51

Bulletin of Glaciological Research ,- (,**0) /+ῌ0+ῌJapanese Society of Snow and Ice

Glacier shrinkages and climate conditions around Jichu Dramo Glacier in the Bhutan
Himalayas from +332 to ,**Nozomu NAITO+, Yutaka AGETA,, Shuji IWATA-, Yoshihiro MATSUDA,, Ryohei SUZUKI,,
KARMA. and Hironori YABUKI/+ Department of Environmental Information Studies, Hiroshima Institute of Technology, Hiroshima 1-+ῌ/+3- Japan, Graduate School of Environmental Studies, Nagoya University, Nagoya .0.ῌ20*+ Japan- Department of Geography, Tokyo Metropolitan University, Hachioji, Tokyo +3,ῌ*-31 Japan. Geological Survey of Bhutan, P. O. Box +1-, Thimphu, Bhutan/ Institute of Observational Research for Global Change, Yokosuka, Kanagawa ,-1ῌ**0+ Japan(Received September ,0, ,**/; Revised manuscript accepted November ++, ,**/)

Abstract
Variations of Jichu Dramo Glacier and some other debris-free glaciers as well as the surrounding
climate were observed through Japan-Bhutan joint ﬁeld activities in the autumns of +332, +333, and,**-. The annual precipitation around the Jichu Dramo Glacier was estimated to be greater than +/**
mm, based on the record over -.* days in +332ῌ+333. The surface level of the glacier, which is locatedin an area strongly inﬂuenced by the summer monsoon, was estimated to be rapidly lowering at an
approximate rate of ,ῌ- m aῌ+ in +332ῌ,**-. This estimate is the ﬁrst example of surface lowering rates
for glaciers in the Bhutan Himalayas. Further, its terminal retreat rate was estimated to be approximately 2 m aῌ+ in +332ῌ,**-. The terminal retreats of some other debris-free glaciers around Jichu
Dramo since the mid-+32*s have also been conﬁrmed by comparing them with photos taken previously. Further monitoring of the remarkable glacier shrinkage in Bhutan is essential to assess thegeneral trend of glacier shrinkage in the entire Himalayas.

+.

Introduction

The variations of mountain glaciers worldwide
have recently attracted considerable attention due totheir signiﬁcance in the rising sea levels. Summeraccumulation type glaciers in the Asian highland regions including the Himalayas are considered to beparticularly vulnerable to global warming (Ageta,+32-; Fujita and Ageta, ,***; Naito et al., ,**+). This isbecause snowfall during summer can easily transform
into rainfall, and the decrease in fresh snow can reduce the surface albedo of glacier, which would lead
to lesser accumulation and greater ablation on theglaciers. In reality, relatively rapid glacier shrinkages
have been reported in the Nepal Himalayas (e.g.,
Fujita et al., +331; Naito et al., ,**,). On the other hand,
Bhutan, which is located near the eastern edge of theHimalayan range, receives heavier precipitation than
Nepal (Eguchi, +33.) due to a stronger inﬂuence of the
Asian summer monsoon. The glaciated area in the
Bhutan Himalayas is spread over an area of +,-+1 km,(Mool et al., ,**+). Karma et al. (,**-) reported that the
recent retreat rates of glacier termini in Bhutan arealmost twice larger than those of glacier termini ineast Nepal obtained by Asahi (+333); further, they suggested that these rates may have resulted due to thestronger inﬂuence of the summer monsoon in Bhutan.
However, thus far, no practical information has beenreported with regard to the volumetric glacier shrinkage in Bhutan, because its evaluation requires theknowledge of the magnitude of not only the retreating area but also lowering surface level. The present
paper reports the observational results on the surface
lowering of a debris-free glacier, terminal retreats ofsome debris-free glaciers in the Bhutan Himalayas, aswell as surrounding local climate.
In addition to the global issue of sea level rise,
Glacier Lake Outburst Flood (GLOF) is another crucial
problem faced by regional countries and people in the
Himalayas (Yamada, +332; Ageta et al., ,***). Potentially dangerous glacier lakes usually grow on theterminal part of debris-covered glaciers, while theglaciers themselves shrink and moraines dam up themelt water. In order to assess the GLOF risk in Bhutan, Japan-Bhutan joint research was initiated in +332
(Ageta and Iwata, +333). Its primary targets have beenglacier lakes and their corresponding debris-covered52

