Glacial Lakes Become More Deadly as Himalayan Ice Melts
喜马拉雅冰川融化加大冰川湖威胁
Researchers map the most dangerous lakes and call on China and Nepal to work together to reduce the threat of catastrophic flooding
研究人员为最高风险的湖泊绘制了地图，并呼吁中国和尼泊尔两国共同努力，减少洪灾的威胁。
New research has identified 47 Himalayan lakes that are critically dangerous and could burst, flooding downstream areas in China, Nepal and India.
最新研究发现喜马拉雅地区有47个极具危险性的湖泊，它们可能会决堤，造成下游地区洪水泛滥。
“Altogether, 3,624 glacial lakes were mapped in the Koshi, Gandaki and Karnali river basins of Nepal, China and India,” said Sudan Bikash Maharjan, one of the authors of the report, which was jointly produced by the International Centre of Integrated Mountain Development (ICIMOD) and the United Nations Development Programme in Nepal.
该报告的作者之一苏丹·比卡什·马哈然（Sudan Bikash Maharjan）表示：“在中国、尼泊尔和印度三国的波曲河、甘达基河和卡纳利河流域，共发现了3624个冰川湖。”该报告由国际山地综合开发中心（ICIMOD）与联合国开发计划署尼泊尔办事处联合发布。
“Of these, 1,410 lakes are equal to or larger than 0.02 square kilometres [2 hectares]… large enough to cause serious damage downstream if they burst. However, 47 need immediate mitigation action.” Twenty-five of these are in the Tibet Autonomous Region of China, 21 are in Nepal and one is in India.
“其中有1410个湖泊面积大于或等于0.02平方公里（2公顷），如此大面积的湖泊，一旦决堤，会对下游造成严重破坏。但是，有47个湖泊需立即采取减灾措施。”其中有25个位于中国，21个位于尼泊尔，1个在印度。
Expanding lakes increase the risks of outburst floods – sudden surges of water that can wreak havoc on mountain communities. A 2011 study by ICIMOD reported 24 outburst floods affecting Nepal since the 1980s – 14 in Nepal itself, and 10 caused by flood surges across the China-Nepal border. Such events result in loss of life, houses, livestock and infrastructure, and can cause millions of dollars of damage.
湖泊不断扩大增加了溃决洪水的风险：大量湖水突泄会对山地住区造成严重破坏。2011年ICIMOD的一项研究报告称，上世纪80年代以来，尼泊尔共遭受了24场洪水的侵袭，其中14起发生在尼泊尔境内，另外10起发生在中国与尼泊尔边境。洪水会夺去人们的生命，摧毁房屋、牲畜和基础设施，能够造成数百万美元的损失。
Melting glaciers, growing lakes
冰川融化，湖泊增加
Several studies have shown that glacier-covered areas in the Himalayas have decreased significantly in the past three decades as temperatures have risen by more than double the global average. If global average temperature rises above 1.5C by 2100, two-thirds of glacier ice in the Himalayas will be lost. As glaciers melt, new lakes have formed and existing ones have expanded.
几项研究表明，由于喜马拉雅地区的气温上升幅度是全球平均水平的两倍多，当地冰川覆盖的区域在过去三十年中已大大减少。如果到2100年全球平均温度上升超过1.5摄氏度，那么喜马拉雅冰川将有三分之二消失。随着冰川融化，新的湖泊形成，旧的湖泊面积扩大。
“Glacial lakes tend to grow in response to higher glacier melt. This can increase the hydrostatic pressure, which can cause structurally weak and unstable dams to breach suddenly. This can result in a sudden, high discharge of debris and water in a few hours, causing catastrophic floods,” said Deepak K.C, a senior climate risk management expert at UNDP Nepal.
“冰川融化速度加快，冰川湖的水量一般会随之增加，这样一来静水压力就会增加，从而可能导致结构脆弱且不稳定的坝体突然决堤，碎石和水突然在几个小时内大量倾泻，造成灾难性洪灾。”联合国开发计划署尼泊尔高级气候风险管理专家迪帕克·K.C（Deepak K.C）说道。
A recent study by NASA found that globally the volume of glacier lakes increased by almost 50% between 1990 and 2018.
美国国家航空航天局（NASA）最近的一项研究发现，1990年至2018年间，全球冰川湖的数量增加了近50%。
In the three river basins that form the Ganga river, the total area of glacial lakes has increased from 179 square kilometres in 2000 to 195 square kilometres in 2015.
在形成恒河的三个流域中，冰川湖的总面积从2000年的179平方公里增加到2015年的195平方公里。
The glacial lakes mapped in the ICIMOD report range from 3,400 to 6,100 metres above sea level. Beyond this altitude, landforms are too steep and cold for permanent lakes to form.
