October 27, 2017

Yanong Glacier, Tibet Retreat Lake Expansion 1992-2017

Posted by Mauri Pelto

Yanong Glacier and North Yanong glacier in Landsat images form 1992 and 2017.  Red arrows indicate 1992 terminus and yellow arrows the 2017 terminus. 

Yanong Glacier  and North Yanong Glacier drain northwest from the western flank of Cho Oyu on the Nepal-China border and are in the Tama Khosi watershed.  The glacier terminates in an expanding proglacial lake like a number of neighboring glaciers Rongbuk Glacier and Lumding Glacier King et al (2017) observe that both Yanong and North Yanong have had large negative balances of -.76 m/year and -0.62 m/year respectively.  They also note surface lowering of 3 m per year in the lower ablation zone.  Zhang et al (2010) observed the loss of glacier area and lake expansion in the region from 1976-2006. Here we examine Landsat imagery from 1992 to 2017 to observe changes. 

In 1992 the Yanong Glacier and North Yanong Glcier terminate at the red arrows.  The proglacial lake at Yanong is 1.7 km long and is 1.3 km long at North Yanong. By 2001 significant retreat of 200-200 m has occurred on each glacier.  By 2015 Yanong Glacier has retreated east of the a former tributary from the north. The North Yanong glacier is now wider at the terminus than in 2001. In 2017 the proglacial lake at Yanong Glacier is 2.8 km long indicating a retreat since 1992 of 1100 m.  The North Yanong Glacier proglacial lake is 2.1 km long indicating a retreat since 1992 of 800 m.  The steep crevassed nature of North Yanong Glacier right to the terminus suggests the glacier is nearing the end of the lake basin.  The Yanong Glacier has a low slope terminus area that suggests the lake will continue to expand.  The Upper Tamakhosi Hydropower project is a 456 MW peaking run of river  is a hydropower project on the Tama Khosi that is just to be finished in 2018. 

Yanong Glacier and North Yanong glacier in Landsat images form 2001 and 2015.  Red arrows indicate 1992 terminus and yellow arrows the 2017 terminus. 

Digital Globe image of Yanong Glacier note the low slope terminus tongue below steep crevassed icefall section, red arrows.

Digital Globe image of  North Yanong Glacier note the l steep crevassed icefall section, red arrows that leads right to the terminus.