Bulletin of Glaciological Researchglaciers; however, debris-free glaciers have also been
a topic of research interests because in comparison todebris-covered glaciers, their variations could more
simply be related to the local climate. In other words,
the clariﬁcation of the relation between the local climate and the variations of debris-free glaciers could
partly contribute to the studies on the growth ofglacier lakes in the region. The present paper is basedon the three ﬁeld activities of the Japan-Bhutan joint
research in the autumns of +332, +333, and ,**-.

,.

Study area and observation methods

The study area in the present paper is a highplateau with an altitude of over /*** m located aroundthe southeastern periphery of the so-called “Lunana”
region in the northern part of Bhutan (Fig. +). Manydebris-free glaciers exist on this plateau. The main
target of this study is a debris-free glacier locatedsouthward of the Jichu Dramo camping site, which ismarked “G+” in Fig. +. In the glacier inventory compiled by Mool et al. (,**+), this glacier is represented
by the code name “Phoῌgr +-+,” and its total area,
based on satellite images captured in the +33*s, isestimated to be -., km,. In the present paper, thisglacier is termed the Jichu Dramo Glacier based onhearing from native villagers. The terminal positions
and surface topography of the lower part of the glacier were repeatedly surveyed on Oct. ++, +332; Oct. +1,+333; and Oct. +., ,**-, using a digital theodolite and alaser distance meter (”SOKKIA SET ,*** series”). In
addition, terrestrial photogrammetry was attemptedon Oct. ++, +332 for the lower part of the glacier.
The topographical survey of glacier extent wasalso executed for a small glacier near Jaze La, which ismarked “G,” in Fig. +, on Oct. ,, +333 using the “SOKKIA SET ,*** series” for future evaluation of its variation. (This glacier “G,” was approached not from Jaze
La but from the eastern valley.) Moreover, simpler
observations of terminal ﬂuctuations in comparison
with photos taken previously were also carried out forsome other debris-free glaciers on the plateau; distinct
examples are marked as “G-”ῌ”G/” in Fig. +. The com
pared photos were taken in +32-ῌ+32. by Mr. Toshihiro
Tsukihara, who belonged to the Kyoto University
Bhutan Expedition team. In the inventory compiled
by Mool et al. (,**+), glaciers “G-” and “G.” are denotedby the code names “Phoῌgr +,3” and “Mangdῌgr 0,”
respectively; their total areas are evaluated to be /.+and *./ km,, respectively. On the other hand, “G,” and“G/” may be recognized as parts of neighboring glaciers, and neither has been described in the inventory
compiled by Mool et al. (,**+).
Air temperature was measured automatically byusing the “Optic StowAway” in a single solar shieldwith a time interval of one and half hours at threesites in the Lunana region from the autumn of +332 tothat of +333. One site was a ﬂat site located in thelateral moraine near the left-bank periphery of the
middle stream part of the Jichu Dramo Glacier(“Upper JD”). The second site was downstream of theglacier terminus (“Terminal JD”), as shown in Fig. +,and the third site was in Thanza village, which islocated at a distance of approximately ,* km in the
direction of NNW from the Jichu Dramo Glacier. Hourly precipitation and the maximum snow depth were
measured only at the “Upper JD” site. The precipitation measurement was performed using a tippingbucket rain gauge and “HOBO Event” logger, and the
maximum snow depth was recorded by soft metallic
sticks attached horizontally with a vertical spacing of/ cm to a vinyl chloride pole. The recording period of-.* days for the hourly precipitation was slightly
shorter than an entire year because the recording was
abruptly terminated possibly due to a battery problem.
The altitudes discussed in the present paper wereoriginally measured using a “Thommen baro altimeter” during the ﬁeld trips. On the other hand, standard
altitudes were adopted at sites where they could beread on +: /*,*** toposheets published by the Surveyof India. The original altitudes at all the ﬁeld sites
were then corrected with respect to relative altitudes
measured by the baro altimeter at the nearby standard sites. For example, the standard altitude of Thanza is .+0* m and the altitudes of “Upper JD” and“Terminal JD” are corrected to be /,./ and /++/ m,
respectively, with respect to the standard Thanza altitude. The accuracy of these corrected altitudes is notvery good; it shows an approximate deviation of a few
tens of meters.
Iwata et al. (,**-) suggested that the lower limit of
the permafrost in the Bhutan Himalayas was locatedat .2**ῌ/*** m a.s.l., based on the distribution of activerock glaciers. On the other hand, Fujii and Higuchi(+310) explained that the altitudinal lapse rate in the
ground temperature at a depth of /* cm, where its
diurnal variation can be considered to be negligible,
should become considerably greater than that in air
temperature above the lower limit of the mountainpermafrost zone, based on observations in the Nepal
Himalayas. In the present study, we attempted a similar observation to detect the lower limit of the mountain permafrost zone in the Lunana region from theview-point of the ground temperature. The groundtemperature at a depth of /* cm was measured manually at a total of +*, sites with various altitudes along
the Snowman Trekking route, a part of which is indicated by the dotted line in Fig. +. It was measured
using a digital thermistor thermometer during thetrekking periods in the autumns of +332 and +333.
Several minutes were allowed to pass for the thermistor to acclimatize after its insertion into the ground.
The manually-measured ground temperature wasNaito et al.

