DRAFT
Glaciers, Glacial Lakes and Glacial Lake Outburst Floods in the Himalaya
Pradeep K. Mool
ICIMOD, GPO Box 3226, Kathmandu, Nepal.
email: pmool@icimod.org
Abstract:
Glacial lakes dammed by moraines and or ice core of retreating glaciers in the Himalaya due
to accelerated global warming. Sudden breach of the unstable moraine ‘dams’ resulting
discharges of huge amounts of water and debris – known as Glacial Lake Outburst Flood or
GLOF – often have catastrophic effects downstream. Even the small glacial lake associated
with hanging glaciers poses high potential for breaching and resulting to GLOF. At least
twenty GLOF events recorded in Himalaya in the last seven decades that resulted in heavy
loss of human lives and their property, destruction of infrastructure besides damages to
agriculture land and forests. Information and knowledge on GLOF is required for the planning
for water resources and flood hazards management. International Centre for Integrated
Mountain Development (ICIMOD) and its partner institutes, in collaboration with United
Nations Environment Programme, the Asia-Pacific Network for Global Change Research
(APN) and the global change SysTem for Analysis, Research and Training (START), carried
out the study of glaciers, glacial lakes and GLOF of selected basins in Himalaya. The studies
generated the baseline information for future monitoring of glaciers, glacial lakes and GLOFs
of the region due to climate change, for the development of monitoring and early warning
systems, for planning and prioritizing disaster mitigation efforts, for estimating future
available water resources and their planning and management. Study also reviled several
potential dangerous glacial lakes in Himalaya. Some of the past GLOF events have damaging
effects in the lower riparian countries. Regional cooperation is required for knowledge
management on GLOF issues due to trans-boundary nature of GLOF phenomena.
Glaciers are nature’s valuable source of fresh water in the form of frozen reservoirs from
which large amounts of melt ice release to many of the major rivers of the Hindu Kush–
Himalaya (HKH) (Xu Jianchu et.al. 2007; Zemp, M., et. al., 2007). They supply water for
drinking, and the needs of agriculture, hydropower, and industry for the millions of people
living downstream.
Glaciers are also repositories of information for exploring quaternary climate changes, as they
remain sensitive to global temperature conditions. This is indicated by the continuous retreat
of glaciers, and the formation of many glacial lakes at the toe of glaciers dammed by the loose
moraine. The rapid accumulation of water in glacial lakes can lead to a sudden breach of their
unstable moraine dams, however. The resultant discharges of huge amounts of water and
debris – a glacial lake outburst flood – often have catastrophic effects downstream. A number
of glacial lake outburst floods (GLOFs) have been reported in the region in the last few
decades, particularly from the eastern sector of the region. GLOFs have resulted in many
deaths for downstream populations as well as destruction of property and infrastructure.
Climate change due to the enhanced greenhouse effect has increased the rate of glacier
melting and thereby the frequency of GLOFs in recent years. Since industrialization, human
activities have resulted in steadily increasing concentrations of greenhouse gases in the
atmosphere, leading to fears of enhanced greenhouse effect. The world’s average surface
temperature has increased between 0.3 and 0.6oC over the past hundred years. The
Intergovernmental Panel on Climate Change (IPCC), in its third assessment report, revealed
that the rate and duration of the warming in the 20th century is larger than at any other time
during the last one thousand years. The 1990s was likely to be the warmest decade of the
millennium in the Northern Hemisphere, and the year 1998, the warmest year (IPCC, 2001a).
According to the World Meteorological Organization (WMO), year 2002 and 2003 have been
the 2nd and 3rd hottest years, respectively ever since climate statistics have been monitored
and documented.
