77

A Social Survey for GLOF Disaster Mitigation in Bhutan
Shuhei TAKENAKA1*, Tadashi SATOH1 and Sonam LHAMO2
1

Earth System Science Co.,Ltd.,
1-23-1, Shinjuku, Shinjuku-ku, Tokyo 160-0022, Japan2
Department of Geology and Mines, Ministry of Economic Affairs,
P.O. Box 173, Thimphu, Bhutan* e-mail: fd5c-tknk@asahi-net.or.jp

Abstract
As part of the JICA/JST Glacial Lake Outburst Floods (GLOFs) project, we carried out a social survey incentral Bhutan in 2010 to acquire fundamental information about local communities and means of communication in case of disasters.The surveyed areas were the Mangde Chhu basin, the target area of the project,
and the neighboring Punatsang Chhu and Chamkar Chhu basins. The survey was conducted interview-style,using questionnaires to seek information from local governments, residential communities and schools. The
findings of the survey were as follows.
Some communities in the Mangde Chhu basin, especially temporary camps for construction workers
located on riverbanks, have a potential risk of human damage from GLOFs. In Zhemgang Dzongkhag, theratio of residents with no communication tools is very high (42%), compared with the other areas (0% - 13%).
Generally, traditional communities in Bhutan are safe from floods, including GLOFs. However, temporary
residents of local communities, such as people living in workers camps on riverbanks, are highly vulnerable tofloods. Accordingly, a concrete disaster mitigation plan, including off-limits zones based on accurate hazard
maps, is necessary. Also, early warning systems are very effective at mitigating damage from GLOFs. As fordevices to alert the residents, other than sirens and loudspeakers, radio and mobile phones are most appropriate because of their high ownership ratios. In general, schools are well equipped with communication tools,
and teachers have a good understanding of their local communities, thus, schools can act as a foothold for disaster mitigation measures providing regular disaster education to entire communities through their students.
Key words: Bhutan, early warning system, GLOF, hazard map, social survey

1. Introduction
Bhutan is a small country, but it has a diverse naturalenvironment – from subtropical plains to high Himalayanridges – and the disasters it encounters are similarly
diverse. Furthermore, due to the recent retreat of glaciersin high mountain areas worldwide, formation and expansion of glacial lakes have also been reported in the
country (Bahracharya et al., 2007). Since these glaciallakes were dammed by moraines, which are generally
fragile, many of them have a potential risk of glacial lake
outburst floods (GLOFs). As described below in Section
3, in October 1994, a GLOF that originated from the
Luggye glacial lake rushed 80 km downstream to the oldtown of Punakha, killing more than 20 people anddestroying part of a local government building. The International Center for Integrated Mountain Development(ICIMOD) has listed 24 glacial lakes in Bhutan with thepotential risk of GLOFs (Mool et al., 2001).
The JICA/JST GLOFs project has been launched tomitigate the threat of GLOFs,. Its objectives are to
Global Environmental Research
16/2012: 77-82
printed in Japanevaluate the risk of GLOFs, create hazard maps and propose suitable early warning systems in the Mangde Chhu
area of central Bhutan (“Chhu” means “river”). As part ofthe project, we carried out a social survey in central
Bhutan to acquire fundamental information about the
local communities, such as their location, size, GLOF
awareness of the residents and means of communicationin case of disasters.

2. Outline of the Survey Area and Methods
The survey was carried out from mid May to early
June 2010. Since the JICA/JST project targeted GLOFs
in the Mangde Chhu region, the Mangde Chhu basin, andthe neighboring two river basins, Punatsang Chhu andChamkar Chhu, were chosen as the study areas (Fig. 1).
Interviews were carried out at local government
offices, in communities and at schools, using different
questionnaire sheets prepared for each group (thequestionnaire items used for each group are listed inTable 1). To avoid linguistic problems, and unnecessary©2012 AIRIESS. TAKENAKA et al.

