Posted on 01 December
2009 - Lunana, Bhutan – The first phase
of an international project to reduce the
risk to a Bhutan valley from the
threatening bursting of a growing and increasingly
unstable glacial lake is emphasising the
huge costs of climate change adaptation
in the Himalayas.
Thorthormi Tsho is a
glacial lake perched precariously at 4428
metres above sea level in the remote Lunana
area of northern Bhutan Rated as one of
Bhutan’s likeliest future catastrophes,
a breach and outburst flood through Thorthormi
Tsho’s unstable moraine walls would most
likely spill into the also vulnerable Raphsthreng
Tsho 80 metres below, with the combined
flood suddenly releasing up to 53 million
cubic metres of water and debris into the
upper catchment of the Po Chu river.
In a valley still bearing
the scars of a just one third as large 1994
Glacial Lake Outburst Flood (GLOF) which
took more than 20 lives and devastated villages
and wrecked transport and power facilities,
the prospect is frightening.
For Bhutan, scenarios
from an outflow from Thorthormi Tsho include
crop destruction and livestock losses over
more than half of the fertile and economically
critical Punakha and Wangdi valleys, loss
of a vital bridge and roads, and damage
to hydropower facilities under construction.
Punakha Dzong, a 14th century royal palace
and religious centre, would be among 16
historic monuments at risk, along with numerous
other buildings including vocational centres
and a noted weekend market.
Monitoring, more intense
since the 1994 disaster, tells its own story
– Thorthormi Glacier had no meltpools in
the 1950s. The new lake has nearly tripled
in size since 2001 while the moraine dam
holding it has halved its height at the
apex over roughly the same period.
The Royal Government
of Bhutan (RGB), monitoring the growth of
the glacier with Japanese assistance, has
sought assistance to reduce the dangers
posed by Lake Thorthormi by artificially
draining its waters.
A large effort by the
government, communities and WWF, supported
by the Global Environment Facility (GEF),
the United Nations Development Programme
(UNDP) and the Austrian Coordination Bureau
this year succeeded in lowering the lake
level by 86 cm, in the first phase of a
project intended to artificially lower the
water level at Thorthormi Lake by 5 metres
in 3 years.
The Cost of Climate
Change: The Story of Thorthormi Glacial
Lake in Bhutan is a WWF Living Himalayas
Initiative report on the project and the
growing risk to Himalayan nations by glacial
lake outburst events.
“The story of Thorthormi
lake is shaping up to be a story of successful
adaptation to climate change,” said Tariq
Aziz, Leader of WWF’s Living Himalayas Initiative.
“However, it is also a story of the risks
that climate change is building for communities
and the costs and complexities of successful
adaptation work.”
A team of over 300 workers
from 20 districts of Bhutan and from all
walks of life -- tourist guides, farmers,
women and yak herders -- walked for up to
10 days to reach the site and dig and realign
existing outlet channels to safely drain
water from the lake. The team braved thin
and frigid air and harsh weather conditions
including the assault of Cyclone ‘Aila’
in May 2009. Heavy rains associated with
the cyclone damaged access to the site and
effort had to be shifted to repairing this.
The bad weather and
extreme climatic conditions led to the initial
target set for this year of draining 1.67
metres of water being lowered to one metre.
When the onset of conditions forced the
end of work in October the team had managed
to lower the water level by 86 cms. The
work will resume in April-May next year.
“This was less than
the target, but nevertheless it has brought
down the threat level of the lake bursting
in the near future,” said Aziz.
The report notes that
although Thorthormi Tsho is the largest
and most dangerous of the new lakes, some
16 new glaciers and 82 glacial lakes have
formed in Po Chu headwaters alone.
“The speed of the changes,
the dimensions of the new risks being faced
by communities and the difficulties of securing
lives and livelihoods against these threats
makes sobering reading,” said Kim Carstensen,
leader of WWF’s campaign to secure a fair,
effective and binding global climate deal
at Copenhagen summit in just two weeks time.
“This gives some perspective
to the calls for substantial funding for
climate change adaptation in the developing
world. It also underlines how vital it is
to come to an agreement to reduce emissions,
reduce the extent of climate change and
reduce the loss of life and livelihoods
in areas that have contributed very little
to the problems they now face.”
The WWF Living Himalayas
Initiative report also gives information
on glacial lakes and glacial lake outburst
floods (GLOFs), potentially dangerous lakes
in the Himalayas and the threats from them
including destruction they are likely to
cause in case of outbursts.
