Himalayan glacial lakes potentially in danger of outburst: Study

Tso Rolpa glacial lake at 4,580m has grown seven times in size in the past 60 years due to global heating.

New Delhi (NVI): As many as 47 glacial lakes within the Koshi, Gandaki, and Karnali river basins of Nepal, the Tibet Autonomous Region (TAR) of China, and India are potentially dangerous, the ones that could damage physical infrastructure and cause loss of human lives and livelihoods downstream, according to a new study.

A new inventory of glacial lakes in Nepal, TAR China, and India, has not only found 3,624 glacial lakes located in the three basins but also identified 47 glacial lakes that could potentially cause glacial lake outburst floods (GLOFs).

The study by the International Centre for Integrated Mountain Development (ICIMOD) and the United National Development Programme (UNDP), has once again rung the alarm bell of the adverse impact of climate change to the high mountain region.

With the rising temperature and climate change, high-mountains have witnessed excessive melting of snow, and most of the Himalayan glaciers are rapidly melting and shrinking.

The rapid shrinking and retreating of glaciers influence the formation and expansion of glacial lakes, multiplying the risk of GLOFs which are caused by a sudden release of water from glacial lakes that have breached their moraine dams.

According to the study, 25 potentially dangerous glacial lakes have been enlisted in China, 21 in Nepal, and one in India, which are at the risk of unleashing GLOFs — a prominent water-induced hazard for Nepal and other mountainous countries in the Hindu Kush Himalaya (HKH) region.

The report pointed out that these glacial lakes need to be closely monitored for minimising the vulnerability of mountain people and protect settlements downstream in the three river basins.

Of the 47 identified potentially dangerous glacial lakes, 42 are within the Koshi basin, making it the river basin with the highest risk. The Gandaki and Karnali basins have three and two such lakes, respectively.

Likewise, out of the total 3,624 glacial lakes identified by the report, 2,070 lakes are in Nepal, 1,509 lakes in the TAR, China, and 45 lakes in India. According to the finding, 1,410 lakes are larger than or equal to 0.02 sq km, which are considered large enough to cause a glacial lake outburst flood.

“Glaciated areas have decreased in higher mountains of Nepal. Reducing glacier areas means either it is flowing down or remaining stuck somewhere in glacial lakes formation,” said Deepak KC, who coordinated the study on behalf of UNDP Nepal.

“With the temperature rising around the world, global glacier lake volume has increased by around 48 percent, an increment of lake numbers by 53 percent and total area by 51 percent between 1990 and 2018. The trend has also continued in Nepal,” he added.

While the rapid melting and the recession of many Himalayan glaciers due to climate change is leading to the formation of new glacial lakes, the enlargement of existing lakes is increasing the risk that their surrounding moraines will not be able to hold it for a long time.