摘要
湖泊是气候、水和生物地球化学循环的关键组分,遥感观测有助于获得湖泊面积变化及对环境的响应信息。本文基于长时间序列遥感观测提出了一种利用像元水淹没/陆地出露比例的湖面变化分析算法,并应用于鄱阳湖的湖面提取及变化分析。首先,用全年遥感数据合成获得当年最大湖面;然后,在此最大湖面范围内,识别出每景数据的水体和陆地状态;最后,统计一定时期内每个像元的水淹没比例,并据此分析湖泊的年际和季节变化特征。该算法的最大优势是克服了云的干扰,以及湖面快速变化造成的年际变化对比分析困难问题。算法应用于2000-2010年MODIS观测,分析结果表明,本算法检测出的湖面面积与鄱阳湖水文站水位观测资料非常一致;算法可以获得鄱阳湖湖面面积的显著季节变化信息;2000-2010年间,鄱阳湖湖面面积在丰水期未发现有规律的变化;在枯水期,2003年后湖面面积急剧减小。
Poyang Lake is the largest freshwater lake in China and is of great important in flood regulation. It is critical to monitor its long-term change to understand the condition and variation of Poyang Lake and to evaluate its response to climate change and human activities. In this paper, an algorithm for extracting water area of Poy- ang Lake using MODIS land surface reflectance data is presented. Firstly, the maximum water area is acquired based on composition of the minimum land surface reflectance in red band for each year. Then, only those pixels in the maximum water coverage region are identified as the water or land status with MODIS land surface reflec- tance in green, near-infrared and shortwave channels. Lastly, the water coverage fraction is calculated during cer- tain periods and used to analyze the seasonal and annual variations of Poyang Lake. This algorithm could elimi- nate the impacts of cloud contamination and rapid seasonal change of lake water area on this analysis. The water area were extracted and analyzed from MODIS 8-day land surface reflectance observations （MOD09A1） during 2000 to 2010. The results show that the water area of Poyang Lake based on our algorithm is of high consistency to the hydrological observations at local sites. The algorithm could represent the significant seasonal variations of the water area of Poyang Lake. From April to September, the lake is vast due to the abundant water from Poy- ang Lake basin and Yangtze River. From October to March in the next year, the lake shrinks significantly. The minimum water area occurs in January, while it is in July for the maximum water area. During 2000 to 2010, no significant change of the water area of Poyang Lake is found during the flood season. After 2003, the lake shows a noticeable decrease in its water area during the dry season.
出处
《地球信息科学学报》
CSCD
北大核心
2013年第3期469-475,共7页
Journal of Geo-information Science
基金
气象行业科研专项(GYHY201106014)
博士后面上基金项目(2012M510343)
