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Jamieson and colleagues published a very neat investigation of the applied glaciology challenges at Kumtor Mine, Kyrgyzstan, this week in the AGU Journal of Geophysical Research: Earth Surface (open access here). The recovery of subglacial gold deposits at Kumtor Mine has necessitated the excavation of an open ice pit into the Lysii and Davidov Glaciers. In addition to excavating glacier overburden, a major geotechnical challenge at Kumtor Mine has been managing the flow of both glaciers. In their study, Jamieson et al. (2015) use a comprehensive set of high resolution satellite images to document recent artificial surges induced in both these glaciers in response to mining activities. Photos released by Radio Free Europe in 2013 suggest that these artificial surges quite adversely impacted mining operations (Figure 1).

Figure 1 – Infrastructure damage resulting from what is now a confirmed glacier advance at the Kumtor Mine in Kyrgyzstan (originally discussed in this earlier post)

The dumping of waste rock on both glaciers, in which waste rock piles reached up to 180 m thick, substantially increased the driving stress of the ice beneath. Given that ice deformation is related to driving stress to an exponent of three, and potentially higher exponents at higher driving stresses, this resulted in a significant increase in ice velocity. Jamieson et al. (2015) estimate that surface velocities of the Davidov Glacier increased from a few meters per year to several hundred meters per year within a decade. During this time, the Lysii and Davidov Glaciers advanced by 1.2 and 3.2 km, respectively, with Davidov Glacier terminus advance reaching 350 meters per year in c. 2012 (Figure “7”).

This study is probably the most textbook-comprehensive documentation of a human-induced artificial glacier surge to date, and will provide a great resource for my students to debate the sometimes fine line between geotechnical misstep and natural hazard!

Reference

(Jamieson, S., M. Ewertowski and D. Evans. 2015. Rapid advance of two mountain glaciers in response to mine-related debris loading. Journal of Geophysical Research: Earth Surface. 120: doi:10.1002/2015JF003504.

Quick blog on new study of human-induced 3.2 km #glacier surge at #Kumtor mine: http://t.co/mTYVeQDzcb pic.twitter.com/ONMkQETlRm

— William Colgan (@GlacierBytes) July 27, 2015

I have a paper in this month’s issue of the Journal of Cold Regions Engineering that examines the ice excavation required to establish and maintain an open ice pit. Excavating an open ice pit is a very non-linear applied glaciology problem, as the excavation of ice from an open ice pit enhances subsequent ice flow into the open ice pit. This is because ice velocity is very sensitive to changes in ice geometry, with third and fourth order dependencies on ice slope and thickness respectively! The paper examines scenarios based on excavating an open ice pit on the Greenland ice sheet margin that extends 1000 m into the ice sheet, with a 200 m high ice wall. That is the approximate dimension of the Isua Prospect, Greenland, which is projected to excavate about 36,000,000 tonnes of glacier ice per year.

Working with such unnatural combinations of ice slope and ice thickness compels you to reconsider fundamental principles of glacier mechanics, such as the appropriate relation between stress and strain at tremendous basal shear stresses, which are inconceivable in virtually all natural glacier settings. Despite an increasingly pressing need for a comprehensive understanding of how glaciers respond to highly transient forcings, however, most private sector glacier management projects cannot contribute meaningful observational data to advance such fundamental science due to proprietary considerations. Perhaps that can change in the future!

W. Colgan. 2014. Considering the ice excavation required to establish and maintain an open ice pit. Journal of Cold Regions Engineering. 28: 04014003. doi:10.1061/(ASCE)CR.1943-5495.0000067. Available here.

Supplementary online material (including animations): http://www.williamcolgan.net/som/CRENG113

Cross sectional ice velocities flowing into an open ice pit at excavation years 2.5 (left) and 10.0 (right) sampled from 30-year animations. Dashed black line denotes original ice surface, dash red line denotes ice pit wall. (from Colgan, 2014)