Fig. +. Location of the study area. The lower ﬁgure is a distribution map depicting glaciers and glacierlakes in the area revised from that provided by Ageta and Iwata (+333) by using a SPOT satellite
image taken on Dec. ++, +33- and the +: /*,*** scale toposheets published by the Survey of India. “G+”indicates the Jichu Dramo Glacier and “G,”ῌ“G/” indicate the other glaciers described in this paper.
“U” and “T” indicate locations of the “Upper JD” and “Terminal JD” sites, respectively. The dottedline indicates the trekking route.

53

54

Bulletin of Glaciological Research

Table +.

Summary of the main results of the meteorological measurements in +332ῌ+333.

Location

ThanzaTerminal JD

Upper JD

Altitude.+0* m/++/ m/,./ mMeteorol. element

Air Temperature

Air Temperature

Air Temperature

Precipitation

Max. Snow Depth

Data logger

Optic StowAway

Optic StowAway

Optic StowAway

HOBO Event(handmade)Starting date
and time

Oct. ,, +332+- : -*

Oct. ++, +332+/ : **

Oct. +,, +332+, : **

Oct. +,, +332+, : **

Oct. +,, +332

Ending date
and time

Sep. ,2, +333+* : -*

Oct. 0, +333+/ : **

Oct. 2, +333+* : -*

Sep. +1, +333+. : **

Oct. 2, +333

Mean Temp.

-.3῍

ῌ,43῍

ῌ,4/῍

Max.Temp.

,.4-῍

+34+῍

,+4+῍

Min. Temp.

ῌ+/4.῍ῌ,/4*῍ῌ,.4,῍Results

Total amount:+-.3 mm//*ῌ0** mm

subtracted with the temperature recorded simultaneously at the meteorological station (,-2* m a.s.l.) in
Thimphu, the capital of Bhutan, to cancel its seasonalvariation.

-.