Climate change is causing the net shrinkage and retreat of glaciers and the increase in size and
number of glacial lakes, especially in the high mountains. Studies using satellite data have
tried to correlate present area under glaciers with historical records, and with fluctuations in
temperature. Results show that the recession rate has increased with rising temperature. For
example, with the temperatures rising by 1oC, Alpine glaciers have shrunk by 40% in area
and by more than 50% in volume since 1850 (IPCC, 2001b & CSE, 2002). Evidence also
show that the changes in temperature are more pronounced at higher altitudes. Analysis of air
temperature trends across 49 stations in Nepal between 1977-1994, for example, revealed a
clearly rising trend, with the change much more pronounced in the higher altitude regions of
the country. (Shrestha et al. 1999)
This has a twofold impact on the mass balance of glaciers. The direct result is to accelerate
their melting. Furthermore, it induces precipitation to occur in liquid instead of solid form,
even at very high altitudes. The absence of a blanketing layer of snow on the ice lowers its
albedo, making glaciers further prone to radiative melting (Mool, P.K et al, 2001a).
Numerous studies carried out during 1999-2001 lend credence to the link between climate
change and glacier melting. All the glaciers in the Himalaya have retreated by approximately a
kilometer since the Little Ice Age [AD 1550-1850] (Mool P.K et al,2001a). The Dokriani
Bamak Glacier in the Himalaya (India) retreated by 20 meters in 1998, compared to an
average retreat of 16.5 meters over the previous five years. (Matny, L., 2000). A long-term
study entitled, ‘The Chinese Glacier Inventory’, by the Chinese Academy of Sciences has
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“Glaciers, Glacial Lakes and Glacial Lake Outburst Floods in the Himalaya”
Pradeep K. Mool
Page 2
reported that during the last 24 years there has been a 5.5 % shrinkage in volume of China’s
46,928 glaciers, equivalent to the loss of more than 3000 sq km of ice. The study predicts that
if climate continues to change at the present rate, two-thirds of China’s glaciers would
disappear by 2050, and almost all would be gone by 2100 (China Daily, 23 September 2004).
Evidence have been conclusive enough to make glacier melting and retreat an important
indicator for climate change.
Table 1: Some recorded GLOF events in Nepal, Tibet Autonomous Region of China and Bhutan
No
Date
Lake
1
Aug-35
Tara-Cho
2
21-Sep-64
Gelhaipco
3
1964
Zhangzangbo
4
25-Aug-64
Longda
5
1968
Ayaco
6
1969
Ayaco
7
18-Aug-70
Ayaco
8
3-Sep-77
Nare
9
23-Jun-80
Nagma Pokhari
River Basin
Source
Country Effected
Cause of GLOF
Tibet (China)
China and Nepal
Dam Piping
Tibet (China)
China and Nepal
Glacier surge
Tibet (China)
China and Nepal
Piping
Tibet (China)
China and Nepal
Not known
Tibet (China)
China and Nepal
Not known
Tibet (China)
China and Nepal
Not known
Tibet (China)
China and Nepal
Not known
Dudh Koshi
Nepal
Nepal
Moraine collapse
Tamor
Nepal
Nepal
Moraine collapse
Tibet (China)
China and Nepal
Glacier surge
Tibet (China)
China and Nepal
Glacier surge
Boqu (Tibet) /
Sun Koshi
(Nepal)
PumQu (Tibet)
/ Arun (Nepal)
Boqu (Tibet) /
Sun Koshi
(Nepal)
Gyrong (Tibet) /
Trisuli (Nepal)
PumQu (Tibet)
/ Arun (Nepal)
PumQu (Tibet)
/ Arun (Nepal)
PumQu (Tibet)
/ Arun (Nepal)
Boqu (Tibet) /
Sun Koshi
(Nepal)
PumQu (Tibet)
/ Arun (Nepal)
10
11-Jul-81
Zhangzangbo
11
27-Aug-82
Jinco
12
4-Aug-85
Dig Tsho
Dudh Koshi
Nepal
Nepal
Ice avalanche
13
12-Jul-91
Chubung
Tama Koshi
Nepal
Nepal
Moraine collapse
14
3-Sep-98
TamPokhari
Dudh Koshi
Nepal
Nepal
Ice avalanche
Tibet (China)
China
Ice avalanche
15
10-Jul-40
Qunbixiama-Cho
KangboquAhmchu
16
10-Jul-54
Sangwang-Cho
Nianchu
Tibet (China)
China
Glacier advance
17
26-Sep-64
Damenlahe-Cho
Nyang
Tibet (China)
China
Ice avalanche
18
23-Jul-72
Poge-Cho
Xibaxiaqu
Tibet (China)
China
Ice avalanche
Tibet (China)
China
Ice avalanche
19
24-Jun-81
Zari-Cho
Yarlung
Zangbo
20
14-Jul-88
Mitui-Cho
Palong Zangbo
Tibet (China)
China
Ice avalanche
21
7-Oct-94
Lugge-Tsho
Pho Chu
Bhutan
Bhutan
Moraine collapse
22
15-Aug-03
Kabache Lake
Madi River
Nepal
Nepal
Moraine collapse
23
8-Aug-04
Kabache Lake
Madi River
Nepal
Nepal
Moraine collapse
Some of the glacial lakes in China in Poiqu basin, which is trans-boundary basin and join with
SunKoshi-BhoteKoshi in Nepal, such as LumuChimi lake and GangxiCo lake have grown
almost double in size within last twentyfive years. These lakes pose potential threat of GLOFs
which most often have devastating effects on local people and the surrounding environment.
