Lakes on the Tibetan Plateau play critical roles in the water cycle of the ecological and environmental systems of the Plateau. A better understanding of lake variations on the Tibetan Plateau is important for evaluating climate change and regional environment consequence under global warming. In this paper, as a typical inland lake and one of three holy lakes on the Tibetan Plateau , as well as a scenic spot in southern Tibetan Plateau, variations of Yamzho Yumco area from 1972 to 2010 and main factors controlling the variations are analyzed using remote sensing and CIS technologies in combination with climate data of meteorological stations within the basin. The results show that mean lake area is 643.98 km2 and mean perimeter is 709. 41 km from 1972 to 2010. The lake areas generally have been decreasing from 1972 to 2010. Specifically, the lake area in the 1970s was 658.78 km2rnwith the highest record of 678.42 km2 in 1972; the lake areas were 636.55 km2 and 635.06 km2 in the 1980s and 1990s, respectively. There is an increasing trend from 1999 to 2004. Hie year 2004 is a turning point for lake area variations, which is the end of increasing since 1999 and the starting point to decease until 2010. The lake areas have been significantly decreasing since 2004 with the mean annual decreasing rate(MADR) of8.59km2/a, which is higher than MADR of 6.85 km2 from 1972 to 1999. Especially, the smallest lake area, 600.26 km2, was recorded in 2010. The gap between the largest in 1972 and the smallest in 2010 for lake areas is 78.16 km2 with 11.52% of net areas in decease. The spatial variations of lake areas are characterized by the general shrinking trend from 1972 to 2010. Particularly, the shrinking distance reached 1. 62 km in eastern part of the lake with 42.63 m/a and 1.52 km in northwestern part of the lake with 40.00 m/a. The area variations of the lake are mainly caused by precipitation fluctuation and the increasing evaporation within the basin. Especially, dramatic increasing in evaporation from 2004 is dedicated to shrinking in lake area, and the significant temperature increases through increasing evaporation accelerate this process. Therefore, the area variation of Yamzho Yumco reflects the response of inland lake mainly supplied by rainfall in semi arid climate zone in Tibetan Plateau to climate change. The impact of human activity and the engineering measures, such power plant construction, on the lake area variation is limited. However, if the design goal of the Yamzho Yumco Pumped Storage Power Station to keep the water in balance between the lake and the river is not fulfilled, the impact of the power station on water volume and lake areas should also be considered.%羊卓雍错(以下简称羊湖)作为西藏高原三大圣湖之一和藏南重要的高原特色风景旅游景区,其具体面积众说纷纭.本文利用遥感和地理信息空间分析方法对1972-2010年羊湖面积变化进行了系统研究,并结合流域气象站资料对其原因进行初步分析.结果表明,1972-2010年湖泊平均面积为643.98 km2.1972-2010年羊湖面积呈波动式减少趋势,其中,1970s平均面积为658.78 km2,之后至1999年面积显著减少；1980s面积为636.55 km2；1990s为635.06km2;1999-2004年面积有所增加；2004-2010年持续缩小,减幅为8.59 km2/a.湖泊空间变化特点是除了空母错和珍错两个小湖面积变化较小之外,羊湖整体面积呈现萎缩态势,其中东部嘎马林曲入口附近退缩程度最大,达1.62 km.流域气象站资料分析表明,湖泊面积和降水的变化波动存在显著耦合关系,降水变化是羊湖面积变化的主要原因；其次,流域蒸发量的明显增加,特别是2004年来连续较高的蒸发量是导致近期面积显著减少的重要原因,气温的升高进一步加剧了这一过程.羊湖的面积变化基本反映了西藏高原南部半干旱季风气候区以降水补给为主的高原内陆湖泊对气候变化的响应.
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