Results and discussion

Air temperature and precipitation in +332ῌ+333
The main results recorded at the three sites in+332ῌ+333 are summarized in Table +. The nearly annual precipitation in this area is +-.3 mm at the “Upper JD” site during the -.* days. The total annual
precipitation around the Jichu Dramo Glacier should
be considered to be greater than +/** mm because of
the following two reasons: +) the recording period did
not consider late September and early October, whenmonsoon precipitation was still expected in the Bhutan Himalayas, and ,) some amount of solid precipitation could not be captured by the rain gauge. By
ignoring these problems, a simple comparison showsthat the annual precipitation at the Jichu Dramo Glacier was more than one and a half times greater thanthat at Shangboche AWS in the Khumbu region, east
Nepal, which was reported to have received a precipitation of 3*1 mm from October +332 to September +333
(Ueno et al., ,**+). Figure , shows the temporal variations in daily precipitation recorded at “Upper JD”
and air temperatures at the three sites. The dailymean air temperature is generally below *῍ from
October to April at “Upper JD.” Almost all the precipitation during the season was recorded in daytime
when the air temperature was above *῍. During winter, the recorded precipitation may be due to thewater from the melting of the snow packed on the rain
gauge; in such a case, the recording time would be ofno signiﬁcance. This fact partly supports the reason ,)mentioned above and the possibility of an annual
precipitation greater than +/** mm at the site. On theother hand, heavy precipitation was concentrated in
the summer monsoon season from late May to September. This implies that glaciers in this region are-.+.

Fig. ,. Temporal variations in daily precipitation at“Upper JD” (bar for right axis) and daily mean air
temperature at the three sites.

strongly characterized by summer-accumulation.
In Fig. ,, the air temperature at “Terminal JD”
appears to be lower than that at “Upper JD” in winter,
despite the altitude of the former being lower by +-*m. This apparent inverse relation of the air temperature in the two sites is clearly shown in Fig. -, where
two types of altitudinal lapse rates in air temperature
are also displayed. It is implied in Fig. - that the airtemperature at “Terminal JD” drops severely in winter, and then, the lapse rate between “Terminal JD”
and Thanza becomes signiﬁcantly high. This was probably because cold air mass moved down the glaciersurface and reached the “Terminal JD” site, i.e., thee#ect of katabatic winds was enhanced in winter.
Thus, the temperature recorded at “Terminal JD” inwinter could not be considered to be representative of
the air temperature at its altitude. On the other hand,“Upper JD” was located laterally outside the glacier;therefore, the katabatic winds could hardly a#ect its
air temperature. The annual average altitudinal lapse
rate in air temperature between “Upper JD” and Thanza is /.3῍ kmῌ+. Incidentally, the lapse rate of 0./῍kmῌ+ between “Terminal JD” and Thanza is averaged
only in the summer from May to September. Even if
an error in the altitude is considered, its e#ect on theNaito et al.

lapse rate would be less than /ῌ. Therefore, the latter
lapse rate in the summer may be slightly inﬂuenced
by the katabatic winds at “Terminal JD.” Finally, it isconcluded that the lapse rate in this region is approximately 0῍ kmῌ+.
Altitudinal distribution of ground temperature
Around one-third of the +*, sites where the ground temperature was measured in the Lunana region
were located on relatively steep slopes. Therefore,
only the data measured at 01 ﬂat sites have been
analyzed in order to dampen the e#ects of di#erential
solar radiation. Consequently, the di#erences in the
ground temperature at a depth of /* cm between Lunana region and Thimphu are plotted against the altitude in Lunana in Fig. .. The altitudinal lapse rate in
the ground temperature shown in Fig. . appears similar to that in air temperature. It is di$cult to recognize a clear change in the lapse rate of the groundtemperature above a certain altitude, such as described by Fujii and Higuchi (+310). Unfortunately, thepresent data should be concluded insu$cient for detecting the lower limit of the mountain permafrost
zone.
-.,.

