Climate Change in Sikkim - Patterns, Impacts and Initiatives

Abstract

Impact of Climate Change: Glacier Lake Outburst Floods (GLOFs)

Full text

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IMPACTS OF CLIMATE CHANGE: GLACIAL LAKE
OUTBURST FLOODS (GLOFS)
Binay Kumar and T.S. Murugesh Prabhu
ABSTRACT
Worldwide receding of mountain glaciers is one of the most reliable evidences of the changing
global climate. In high mountainous terrains, with the melting of glaciers, the risk of glacial
related hazards increases. One of these risks is Glacial Lake Outburst Floods (GLOFs). As glaciers
retreat, glacial lakes form behind moraine or ice ‘dams’. These ‘dams’ are comparatively weak and can breach
suddenly, leading to a discharge of huge volume of water and debris. Such outbursts have the potential of
releasing millions of cubic meters of water in a few hours causing catastrophic ooding downstream with
serious damage to life and property. Glacier thinning and retreat in the Sikkim Himalayas has resulted in the
formation of new glacial lakes and the enlargement of existing ones due to the accumulation of melt-water.
Very few studies have been conducted in Sikkim regarding the impacts of climate change on GLOFs. Hence
a time-series study was carried out using satellite imageries, published maps and reports to understand the
impacts of climate change on GLOFs. The current study is focussed on nding the potential glacial lakes in
Sikkim that may be vulnerable to GLOF. The results show that some of the glacial lakes have grown in size
and are vulnerable to GLOF. Though extensive research is required to predict GLOFs, it is recommend that
an early warning system, comprising of deployment of real time sensors network at vulnerable lakes, coupled
with GLOF simulation models, be installed for the State.
KEYWORDS: Climate Change, Glacier, Glacier Retreat, Glacial Lake Outburst Floods (GLOFs), Remote
Sensing, Moraine Dammed Lakes, Snout
Remnants of Glacial Lake Outburst Flood (GLOF) in Teen-kune Pokhri, below Mt. Pandim in West Sikkim
Photo courtesy: Sandeep Tambe

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Fig. 1: Chho Lhamo (5217 m) in North Sikkim, one of the lakes having GLOF potential

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Glacial lakes in the Himalaya are known to have mostly formed within the last 5 decades. Warming
in the Himalayas in the last three decades has been between 0.15°C and 0.60°C per decade (Shrestha
et al. 2010). As a result of global warming, the glacial lakes are increasing in number and size. The
GLOF events have trans-boundary effect resulting in loss of lives, as well as the destruction of houses, bridges,
elds, forests, hydro-power stations, roads, etc. Regular monitoring of glaciers and glacial lakes and adaptation
measures including early warning systems and mitigation measure are required in areas vulnerable to GLOF
(Bajracharya 2006).
Effects of climate change like unseasonal rainfall, lake outbursts, rising temperatures, increased ooding, ash
oods, rock avalanches from destabilized slopes leading to road blockages are already being experienced in
Sikkim. Very few studies have been conducted in Sikkim regarding the impacts of climate change on GLOFs
so far. It is imperative that the State builds a knowledge database on the climate change so that it can prepare
itself for reducing the impacts and adapting to the forecasted changes. Our knowledge of GLOFs is very
limited and advanced research needs to be undertaken to predict and reduce their effects.
Remote sensing with its advantages of spatial, spectral and temporal availability of data covering large and
inaccessible areas within short time has become a very handy tool in assessing and monitoring disaster prone
zones in high altitude regions. Moraine dam lakes have been mapped and monitored by using remote sensing
data in the Sikkim Himalayas. The glacial lakes were mapped and monitored from the disaster point of view
and in relation to climatic variations.
The frequency of GLOF events is increasing in the Hindu Kush Himalayan (HKH) region since the second
half of the 20th century due to the combined effects of climate change and deforestation. Satellite observation
of the mountain top lakes in the region have revealed a steady increase in the size and volume of many of
these glacial lakes at high altitudes, enhancing the possibility of a devastating outburst ood affecting sizeable
populations, damaging precious socio-economic infrastructure and development assets in the Himalayan belt
(UNDP 2010).
CLIMATE CHANGE
“Climate Change” in Intergovernmental Panel on Climate Change (IPCC 2007) parlance refers to a change
in the state of the climate that can be identied (e.g. using statistical tests) by changes in the mean and/or the
variability of its properties and that persists for an extended period, typically decades or longer. It refers to any
change in climate over time, whether due to natural variability or as a result of human activity. As per United
Nations Framework Convention on Climate Change (UNFCCC 1992) usage, it refers to change of climate that
is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and
that is in addition to natural climate variability observed over comparable time periods.
Globally, the impacts of climate change include among others, rising temperatures, shifts in rainfall pattern,
melting of glaciers and sea ice, risk of glacial lake outburst oods (GLOFs), sea level rise and an increased
intensity and frequency of extreme weather events (Ganguly et al. 2010). Global warming is the prime factor
for the accelerated glacial melt and retreat, giving birth to hazardous glacial lakes in the Sikkim Himalayas.

