Applied Glaciology

New Report: Applied Glaciology Primer

Posted by William Colgan on November 13, 2015
Applied Glaciology, Glaciers and Society / No Comments

The Geological Survey of Denmark and Greenland (GEUS) has been involved in several applied glaciology projects since the early 1980s, such as assessments for the hydropower plants now operating at Ilulissat and Nuuk, and glacial lake outburst flood assessments for Isortuarsuup and Qorlortossup in South Greenland. In a report entitled “Unique applied glaciology challenges of proglacial mining” in this year’s Report on Geological Survey Activities, we provide a brief overview of four unique glacier-related geotechnical challenges confronting industrial operations adjacent to a glacier. We discuss these four especially unique applied glaciology challenges in the context of a new generation of mining projects that seek to excavate through glaciers to reach sub-glacial ore, such as the active Kumtor Mine in Kyrgyzstan and the approved Isua Mine in Greenland. The four uniquely glacier-related geotechnical challenges we discuss are supraglacial runoff, subglacial water flow, ice movement and supraglacial access roads. We also highlight how climate change is poised to further exacerbate these geotechnical challenges, as increased meltwater production generally enhances both water flow and ice flow into proglacial sites. We hope this report can serve as a quick survey of recent applied glaciology activities for non-specialists.

ROSA_sites

Site overviews of the recently approved Isua project in Greenland (left) and the recently approved Kerr-Sulphurets-Mitchell and Brucejack projects in Canada (right).

*W. Colgan, H. Thomsen and M. Citterio. 2015. Unique applied glaciology challenges of proglacial mining. Geological Survey of Denmark and Greenland Bulletin. 33: 61–64.

*This report serves as the citation for the proglacial mining projects open-file located here.

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Artificial Glacier Surges at Kumtor Mine

Posted by William Colgan on July 27, 2015
Applied Glaciology, New Research / No Comments

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).

Kumtor_glacier_damage

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”).

Jamieson1

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.

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New Estimate of Ice Sheet Runoff at Isua Site

Posted by William Colgan on April 14, 2015
Applied Glaciology, New Research / No Comments

My colleague Lukas Arenson and I have a paper in the Proceedings of Mine Water Solutions in Extreme Environments this month, which uses the Isua site in Southwest Greenland as a case study for extreme runoff in proglacial environments (Arenson and Colgan, 2015). The recently approved Isua mine will be an open pit mine intersecting the ice sheet, with ice pit walls around about half the pit, to access what is presently a subglacial iron deposit (site overview here). Using a Monte Carlo approach, we estimate a 95 % (or two sigma) upper confidence limit of 2.8·109 L/day of ice sheet runoff potentially reaching the Isua site in July and August. While this potential inflow rate, equivalent to 44 t/s, is relatively large in the context of conventional mine water management, it is relatively small in the context of contemporary Greenland ice loss due to climate change, which is approximately 8,300 t/s when averaged over a year (Andersen et al., 2015).

Isua_meltwater_runoff_estimate

Minimum and maximum plausible supraglacial ice sheet catchments associated with the Isua site. Shading denotes mean annual meltwater runoff over the 2004 to 2013. Background image source is Landsat 8 (source: Arenson and Colgan, 2015).

To place our estimate in context, London Mining Plc, the initial developer of the Isua site, presented a pre-feasibility study water balance in which ice sheet runoff into the pit was estimated as 7.8·106 m3/year (London Mining, 2011). Assuming a 60-day melt season, this is equivalent to an average site inflow of 1.3·108 L/day. Our estimate is therefore 22 times greater than the design estimate. There are many potential sources of uncertainty when assessing ice sheet runoff, including model uncertainty and climatic variability, but by far the biggest source of uncertainty is delineating the ice sheet catchment draining to a specific portion of the ice sheet margin. Regardless of whether 108 or 109 L/day of meltwater is flowing into the Isua site, it will certainly be a challenging operating environment, and will require some very adaptive engineering to minimize site contact water!

Isua_SNC_Budget

Proponent water budget for the Isua Mine (source: London Mining, 2011).

Isua_2011 173

Oblique aerial photograph looking west from the Greenland ice sheet across the Isua site in 2011. Deeply incised supraglacial meltwater channels are visible draining towards the margin. (source: Lukas Arenson)

References

Andersen et al., 2015. Basin-scale partitioning of Greenland ice sheet mass balance components (2007–2011). Earth and Planetary Science Letters 409: 89-95.

Arenson and Colgan. 2015. Water management challenges associated with mining projects in Greenland. Proceedings of Mine Water Solutions in Extreme Environments. 533-543.

London Mining PLC. 2011. Isua iron ore project: Isua 15 Mtpa scoping study report.