Fig. -. Seasonal variations in monthly averaged airtemperature di#erence at “Terminal JD” to “Upper
JD,” ῎T; and altitudinal lapse rates in air temperature, G, for the two sites with respect to Thanza(on right axis).

55

Variation of Jichu Dramo Glacier
The Jichu Dramo Glacier was selected in +332 as atarget for monitoring the variation of debris-free glaciers. Its surface topography is fairly wavy in its lower
part, as seen in Fig. /. Figure 0 is a map of the Jichu
Dramo Glacier obtained from terrestrial photogrammetry performed in +332. Based on repeated topographical surveys conducted in +332, +333, and ,**-, thelocations of the glacier terminus and some surface
bumps on the lower part of the glacier are depicted inFig. 1. At ﬁrst, the retreat of the glacier terminus isclearly identiﬁable. By dividing the area between thesurveyed termini by the surveyed glacier width, theaverage terminal retreat rates are evaluated to beapproximately ++ and 1 m aῌ+ in +332ῌ+333 and +333ῌ,**-, respectively. Then, the average retreat rate during the period +332ῌ,**- is 2 m aῌ+.
Among the surface bumps surveyed, a total of +,bumps were surveyed more than twice. These areindicated in Fig. 1 as solid symbols with tentative
names. From their horizontal displacements, their horizontal velocities were calculated, as listed in Table ,.
Generally, the horizontal speed decreases upstream todownstream, as usually seen in the ablation area of a-.-.

Fig. .. Altitudinal distribution of ground temperature
at /* cm depth in Lunana region. The groundtemperature is subtracted with that at Thimphu tocancel its seasonal variation.

Fig. /. Photo of the lower part of the Jichu Dramo Glacier taken near the “Upper JD” site in the left-bank lateral moraineon Oct. ++, +332. The main stream of the glacier runs from right to left in this photo.

56

Bulletin of Glaciological Research

Fig. 0. Map of the lower part of the Jichu Dramo Glacier compiled from terrestrial photogrammetry performed on Oct.
++, +332. Light and dark shaded parts are glaciated and non-glaciated (bedrock and moraines) areas, respectively. The
blank part is invisible from the benchmarks.

Fig. 1. Horizontal location of the terminus and surface
bumps of the Jichu Dramo Glacier surveyed on
Oct. ++, +332; Oct. +1, +333; and Oct. +., ,**-. Solidsymbols indicate the surface bumps surveyed morethan twice, the names of which are same as thosein Table ,. Geographical coordinates of the twobenchmarks were measured with GPS as (,1ῌ//ῌ
0.3῍N, 3*ῌ+.ῌ.2.1῍E) and (,1ῌ//ῌ2.*῍N, 3*ῌ+.ῌ.1.0῍E),
according to personal communication from Dr.
Koji Fujita who visited the site in ,**..

glacier. The horizontal direction of the velocity distributes from NW to NNE, that is, it has an averagenorthward direction. The surveyed altitudes of the +,bumps are then projected on the northward distance

relative to bump “C+” in +332, as shown in Fig. 2. Twopairs of regression lines in Fig. 2 are obtained for thesame bumps. Both the pairs indicate that the averagesurface level of the bumps has lowered. The lowering

Naito et al.

surface levels in +332ῌ+333 and +333ῌ,**- are obtained
as ,.-ῌ-.3 and 1..ῌ+,., m, respectively. Their averagesurface lowering rates in +332ῌ+333 and +333ῌ,**- are-., and ,.. m aῌ+, respectively. Therefore, by assuming
no change in the surface undulation, the surface lowering rate in the lower part of the Jichu Dramo Glaciercan be estimated as approximately ,ῌ- m aῌ+.
Table ,. Horizontal velocities of resurveyed surface
bumps on the Jichu Dramo Glacier. The names ofbumps are same to those displayed in Fig. 1. The
velocity is expressed as horizontal speed U andazimuth from the north HA.
Name ofbump

C+In +332ῌ+333

In +333ῌ,**-

U

HA

U

HA

(m aῌ+)(deg.)(m aῌ+)(deg.)