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GLACIAL LAKE OUTBURST FLOODS (GLOFS)
The acronym GLOF is used for glacier oods caused by the drainage of naturally dammed lakes in the glacier,
on or at the margin of glaciers. GLOFs are not a new phenomenon but with the worldwide receding of glaciers
and rising temperature the probability of their occurrences has risen in many mountain ranges. “Glacier oods
represent in general the highest and most far reaching glacial risk with the highest potential of disaster and
damages” (Richard et al. 2003).
A lake outburst can be triggered by several factors: ice or rock avalanches, the collapse of the moraine dams
due to the melting of ice buried within, the washing out of ne material by springs owing through the dam
(piping), earthquakes or sudden inputs of water into the lake e.g. through heavy rains or drainage from lakes
further up-glacier. Self-destruction is caused by the failure of the dam slope and seepage from the natural
drainage network of the dam (WWF Nepal Program 2005).
IMPACT OF CLIMATE CHANGE ON GLACIERS AND GLACIAL LAKES
The climatic change/variability in recent decades has made considerable impacts on the glacier lifecycle in the
Himalayan region. The Himalayas are geologically young and fragile and are vulnerable to even insignicant
changes in the climatic system (Lama et al. 2009). Studies conrm that many glaciers of the Sikkim Himalayas
are leaving glacial lakes with increasing intensity, which in fact is corroborating with the intermediate effects
of long term Climate Change by majority of scientists.
Glacier thinning and retreat in the Sikkim Himalayas has resulted in the formation of new glacial lakes and the
enlargement of existing ones due to the accumulation of melt-water behind loosely consolidated end-moraine
dams. Such lakes are inherently unstable and subject to catastrophic drainage, they are potential sources of
danger to people and property in the valleys below them (ICIMOD 2011). Local communities living in the
region are dependent upon the lakes for their livelihood regardless of whether they are settled or nomadic
(SAC 2011).
Recent studies being carried out by Centre for Development of Advanced Computing (C-DAC), Pune jointly
with Sikkim State Council of Science & Technology, Gangtok, have shown that many glacial lakes in Sikkim
Himalayan region have grown over the years revealing the impact of climate change on glacial lakes and
associated hazards.
The state of Sikkim shelters many Glaciers, mainly Zemu Glacier, Rathong Glacier and Lhonak Glacier.
The status of these Glaciers has become a measuring stick of climate change (SAC 2010). The East Rathong
Glacier is one of the important glaciers of Sikkim which has been affected by climate change. The glacier
has retreated signicantly since 1965 and a marked shift in its Snout position has been observed. A glacier
terminus, or snout, is the end of a glacier at any given point in time, the position of which is impacted by
localized or regional temperature change over time (NSIDC 2007). A glacial lake is in formation behind the
terminal moraines due to blockage of the melt water. Its current state as observed today is shown in Fig. 2
below.
DATABASE AND METHODOLOGY
Various types of data such as satellite borne remote sensing data and other published maps and reports constitute
the database necessary for the mapping and monitoring of glacial lakes in the Sikkim Himalayas. Multi-
date Indian Remote Sensing Satellites - IRS-1A/1B/1C/1D/P6, United States Geological Survey (USGS)
Declassied Imagery (CORONA, KH-Series), Land Observation Satellites (LANDSAT- MSS, TM, ETM),
and Google Earth, etc. data in digital format were used in conjunction with secondary or collateral data.