While human activities cause climate change, and climate change accelerates glacier melting
and GLOFs, GLOFs in turn cause widespread damage in the human and natural systems.
Glacier melting and GLOFs exacerbate land degradation, increase variations in the
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“Glaciers, Glacial Lakes and Glacial Lake Outburst Floods in the Himalaya”
Pradeep K. Mool
Page 3
hydrological regime, degrade biodiversity, and trigger many socioeconomic externalities.
Climate change will thus intensify and accelerate these impacts and further burden the human
and natural systems over a wide area, far beyond the mountain ecosystem.
Hence apart from adapting to GLOFs, a long term solution to the impacts of glacier melting
and GLOF events is to promote adaptation and mitigation strategies for climate change.
GLOFs will increase land degradation through vertical and lateral channel erosion, and the
undercutting of colluvial deposits with further downstream transport and aggradations. It has
the potential to destabilise talus slopes and to initiate new debris flows and landslides
(Bajracharya, S.R., et.al, 2007). These processes leave a long stretch of unstable slope sections
with broken vegetation cover. Further downstream, where the channel gradient tapers off,
aggradations dominate degradation. The valleys affected by GLOFs will have unusually high
loads of sediment deposit (Ives, J.D.1986). Past GLOFs have shown transboundary
damaging effects downstream.
The socioeconomic impacts of GLOFs could be loss of lives, damage to hydropower facilities,
roads, bridges, trekking trails, whole villages, and agricultural lands. Both small and large
hydro power infrastructure could be affected by a combination of variable flows, flooding
risks, increased sedimentation, and increased monsoon precipitation caused by GLOFs. This
could destroy, damage, clog and derate the hydropower infrastructure in risk areas.
In recent years, GLOFs have happened in the Himalayan region. A list of GLOF events that
have occurred in the region and associated damages caused are given in table 1.
The most significant GLOF event since detailed recording started, occurred in Dig Tsho lake
at Bhote Kosi in Nepal in 1985. It destroyed a nearly completed small hydropower project
(estimated cost of US$ 1.5 million), numerous foot-bridges, trekking trails and caused loss of
many lives (P. K. Mool, 1993). A huge rapid landslide dammed the Yigong river (China) on 9
April 2000. After two months, on 10 June 2000, the outburst flood from the landslide dam
extended 500 km downstream uptil the state of Arunachal Pradesh, North-Eastern India
causing heavy damages (Zhu and Li, 2001). In June 2005, outburst of landslide dam lake on
Parechu river (China) caused a transboundary flood in Himachal Pradesh (India).
Glaciers thus determine and limit socioeconomic activity to some extent and indicate global
climate change. Knowledge of this resource seems an outstanding requirement for future
planning of water resources and mitigation of GLOF hazards.