,.4*

-.,4/

(no survey in ,**-)

C,(no survey in +332)

24-

*4/

C-

(no survey in +332)

14-

-/040

-//42

14,

-/+4/

(no survey in +332)

,4/

,14*

C.
C/

34+

(no survey in ,**-)

R+

,*4/

-/-4,

R,

+-43

-/*42

143

14/

(no survey in +332)

04/

-/34.

RL+

+*40

-.24/

34*

-//4*

L,

/4,

-.043

.4,

-,+4/

(no survey in +332)

04,

-/-43

LL.

14/

-,+4-

57

This estimate is the ﬁrst example of surface lowering rates for glaciers in the Bhutan Himalayas.
Naito et al. (,**,) tabulated the average surface lowering rates of entire areas of three debris-free glaciers(Fujita et al., +331, +332, ,**+) and the ablation areas oftwo debris-covered glaciers (Kadota et al., ,**,; Naitoet al., ,**,) observed in the Nepal Himalayas; theirrates ranged up to approximately , m aῌ+. The present
estimate of ,ῌ- m aῌ+ for the surface lowering rate in
the lower part of the Jichu Dramo Glacier is, in a
simple comparison, greater than the rates observed in
Nepal. However, the di#erence in the estimated areaof each glacier complicates this simple comparison.
Nevertheless, the fairly rapid glacier shrinkage might
be due to the stronger inﬂuence of the summer monsoon in the Bhutan Himalayas because the strongly
characterized summer-accumulation type glaciers
would be considerably vulnerable to global warming.
Further studies on glacier shrinkage in the Bhutan
Himalayas are strongly desired to conﬁrm its generaltrend.
Variations of the nearby debris-free glaciers
The map in Fig. 3 shows surface topography andextent of a small debris-free glacier near Jaze La (”G,”in Fig. +) surveyed in +333. This map will be useful for
future evaluations of the glacier variation.
-...

(no survey in ,**-)

Fig. 2. Vertical proﬁle of the resurveyed +, bumps
along the northward direction. The bumps in +333
are indicated in two categories; “+333 (32)” for 1
bumps which were surveyed both in +332 and +333,
and “+333 (*-)” for 3 bumps which were done bothin +333 and ,**-. (The . bumps that were surveyed
for all three times belong to both the categories.)
Two solid regression lines are obtained for eachcategorized bumps in +333. The dashed and dotted
regression lines are obtained for the bumps in +332
and ,**-, respectively.
Fig. 3. Map of a small glacier near Jaze La (“G,” inFig. +) surveyed on Oct. ,, +333.

58

Bulletin of Glaciological Research

Photographs of many other debris-free glaciers inthe study area were taken during the trekking periods, particularly of those glaciers that were previously photographed in +32- and +32.. Figures +*ῌ+,are three photo sets of glaciers; these ﬁgures distinctly show their variations. The terminus of a glacier northward of Gangrinchemzoe La (Fig. +* and “G-” in Fig. +) retreated remarkably and a proglacial lake
was formed during the period +32.ῌ+332. Manual projection of the terminal locations on the +: /*,*** toposheet published by the Survey of India revealed an
approximate retreating distance of -**ῌ.** m in the +.
years. The average retreat rate of ,*ῌ-* m aῌ+ is signiﬁcantly greater than those observed in the Nepal
Himalayas, which were tabulated by Naito (,**+); thisis probably because this rapid retreat has been enhanced by calving into the proglacial lake. This glacier has continued to retreat at a relatively moderate

rate after +332. Apparent terminal retreats were also
found for the glaciers southwestward of Gangrinchemzoe La (Fig. ++ and “G.” in Fig. +) and northwestward of Gophu La (Fig. +, and “G/” in Fig. +). In the
future, the execution of terrestrial photogrammetry
for such inaccessible glaciers is desired in order toaccumulate quantitative information on glacier variation.