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All the glacial lakes of Sikkim were demarcated and delineated using remote sensing data, published maps &
reports, and eld data. Moraine dammed lakes are an important component of glacier studies. These lakes are
important in monitoring of disaster prone zones in high altitude regions. Time-series analysis of the glacial
lakes was carried out with the available cloud-free satellite imageries for the region. Geographic Information
System (GIS) software package was used for creation of digital database and data analysis.
CRITERIA FOR IDENTIFICATION, SELECTION AND MONITORING OF GLACIAL LAKES
1. Lake area expansion over the years
2. Increase in water level of glacial lakes due to expansion of lake area
3. Formation of new glacial lakes
4. Signicant glacier retreat
5. Lakes located at an altitude 4,500 m and above
6. Area of lakes more than 0.05 sq. km.
7. Position of the lakes – near to ablation area of the glacier
8. Proximity of the glacial lakes to the parent glacier
9. Lakes formed due to the damming of the channel ow by the end/terminal moraines
Fig. 2: East Rathong Glacier, West Sikkim – glacial geomorphological features such as glacial lake,
snout, moraines and the parent glacier are seen. Photo courtesy: Binay Kumar, May 2011)

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Glacial Lakes Monitored for the study (1965 to 2010)
In Teesta and Rangit basins of Sikkim Himalayas moraine-dammed lakes were observed from 1965 to 2010
using satellite imageries. For the current study, lakes meeting most of the above criteria were identied and
monitored. The glacial/moraine dammed lakes which were further monitored and mapped are listed below:
NORTH SIKKIM
a. Gurudongmar Chho Complex* (3 lakes denoted as A, B and C)
i. Gurudongmar Chho “A” (elevation 5,174 m)
ii. Gurudongmar Chho “B” (elevation 5,253 m)
iii. Gurudongmar Chho “C” (elevation 5,218 m)
b. Chho Lhamo (elevation 5,217 m)
c. Khangchung Chho (elevation 5,325 m)
d. Lachen Khangse Chho (elevation 5,181 m)
e. Glacial Lake feeding river Shako Chhu (elevation 4,975 m)
f. Khora Khang Chho (elevation 5,097 m)
g. South Lhonak Chho (elevation 5,210 m)
h. Lhonak Chho (elevation 5,451 m)
WEST SIKKIM
a. Bhale Pokhari (elevation 4,727 m)
b. Glacial Lake feeding river Tikip Chhu (elevation 4,877 m)
*Gurudongmar Chho Complex: The Gurudongmar Chho Complex in the current study comprises of 3
lakes - Gurudongmar Chho (elevation 5174 m, denoted as “A”) and two other lakes located at the terminus
of Gurudongmar glacier (elevations 5253 and 5218 m and denoted as B” and “C” respectively) feeding the
Gurudongmar lake.
ANALYSIS
Glaciers continually adjust their size and ow speed to seek equilibrium with climate. By comparing newer
remote-sensing derived glacial lake outlines with older data sets derived from topographic maps or older
imagery, the changing face of glacial lakes could be seen.
Monitoring and tracking of the lakes in West and North Sikkim has revealed that quite a few of them are
expanding due to accelerated glacial retreat and melting due to climate change impacts. The lakes have been
increasing in size and volume since 1965. Their area has increased signicantly in about 45 years and this
indicates the lakes are important from the disaster point of view and also in view of climatic variations in last
three decades. In addition, new lakes have also developed due to glacier retreat and melting. During the retreat
the glaciers leave behind moraines (accumulation of boulders, stones or other debris) in the valley. A Moraine-
laden valley in North Sikkim, carved by a retreated glacier is shown in Fig. 3.
Field observations give an impression of a past GLOF event in the Sebu Chhu valley, North Sikkim. The wide
spread of the moraines in the valley might have been carried downstream by the ood waters from the Sebu