The International Centre for Integrated Mountain Development (ICIMOD) and its partner
institutes, in collaboration with United Nations Environment Programme /Regional Resource
Centre for Asia and the Pacific (UNEP/RRC-AP) carried out a systematic inventory of
glaciers and glacial lakes of Nepal and Bhutan in 1999–2001. Later, the study was continued
in collaboration with the Asia-Pacific Network for Global Change Research (APN) and the
global change SysTem for Analysis, Research and Training (START), and expanded to all the
ten sub-basins of the Indus River in Pakistan, all sub-basins of the Ganges in the Tibet
Autonomous Region of the Peoples’ Republic of China, and Tista River Basin along
Himachal Pradesh Himalaya and Uttaranchal Himalaya of India (http://www.icimodgis.net/glof/glof.php). Once the study on Arunanchal Pradesh Himalaya and Jammu &
Kashmir Himalayas, northern Afghanistan and Myanmar area are completed, the entire
database of the Hindu Kush–Himalayan region will be served at the scale of 1:50,000.
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“Glaciers, Glacial Lakes and Glacial Lake Outburst Floods in the Himalaya”
Pradeep K. Mool
Page 4
Figure: Map of the Hindu Kush-Himalaya showing the areas covered by
the Inventory of Glaciers and Glacial Lakes Studies
Table 2: Summary of glaciers and glacial lakes in the mountains of
Pakistan, India, and China/Tibet Autonomous Region compiled by
ICIMOD.
Glaciers
Glacial Lakes
River Basins
Total
number
Area
(km2)
Total
number
Area
(km2)
Pakistan Himalaya
Indus Basin
5218
15040.7
2420
126.35
Himachal Pradesh
2554
4160.58
229
379.72
Uttaranchal
1439
4060.04
127
2.49
Tista River
285
576.51
266
20.20
India Himalaya
The main objective of
the study is to link
priority topics in the
research framework by
identifying the
formation of dangerous
glacial lakes in the
region as a result of
global climate change,
with direct impacts on
terrestrial change and
human vulnerability
and adaptation.
The results and
database generated
Sub-basins of Ganges
1578
2864.33
824
85.19
from the present
studies provide the
Nepal Himalaya
3252
5323.89
2323
75.70
baseline information
on the region for the
Bhutan Himalaya
677
1316.71
2674
106.87
development of
monitoring and early
Within the study area
15003
33342.76
8863
796.52
warning systems, and for planning and prioritizing disaster mitigation efforts. In addition, the
study is anticipated to help lay down the planning guidelines for infrastructure and
development and water resources and land-use in the region and in the individual countries of
the HKH. Along with information on climate change and future monitoring of glaciers, glacial
lakes and GLOFs, this database can provide the basis for estimating future available water
resources and their planning and management.
Tibet Autonomous Region of the Peoples’ Republic of China
A summary of the inventoried glaciers and glacial lakes in the Himalaya of Pakistan, India,
Tibet Autonomous Region (People’s Republic of China), Nepal, and Bhutan is given in Table
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“Glaciers, Glacial Lakes and Glacial Lake Outburst Floods in the Himalaya”
Pradeep K. Mool
Page 5
2. The database indicates that the number of glacial lakes and glacial lake outburst floods in
the eastern Himalaya is comparatively higher than in the western Himalaya.
Regular assessment monitoring of glaciers and glacial lakes and adaptation measures
including engineering structure and policy linkage for potential dangerous glacial lakes are
required. Field validation of these glaciers and glacial lakes are also needed.
Advanced scientific knowledge of potential GLOF hazards, building capacity among local
institutions and agencies for undertaking or monitoring these studies, and linking this
knowledge to policy and planning are, therefore, of immense importance to the lives of
millions of mountain dwellers and their downstream neighbors
(http://dev.icimod.org/elibrary/index.php/search/publication/169
http://books.icimod.org/index.php/search/publication/131
http://books.icimod.org/index.php/search/publication/286
http://ekh.unep.org/m-eKH/GLOF_NEPAL/GUIDE/movie.html
http://www.rrcap.unep.org/issues/glof/glof/index.htm)
International Centre for Integrated Mountain Development (ICIMOD) is undertaking several
projects on study of glacial lakes and glaciers in the region.