78

Fig. 1 Location of study areas. The broken blue dotted lines show the Punatsang Chhu, Mangde Chhu and Chamkar Chhu areas, from left
to right. The black dashed lines show the borders of the dzongkhags with the locations of dzongs in red solid circles.
Table 1 Questionnaire items.
Que stionnaire ite ms fo r lo cal go ve rnme nt
1. Dzongkhag disaster prevention division
2. Disaster prevention measures
3. Disaster prone areas
4. History of disaster damage
5. Emergency information relay
Questio nnaire items for local reside nts
1. Basic social information
2. Knowledge of natural disasters
3. Ownership of information tools
4. Awareness of disaster prevention
5. Awareness of GLOFs
Que stionnaire ite ms fo r schoo l te ache rs
1. Basic social information
2. Knowledge of natural disasters
3. Ownership of information tools
4. Awareness of disaster prevention
5. Awareness of GLOFs

stress to the interviewees, the interviewers were
Bhutanese participants. In terms of administration,
Bhutan is divided into 20 dzongkhags (districts). The
survey was conducted in five dzongkhags (Punakha,
Wangdue Phodrang, Trongsa, Zhemgang and Bumthang).
Each dzongkhag consists of gewogs (villages), andchewogs (settlements). The interviewees at the dzongs,
the local government offices of the dzongkhags, weremainly officials in charge of disaster prevention. We also
attempted interviews in gewogs and chewogs as well,although no such officials were posted in most cases.
Furthermore, we interviewed residents of communities that were specified as flood disaster-prone areas by

the local government. Naturally, these communities werelocated along rivers. Teachers from schools that werelocated near the rivers were also interviewed. In general,
the interviewees were principals or vice-principals of theschools.
Additionally, where possible, on-site inspections
were also conducted. If a gauging station existed in thearea, available records of floods (hydrographs) were alsocollected.

3. Results
3.1 Local governments
Table 2 shows a summary of the results of this survey,
based mainly on the interviews of local government
officials.
The following were commonly observed among the
local governments of the dzongkhags. The officials incharge of disaster prevention were also assigned to otherposts, such as development, forestry or environment
divisions. Additionally, their terms at the post tended tobe relatively short. In case of an emergency, the officials
were charged with relaying the information to the gewog
personnel using either fixed-line phones or mobile
phones. In areas where such communication means were
not available, on-foot messengers were used instead.
In May 2009, when Cyclone Aila caused heavy
flooding in all three of the river basins, damage to workers camps, farmland, roads and bridges was observed,
although no human damage was reported.
3.2 Community Residents
Table 3 shows the statistical results of the questionnaire surveys of community residents.
Regarding occupation, in most areas, more thanA Social Survey for GLOF Disaster Mitigation in Bhutan

79

Table 2 Summary of the survey results.
Dzongkhag

Watershed

Disaster Prevention Measures

Characteristics of the Region

Other Notes

Phunaka

Phunatsang
Chhu# Infrastructure such as roads and means ofcommunication such as fixed-line phones
were well developed.

# Phunaka experienced GLOFs in
1957, 1960 and 1994.

Wangdue

Phunatsang
Chhu# DDM*1 implemented CBDRM*2 at the# Farmlands, arterial roads and high school grounds
dzongkhag and gewog levels, and had planned
were inundated by Cyclone Aila.
to extend it to the chewog level.
# Roads on the left bank of the Phunatsang Chhu and# DDM was implementing a "School Safety
three houses at Bajothang were inundated byPlan" at schools.
Cyclone Aila. Many reports of inundation of
farmlands.
# DDM completed a flood hazard map along thePhunatsang Chhu.
# The dzongkhags had activities to develop
disaster prevention awareness among local
residents.

# Electricity, fixed-line phones and mobile
services were unavailable in upstream areas.

Trongsa

MangdeChhu

Disaster Prone Area

# More than five bamboo shelters were on the lower
terrace along Mangde Chhu at Bjeezam.

# In the 1994 GLOF, more thantwenty workers were killed, andpart of the dzong and some houses
were destroyed.

# A worker’s camp was washed away by Cyclone
Aila at Yurmung.
# An arterial road was washed away by Cyclone Aila
for 1.5km in length at Yurmung, Langthel Gewog.
The road was blocked for 1.5 months.

Zhemgang

MangdeChhu# Farmlands and roads near Takabi were washedaway by Cyclone Aila.