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Fig. 4: Zemu river originates from Zemu glacier and lateral
landslides pose the danger of damming the river and causing
oods downstream
Fig. 3: : Moraine-laden glacier valley. Moraines are left
behind by the retreating glaciers. Also seen is the ow of
melt water feeding Sebu Chhu, North Sikkim.
Photo courtesy: Binay Kumar, Nov 2010
Chho, which appears to have breached in the past (Fig. 14). Local information also supports an event of a ash
ood in the Sebu Chhu Valley. The change in the area of the glacial/moraine dammed lakes monitored since
1965 has been shown in Table-1.
Table-1: Statistics showing growth in the area of glacial/moraine dammed
lakes over the years. The lake areas are in sq. km.
Lake Name/Year 1965 1976 1989 1997 2000 2005 2010
Gurudongmar Chho A 1.048 1.099 1.099 1.099 1.104 1.115 1.134
Gurudongmar Chho B 0.249 0.322 0.925 1.046 1.046 1.073 1.076
Gurudongmar Chho C 0.480 0.687 0.718 0.728 0.732 0.745 0.745
Chho Lhamo 0.649 0.963 1.031 1.031 1.031 1.031 1.031
Khangchung Chho 1.178 1.261 1.605 1.630 1.661 1.661 1.734
Lachen Khangse Chho 0.360 0.370 0.516 0.523 0.586 0.613 0.613
Glacial Lake feeding
river Shako Chhu 0.273 0.409 0.561 0.561 0.561 0.561 0.561
Khora Khang Chho 0.166 0.217 0.269 0.296 0.302 0.342 0.351
South Lhonak Chho 0.242 0.251 0.410 0.633 0.691 0.794 1.028
Lhonak Chho 0.231 0.282 0.418 0.460 0.494 0.652 0.656
Bhale Pokhari 0.090 0.104 0.108 0.114 0.114 0.114 0.114
Glacial Lake feeding
river Tikip Chhu 0.069 0.108 0.214 0.257 0.308 0.311 0.311

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Fig. 5: Monitoring of Gurudongmar Chho complex, North Sikkim
USGS declassied image 1965 LandSAT MSS image 1976 LandSAT TM image 1989
IRS 1C image 1997 LandSAT TM image 2000 LandSAT TM image 2005
IRS P6 image of 2010 Lake Area Change Map
Gurudongmar Chho Complex
North Sikkim Gurudongmar Chho Complex
North Sikkim Gurudongmar Chho Complex
North Sikkim
Gurudongmar Chho Complex
North Sikkim Gurudongmar Chho Complex
North Sikkim Gurudongmar Chho Complex
North Sikkim
Gurudongmar Chho Complex
North Sikkim Gurudongmar Chho Complex
North Sikkim

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Fig. 6: Panoramic view of the frozen moraine dammed lake feeding Tikip Chhu, West Sikkim. Photo courtesy: Mr. Safal Pradhan, May 2011

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IRS P6 image of 2010 Lake Area Change Map Snout Position Map
Fig. 7: Monitoring of Glacial Lake feeding Tikip Chhu, West Sikkim
USGS declassied image 1965 LandSAT MSS image 1976 LandSAT TM image 1989
IRS 1C image 1997 LandSAT TM image 2000 LandSAT TM image 2005
Glacial Lake feeding Tikip Chhu
West Sikkim Glacial Lake feeding Tikip Chhu
West Sikkim Glacial Lake feeding Tikip Chhu
West Sikkim
Glacial Lake feeding Tikip Chhu
West Sikkim Glacial Lake feeding Tikip Chhu
West Sikkim Glacial Lake feeding Tikip Chhu
West Sikkim
Glacial Lake feeding Tikip Chhu
West Sikkim Glacial Lake feeding Tikip Chhu
West Sikkim Glacial Lake feeding Tikip Chhu
West Sikkim

