yamada_2004.htm
Bulletin of Glaciological Research 21 (2004)
79-90
©Japanese Society of Snow and Ice
Outline of 2002 - research activities on glaciers and glacier lakes in Lunana region, Bhutan Himalayas
Tomomi YAMADA1, Nozomu NAITO2, Shiro KOHSHIMA3, Hiroji FUSHIMI4,
Fumio NAKAZAWA5, Takahiro SEGAWA3, Jun UETAKE3, Ryohei SUZUKI6, Nariyuki SATO7,
KARMA8, Indra K. CHHETRI8, Lobzang GYENDEN8, Hironori YABUKI9 and
Kazuhisa CHIKITA10
1 Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819 Japan
2 Department of Environmental Information, Hiroshima Institute of Technology, Hiroshima 731-5193 Japan
3 Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Tokyo 152-8551 Japan
4 School of Environmental Science, University of Shiga Prefecture, Hikone 522-8533 Japan
5 Graduate School of Science, Nagoya University, Nagoya 464-8601 Japan
6 Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601 Japan
7 Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060-1810 Japan
8 Geological Survey of Bhutan, P. O. Box 173, Thimpu, Bhutan
9 Frontier Observational Research System for Global Change, Yokohama 236-0001 Japan
10 Graduate School of Science, Hokkaido University, Sapporo 060-0810 Japan
Abstract
For the purpose to investigate formation and expansion mechanism of a moraine-dammed glacier lake in connection with shrinkage process and mechanism of a glacier, field observations were carried out on Lugge Tsho (Lugge glacier lake), debris-covered Lugge and Thorthormi Glaciers and debris-free Ganju La Glacier in the Lunana region, Bhutan Himalayas in the late September to the early October 2002 as the first year’s activity of the three-year-joint research project between Japan and Bhutan. Surveys were performed on lake-basin mapping of the Lugge Tsho and position of shorelines of the down- and up- lake ends, which are expansion fronts of the lake, for assessing expansion process and rate. The deepest lake depth was revealed to be 126 m, the mean depth to be 49.9 m, and the stored water to be 58.3 million m3. The thermal and density structure of the Lugge Tsho were also revealed using a TTD Profiler. The discharge and daily runoff from the lake watershed of 54.2 km2 in this season were clarified to vary from 2.5 to 5 m3 s -1 and from 4.3 to 6.8 mm, respectively. Surface topographies of the Lugge and Thorthormi Glaciers were surveyed, too, in each ablation area for detecting surface lowering, which could control formation of glacier lake. The total of 31 stakes were embedded in the areas to measure surface mass balance and flow. A 50 cm depth pit observation and a 614 cm depth core drilling were performed on the Ganju La Glacier. The samples are being analyzed by various dating methods to clarify annual net accumulation. The outline of the field activities carried out in 2002 is reported with preliminary results obtained also by other observations.