ICIMOD报告中绘制的冰川湖都位于海拔3400至6100米之间。超过此高度，地形过于陡峭和寒冷，无法形成永久性湖泊。
The researchers classified the 47 most dangerous lakes into three ranks of risk, based on remote sensing and past studies – though they said it was not possible to rank them precisely.
根据遥感和过去的研究，研究人员将47个最危险的湖泊分为三个风险等级，尽管他们称不可能对它们进行精准的排序。
“Outburst [floods] can occur that have no precedent, especially in view of the current atmospheric warming,” said Samjwal Ratna Bajracharya, another author of the report.
该报告的另一作者萨姆瓦尔·拉特纳·巴吉拉查娅（Samjwal Ratna Bajracharya）说：“爆发（洪水）可能会是史无前例的，特别是考虑到当前的气候变暖形势。”
“The [lakes] under rank I have a greater possibility of expansion, are dammed by loose moraine material, and could experience snow and/or ice avalanches and landslides in their surroundings that may impact the lake and the dam. A slight rise in the water levels of these lakes or a reduction in the strength of their dams could cause a breach. The lakes classed under ranks II and III have the potential to grow, and hence need close and regular monitoring,” added Bajracharya.
“被列为等级I的[湖泊]扩大的可能性更大，其坝体为冰碛物且结构松散，周围可能会发生雪崩和/或冰崩，以及滑坡，会影响湖泊和坝体。这些湖泊水位轻微上升或坝体强度降低都可能导致溃决。巴吉拉查娅补充说，等级II级和等级III的湖泊具有扩大的潜力，因此需要定期进行密切的监测。
Of the 47 lakes, 31 are classed as rank I, 12 as rank II and four as rank III.
在47个湖泊中，有31个被划为I级，12个被划为II级，4个被划为III级。
Koshi – A hotspot for dangerous lakes
危险冰川湖集中区
The report says the Koshi river basin – a major tributary of the Ganga – is a growing hotspot for dangerous glacial lakes in the Himalayas. Forty two out of the 47 potentially dangerous lakes are in the Koshi basin.
这份报告称，恒河的主要支流波曲河流域正成为喜马拉雅地区危险冰川湖泊最集中的焦点地区。47个存在潜在危险的湖泊中，有42个位于波曲河流域。
The Koshi basin also has most glacial lakes.
波曲河流域也是冰川湖泊数量最多的地区。
Between 2000 and 2015, the total area of glacial lakes in the Koshi basin increased by 12%, 8% in the Gandaki basin, and 1.27% in the Karnali basin.
2000年至2015年之间，波曲河流域的冰川湖总面积增加了12%，甘达基流域增加了8%，卡纳利流域增加了1.27%。
The overall number of glacial lakes has decreased in the Koshi basin from 2,119 in 2000 to 2,064 in 2015, as smaller glacier lakes have merged. “But the overall lake area has increased,” added Arun Bhakta Shrestha, another member of the ICIMOD research team.
由于较小的冰川湖合并，波曲河流域的冰川湖总数从2000年的2119个减少到2015年的2064个。ICIMOD研究小组的另一位成员阿伦·巴克塔·什雷斯塔（Arun Bhakta Shrestha）补充说：“但是湖泊总面积增加了。”
Transboundary cooperation – A must
跨界合作必不可少
More than 50% of the dangerous lakes identified by ICIMOD are in Tibet.
ICIMOD确定的高风险湖泊中有50%以上位于中国西藏自治区境内。
A study published in June by Chinese researchers mapped 654 glacier lakes in the Tibetan Plateau of China. It identified 246 of them as dangerous.
中国研究人员在6月发表的一项研究中绘制了中国青藏高原的654个冰川湖泊的地图。发现其中246个处于危险状态。
“We not only analysed the characteristics of the lakes, such as coverage area and growth speed, but also considered if there are communities and infrastructure downstream,” said Wang Shijin, an associate researcher at the Chinese Academy of Sciences and one of the authors of the study.
“我们不仅分析了湖泊的特征，例如覆盖面积和面积扩张率，还考虑了下游是否有居民点和基础设施。”中国科学院副研究员、本项研究的作者之一王世金表示。
Liu Shiyin, a researcher at the Institute of International Rivers and Eco-security at Yunnan University, said that mitigation measures are already being planned at some high-risk glacier lakes. “This will also reduce the risks for countries downstream,” Liu added.