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Fig. 8: Panoramic view of the frozen moraine dammed lake feeding Tikip Chhu, West Sikkim. Photo courtesy: Mr. Safal Pradhan, May 2011

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Fig. 9: Monitoring of Khangchung Chho, North Sikkim
USGS declassied image 1965 LandSAT MSS image 1976 LandSAT TM image 1989
IRS 1C image 1997 LandSAT TM image 2000 LandSAT TM image 2005
IRS P6 image 2010 Lake Area Change Map
Khangchung Chho
North Sikkim
Khangchung Chho
North Sikkim Khangchung Chho
North Sikkim Khangchung Chho
North Sikkim
Khangchung Chho
North Sikkim Khangchung Chho
North Sikkim
Khangchung Chho
North Sikkim
Khangchung Chho
North Sikkim

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In 2007, a ash ood washed away the riverine vegetation along the Zemu river

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Fig. 10: Monitoring of Lhonak and South Lhonak Chho, North Sikkim
IRS P6 image 2010 Lake Area Change Map Lake Area Change Map
USGS declassied image 1965 LandSAT MSS image 1976 LandSAT TM image 1989
IRS 1C image 1997 LandSAT TM image 2000 LandSAT TM image 2005
Lhonak and South Lhonak Cho
North Sikkim Lhonak and South Lhonak Cho
North Sikkim Lhonak and South Lhonak Cho
North Sikkim
Lhonak and South Lhonak Cho
North Sikkim Lhonak and South Lhonak Cho
North Sikkim Lhonak and South Lhonak Cho
North Sikkim
Lhonak and South Lhonak Cho
North Sikkim Lhonak and South Lhonak Cho
North Sikkim Lhonak and South Lhonak Cho
North Sikkim

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RESULTS / FINDINGS
The climatic change/variability in recent decades has made considerable impacts on the glacier lifecycle in
the Sikkim Himalayas. The melting of glaciers and accumulation of melt water in the lakes has signicantly
increased the volume of water in the glacial lakes. The areal expansion of the glacial lakes monitored under
the current study has been graphically represented in the Fig. 11 below.
Fig. 11: Areal expansion of glacial lakes between 1965 and 2010.
From the graph it is evident that other than lakes Gurudongmar Chho “A” and Bhale Pokhari, the area of all other
lakes has increased signicantly between 1965 and 1989. Between 1989 and 2010, other than the lakes Chho
Lhamo, Gurudongmar Chho “A”, “C”, the glacial lake feeding river Shako Chhu, and Bhale Pokhari, the area
of other lakes has changed. Field observations carried so far conrm this. This signicant trend in the increase
in area of most of the glacial lakes may be attributed to the global warming phenomenon. The rising trend in the
graphs signies the impact of climate change on glaciers. The increase in area of glacial lakes behind unstable
moraine dams poses more danger of GLOFs. The stagnation in areal growth of the lakes between 1989 and 2010
may be attributed to equilibrium between the melt water in-ow to the lake and the water getting drained out of
the lake.
The graphical representation of the areal change of glacial lakes between 1965 and 2010 has been shown in Fig.
12 and Fig. 13.

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Glacial Lake Area Change
Fig. 12: Change in lake area between 1965 and 1989.
Fig. 13: Change in lake area between 1989 and 2010.
The area of lake “B” in the Gurudongmar Chho Complex has increased nearly 4 times between 1965 and
1989, whereas of lake ‘C”, it’s nearly double. The signicant increase in the areas of lakes “B” and “C” is a
clear indicator of the glacier retreat/melt and accumulation of more melt water in the moraine dammed lakes,
as shown in Fig 12 and Fig. 13. Between 1989 and 2010, Gurudongmar Chho “B” has grown by one-sixth of
its size in 1989. The volume of water these 3 lakes together hold could be easily estimated. The risk associated
with the GLOF event, in case any of the above dams particularly “B” and “C” break could easily be perceived.
The Khanchung Chho, origin of the River Teesta is another moraine dammed lake which has grown noticeably
over past few years, as evident in Figs. 9, 11 12 and 13. Its area has increased nearly 1.5 times between 1965
and 1989 and approximately one-tenth of its size in 1989 between 1989 and 2010. The parent glacier is in
contact with the lake which further enhances the vulnerability of the lake to cause GLOF.