..

Concluding remarks

The present paper partly supports the idea thatthe glaciers in the Bhutan Himalayas are located in anarea that is strongly inﬂuenced by the summer monsoon, and they are considerably vulnerable to global
warming. The annual precipitation around the Jichu
Dramo Glacier was estimated to be greater than +/**
mm, based on the record over -.* days in +332ῌ+333.

Fig. +*. Photos of the glacier “G-” in Fig. + taken at Gangrinchemzoe La on Oct. ,, +32. (top; provided by Mr. Toshihiro
Tsukihara); Oct. +-, +332 (middle); and Oct. +/, ,**- (bottom).

Naito et al.

59

Fig. ++. Photos of the glacier “G.” in Fig. + taken on Sep. ,/, +32- (upper; provided by Mr. Toshihiro Tsukihara) and Oct.
3, +333 (lower). The arrow indicates the same rock in each photo.

Surface lowering rate of approximately ,ῌ- m aῌ+ for
the Jichu Dramo Glacier during +332ῌ,**- is the ﬁrst
attempted estimate for glaciers in Bhutan. The terminal retreat rate of the glacier during the same period
was calculated as approximately 2 m aῌ+. Glacier retreats have been also observed on some other debrisfree glaciers in adjacent locations since the mid-+32*s.
On the basis of a simple comparison, these remarkableglacier shrinkages/retreats appear to be quicker thanthose observed in the Nepal Himalayas. This implies
that the extrapolation of the glacier shrinking volume
to the general trend in the entire Himalayas based on
the limited information obtained in Nepal could be anunderestimate. Finally, the information on glacier shrinkage in Bhutan should be concluded as essential forthe assessment of the general trend in the Himalayas;
therefore, further investigations are strongly desired.

Acknowledgments
We are deeply indebted to Mr. Dorji Wangda andother sta# at the Department of Geology and Mines,
Bhutan, for their consideration and support toward
the Japan-Bhutan joint research. We thank Dr. Akiko
Sakai, Dr. Chiyuki Narama, Mr. Daisuke Nishikawa,and Dr. Shiro Kohshima for their cooperation in theﬁeld activities and the sta# of Lhomen Tours andTrekking for their logistic assistance. We would liketo express special gratitude to Dr. Tsutomu Kadota
for his assistance with compiling the Jichu Dramo
Glacier map from terrestrial photogrammetry; Mr. Toshihiro Tsukihara, Fukui University, for providing
the valuable photos of glaciers in Bhutan; and Dr. Koji
Fujita for his assistance with compositing the panorama photos. The manuscript was improved by theuseful comments from Dr. Koji Fujita and Dr. Takane
Matsumoto. The three ﬁeld activities were ﬁnancially
supported by the Inoue Field Scientiﬁc Research Fundfrom the Japanese Society of Snow and Ice; and Grants-in-Aid for Scientiﬁc Research (Nos. +--1-**0 and*3*.++*-) from the Ministry of Education, Culture,
Sports, Science and Technology (MEXT), Japan. In
addition, data analyses were ﬁnancially supported by
Grants-in-Aid for Scientiﬁc Research (No. +01+**+*)and the “Academic Frontier” Project for Private Universities: matching fund subsidy, ,**.ῌ,**2, from
MEXT, Japan.

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Bulletin of Glaciological Research

Fig. +,. Photos of the glacier “G/” in Fig. + taken on Oct. +1, +32. (upper: provided by Mr. Toshihiro Tsukihara) and Oct.
-, +333 (lower). Arrows indicate the same rocks in each photo.

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Joint Research +332 on the Assessment of Glacier Lake
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relation to permafrost occurrences in the Khumbu region and Hidden Valley. Seppyo, -2, Special Issue, +,/ῌ+,2.
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