large trekking group advancing toward Tashi Lapcha pass,
a reminder of the exposure of tourism to the GLOF hazard

Chronology of Tsho Rolpa GLOF Hazard Response

Panic!

In 1996, the likelihood that a GLOF from Tsho Rolpa would impact Khimti Hydropower plant motivated HMG to commission the Bhutwal Power Company to model the GLOF.

From May 20th to May 31, 1997, a British consultant and his colleagues from HMG's Department of Hydrology and Meteorology (DHM) undertook a survey of Tsho Rolpa. Their conclusions (presented on June 6th) gave journalists the impression that Tsho Rolpa’s GLOF was imminent. Eventually, most of the inhabitants of Rolwaling valley were evacuated -- and the flood did not occur. Nevertheless, the media flap continued for several years.

Glacial Lake Causes Panic in Nepal (CNN Custom News July 22, 1997)

The Tsho-Rolpa glacial lake in the Himalayas has not only caused panic in the flood-prone areas, but also arrested the attention of the whole of Nepal. Studies revealed in mid-June that the glacial lake, situated 4,580-meter high in the Rolwaling Valley about 80 kilometers east of here, has expanded from 1.37 sq.m. to 1.65 sq.m. and might burst this summer.

[The following is an excerpt from an article by Jan Sharma, former editor of The Independent in Kathmandu, Nepal, for Gemini News, 26 August 1997.]

Hundreds of Nepali villagers feared being swept away by a swollen Himalayan glacier lake.They feared it would burst and inundate their homes and farms. A hydroelectric power station in process of construction also stood in the path of the waters.

According to a local Member of Parliament, widespread alarm was caused by a government warning about the danger posed by the lake and thousands of people in the Koshi river basin panicked. Acting on Home Ministry instructions, district officials posted red flags 20 metres above the river bed to indicate "safe" areas.

Perched 4,580 metres above sea level, Tsho Rolpa glacial lake was created and fed by a melting glacier. The lake is unstable because its walls are made of ice rocks, silt and debris carried down from the mountains by the glacier. The immediate cause of alarm was the speed at which the glacier was melting, recent heavy rains and the consequent rapid expansion of the volume of water in the lake.

The arrival of the monsoon rains could aggravate the situation, warned Rijan Bhakta Kayastha, a glaciologist with the Department of Meteorology and Hydrology, Nepal. "It is difficult to predict a lake burst," said Kayastha, "because by their very nature they are sudden. The lake is inherently unstable and it is better to be ready for the disaster, just in case." Kayastha was a member of a team led by British glaciologist Dr J. Reynolds, which in May 1997 confirmed a speeding up of the melting of the glacier, first noticed in August 1996.

"Its area has increased seven times since 1959," noted Kayastha. "The lake now covers 1.68 square kilometres and contains 80 million cubic metres of water."

According to chief district officer Ritu Raj Bhandari inquiries from far and wide poured regarding when the lake would burst and what preventive measures were being taken". He admitted that there was little they could do other than collect information and pass it on to the people. If the lake did burst, at least 16 suspension bridges and three permanent bridges would have been washed away.

Natural disaster relief committees have been activated in four districts which would be affected by a burst. Emergency and relief materials were requested from Kathmandu. Satellite telephone links were being established to improve the warning system. Their installation was delayed by incessant rain, which made it impossible for glaciologists and other specialists to arrive by helicopter.

Interestingly, fear was not the only reaction. Many of the predominantly Sherpa people living close to the lake area were more philosophical.

"We were told that the lake would burst last August. Nothing happened. We are told again this year. Nothing will happen, by the grace of God", says Krishna Bahadur Gurung, chairman of the Gaurishanker village development committee.

Agrees Tasinam Tshering Sherpa, a farmer who owns several cattle sheds around the lake: "The water in the lake has increased but nothing will happen."

One expert agreed with the sherpas. Pradeep Mool of the International Centre for Integrated Mountain Development (ICIMOD) believed that the panic was unfounded. Even if the lake collapsed, he argued, only half the water would escape, and it would occur in phases rather than in a single torrent.

Nepalis are used to mountain avalanches, landslides, and seasonal floods, particularly in the June-September monsoon season. But the phenomenon of the "glacial lake outburst flood" has been recognised only comparatively recently.

In August 1985, the Dig Tsho glacial lake burst in the Khumbu Valley in eastern Nepal, washing away a small hydropower plant at Namche, near Mt. Everest, together with many bridges, trails and farms.

Six years later, the Tshubing glacial lake - near Tsho Rolpa- also burst.

Alerted to the problem, Nepal's Water and Energy Commission and China's Lanzhau Institute of Glaciology and Geocryology undertook a joint study of glacial lakes in Nepal and Tibet, where most of Nepal's rivers originate.

The Netherlands to support Risk Reduction at Tsho Rolpa

The Dutch government is providing a grant of nearly Rs. 200 million to a project to help reduce the risk of a glacier lake outburst flood at Tsho Rolpa.The project will help reduce water levels at the Tsho Rolpa lake to reduce the risk of a breach in the natural moraine dam. Experts say the rising waters are a threat to thousands of lives in downstream areas in the Rolwaling and Tamakoshi Valleys and an outburst of the lake could wash away the Khimti hydropower plant currently under construction.

