基于MODIS遥感影像数据的洞庭湖蓄水量估算

以洞庭湖为研究对象,应用MODIS遥感影像、水位以及湖底DEM数据估算洞庭湖蓄水量.根据水体在近红外和红外波段的吸收特性,通过对MODIS数据NDVI指数和NIR波段分别设置阈值的方法来实现对洞庭湖水面的动态提取.根据洞庭湖流域各水文/水位站的水位数据,进行空间插值,得到洞庭湖多个时段的水位空间分布.结合洞庭湖水面提取数据、水位插值数据和湖底DEM,估算洞庭湖蓄水量,并以此初步分析三峡截流前后洞庭湖流域的水文响应.结果显示,该方法能有效实现对洞庭湖蓄水量的估算,计算得出的水面面积、蓄水量有明显的相关性;洞庭湖蓄水量与城陵矶水位呈现明显的3次曲线关系,截流前后3年拟合方程决定系数分别达到了0.915和0.928;截流后三峡工程调蓄功能初显,连续3年洞庭湖汛期累积水量占全年水量比重减小;与此同时夏末秋初三峡水库蓄水,下泄水量减少加剧了2006年洞庭湖流域夏秋连旱的影响.

Estimation of the Water Volume of the Dongting Lake with TERRA/MODIS Data

This paper studied the water volume of the Dongting Lake by using Terra/MODIS satellite data,water level and lake bottom DEM(Digital Elevation Model).As water has a high absorption rate in the near infrared and infrared band,the water area of the Dongting Lake was extracted by setting thresholds on NDVI(Normalized Difference Vegetation Index) and NIR(Near InfraRed).A water level distribution map was obtained by interpolating the water level data from hydrological stations.The volume of the Dongting Lake was estimated by using the water area map,the water level distribution map and the lake bottom DEM.The hydrological response of the Dongting Lake on the Three Gorges was studied by using the water level,area,and volume data.The result has shown that the method mentioned above can be used for water volume estimation of the Dongting Lake.The water area,water volume and water level have a high correlation.The water level of Chenglingji and water volume of the Dongting Lake was fitted by cubic curve,and the coefficients of the determination of the fitting curves were 0.915 and 0.928,respectively.The Three Gorges Project has shown the ability of flood storage after interception,and the cumulative water volume ratio of flood season decreased year by year from 2004 to 2006.At the same time,during late summer and early autumn,the impoundment of the Three Gorges Project causes the decrease of water discharged,which increases the drought of the Dongting Lake.