# Average household income in survey areas
was low.

# A natural dam was formed by debris flows at theconfluence of the Mangde Chhu and Chamkhar
Chhu. It had an outburst with a water level fivemeters higher than usual.

# Average disaster prevention awareness of
local residents was low.
# Development of infrastructure such as roads
and means of communication was behindthat of other dzongkhags.

# DDM*1 implemented CBDRM*2 at the# A landslide caused by Cyclone Aila killed six local
dzongkhag and gewog levels, and had planned
people picking Cordyceps in the headwaters area
to extend it to the chewog level.
(>4,000m a.s.l.) of the Chamkhar Chhu.
BhumtanChamkharChhu# DDM was implementing a "School Safety
Plan" at schools.

# Farm roads, farmlands and wooden bridges were
washed away by Cyclone Aila.

# Electricity, fixed-line phones and mobile# DGM had completed a flood hazard
services were unavailable in upstream areas.
map of the Chamkar Chhu, but the
local government hadn’t received ityet.

# DDM completed a flood hazard map along thePhunatsang Chhu.

*1 DDM: Department of Disaster Management, Bhutan.
*2 CBDRM: Community Based Disaster Risk Management.

Table 3 Statistical results from the questionnaires provided to community residents.
Dzongkhag
Category

Item

Punakha

Wangdue
PhodrangTrongsaZhemgang Bumthang

AverageMobile Phone

100%

100%

71%

39%

67%

Fixed Phone

0%

0%

5%

0%

0%

1%

Radio

75%

71%

85%

39%

97%

77%

TV

73%

57%

0%

6%

27%

24%

No Tools

0%

13%

10%

44%

3%

13%

Agriculture

87%

100%

38%

83%

83%

74%

Occupation
Livestock(multiple answers allowed) Shopkeeper

92%

31%

24%

61%

80%

66%

20%

13%

29%

6%

10%

14%

Government Employee

0%

40%

29%

0%

7%

10%

0 Nul

0%

0%

0%

28%

3%

7%

1-500 Nul

0%

0%

14%

44%

3%

13%

Ownership ratio of
information tools

Income of household(Nul/month)

501-5000 Nul

63%

67%

62%

22%

40%

46%

5001-10000 Nul

31%

33%

0%

6%

27%

17%
15%

10001-20000 Nul

6%

0%

24%

0%

20%

Above 20001 Nul

0%

0%

0%

0%

7%

2%

5,156

5,000

5,264

837

12,013

6,765

75%

100%

81%

68%

93%

83%

16

5

21

19

30

Total 91

Average
Awareness of GLOFs

71%

Yes

Sample Number

80 percent of the residents were engaged in agriculture if
cases in which agriculture was a side-job are included. In
most dzongkhags, the majority of monthly householdincomes range from 500 Nul to 5,000 Nul (100 Nul isabout 2.2 USD as of August 2011). Only in Zhemgang
Dzongkhag, downstream of Mangde Chhu, in the southern, low-altitude part of the survey area, more than halfof the interviewees’ household incomes were less than
500 Nul. On the other hand, the incomes of the residentsof Bumthang were considerably higher than in otherareas, which might be due to the area being popularamong foreign travelers, and some of the residents
having side-jobs picking Cordyceps fungi, which aretraded at a high price.
The ownership ratio of radios is very high in all areas,
and generally, the ownership ratio of mobile phones isalso very high, except in Zhemgang Dzongkhag andupstream areas, where mobile phone networks are not yet
available. It is worth noting that the ratio of “no tools” inZhemgang Dzongkhag is therefore comparably high(42%), compared with the other dzongkhags (0% - 13%).
On average, there was high awareness of GLOFs
among community residents (83%) – whether or not theinterviewee knew what a “GLOF” was. Even in
Zhemgang Dzongkhag, despite residents being considered less well informed, it was 68%. Surprisingly, in
Punakha, despite their experience of three GLOFs, themost recent being in 1994, and the fact that most of theinterviewees were living on the banks of the Punatsang
Chhu, the awareness was comparably low (75%).
Concrete measures, such as having discussions on
disaster prevention among residents, had never beentaken in any of the communities.