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Glaciolacustrine Sediment and Tailings Ponds

Posted by William Colgan on March 05, 2015
Applied Glaciology / No Comments

In August of 2014, a mixed earth and rockfill dam impounding a tailings pond at the Mount Polley Mine in Canada breached1. Over the following four days, c. 4.5 million m3 of tailings slurry was released into Polley Lake. An expert inquiry reviewed potential causes of the breach: cracking, overtopping, foundation failure, and human intervention. The inquiry noted that “the presence of a glacially pre-sheared surface in the dam foundation posed significant uncertainty throughout the design process”, and, after eliminating overtopping and human intervention, assigned maximum likelihood to the scenario of foundation failure stemming from preferentially oriented glaciolacustrine deposits underlying the dam.

While glaciofluvial deposits and glacial tills were also present beneath the dam, the fine silt and clay of the glaciolacustrine deposits made them the most likely culprit for instability. The presence of glaciolacustrine deposits was well documented in borehole records. In c. 2005 the mine operator (Mount Polley Mining Corporation) recorded that “the glaciolacustrine deposit encountered in [borehole] GW96-1A is a discontinuous unit and will not adversely affect the dam stability”. The breach occurred c. nine years later 300 m due west of borehole GW96-1A.

mount-polley-mine-tailings-pond

Breach of the earthen dam at the Mount Polley Mine tailings pond in August 2014 (from CBC.ca).

Although the Mount Polley Mine is located more than 50 km away from present-day glaciers, the site was covered by the Cordilleran Ice Sheet during the last glaciation, which reached a maximum c. 22 kaBP. During the subsequent deglaciation, which lasted until c. 11 kaBP, proglacial rivers and lakes evidently left substantial lacustrine deposits as the ice margin retreated through the site. Despite the last deglaciation ending millennia ago, the strong residual imprint of glacier processes on local stratigraphy compels them to be considered in the design of sensitive infrastructure in formerly glacierized areas.

The Kumtor Mine, Kyrgyzstan, shares some analogous geotechnical challenges with the Mount Polley Mine. At the Kumtor Mine, an earth dam impounds a c. 3.4 million m2 tailings pond, which is located c. 7.5 km downstream of the Petrov Glacier. The Petrov Glacier terminates in the proglacial Petrov Lake, which is itself impounded by glacial moraines and tills. Given the equilibrium line lowering and growth of glaciers during the past glaciation2, it is very likely that glaciolacustrine and glaciofluvial deposits are present in the vicinity of the Kumtor tailings pond. The growth of Petrov Lake upstream of the tailings pond, from 1.8 to 4.3 million m2 between 1977 and 2014 (due to climate change enhancing glacier retreat and melt), presents an additional geotechnical hazard: glacial lake outburst floods upstream of the tailings pond3.

Kumtor_tailings_lakes_1977_2014

Evolving hydrological and glaciological features in the vicinity of the Kumtor Mine, Kyrgyzstan, between 1977 and 2014.

When existing infrastructure is confronted with such unique geotechnical challenges associated with operating in a proglacial setting, adaptive engineering solutions are often be employed. For example, deformation and creep of glaciolacustrine sediment rich embankments can be monitored with cm-scale accuracy using spaceborne radar, and mm-scale accuracy with ground-based radar. While this may potentially allow embankments to be reinforced as needed, given that the Mount Polley tailings pond instability progressed to a complete breach in just a few days, monitoring alone may be insufficient to avoid a breach. Perhaps the lesson from the Mount Polley Mine, for sites like the Kumtor Mine, is to ensure that unstable glacial sediment is comprehensively identified and factored into robust hazard management and infrastructure design plans!

1Mount Polley Review Panel. 2015. Independent Expert Engineering Investigation and Review Panel: Report on Mount Polley Tailings Storage Facility Breach. Province of British Columbia.

2Koppes et al., 2008. Late quaternary glaciation in the Kyrgyz Tien Shan. Quarternary Science Reviews. 27: 846-866.

3Jansky et al., 2009. The evolution of Petrov Lake and moraine dam rupture risk (Tien-Shan, Kyrgyzstan). Natural Hazards. 50: 83-96.

Twitter: @GlacierBytes

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Glacier Mining Photos & Videos (Open File)

Posted by William Colgan on February 03, 2015
Applied Glaciology, Glaciers and Society / No Comments

I have started this open file of selected glacier mining photos and videos with content mostly gleaned from Twitter. At present its coverage is limited to Kumtor Mine, Kyrgyzstan, but I am interested in content that illustrates the unique geotechnical challenges of working with glaciers from other proglacial mining projects too. So please contact me if you have some!

Photos

Open ice pit at Kumtor Mine, Kyrgyzstan in 2013 (via Ryskeldi Satke).

