However, based on the Nepal quake, Jaxa experts say there is no cause for concern

GLOF: At least 10 glacial lakes in northern Bhutan have grown substantially in the past two years, researchers from the Japan Aerospace Exploration Agency (JAXA) said.

JAXA researcher (Dr) Hiroto Nagai has been studying the lakes and the possibility of glacial lakes outburst floods (GLOF) in the area.

The 10 lakes include a few newly formed lakes and the Thothormi lake at the source of the Phochhu in Lunana. However, he said predicting a GLOF is difficult as it depends on multiple factors: blockage of outlet, glacial melt, and merging of supra-glacial lakes, among others.

Hiroto Nagai also studied the GLOF of the Lemthangtsho that drained entirely in to the Mochhu basin on June 28 last year. He found the lake behaved in a unique manner.

“Unlike other glacial lakes, it expanded rapidly within a short period, about a month, and collapsed,” Hiroto Nagai said, pointing out that this was unusual behaviour.

The latest observation was after the heavy monsoon rain in July this year to check if there is any potential danger of GLOF.

“We need to study further as to how much was the monsoon rain responsible for the growth of the lakes,” Hiroto Nagai said. “It’s possible and we’ll look in to it.”

Glacier areas have been decreasing consistently, reaching 600 square kilometres.

To qualify for inventory, a glacial lakes should be 100 by 100 metres at least slightly bigger than the size of a football field.

About 2,500 square kilometres of the country remains under snow cover throughout the year.

A partial breach of the Luggye Tsho on October 7, 1994 was the most catastrophic event in recent history of the country, both in terms of its magnitude and the loss of life, property, and infrastructure downstream.

The GLOF killed 20 people, and damaged several houses, and pasture lands The event prompted the government to commission several research activities on glaciers and glacial lakes.

The country has embarked on mitigating GLOF risks since 2008 reducing the Thothormi lake, the most potentially dangerous lake. The hydro met department  installed early warning systems along the Punatsangchhu basin and Chamkharchhu.

In September last year, the Department of Hydro-Met Services (DHMS) dispatched a team of geologists, foresters, GIS technicians and hydrologists to the glacial lakes and villages of Lunana gewog to survey lakes, profile rivers and conduct a vulnerability assessment on the local people living in the area.

Expanding glacial lakes, in the wake of seismologists suggesting the region could be hit with a major earthquake, is a major cause of concern for Bhutan.

However, JAXA experts say that from the Nepal experience it’s unlikely that the lakes would pose a major threat. A senior JAXA researcher, (Dr) Takeo Tadono said that in Russia heavy rains would trigger GLOFs but it is unlikely in Bhutan.

“The Nepal earthquake did not cause any GLOF in the country,” he said.

After Pakistan, Bhutan is the second country that is vulnerable to GLOF in the SAARC region. The region has more than 7,683 glacial lakes of which nearly 3,000 are in Bhutan. There are 125 potentially dangerous glacial lakes in the region, of which 25 are in the country. Thorthormi Lake is considered the most potentially dangerous.

Tshering Palden | Japan