Nepal's nature
Nepal's Glaciers
Nepal Himalayas Glaciers
The Tsho Rolpa Lake
Tsho Rolpa early warning system
Rolwaling: Tsho Rolpa Project
Glacial Lakes Outburst Flood(GLOF)
Nepal Information
Melting glaciers: Danger of flashfloods
Trekking Information
Nepal Glaciers: Global Warming - Tsho Rolpa Risk Reduction Project
The Tsho Rolpa Lake
Tsho Rolpa, Rolwaling Valley, 1996
The Tradkarding glacier, which feeds the Tsho Rolpa glacial lake in Nepal's Rolwaling Valley, is retreating at a rate of over 20 metres a year and, in some years within the last decade, reached 100 metres per year.

This is the Tsho Rolpa Lake that feeds the Rolwaling and Tama Koshi valleys in the Dolakha District of Nepal.

The researchers have found that, as a result of the melting of a nearby glacier, the lake has grown six-fold, from an area of 0.23 square kilometres (56 acres) in the late 1950s to one of 1.4 square kilometres (346 acres) now.

"A flood from this lake could cause serious damage down to the village of Tribeni, which is 108 kilometers (67 miles) downstream, threatening about 10,000 human lives, thousands of livestock, agricultural land, bridges and other infrastructure," a researcher said.

Tsho Rolpa Risk Reduction Project
Glacial Lake is located at an elevation of 4580m and is approximately 3 km long, 0.5 km wide and up to 130 m deep. It contains approximately 80 million cubic meters of water and is the largest glacial lake in Nepal. The lake is contained by a 140m high natural moraine dam that is unstable and threatens to burst. The resulting flood would inundate parts or all of 20 villages for over 100 km downstream, threatening up to 6000 lives, the construction site for the 60 MW Khimti hydroelectric project, and other infrastructure.
In August 1985, a sudden out burst flood from the Dig Tsho glacial lake in Nepal destroyed 14 bridges and $1.5 million worth of damage was caused to the nearly completed Namche Small Hydropower Plant. The new research began in 1999 and is based on topographic maps, aerial photographs and satellite images from Landsat, Spot and IRS craft. The survey has identified 3,252 glaciers and 2,323 glacial lakes in Nepal and 677 glaciers and 2,674 glacial lakes in Bhutan. The researchers estimate 20 glacial lakes in Nepal and 24 in Bhutan are potentially dangerous.
Tsho Rolpa, Rolwaling Valley
A high tech communications network of sensors and sirens has been linked from the lake to villages at risk from floodwaters.

Engineering work has finished to lower the water levels at Tsho Rolpa by 30 metres (98 feet).

The construction began in April 1999 and was stopped in October due to severe weather conditions and started again in May 2000.

All the construction work was completed by early June 2000 and the draw-down of the lake water-level was initiated on June 8, maintaining below 25 cm per day to avoid catastrophic slumping and failure of moraine slopes and damage to the canal lining. The level lowering was accomplished on June 24, 2000.

The reduction of lake water-level by three metre is just an immediate solution and the second project named Tsho Rolpa GLOF Permanent Remediation Project (TRPRP) aims to reduce the lake water-level by additional 17m making 20m lower from the original lake water surface and then only the lake will be permanently free from GLOF risk.

The risk of failure is considered to be high. As a result of the number of lives at risk and the potential damage to the economy of Nepal, two projects have been undertaken to reduce the risk to lives and the economy. The first project, the subject of this paper, was the installation of a fully automated remote warning system for the villages of the Rolwaling and Tama Koshi Valleys. The Nepalese Government has installed in co-operation with foreign partners a of the Glacial Lake Outburst Flood (GLOF) warning system downstream of Tsho Rolpa.The second project was to lower the lake initially by 3 meters.

Sources: GRIDA, UNDEP, Tsho Rolpa GOLF Risk Reduktion Project


more information
Weather in Nepal Nepal Maps
Rolwaling Valley Map
Charikot - Dolakha district
The Himalayas Bhutan's Glacial Lakes
Snow, Ice, Glaciers, Glacial Lakes and Floods - Reports
Himalayas Snow, Ice, Glacier, Glacial Lakes and Floods Reports
External link
GRID-Arendal News NASA's Global Change Master Directory United Nations Environment Programme World Glacier Monitoring Service International Centre for Integrated Mountain Development
Tsho Rolpa Hazard Mitigation Project
external link
Tsho Rolpa, Rolwaling Valley
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