西藏多庆错湖面变化及原因分析

论文根据1975年地形图、20世纪70年代至2009年7期MSS/TM卫星遥感资料对西藏日喀则地区东南部多庆错、嘎拉错湖泊面积变化进行分析。结果表明,多庆错和嘎拉错湖泊面积波动变化一致,2002年之前,除1976年湖泊面积较小外,其他年份多庆错、嘎拉错湖泊面积分别在80和10 km²以上,2000年湖泊面积最大,2002年之后,两个湖的面积都明显缩小。从冰川变化情况看,近34 a来,虽然该流域周围冰川与高原其他区域冰川变化趋势一致,处于消退状态,但其融水量对湖泊补给作用不明显。该流域气候变化趋势为温度升高、蒸发量减少,降水量呈波动变化。湖泊面积的涨、缩与降水量有较好的正相关关系,而与温度变化呈负相关。综合分析表明,多庆错流域湖泊变化与冰川退缩关系不密切,降水是湖面波动的主要原因。

Study on the Variation of Lake Area and Its Reasons of Duoqing Lake in Tibet

This paper investigated the area variation of Duoqing and Gala lakes in the southwestern part of Xigaze region in Tibet based on the topographic map in 1975 and seven periods of MSS/TM satellite dataset during the 1970s to 2009. Results show that the area of the above two lakes has the same variation trend. Namely, the area of Duoqing and Gala lakes was lager than 80 km² and 10 km² respectively in other years except in 1976 which has smaller areas before the year 2002. Furthermore, the areas reached the maximum value in 2000 and they obviously narrowed the range after 2002. Considering the variation of the glaciers, the supply function of their melt water to the lakes is not evident though the variation of glaciers in the above basin exhibited degrading status as glaciers in other regions of the Tibetan Plateau. The climatic variation trend over the above region has the characteristics of increasing temperature, decreasing evaporation and fluctuation precipitation. The precipitation was positively related to the expansion and shrinkage of lake areas, but negatively related to the air temperature. Comprehensive analysis shows that the variation of lake areas has no close relation with the shrinkage of glaciers and the precipitation was the main reason for the lake area variation.