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The Chho Lhamo (Fig. 1), a glacial lake that has grown in size signicantly is located near the border of
Sikkim and Tibet Autonomous Region (TAR) and feeds River Teesta. In 1989, its area has increased by 1.5
times its size in 1965. Since then its area has remained almost same till 2010.
The increase in area of the Lhonak and South Lhonak glacial lakes over the last 45 years is signicant. Both
these lakes have grown in area by 2 times between 1965 and 1989. Lhonak has grown nearly 1.5 times and
South Lhonak nearly 2.5 times of their initial size in 1989, as shown in Fig. 10, Fig. 12 and Fig. 13. The increase
in size is not the only factor that lists this lake as a potential GLOF source. An earthquake of magnitude 4.9
of Sept 21, 1991 (as reported by United States Geological Survey) near the parent glacier feeding the South
Lhonak Lake and the recent earthquake (magnitude 6.9) of Sept 18, 2011 approximately 70 km from the lakes
and future earthquakes may trigger the GLOF events. In future also the earthquakes may occur considering the
fact that the state of Sikkim falls in Zone-IV of the Indian Seismicity Chart.
The moraine dammed lake feeding Tikip Chhu (Fig. 8) in West Sikkim has increased noticeably by nearly ve
times since 1965. The areal growth of the lake and the position of snout (terminus of glacier) over the years
have been depicted in Fig. 7. It is very interesting to note that this lake is newly formed due to glacier retreat
and is not present in Survey of India Topographic sheets.
The moraine dammed lake feeding Shako Chhu has increased by nearly two times between 1965 and 1989
and the area remains almost same thereafter till 2010.
Fig. 14: Green Lake (Tikuchia Pokhari), West Sikkim - a moraine dammed lake formed due to the retreat of glacier near
Goecha La. Photo courtesy: Swapnil Awaghade, May 2011

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Another lake in West Sikkim is Green Lake (Tikuchia Pokhari), which is a moraine dammed lake, has formed
due to the retreat of glacier near Goecha La is shown in Fig. 14. Field observation show that the lake is
surrounded by boulders (moraines) and there is considerable seepage of water from the southern part of lake.
GLOF EARLY WARNING SYSTEM IN SIKKIM – A C-DAC INITIATIVE
Although extensive research is required to predict GLOFs, an early warning system capable of providing alerts
in case there is a threat of GLOF is essential. C-DAC has taken up a project funded by the Department of
Information Technology, Government of India to set up a GLOF Early Warning System at Sikkim by deploying
eld sensors at 2 lakes on pilot basis. C-DAC has taken up the challenge to design and develop real time
eld sensors for recording rise in water level in selected moraine dammed lakes. The eld sensor data will
be transmitted through satellite communication network and will be used in the ood simulation model for
prediction of GLOF/ash oods, areas likely to be inundated/affected by GLOFs, and Impact assessment of
GLOFs.
CONCLUSION
From the time-series study carried out using satellite imageries of the Sikkim Himalayas, to understand the
climate change induced risks and vulnerabilities of GLOFs, it is evident that many glacial lakes have expanded
over the years. As a result, many big glaciers have melted rapidly, forming a large number of glacial lakes.
Fig. 15: Glacial Lake at the end of Changme Khangpu Glacier, North Sikkim. Also seen the moraines
spread around the area, giving an impression of a past GLOF event at Sebu Chho.
(Photo courtesy: N. P. Sharma, Nov 2010)