Open ice pit at Kumtor Mine, Kyrgyzstan in 2013 (via Ryskeldi Satke).

6 - активисты Саруу, июль 2013 посещ Кумтор

An excavator used for glacier mining at Kumtor Mine, Kyrgyzstan (via Ryskeldi Satke).

4 - активисты Саруу, июль 2013 посещ. Кумтор

A glacier cut face at Kumtor Mine, Kyrgyzstan (via Ryskeldi Satke).

 

Videos

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Proglacial Mining Projects (Open File)

Posted by William Colgan on January 08, 2015
Applied Glaciology, Glaciers and Society / No Comments

Proglacial mines, meaning mining operations adjacent to, or very close to, glaciers, face a variety of unique glaciological challenges not present in conventional mining operations: (1) Removing ice overburden to access a subglacial ore introduces both ice excavation and ice flow management challenges. (2) In addition to potential crevasse hazards, supraglacial vehicle access roads must use adaptive engineering to counteract ice movement (both horizontal and vertical) as well as differential surface ablation. (3) Tremendous glacier meltwater runoff, concentrated during the summer melt season, can be difficult to route across highly transient glacier surfaces in order to minimize site inflow/contact water. (4) The dust created by open pit operations or access roads can darken the surface of nearby glaciers, enhancing their solar absorption and surface melt rates, and ultimately expand the impact footprint of a mine. (5) The catastrophic drainage of supraglacial and/or ice-dammed lakes represent outburst flood hazards which can rapidly increase site inflow rates. (6) Subglacial hydrology can interact with the groundwater seepage in underground mining operations beneath glaciers. We touch on some of these glaciological hazards in the new textbook: “Snow and Ice-Related Hazards, Risks, and Disasters”. These geotechnical challenges make proglacial mining projects very unique. I started this “open file” inventory of proglacial mining projects (past, present and future) and their associated glaciological challenges as I pull together information for an applied glaciology review paper. Please alert me to any errors or oversights!

ProjectPrime
Minerals
LocationGlaciological ChallengesApparent
Status
Isua
[Fig. 1]
Fe 65.195 °N, 49.790 °W
(Greenland)
- ice removal / flow management
- glacier access roads
- meltwater runoff
- supraglacial lake outbursts
- darkening of nearby glaciers
Approved in 2013.
Kumtor
[Fig. 2]
Au41.862 °N, 78.196 °E
(Kyrgyzstan)
- ice removal / flow management
- glacier access roads
- meltwater runoff
- darkening of nearby glaciers
Active since 1997.
Kerr-Sulphurets-
Mitchell
[Fig. 3]
Au, Ag, Cu, Mo56.491 °N, 130.335 °W
(Canada)
- glacier access roads
- meltwater runoff
- darkening of nearby glaciers
Approved in 2014.
TutoN/A76.417 °N, 68.269°W
(Greenland)
- ice removal / flow management
- glacier access roads
- meltwater runoff
Historic project (1955 to 1959).
GranducCu56.247 °N, 130.089 °W
(Canada)
- ice removal / flow management
- meltwater runoff
- darkening of nearby glaciers
Historic project (1964 to 1983).
MalmbjergMo 71.964 °N, 24.289 °W
(Greenland)
- glacier access roads
- meltwater runoff
- darkening of nearby glaciers
Prospect.
Brucejack
[Fig. 3]
Au, Ag56.468 °N, 130.164 °W
(Canada)
- glacier access roads
- meltwater runoff
Approved in 2015.
Maarmorilik
(Phase Two expansion)
Zn, Pb71.094 °N, 51.027°W
(Greenland)
- meltwater runoff
- darkening of nearby glaciers
Prospect.
Svea Nord | Gruve
[Fig. 6]
C77.893 °N, 16.689 °E
(Norway)
- subglacial miningActive since 2001.
El Morro
(La Fortuna expansion)
[Fig. 4]
Cu, Au33.167 °S, 70.274 °W
(Chile)
- darkening of nearby glaciersActive since c. 2008.
Permit suspended in 2014.
Pascua Lama
[Fig. 5]
Au, Ag29.327 °S, 70.035°W
(Chile / Argentina)
- darkening of nearby glaciersActive since 2010.
Permit suspended in 2013.
KvanefjeldU60.963 °N, 45.957 °W
(Greenland)
- darkening of nearby glaciersProspect.
Red MountainAu, Ag55.970 °N, 129.721 °W
(Canada)
- proglacial and/or subglacial depositsProspect.
Grasberg [Fig. 7]Au, Cu4.060 °S, 137.146 °E
(Indonesia)
- darkening of nearby glaciers
- glacier removal to access subglacial deposit
Active since c. 1995.

