可可西里盐湖湖水外溢可能性初探

Overflow probability of the Salt Lake in Hoh Xil Region

2011年9月可可西里地区卓乃湖溃决后,关于盐湖湖水能否外溢进入楚玛尔河继而成为长江的最北源是公众及学界普遍关注的话题。本研究基于2010-2015年Landsat TM/ETM+/OLI遥感影像、SRTM 1弧秒数据、Google Earth高程数据和五道梁气象台站观测数据,首次对盐湖变化、湖水外溢条件及其可能性进行分析。结果表明:卓乃湖溃决后,盐湖在2011年10月至2013年4月期间面积急剧增加,之后湖泊进入稳定扩张期,2015年10月27日盐湖面积为151.38 km^2,是2010年3月3日湖泊面积的3.35倍。盐湖发生湖水外溢的条件是湖泊面积达到218.90~220.63 km^2。由于SRTM和Google Earth高程数据间的差异,盐湖湖水外溢时的水位将比当前高12 m或9.6 m,相应湖泊库容增加23.71 km3或17.27 km3,届时湖水将由湖泊东侧流入清水河流域。尽管盐湖在未来10年内不可能发生湖水外溢,但是随着盐湖集水区的扩大及预估的区域未来降水量的增加,在更长时间尺度内盐湖发生湖水外溢并成为长江支流的可能性依然存在。

After the bursting of Huiten Nor in Hoh Xil region in September, 2011, the topic on whether the water overflow from the Salt Lake would enter the Chumaer River and become the northernmost source of the Yangtze River has aroused wide concern from public and academic field. Based on Landsat TM/ETM＋/OLI remote sensing images during 2010-2015, SRTM 1 arcsecond data, Google Earth DEM data and the observation data from the Wudaoliang meteorological station, the study analyzed the variation of the Salt Lake and its overflowing condition and probability. The results showed that the area of the Salt Lake expanded sharply from October 2011 to April 2013, and then it stepped into a stable expansion period. On October 27, 2015, the area of the Salt Lake reached an area of 151.38 km^2, or about 3.35 times that of the lake on March 3, 2010. The Salt Lake will overflow when its area reaches the range from 218.90 km^2 to 220.63 km^2. Due to the differences of the data between SRTM and Google Earth DEM, the water level of the Salt Lake modeled would be 12 m or 9.6 m higher than the current level when the lake overflowed, and its capacity would increase by 23.71 km3 or 17.27km3, respectively. Meanwhile, the overflowed water of the Salt Lake would run into the Qingshui River basin from its eastern part. Although the Salt Lake does not overflow in the coming ten years, with watershed expansion of the Salt Lake and the projected precipitation increase in Hoh Xil region, that fact that the probability of water overflow from the Salt Lake and the lake is becoming a tributary of the Yangtze River will exist in the long term.