Past glacier lake floods were investigated by using satellite imagery, visits to the site of the bursts, investigations of river-bed deposits and collecting information from people in the region. The researchers concluded that there had been 16 bursts since 1935, enough to justify serious study and monitoring.

Of the 60 glacial lakes which have been identified, seven have are listed as the "most vulnerable"on the basis of their increasing water volume. Tsho Rolpa is among the seven.

Tomomi Yamada of the Institute of Low Temperate Science at Japan's Hokkaido University explains that lake bursts carry enormous amounts of debris in the form of stones, gravel, sand and silt. This, he says, makes them more devastating then floods. - Gemini News

Nepal's Glacial Lakes May Burst Again in Monsoon Rains
(c) Environment News Service (ENS), June 25, 1999; by Deepak Gajurel
KATHMANDU, Nepal, June 25, 1999 (ENS) - The heavy rains of the monsoon season are starting, and scientists warn that glacial lakes situated high in the Himalayas of Nepal could again burst their banks causing the rivers of southern Asia to flood. A monsoon climate means strong seasonal winds, a dry winter and a wet summer phase that lasts from June to September.
There is an increasing danger of glacial lake outburst floods as global warming continues to change the fragile Himalayan environment. The monsoon rains provide ideal conditions for a rise in water levels and icefalls into hundreds of glacial lakes across the Himalayan mountain range. Outburst floods in the high mountains mean devastating floods for the lowland countries downstream.
Scientists say the effects of global warming have accelerated the rate of the formation of glacial lakes. Most the these lakes are believed to have formed during the last 50 years. Recent studies conducted in India have revealed that glacial lakes are widening in area and also increasing in number, as the glaciers are gradually melting away.
Among dozens of known glacial lakes in Nepal, some are identified as "dangerous," according to a report published on the Bulletin of Water and Energy Commission (WEC). Seven such lakes in Nepal Himalayas were identified as dangerous by Tomomi Yamada Hokkaido University of Japan on the basis of aerial research in 1993.
These dangerous glacial lakes include Thulagi in the Annapurna area, Tsho Rolpa in the Rolwaling area, Imja in the Khumbu region and Mojang, Dudh Kunda, and Barun glacial lakes situated in the country's eastern Himalayan region.
Sabai Tsho glacial lake, also on this list, burst out last September resulting a massive flood of the Koshi river. A dam known as the Koshi barrage spans the Sapta Koshi river, one of Nepal's three major river systems. The lake is situated at an altitude of 5,000 meters (16,250 feet) above sea level high in the Himalayas.
"Nobody knew that the unprecedented flood in the Koshi River September 3 last year was due to a glacial lake outburst," says Shree Kamal Dwivedi, geologist at the Water and Energy Commission Secretariat. "On the wee hours of that day Sabai Tsho glacial lake high up in the Khumbu region had exploded."
Floods on the Koshi River threaten not only the eastern Terai plains of lowland Nepal, they create a problem for India's Bihar state. The Koshi barrage, where two irrigation canals for Bihar originate, is on the frontier if the Koshi again floods to a dangerous level.
There was panic last year amongst the general public living downstream of the Koshi barrage in Nepal and in Bihar when experts warned that the Tsho Rolpa lake could burst its banks. A Tsho Rolpa outburst would be devastating, hydrologists say.
Monitoring done at the Tsho Rolpa glacial lake since late fifties shows that the depth and width of the lake has increased by dramatically during the last 40 years.
Lake Tsho Rolpa covered 0.23 square kilometer in the late 1950s. The area quadrupled to 0.80 square kilometres in the mid-1970s and increased again to 1.27 square kilometres during by 1990. The area of this much feared glacial lake currently stands at 1.65 square kilometres, and it is continuing to increase.
Last year's alarm over Tsho Rolpa prompted urgent mitigation efforts. Drainage construction work to lower the possible breach at the lake has been started.
Officials say they will complete the construction work by October or November, adding that the chance of a Tsho Rolpa outburst can not be ruled out during this monsoon season.
Not much has been done in other lakes categorized as dangerous due to the lack of humanpower and funding. Technical teams have been monitoring Imja and Thulagi glacial lakes, but officials say they have not even been able to go to other places.
The United Nations Environment Programme (UNEP) through its facilities at Environment Assessment Program for Asia-Pacific. The Asian Institute of Technology, Bangkok is trying to establish an operational early warning system to monitor GLOF hazards in the Hindu Kush Himalayan region. Environment Assessment Program for Asia-Pacific will implement the project in collaboration with the International Center for Integrated Mountain Development in Nepal.
The project will implement the UNEP contribution to the establishment of an operational early warning system to mitigate natural hazards like forest fire, drought and glacier lake outburst flood.
The project will also help in assessing the environmental condition of the high mountainous regions. The expected outputs of the proposed study are an inventory of existing glacier lakes along the Hindu Kush Himalaya; monitoring of potential risk lakes for draining; and an operational early warning mechanism for glacial lake outburst flood hazards.

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Tsho Rolpa, late autumn 1999

Northern bank of Tsho Rolpa, late autumn 1999