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3.3 Schools
The results of the questionnaire survey of school
teachers are summarized as follows.
Some students were walking to school for more than
two hours each way, since some schools are in very
mountainous areas. Most schools had disaster educationand drills once a year. In Punakha and Bumthang
Dzongkhags, a School Safety Program is being enforced
under the leadership of the Department of Disaster
Management (DDM).
The schools were well maintained, and equipped with
communication tools, such as phones (either fixed-line ormobile), modems and PCs. Additionally, most teachers
had a good understanding of the individual life circumstances of their students. Therefore, for example, they
were able to send messages to the students’ homes
instructing them not to come to school when Aila wasapproaching in May 2009.
3.4 On-site inspections
The following is a summary of our inspections of sitesof past flooding.
The GLOF that originated from the Luggye glaciallake in the Lunana area, on a weekend morning in
October 1994, killed more than 20 people in Punakha,
Punakha Dzongkhag. They were construction workers
who were camped on a riverbank of the Punatsang Chhu.
Furthermore, a part of the dzong wall was also destroyed.
At Bjeezam in Trongsa Dzongkhag, there were several bamboo shelters on the lower terrace of the bank of
the Mangde Chhu for construction workers, numbering
more than ten, and described by local community residents as “temporary residents,” most of whom wereabsent when we visited. Perhaps the absence of their data
elevated the average monthly income of the region andownership ratio of information tools in Table 3. Although
Aila’s flood did not damage any of these shelters, thewater level came quite close to the terrace.
At Yurmung in Trongsa Dzongkhag, a worker’s camp

and an arterial road were washed away by Aila’s flood.
The planned site of a power station for a hydroelectric
dam that is scheduled to operate in 2015 is also in thevicinity.
In the Thingtibi district of Zhemgang Dzongkhag, asettlement in Takabi suffered damage to farmland from
Aila’s flood. Generally, the quality and extent of infrastructure, such as road networks and communications
systems in the area was poor, compared with other areas.
In all of the traditional Bhutanese communities wevisited, we observed no serious damage from Cyclone
Aila.

4. Discussion
Figure 2 shows hydrographs of the 1994 GLOF andthe rain flood caused by Cyclone Aila, observed at the
Wangdue Phodrang hydro-station (Tenjin, 2009), about
10 km downstream of Punakha. Cyclone Aila broughtrecord-high rain at most of the rain gauge stations in
Bhutan (Komori et al., 2010). It should be noted that thepeak water level of Cyclone Aila was slightly higher thanthat of the 1994 GLOF. From the results of the field study
and preliminary satellite imagery analysis in this project,
the Luggye glacial lake, from which the 1994 GLOF
originated, is comparable in area and volume to otherlarge glacial lakes in the Bhutan Himalayas. Furthermore,
although further detailed studies are needed, Cyclone
Aila’s peak water level can be used as a good rough visual reference for possible peak water levels of GLOFs,
since it is similar in magnitude, though slightly higher
than that of the 1994 GLOF, and unlike GLOFs, flood
marks made by Cyclone Aila have been observed in all
three of the river basins. Applying this reference to theobservations of this survey, we could say that, generally,
traditional communities along the major rivers in Bhutan
are established on terraces high enough to be safe fromfloods, including GLOFs.
However, recent development has sometimes put

Fig. 2 Hydrograph of the 1994 GLOF and Cyclone Aila at Wangdue, about 10 km downstreamof Punakha. Note that the peak water level of Cyclone Aila was slightly higher than that of
the 1994 GLOF, but the former's ascent was slower when compared with the latter.

