China’s Asejiaguo Glacier Is Retreating

Asejiaguo Glacier drains east from the China-Nepal border and is at the headwaters of the Yarlung Tsangpo, which becomes the Brahmaputra River. The Yarlung Tsangpo powers the 510 megawatt Zangmu Hydropower Station.  Gardelle et al (2013) identified this glacier as part of the West Nepal region, which experienced mass loss averaging -0.32 meter/year from 1999-2011. The changes of the Asejaguo Glacier are examined for the 1993 to 2018 period using Landsat imagery. Neckel et al (2014) examined changes in the surface elevation of the glaciers and found this region lost 0.37 m/year from 2003 to 2009.

In 1993 the glacier terminated in a small proglacial lake that is ~1 kilometer long at 4,900 m. At Point 1-2 there is limited exposed bedrock at 5,400-5,600 m, which is near the snowline; the head of the glacier is at 6,000 m.  There is a prominent medial moraine that begins at 5,300 m where the north and south tributaries join.  The greater width of the southern tributary indicates this is the large contributor. In 1994, the snowline is higher, at 5,500 m, but there is still only a small outcrop of bedrock at Point 2. By 2016 the proglacial lake has expanded to a length of over 2 km. At Point 1 and 2 there is a greatly expanded area of bedrock and the separation of a former tributary near Point 1 from the main glacier. In November 2018 there is fresh snowfall obscuring the exposed bedrock at Point 1 and 2. The retreat from 1993-2018 is 1.5 km, and the expanding proglacial lake is over 2.5 km long. The expanding bedrock areas in the 5,400-5,600 m range indicate the reason rise in snowline that has generated mass loss and ongoing retreat.

Asejiaguo Glacier in Landsat images from 1993 and 2018. The yellow arrow indicates the 2018 terminus and the red arrow the 1993 terminus location. Point 1 and 2 are areas of expanding bedrock at the elevation of 5,400-5,600 meters.
Asejiaguo Glacier in Landsat images from 1994 and 2016. The yellow arrow indicates the 2016 terminus and the red arrow the 1994 terminus location. Point 1 and 2 are areas of expanding bedrock at the elevation of 5,400-5,600 meters.
Asejiaguo Glacier, blue arrows indicate flow direction. M indicates the medial moraine; the China-Nepal border is also noted.

This article originally appeared on the American Geophysical Union blog From a Glacier’s Perspective.

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