| Bhutan's
glaciers and glacial lakes : Lunana |
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Bhutan Glaciers - Glacial Lakes |
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Bhutan Glaciers - Glacial Lakes |
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Lunana's
glacial lakes: Thorthormi Tsho
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Thorthormi Mitigation Project
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Work
on Lunana lake is delayed
Work
to prevent the flooding of the largest glacial lake in Lunana has been
delayed by the shortage of funds.
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lake - Thorthormi (Thortomi)- meanwhile, is becoming more vulnerable, according
to experts, because its body of glacier is melting fast and filling up
the lake.
"We
must start the mitigation works before the situation becomes critical,"
the director of the geology and mines department, Dorji Wangda said.
In
1994 one of the glacial lakes in Lunana - Luggye Tsho - formed by the melting
of glaciers, partially burst, causing the Pho Chhu to flood. |
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It killed
23 people in the Punakha valley and cost the government more than Nu. 43
million on flood relief measures.
The
government then sent several expeditions to the Lunana region to assess
the risk of glacial outbursts. A Bhutan-India team discovered that a glacial
lake - Raphstreng Tsho - was on the brink of rupture. The water from the
lake was quickly drained and the risk of an outburst reduced.
A
Bhutan-Austrian team later, in 2000, saw a threat about 60 meters above
the Raphstreng Tsho. Situated at 4,500 metres above sea level, the Thorthormi
(Thortomi) glacier was melting and had created multiple lakes at its terminal.
The team after studying the glacier for more than three years concluded
that, in 10 years, these numerous lakes would extend and grow into one
huge lake in the region.
Given
that the Thorthormi (Thortomi)'s southern flank, also called its left lateral
moraine dam, was eroded by the 1994 flood and thus weakened, the pressure
from the growing water body could cause the lake to give way. If that happened,
the team's findings stated, the Raphstreng Tsho, another large glacial
lake situated downstream, could be pressured to burst as well because of
the weak moraine ridge separating the two lakes.
The
team pointed out that, if the two lakes erupted they would unleash about
53 million cubic meters of water and carry a large volume of debris. That
is about three times the ferocity of the 1994 Punakha flood.
Thorthormi
(Thortomi) and Raphstreng are both sources of the Pho Chhu.
In
2003, the team urgently submitted their findings to the government and
recommended three projects in the region to mollify the threat. The first
and an immediate one was to manually lower the water level of the Thorthormi
(Thortomi) Lake by draining out the water from an outlet. The second was
to install a "glacial lake outburst flood" technical early warning system
which could warn settlements downstream like Punakha within ten minutes
of the impending outburst. The third was to map and identify places which
could be affected in case of an outburst.
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projects are yet to take off. |
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Officials
of the geology and mines department said that the cost was very high and
the government did not have the funds.
Manually
lowering the lake alone is estimated to cost Nu. 121.6 million (almost
US$ 3 million) in addition to about Nu. 17 million (US$ 400,000) to install
a warning system.
"We
are trying to seek external funding," said Dorji Wangda. His department
was also monitoring the glacial lakes every year, he added.
Officials
in the department of local governance, under the Ministry of Home and Cultural
Affairs, which is at present working on the "disaster preparedness" policy,
maintained that they have not received the proposals to mitigate the glacial
threats.
Meanwhile
the Thorthormi (Thortomi) Lake is filling up because rising temperatures
are melting the glaciers and surrounding snowfields that feed it, said
glaciologist, Karma, of the geology and mines department. "Every year we
see the same thing: Thorthormi (Thortomi) lake is growing bigger and bigger,"
he said.
| Source:
Kencho Wangdi, Kuensel 2005 |
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| Information |
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| Links |
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External
links |
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| GRID-Arendal
News |
NASA's
Global Change Master Directory |
United
Nations Environment Programme |
World
Glacier Monitoring Service |
International
Centre for Integrated Mountain Development |
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