1975-2013年西藏佩枯错湖面变化及分析

根据1975年地形图、1970s末至2013年19期Landsat（MSS、TM、ETM⁺）陆地资源卫星和20032009年ICESat卫星数据，以及近40年气象资料，对西藏佩枯错湖泊面积变化进行分析.结果表明，湖泊面积、湖泊高度变化波动较大，均呈减少和退缩趋势.19752013年间湖泊面积减少10.68 km²，减幅为3.79%.从空间动态变化来看，变化较明显的区域位于该湖的南岸和东北岸，南岸、东北岸湖岸线分别向北、向西南萎缩.20032009年湖面高度和湖泊面积均呈现出下降趋势，分别下降了0.17 m和4.4 km².19992013年之间对该流域湖泊有影响的冰川变化分析显示，冰川呈现出退缩、面积减少趋势.数据显示冰川面积总共减少了17.17 km²，减少率为7.91%.自1971年以来，流域气温总体呈上升趋势，2000年以后升温显著.佩枯错43 a来降水量年际变化波动较大，年降水量呈减少趋势，总的来说降水量每10 a减少6.99 mm.虽然佩枯错属于降水和冰雪融水补给湖泊，但该流域湖面增减与周围冰川变化的关系并不明显，与温度变化呈负相关，而与流域内降水量呈正相关.综合分析表明，佩枯错流域湖泊变化与冰川退缩关系不密切，降水量是湖泊变化的主要原因.

Lake area variation of Peiku Tso(lake) in 1975-2013 and its influential factors

In this study, the variation in area of Peiku Tso in Tibet is investigated, mainly based on the topographic map in 1975, nineteen scenes of Landsat (MSS, TM, ETM⁺) satellite images beginning the late 1970s through 2013, ICESat satellite data during the period of 2003 to 2009, along with 43 years of meteorological data near the lake. Results show that the lake area experienced a decreasing trend, so did the elevation of lake. In particular, the area was reduced by 10.68 km² (3.79%) during the period of 1975-2013. The spatial pattern concerning the times series of lake area maps indicates that the region with striking changes is located in the southern and the northeast part of Peiku Tso, where the water body shrinks toward north and southwest, respectively. Similarly, both the elevation and area of Peiku Tso exhibited a decreasing trend during the 2003-2009 years, respectively decreasing 0.17 m,4.4 km². The annual mean temperature exhibited upward trend and the mean annual precipitation saw downward trend in the watershed of Peiku Tso during the last 40 years. The precipitation was positively related to the shrinkage of lake area, but negatively to the temperature. Therefore, we infer that the decreasing precipitation is likely to be the main factor of the lake shrinking. Considering the variation of the glaciers, the supply function of their melt water to the lake is not evident though the variation of the glaciers in the above basin exhibited degrading status as glaciers in other regions of the Tibetan Plateau.