Water volume of Imja lake doubles in three years



KATHMANDU, Oct 9: In yet another sign that exposes vulnerability of Imja Tsho, one of Nepal´s highly dangerous glacial lakes, a new study has revealed that the lake´s water volume has nearly doubled over the last three years.

The new study, conducted by the High Mountains Adaptation Partnership (HiMAP), coordinated by the University of Texas and The Mountains Institute (TMI) with support from the USAID, reveals that Imja Tsho now contains over 60 million cubic meter water — almost double the lake´s previously-stated water volume.

In 2009, a study by the International Center for Integrated Mountain Development (ICIMOD) had stated that Imja Tsho, which glaciologists say was formed just half a century ago, contained about 35 million cubic meter water.

Contrary to what the ICIMOD report-2009 stated, the HiMAP study, conducted in September last year, says that the volume of water in Imja Tsho has increased alarmingly by 2012. The finding of the study was revealed for the first time at the inception workshop of Community Based Flood and Glacial Lake Outburst Risk Reduction Project (CFGORRP), an initiative taken to deal with the impact of climate change in the Khumbu region, on Wednesday in Kathmandu.

“Our study only reasserts the fact that Imja Lake is getting more vulnerable,” said Marcelo Somos-Valenzuela, a PhD candidate at the University of Texas, who was involved in mathematical calculation for finding out the lake´s water volume. “The increase of water volume in Imja Lake can be related to the rise in temperature in high mountain ecosystems.”

National Project Manager of the CFGORRF Top Bahadur Khatri says it is too early to conclude whether the finding of the HiMAP study is absolutely correct. “Other findings should validate what the HiMAP study states,” said Khatri. “But, we have no doubt that the lake´s size and water volume are both increasing constantly.”

According to the HiMAP study, the calculated volume of water that could get discharged from Imja Lake in case of a Glacial Lake Outburst Flood (GLOF) has also increased to 34 million cubic meters. Earlier, the GLOF water was calculated to be just around 20 million cubic meters.

Assessing the risk of potential GLOF events in the Khumbu region, government authorities are now accelerating efforts to lower Imja Lake´s water level by at least three meters under the CFGORRF. After Tsho Rolpa, this is the first time that a glacial lake´s water level is likely to be lowered in Nepal. Earlier in 2000, Tsho Rolpa´s water level was lowered by three meters.

Asked whether lowering of Imja Lake´s water level by three meters, especially in view of the HiMAP study´s new finding, is sufficient to avert GLOF events in the Khumbu region, glaciologist Dr Rijan Bhakta Kayastha said, “Reduction of Imja Lake´s water level by three meters is good enough for now.”

According to Dr Shrestha, an associate professor at the Kathmandu University (KU), the height of Imja Lake´s end moraine is just 30 meters, nearly 100 meter lesser than that of Tsho Rolpa. “Thanks to its low end moraine, lowering of water level by three meters is adequate for now despite the increase in the water level,” he explained.

More than 30,000 people could be affected if Imja Lake, located at an altitude of 5,000 meters just above Namche bazaar in Solukhumbu district, bursts, according to experts. The lake, surface area of which was just 0.03 square kilometers in 1960, has already developed into a 1.01 square kilometer lake.

As part of the CFGORRF, funded by the Least Developed Countries (LDC) fund of the Global Environment Facility (GEF), early-warning system will also be developed in the Khumbu region. “We will follow best practices of Tsho Rolpa while lowering Imja Lake and developing early warning system in the Khumbu region,” said Khatri.

Published on 2013-10-10 00:35:37

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