Nie Yong, Liu Qiao, Liu Shiyin
Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China.
State Key Laboratory of Cryosphere Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, China.
PLoS One. 2013 Dec 20;8(12):e83973. doi: 10.1371/journal.pone.0083973. eCollection 2013.
Glacial lake outburst flood (GLOF) is a serious hazard in high, mountainous regions. In the Himalayas, catastrophic risks of GLOFs have increased in recent years because most Himalayan glaciers have experienced remarkable downwasting under a warming climate. However, current knowledge about the distribution and recent changes in glacial lakes within the central Himalaya mountain range is still limited. Here, we conducted a systematic investigation of the glacial lakes within the entire central Himalaya range by using an object-oriented image processing method based on the Landsat Thematic Mapper (TM) or Enhanced Thematic Mapper (ETM) images from 1990 to 2010. We extracted the lake boundaries for four time points (1990, 2000, 2005 and 2010) and used a time series inspection method combined with a consistent spatial resolution of Landsat images that consistently revealed lake expansion. Our results show that the glacial lakes expanded rapidly by 17.11% from 1990 to 2010. The pre-existing, larger glacial lakes, rather than the newly formed lakes, contributed most to the areal expansion. The greatest expansions occurred at the altitudinal zones between 4800 m and 5600 m at the north side of the main Himalayan range and between 4500 m and 5600 m at the south side, respectively. Based on the expansion rate, area and type of glacial lakes, we identified 67 rapidly expanding glacial lakes in the central Himalayan region that need to be closely monitored in the future. The warming and increasing amounts of light-absorbing constituents of snow and ice could have accelerated the melting that directly affected the glacial lake expansion. Across the main central Himalayas, glacial lakes at the north side show more remarkable expansion than those at the south side. An effective monitoring and warning system for critical glacial lakes is urgently needed.
冰川湖突发洪水（GLOF）是高山地区的一种严重灾害。在喜马拉雅山脉，近年来GLOF的灾难性风险有所增加，因为在气候变暖的情况下，大多数喜马拉雅冰川经历了显著的消退。然而，目前关于喜马拉雅山脉中部冰川湖的分布及其近期变化的了解仍然有限。在此，我们基于1990年至2010年的陆地卫星专题制图仪（TM）或增强型专题制图仪（ETM）图像，采用面向对象的图像处理方法，对整个喜马拉雅山脉中部的冰川湖进行了系统调查。我们提取了四个时间点（1990年、2000年、2005年和2010年）的湖泊边界，并使用了一种时间序列检查方法，结合陆地卫星图像一致的空间分辨率，持续揭示了湖泊的扩张情况。我们的结果表明，1990年至2010年期间，冰川湖迅速扩张了17.11%。面积扩张主要是由既有的较大冰川湖而非新形成的湖泊造成的。最大的扩张分别发生在喜马拉雅山脉主脉北侧海拔4800米至5600米的区域以及南侧海拔4500米至5600米的区域。根据冰川湖的扩张速率、面积和类型，我们在喜马拉雅山脉中部地区识别出67个迅速扩张的冰川湖，未来需要对其进行密切监测。冰雪中吸光成分的增加和变暖可能加速了融化，直接影响了冰川湖的扩张。在整个喜马拉雅山脉中部，北侧的冰川湖比南侧的表现出更显著的扩张。迫切需要建立一个针对关键冰川湖的有效监测和预警系统。
