体指数法提取了天然湖体水面面积,揭示了不同水位下鄱阳湖天然湖体水面的空间扩展过程与特征,建立了汛期与非汛期水面-水位关系模型并确定了相应代表性水位站。结果表明:①在鄱阳湖,水体指数法水体提取精度优于谱间关系法;②受地形影响,不同水位条件下鄱阳湖天然水面的空间扩展特征大致呈"菱形"沿湖岸以顺时针方向(即:北→东→南→西→北)推进;③水位为6~15 m时,鄱阳湖天然湖体水面随水位变化呈线性变化,水面变化显著;而在水位介于15~22 m时,天然湖体水面随水位变化则呈对数变化。基于水面-水位关系模型,确定汛期代表性水位站为星子站、都昌站与吴城站;而非汛期代表性水位站为棠荫站。

Natural Water Surface of Poyang Lake Monitoring Based on Remote Sensing and the Relationship with Water Level

Using one hundred Landsat TM/ETM+scenes (Path/row 121/40) from 1989 to 2010 which cover the Poyang Lake, this paper firstly made a comparison of the two major methods for water body extraction. With the natural water surface area of Poyang Lake derived from satellite imagery by water body extraction index, it then investigated the process and feature of spatial extension of inundation of Poyang Lake under different water levels. Combining the observed hydrological data, the relational models between natural water surface area and water level of major hydrological stations of Poyang Lake during flood and non-flood seasons were established. According to the relation models, the corresponding representative hydrological stations were determined. The results showed that: 1) the water body extraction index (i. e. Modification of Normalized Difference Water Index, MNDWI) approach performed better than that of spectrum-photometric method for the water body discrimination of Poyang Lake. 2) Under different water-level scenarios, the natural water surface of Poyang Lake expanded along the lakeshore as a rhombus shape in a clockwise direction (i. e. north→east→south→west→north). 3) During low water-level (6-15 m) period, natural water surface area was significantly linearly related to water level. Whereas during high water-level (over 15 m) period, natural water surface area varied logarithmically with water level. The relational models of water surface and water level indicated that the most representative gauging stations during flood season are Xingzi, Duchang, and Wucheng, while the most representative gauging station during non-flood season was Tangyin.