A Social Survey for GLOF Disaster Mitigation in Bhutan

schools, roads, worker’s camps and power stations closer
to the rivers. In particular, temporary residents of local
communities, such as people living in worker’s camps,
were highly vulnerable to floods. Since they were notfamiliar with the area, they did not have enough knowledge of the risks. The above-mentioned temporary residents of bamboo shelters in Bjeezam, and workers in theworkers camp in Yurmung in Section 3 are such examples. Such targets requiring protection, especially thosewith the potential risk of human damage, are expected toincrease as the development of Bhutanese land expands.
Accordingly, a concrete disaster mitigation plan, including off-limits zones based on accurate hazard maps, isnecessary.
One should note that while Cyclone Aila brought very
heavy rains to the basins, its hydrograph in Fig. 2 shows arelatively slow ascent to the peak, taking 14 hours. Thus
the residents living on riversides were warned by unusual
rain and the rising water itself. In contrast, the 1994
GLOF’s hydrograph took only 2.5 hours to reach its peak.
The difference can be explained in terms of a rain flood
occurring as a result of concentrated discharge ofprecipitation from various points throughout the wholebasin, whereas a GLOF occurs due to a sudden failure ofa moraine damming a glacial lake, releasing a huge massof water to rush down the valley. Unlike a rain flood, a
GLOF is not accompanied by any precursors, so a GLOF
that occurs at night or early in the morning can be much
more hazardous. Perhaps, this was part of the reason
there were more than 20 victims of 1994 GLOF that
occurred in the early hours on a weekend. Currently,
procedures to relay emergency information between
local governments and the communities are established,but they are not instantaneous processes, and are likely to
be disabled at night.
On the other hand, a GLOF originates from a highaltitude, in sparsely populated areas, and takes several
hours to reach downstream communities. If an early
warning system’s sensor near the glacial lake detected a
GLOF’s occurrence, community residents could be
warned hours before its arrival. Therefore, riverside residents could safely evacuate, even if the GLOF occurred81

at night, provided that they had been educated based on
the disaster mitigation plan.
As for devices to alert the residents, in addition tosirens or loudspeakers, radio and mobile phones would
the most appropriate options because of their high ownership ratios in the study areas.
Punakha suffered a GLOF only 16 years ago. Despite
this, the survey shows that 25% of riverside residents
have no awareness of GLOFs. This highlights the factthat even experience of such fatal disasters can beforgotten without regular reminders, such as disastereducation. However, it is not easy to provide sucheducation to local community residents in a developing
country like Bhutan. On the other hand, as described in
Section 3, most schools have disaster education and drills
once a year.
The DDM has been promoting a School Safety
Program, since young students are the most vulnerable
members of the communities. However, based on thissurvey, it can be suggested that schools could play aneven more important role in disaster mitigation in communities, since Bhutan has schools well distributed
throughout the country (Fig. 3), which are well equippedwith communication tools. Additionally, teachers havevery good understanding of their local community, since
they have close contact with their students. If carefulplanning were done, teachers could provide regulardisaster mitigation knowledge through their students not
only to the parents, but to the entire local community.
Therefore, schools could be countrywide footholds fordisaster mitigation measures in communities in Bhutan.

5. Conclusion
This social survey was carried out in central Bhutan toacquire fundamental information about the local communities and means of communication in case ofdisasters.
In Yurmung, Trongsa Dzongkhag, construction
workers camps located on riverbanks were washed away
by record-high flooding caused by Cyclone Aila in May
2009. At Bjeezam, Trongsa Dzongkhag, also, the water

Fig. 3 Students at a school in a remote community.

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S. TAKENAKA et al.

level of Aila’s flooding came quite close to bamboo
shelters of temporary residents.
In Zhemgang Dzongkhag, the ratio of residents withno communication tools is high (42%) compared with theother areas (0% - 13%). Infrastructure, such as road networks and communication systems is also not welldeveloped.
Generally, procedures to relay information between
local governments and communities are established,although sometimes they include on-foot messengers.
On average, the awareness of GLOFs among community residents is high (83%). However, riverside residents in Punakha have comparably low awareness (75%),
despite having been hit by a GLOF only 16 years ago.
In general, schools are well equipped with communication tools, and teachers have a good understanding of
their local community. Most schools have disastereducation and drills once a year.
Judging from the flood marks of Cyclone Aila, traditional communities along the major rivers in Bhutan are
generally established on terraces high enough to be safe
from floods, including GLOFs. However, temporary
residents of local communities, such as people living inworkers camps on the riverbanks, are highly vulnerable
to floods. Accordingly, a concrete disaster mitigation
plan, including off-limits zones based on accurate hazard
maps, is necessary.
Although a GLOF takes hours to reach downstream
communities from the glacial lake, unlike a rain flood, a
GLOF is not accompanied by any precursors, and its rateof water level rise is much faster. For this reason, early
warning systems that detect a GLOF’s occurrence at its
origin are indispensable. As for devices to alert the residents, other than sirens and loudspeakers, radio andmobile phones are most appropriate because of their highownership ratios.
As shown by the rate of awareness of GLOFs in
Punakha, without regular reminding, people forget eventhe experience of such fatal disasters. School teachers canprovide regular disaster mitigation knowledge to their
entire local community through their students. Therefore,
schools can be countrywide footholds for disastermitigation measures in communities in Bhutan.