ICIMOD with support of the World Bank and in collaboration with partners from Nepal is
implementing the project entitled “GLOF Assessment and Mitigation Study of Potential
Glacial Lake Outburst Flood (GLOF) lakes in Nepal” from September 2008. The objectives of
the study project are (1) to develop recommendations for adaptation and mitigation against
GLOF hazards against potential dangerous glacial lakes in Nepal, and (2) to assist Nepal in
the development of an overall strategy on how to address risk from GLOF s in the future.
ICIMOD is also implementing since 2008 for three year Sida funded project “Too much
Water, Too little water- Adaptation strategies to climate induced water stress and hazards in
the Greater Himalayan region”. Among the four major activities of the project, the first
activity is to strengthen the capacity within ICIMOD, and its national partners, to undertake
regular monitoring of glaciers, snow and ice fields, and pro-glacial lakes, on a regional scale,
with the purpose of supporting researchers and policy and decision makers in the region and
beyond with timely and adequate data and information on the status of these features.
ICIMOD together with the Center for International Climate and Environmental Research,
Oslo (CICERO) and UNEP will undertake a feasibility study for a Himalayan Climate Change
Impact and Adaptation Assessment (HICIA). This study will take place during 2008 and 2009.
During initial planning meetings it was decided that the feasibility phase shall focus on a
GLOF and flash flood risk assessment. The feasibility phase of HICIA will also foster an
inventory of ongoing modeling activities and capacity in the region as those tools are of
strategic importance to understand the impact of climate change on water resources in the
HKH.
BIBLIOGRAPHY
Bajracharya, S. R., Mool, P. K., Shrestha, B. R, (2007), Impact of climate change on Himalayan glaciers and
glacial lakes: case studies on GLOF and associated hazards in Nepal and Bhutan. ISBN 978 92 9115 032 8
ICIMOD, Nepal. 119p (http://books.icimod.org/index.php/search/publication/169)
Center for Science and Environment (2002) “Melting into Oblivion,” Down To Earth, 15 May 2002
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“Glaciers, Glacial Lakes and Glacial Lake Outburst Floods in the Himalaya”
Pradeep K. Mool
Page 6
ICIMOD (2003, 2004, 2005), Reports of APN 2004-03-CMY Project “Inventory of Glaciers and Glacial Lakes
and the Identification of Potential Glacial Lake Outburst Floods (GLOFs) Affected by Global Warming in the
Mountains of India, Pakistan and China/Tibet Autonomous Region”
(http://www.icimod-gis.net/gis/naturalhazard.php)
(http://www.rrcap.unep.org/issues/glof/glof/index.htm)
IPCC (2001a) IPCC Third Assessment Report- Climate Change 2001. Working Group I: Technical Summary.
Geneva, WMO and UNEP.
IPCC (2001b) IPCC Third Assessment Report- Climate Change 2001. Working Group II: Impacts, Adaptation
and Vulnerability. Summary for Policy Makers. Geneva, WMO and UNEP.
Ives, J.D(1986), Glacial Lake Outburst Floods and Risk Engineering in the Himalaya, ICIMOD Occasional Paper
No.5, ICIMOD, Nepal, 42 p. (http://books.icimod.org/index.php/search/publication/379)
Matny, L. (2000) Melting of Erth’s Ice Cover Reaches New High. Worldwatch News Brief, 06 March 2000.
Mool P.K(1993) Glacier Lake Outburst Floods in Nepal, WECS Bulletin June 1993
Mool, P.K et al(2001a), Inventory of Glaciers, Glacial Lakes and Glacial Lake Outburst Floods, Monitoring and
Early Warning Systems in the Hindu Kush-Himalayan Region: Nepal, ICIMOD & UNEP RRC-AP
(http://books.icimod.org/index.php/search/publication/131)
(http://ekh.unep.org/m-eKH/GLOF_NEPAL/GUIDE/movie.html)
Mool, P.K et al (2001b), Inventory of Glaciers, Glacial Lakes and Glacial Lake Outburst Floods, Monitoring and
Early Warning Systems in the Hindu Kush-Himalayan Region: Bhutan, ICIMOD & UNEP RRC-AP
Shrestha, A.B.; Wake, C.P.; Mayewski, P.A.; Dibb, J.E. (1999) “Maximum Temperature Trends in the Himalaya
and its Vicinity: An Analysis Based on Temperature Records from Nepal for the Period 1971 – 94.” In Journal of
Climate, 12:2775 – 2767
Xu, J., Shrestha, A. B., Vaidya, R., Eriksson, M., Hewitt, K., (2007), The Melting Himalayas: Regional
Challenges and Local Impacts of Climate Change on Mountain Ecosystems and Livelihoods, ISBN: 978-929115-047-2, ICIMOD, Nepal, 15p, (http://books.icimod.org/index.php/search/publication/286).