云南大学国际河流与生态安全研究所研究员刘时银说，一些冰湖的治理已在计划中。他补充说：“这些努力也是保障尼泊尔境内居民安全的举措。”
Experts have urged countries for more cooperation in monitoring glacial lakes and reducing the risks they pose. “We have consulted with some research agencies in China including the Chinese Academy of Sciences with whom we have a good relationship. We are hoping to do more field studies together to validate this information,” said David Molden, director-general of ICIMOD.
专家敦促各国加强合作，对冰川湖进行监测，降低其风险。“我们已经与包括中科院在内的一些中国研究机构进行了协商。我们与他们的关系很好。我们希望共同开展更多的实地研究，以验证这些信息。”ICIMOD总干事戴维·莫尔登（David Molden）表示。
Wang said that researchers in upstream and downstream countries should work together to address the problem. “Assessing the outburst risk of high-risk glacier lakes in China, the upstream country of the rivers, could provide scientific analysis for the countries downstream,” he said. ICIMOD has made efforts to foster more cooperation, but geopolitical tensions in the region have got in the way.
王世金表示，上游和下游国家的研究人员应通过合作交流解决这一问题。他说：“共同评估上游中国境内高危冰湖的溃决风险，可以为下游提供科学合理的分析结果。”ICIMOD在努力促成更多的合作，但该地区的地缘紧张局势给合作带来了挑战。
Out of 20 agreements and memorandums of understanding signed between Nepal and China, one is on disaster risk reduction and emergency response. Several high-level meetings between the two countries have taken place in the past few years, but high mountain transboundary research has not been prioritised.
中尼之间签署的20项协议和谅解备忘录中包括一项有关减少灾害风险和应急响应的谅解备忘录。过去几年，两国之间举行了几次高级别会议，但跨界高山研究并不是会议的重点议题。
“If those lakes in Tibet burst [water] will eventually flow south to Nepal, devastating communities here [in Nepal]. There needs to be stronger cooperation between the two countries to curb this problem but I don’t see much progress,” said Ngamindra Dahal, chair of Nepal Water Conservation Foundation.
“如果中国境内的这些湖泊溃决，（水）最终将向南流到尼泊尔，破坏（尼泊尔）这里的社区。两国之间需要加强合作，来共同控制这个问题，但我现在看不到任何进展。”尼泊尔水利保护基金会主席纳米德拉·达哈尔（Ngamindra Dahal）说。
One example in the new ICIMOD report highlights the lack of cooperation and information exchange. It describes past efforts to lower the water level in four rank I lakes in Tibet to reduce the risk of glacial lake outburst floods. “The water level of Tsho Rolpa in Nepal was lowered by more than 3 metres in 2000, and of Imja Tsho, also in Nepal, by 3.4 metres in 2016. Similarly, the water levels of two lakes in the Tibet Autonomous Region, China, had also been lowered, but the details are not known.”
ICIMOD最新报告中举的一个例子凸显了缺乏合作和信息交流的问题。报告介绍了过去为降低西藏自治区境内四个I级湖泊的水位，减少冰川湖溃决风险而做出的努力。“尼泊尔的罗尔帕（Tsho Rolpa）水位在2000年下降了3米多，伊姆札湖（Imja Tsho）的水位在2016年也下降了3.4米。同样，中国境内的两个湖泊的水位也已降低，具体细节尚不清楚。”
At a local level, however, some cooperation has been reported recently. According to local media outlets, in July this year local authorities in Tibet along the Bhotekoshi river warned their counterparts in Nepal’s Sindhupalchowk district of a possible outburst flood from Keyrung Tshyo glacial lake in Tibet. This meant that Nepali communities could be alerted.
但是，最近报道称，地方层面上开展了一些合作。据当地媒体报道，今年7月，中国波曲河沿岸的地方政府警示尼泊尔辛杜帕尔乔克地区（Sindhupalchowk）的政府官员关于冰川湖可能存在爆发洪水的风险。这说明尼泊尔社区可以得到预警。
While there is still little research in high mountain areas, the agencies involved said that the new ICIMOD data will help governments take climate change more seriously and enhance transboundary cooperation. “We believe that this new information will be taken as an opportunity to work together by the governments as it is of critical importance to all countries that share these basins,” said Ayshanie Medagangoda-Labe, resident representative at the United National Development Programme in Nepal.
尽管在高山地区的研究还很少，但有关机构表示，新的ICIMOD数据将有助于政府更认真地对待气候变化并加强跨界合作。联合国开发计划署尼泊尔常驻代表Ayshanie Medagangoda-Labe表示：“我们认为，这一新的信息将为各国政府合作提供契机，因为这对这些流域周边的所有国家都至关重要。”
英文、中文版本下载：http://www.yingyushijie.com/shop/source/detail/id/2540.html