Acknowledgements
We are grateful to the Department of Geology and
Mines and the Department of Disaster Management, theRoyal Government of Bhutan. We thank all the
Bhutanese people concerned with this survey for theircooperation. We also thank Ms. A. Yoda and Dr. J.
Komori from the JICA Bhutan office, and Mr. T. Koike
from Earth System Science Co.,Ltd. for their thoughtful
coordination and helpful advice on our survey plan. Dr. S.
Dalgleish gave us invaluable advice on writing English
text. This study was funded by JICA from the Ministry ofForeign Affairs and JST from the Ministry of Education,
Culture, Sports, Science and Technology, the Japanese
Government.

References
Bahracharya, S.R., P.K. Mool and B. Shrestha (2007) Impact of
Climate Change on Himalayan Galciers and Glacial Lakes:
Case Studies on GLOF and Associated Hazards in Nepal andBhutan, ICIMOD, Kathmandu, 37-53.
Iwata, S. (2007) Risk of glacial lake outburst floods threaten
Kingdom of Bhutan: necessity of urgent monitoring. E-journal
GEO, 2 (1): 1-24.
Komori, J., T. Koike, D. Higaki and P. Tshering (2010) Natural
disaster in Bhutan in 2009-Geo-hydrological and climatic
hazards, Journal of Japan Society for Natural Disaster Science,29(2): 233-243. (Japanese with English abstract)
Mool, P.K., S.R. Bahracharya and S.P. Joshi (2001) Inventory of
Glaciers, Glacial Lakes and Glacial Lake Outburst Floods:
Monitoring and Early Warning Systems in the Hindu KushHimalayan Region – Bhutan, ICIMOD, Kathmandu, 254p.
Tenjin, S. (2009) Comparison between 1994 GLOF and Cyclone
Aila at Wangdue FW Station, Unpublished data prepared by
Flood Warning Section, Hydro-Metrological Service Division,
Department of Energy, Ministry of Economic Affairs, Bhutan.

Shuhei TAKENAKA
Shuhei TAKENAKA is dedicated staff of Earth
System Science Co., Ltd., for the JICA/JST
Bhutan GLOFs project. Although he got his
M.Sc. in Glaciology from Nagoya University 30
years ago, prior to joining the project, he worked
as a manager at an electronic device company.
Some five years ago, he decided to return from “cyber space” to “the realworld” looking for a chance to perform field work and more directly
contribute to the human community. On Himalayan trails, he feels happy
with his decision despite the aches in his back and knees. In addition to
glaciers, he is interested in how local communities in remote areas arebeing changed by modern technologies like TVs and cell phones.

Tadashi SATOH
Tadashi SATOH is a Consultant Engineer ofDisaster Management and Water Resources at
Earth System Science Co., Ltd. He traveledaround the world by bicycle when he was young.
During that time, he was supported by many
people in many countries. Therefore, he would
like to support many people in return, and has embarked on a career atEarth System Science Co., Ltd., which implements the various projects
overseas. He is interested in preventing disasters such as floods andlandslide, and is also interested in water resource development. Currently,
he is working in Japan and overseas, mainly in Africa as a consultant.

Sonam LHAMO
Sonam LHAMO is a geologist by profession,working with the Department of Geology and
Mines, Ministry of Economic Affairs, Royal
Government of Bhutan. She works for the
Glaciology Division and is interested in theeffects of melting glaciers, their impacts on water
resources in the Himalayas and natural resource management forsustainable development. She has a Bachelor of Science degree in Geology
from the University of Pune, Maharashtra, India.

(Received 28 October 2011, Accepted 13 February 2012)