卫星遥感检测高原湖泊水面变化及与气候变化分析

Plateau lake variation monitored by satellite remote sensing and the relation to climate change

对西藏西部的玛旁雍错、中部的纳木错和南部的普莫雍错三大湖泊地区,采用中巴资源卫星自1999年至2007年长时间序列的影像数据,通过最佳波段组合和时相的选取,高精度几何配准和镶嵌以及进行边缘信息提取等处理,绘制湖面变化解译图。并用一景同期ETM+图像作为辅助数据计算湖区地物光谱反射率曲线以辅助分类。为避免个别年份湖面变化出现偶然性,采用几个相邻年份湖面求取平均值的方法统计近年湖面面积。其结果与1984年中国科学院青藏高原综合科学考察队的数字对比表明,西藏南部的普莫雍错和中部的纳木错湖面有明显扩张,分别扩张了大约4.01%和4.55%;而西部的玛旁雍错近年间变化不大,甚至略有萎缩趋势,相比1984年也仅增长了1.31%。为研究西部地区和中东部地区出现不同变化的主要原因,通过对水位数据和气象特征因子的相关性分析,及对三地区近34年的气象资料,包括年均温度、年均降雨量、年均蒸发量等进行距平均值曲线拟合,发现中东部年均温和降雨量均呈显著增加趋势,而西部降雨量则呈微弱减少趋势。这说明近期湖面的扩张与气象资料分析的变化情况具有很好的一致性,反映遥感方法在湖泊水域变化检测方面具有较高的可用性。

In recent years, the lakes on Tibetan Plateau have significant changes. Based on the satellite data and climate data, this paper analyzes the variation of three inland lakes, Pumoyong Co （at the south of the Tibet）, Nam Co （ at the middle of Tibet） and Mapangyong Co （ on the west of Tibet）. Using CBERS CCD data from the year 1999 to 2006, the paper chooses the best wave bands, performs image progress such as fine correct, image register and mosaic separately, then detects the brim information and draws the change data of these lakes. With an ETM ＋ image of the same period of 2000 as assistant, the paper calculates and draws the spectral reflective curve to identify the change area. For avoiding the contingency, the lake areas of the recent continuous years are used to calculate the average area of each lake. The results show that The Pumoyong Co Lake and Nam Co Lake have expanded about 4.01% and 4.55 % respectively, and the Mapangyong Co Lake does not change much, only 1.31 % compared with the data of the year 1984. This paper also uses the meteorological analysis to find out why the three lakes have changed so differently. Taking the Pumoyong Co Lake for example, the paper calculates the related coefficients of water lever data and temperature, rainfall, evaporation and humidity data of the nineteen years to find main effective factors, which shows that temperature and rainfall have the direct effect on the lake level change. Then the paper analyzes the trend of the meteorological data including average temperature, rainfall, evaporation and humidity per year from the nearest meteorological stations of Langkazi, Dangxiong and Pulan. The result shows that the temperatures of three areas have the ascending trends, but the rainfall appears the different tendencies. The rainfalls at south and middle areas of the Tibet increase significantly, but the west part has a descending trend with about 25.8 % lower than the average data of before the year of 1998. This trend has good consistency to the results of remote sensing detecting, with shows that remote sensing method has high usability on the plateau lake monitoring.