Zemp, M., Haeberli, W., Bajracharya, S., Chinn, T.J., Fountain, A.G., Hagen, J.O., Huggel, C., Kääb, A.,
Kaltenborn, B.P., Karki, M., Kaser, G., Kotlyakov, V.M., Lambrechts, C., Li, Z.Q., Molina, B.F., Mool, P.,
Nellemann, C., Novikov, V., Osipova, G.B., Rivera, A., Shrestha, B., Svoboda, F., Tsvetkov D.G. and Yao, T.D.
(2007): Glaciers and ice caps. Part I: Global overview and outlook. Part II: Glacier changes around the world. In:
UNEP (ed.): Global Outlook for Ice & Snow. UNEP/GRID-Arendal, Norway: 115-152pp.
Zhu Pingyi and Li Tianchi (2001) Flash Flooding Caused by Landslide Dam Failure. In ICIMOD's Newsletter
No. 38, Winter 2000/2001, pp. 4-5.
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“Glaciers, Glacial Lakes and Glacial Lake Outburst Floods in the Himalaya”
Pradeep K. Mool
Page 7
About ICIMOD and IWHM programme
The International Centre for Integrated Mountain Development, established in 1982 as a regional research and
development agency, has been working towards sustainable mountain development in the Hindu KushHimalayan (HKH) region and its mission is to help promote the development of an environmentally and
economically sound mountain ecosystem and to improve the living standards of mountain populations in the
Hindu Kush-Himalayan (HKH) region. Regional member countries are Afghanistan, Bangladesh, Bhutan, China,
India, Myanmar, Nepal, and Pakistan. In pursuing its mandate, ICIMOD works mainly at the interface between
research and development and acts as a facilitator for generating new mountain-specific knowledge of relevance
to mountain development. ICIMOD has recently started a new Five Year Medium-Term Action Plan (MTAP-II)
for the period 2008-2012. The Integrated Water and Hazard Management (IWHM) is one of the strategic
programme with the main goal to establish ICIMOD as a competent reference centre for regional level
knowledge, information and skills related to water and hazards. The programme plans to build a credible research
base, appropriate technologies and integrated approaches, developed in full consultation with national and
regional partners. It aims to contribute to the four medium-term outcomes related to improved assessment of
snow, ice and water resources, disaster risk reduction and taking a holistic view from upstream sources to
downstream impacts. More information on ICIMOD and its programmes is available in http://www.icimod.org
During MATAP-II (2008-2012) in collaboration with national partners of the Regional Member Countries
(RMCs) in Hindu Kush-Himalaya (HKH) region and donors, International Centre for Integrated Mountain
Development (ICIMOD) is implementing different studies of flash floods, glaciers, glacial lakes, GLOF, disaster
risk reduction, and related issues.
Acknowledgement:
I would like to thank, ICIMOD for support, to my colleagues and other study team members from ICIMOD and
partners for their contribution in preparing the information.
Contact address:
Pradeep K Mool
Remote Sensing Specialist
Action Area Team Leader for
Monitoring and Assessment of Ice and Water Resources
Integrated Water and Hazard Management Programme
International Centre for Integrated Mountain Development
Khumaltar, Lalitpur
PO Box 3226 Kathmandu, Nepal.
Email : pmool@icimod.org
Phone: 977-1-5003222 (Office);
Fax: 977-1-5003299;
URL: www.icimod.org
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“Glaciers, Glacial Lakes and Glacial Lake Outburst Floods in the Himalaya”
Pradeep K. Mool
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