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Due to an increase in the rate at which ice and snow melted, the accumulation of water in these lakes started
increasing rapidly. Sudden discharge of large volumes of water with debris from these lakes potentially causes
glacial lake outburst oods (GLOFs) in valleys downstream. These result in serious death tolls and destruction
of valuable natural resources, such as forests, farms, and costly mountain infrastructures. The Hindu Kush-
Himalayan region has suffered several GLOF events originating from numerous glacial lakes, some of which
have trans-boundary impacts (Bajracharya et. al., 2006).
The areal growth of the lakes Gurudongmar “A”, Chho Lhamo and Bhale Pokhari (Fig. 11) seems to have
ceased since the last 2 decades and may not be an immediate threat, but nevertheless their vulnerability remains
high from the GLOF point of view. All other lakes whose areas have increased signicantly over the last 45
years should be considered dangerous and GLOF prone.
It is vital to identify potentially dangerous glacial lakes and the risks they pose, and highlight the critical ones.
Some glacial lakes may have caused GLOF in the past and may breach again in future. Hence, identication
and monitoring of such lakes need to be carried out, by evidences of past GLOF events. Remote sensing
imageries are very useful in monitoring of the glaciers and glacial lakes as new glacial lakes are being created
and existing ones continue to grow. Regular monitoring of glacial lakes, identication of critical lakes and
GLOF prone areas, installation/deployment of eld sensors in glacial lakes, setting up of early warning system,
creating awareness among the people and adopting mitigation measures, may reduce the intensity of the disaster
associated with GLOFs.
Though extensive research is required to predict GLOFs, it is recommend that an early warning system be
installed for the State. The early warning system should be capable of providing alerts to the Government
authorities in case there is a threat of GLOF. Deployment of real time sensors network at vulnerable lakes,
capable of measuring rise and discharge of water, will enable the authorities to set up an early warning system.
The early warning system coupled with GLOF simulation models capable of predicting the time of arrival of
Fig. 16: : South Lhonak Chho depicting the moraine dam breach-section (shown in red box on inset picture),
an evidence of past GLOF event. There is a possibility that the lake may rell & may cause GLOF.

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the ash ood and showing the ooded areas downstream will enable the local authorities to take precautionary
measures in the event of a GLOF.
ACKNOWLEDGEMENT
This paper forms a part of the project “Mapping of Glacier Lakes and development of GIS based Glacier Lake
Management Information System for the State of Sikkim” funded by the Department of Information Technology,
Government of India. We thank the Sikkim State Council of Science and Technology, Department of Forests,
and the Government of Sikkim for their permission to carry out research work in protected areas. We also
thank Mr. Sandeep Kumar Srivastava, Associate Director and HoD, Geomatics Solutions Development Group
(GSDG), Centre for Development of Advanced Computing (C-DAC) for his motivation. Our sincere thanks to
Shri M. L. Arrawatia (IFS) the then Member Secretary - Sikkim State Council of Science & Technology and
Chairman, Sikkim Public Service Commission in developing the concept of GLOF Early Warning System for
Sikkim and Dr. Sandeep Tambe (IFS), Special Secretary, Rural Management and Development Department,
Government of Sikkim for sharing some of the valuable photographs. We also thank the scientists and staff of
Sikkim State Council of Science & Technology for their support, help and participation in the eld studies. We
also extend our gratitude to the management of C-DAC for their support and guidance.
ACRONYMS
C-DAC – Centre for Development of Advanced Computing
ETM – Enhanced Thematic Mapper
GIS – Geographic Information System
GLOF – Glacial Lake Outburst Flood
ICIMOD - International Centre for Integrated Mountain Development
IPCC - Intergovernmental Panel on Climate Change
IRS – Indian Remote Sensing Satellite
LandSAT – Land observation Satellite
MSS – Multi Spectral Scanner
NSIDC- National Snow and Ice Data Center
SAC – Space Applications Centre (ISRO)
TM – Thematic Mapper
UNDP - United Nations Development Program
UNFCC - United Nations Framework Convention on Climate Change
USGS – United States Geological Survey
WWF – World Wildlife Fund

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AUTHORS
Binay Kumar and T.S. Murugesh Prabhu
Geomatics Solutions Development Group (GSDG)
Centre for Development of Advanced Computing (C-DAC), 6th Floor, NSG IT Park, Above Croma, Hotel
Sarja Lane, Aundh, Pune – 411 007, Maharashtra
Email: binay@cdac.in
E-mail: murugeshp@cdac.in