Japan Geoscience Union Meeting 2016

Presentation information


Symbol H (Human Geosciences) » H-SC Social Earth Sciences & Civil/Urban System Sciences

[H-SC16] Human environment and disaster risk

Mon. May 23, 2016 9:00 AM - 10:15 AM 105 (1F)

Convener:*Tatsuto Aoki(School of Regional Development Studies, Kanazawa University), Nobuhisa Matsuta(Okayama University Graduate School of Education), Toshihiko Sugai(Department of Natural Environmental Studies, Institute of Environmental Studies, Graduate School of Frontier Science, The University of Tokyo), Chair:Tatsuto Aoki(School of Regional Development Studies, Kanazawa University)

9:45 AM - 10:00 AM

[HSC16-04] Satellite observation of a glacier lake outburst flood in western Bhutan

*Hiroto Nagai1, Takeo Tadono1, Shinichi Suzuki1 (1.Japan Aerospace Exploration Agency)

Keywords:GLOF, PALSAR-2, Bhutan

Following a glacial lake outburst flood (GLOF) on Jun. 28, 2015, in western Bhutan, the Japan Aerospace Exploration Agency performed an emergency observation on Jul. 2, 2015 using the Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) onboard the Advanced Land Observing Satellite-2 (ALOS-2, "DAICHI-2"). Based on a dataset generated from the Advanced Land Observing Satellite (ALOS) imagery, "The Glacial Lake Inventory of Bhutan using ALOS Data", the glacier lake that potentially contributed to this GLOF were identified at 28º4’7.7"N, 89º34’50.0"E, in a headwater of the Mo Chu river basin, western Bhutan.
A post-event lake outline was delineated manually using the acquired PALSAR-2 image. Pre-event outlines were delineated from previously acquired PALSAR-2 images (Apr. 23, 2015), Landsat 8 (Mar. 8, 2015), and ALOS (Dec. 22, 2010). The differences between these outlines reveal a remarkable expansion (+48.0%) from Mar. 8 to Apr. 23, 2015, followed by a remarkable shrinkage (-52.9%) from Apr. 23 to Jul. 2, 2015. This result indicates the lake to be a highly likely source of the flood. Topographically, it is located at a glacier terminus, surrounded by a moraine. Differing backscatter patterns between successive PALSAR-2 images in a certain part of the moraine suggest that it underwent some collapse, possibly as a result of the GLOF.