Below are some site overview figures, they are available for distribution without attribution tags as well. I hope to make one for each project by the end of 2015. Content on this page can be cited as:

Colgan, W., H. Thomsen and M. Citterio. in press. Unique Applied Glaciology Challenges of Proglacial Mining. Geological Survey of Denmark and Greenland Bulletin.

Isua_Mine

Figure 1 – The Isua Mine in Greenland: Contemporary ice margins, proposed approximate pit area, and winter 2005/06 ice surface velocity vectors overlaid on a 2014 Landsat image.

Kumtor_Mine

Figure 2 – The Kumtor mine in Kyrgyzstan: Historic ice margins and contemporary mine area overlaid on a 2014 Landsat image.

Kerr-Sulphurets-Mitchell_Mine_Brucejack_Prospect

Figure 3 – The Kerr-Sulphurets-Mitchell Mine and Bruckjack Prospect in Canada: Contemporary ice margins, approximate mine surface areas, and proposed supraglacial access roads overlaid on a 2014 Landsat image.

El_Morro_Mine

Figure 4 – The El Morro mine in Chile: Contemporary ice margins and mine area overlaid on a 2014 Landsat image.

Pascua_Lama_Mine

Figure 5 – The Pascua Lama mine on the Chile/Argentina border: Contemporary ice margins and mine area overlaid on a 2014 Landsat image. The Valadero mine is also visible immediately south of the Pascua Lama mine.

Svea_Nord_and_Gruve_Mines

Figure 6 – The Svea Nord / Gruve Mines in Svalbard (Norway): Contemporary ice margins and underground mine area overlaid on a 2014 Landsat image.

Grasberg_w_label2

Figure 7 – Grasberg Mine in Indonesia: Contemporary mine area and ice margins in a 2003 Landsat image.

 

 

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Glacier Mining: Geotechnical and Social Exceptionalism

Posted by William Colgan on November 07, 2014
Applied Glaciology, Climate Change, Glaciers and Society / 1 Comment

When the glaciology lexicon was in its infancy, Carl Benson described glaciers as “monomineralic metamorphic rocks” in his pioneering work with the US Army Engineers1. Given the lower density and strength of ice than coal, it may seem like glacier ice is an easy overburden to remove for open pit mining. Experience, however, has demonstrated that there are exceptional geotechnical challenges associated with removing glacier ice overburden. These challenges stem from geometry, hydrology and phase, all of which change far more rapidly in glaciers than hard rock2. The apparent surge of a waste rock pile at the Kumtor Mine, in Kyrgyzstan, highlights the exceptional geotechnical challenges confronting Centerra Gold in maintaining the world’s largest open ice pit mine.

With glaciers serving as a highly visible indicator of climate change, glacier mining projects often face exceptional social challenges in comparison to conventional hard rock mining projects. The Pascua Lama Mine, which spans the Chile-Argentina border, highlights how glacier preservation is a global movement that adapts to local issues. Glaciers therefore serve as the basis for a “glocal”, or globalized local, social movement3. Barrick Founder Peter Munk has commented on the social challenges confronting Pascua Lama: “It’s not enough to have money, it’s not enough to have reserves, it’s not enough to have great mining people. Today, the single most critical factor in growing a mining company is a social consensus – a license to mine.”4

The combination of long term increases in resource demand, retreating glaciers due to climate change, and improved mining technology and prospecting techniques, are making the exploitation of pro- and sub-glacial mineral deposits more feasible. This means a more widespread confrontation of the geotechnical and social exceptionalism of glacier mining in the coming decades!

Kumtor_1975_2013

Glacier and waste rock extent between 1975 and 2013 in the vicinity of Kumtor Mine (from Landsat archive).

PascuaLama

Glaciers in the vicinity of the Pascua Lama Mine on the Chile-Argentina border (from WikiCommons).

1Benson, C. 1962. Stratigraphic studies in the snow and firn of the Greenland ice sheet. Snow, Ice and Permafrost Research Esatablishment. US Army. Research Report 70.

2Colgan, W. and L. Arenson. 2013. Open-Pit Glacier Ice Excavation: Brief Review.
Journal of Cold Regions Engineering. 27: doi:10.1061/(ASCE)CR.1943-5495.0000057.

3Urkidi, L. 2010. A glocal environmental movement against gold mining: Pascua–Lama in Chile. Ecological Economics. 70: 219-227.

4Smith, C. 2014. Sustainability Challenges: When Good Intentions Backfire. NSEAD Knowledge

Additional Landsat images of Kumtor here.

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KSM Project gets provincial approval

Posted by William Colgan on November 03, 2014
Applied Glaciology, Climate Change, Glaciers and Society / No Comments

The Kerr-Sulphurets-Mitchell (KSM) gold mine in British Columbia received provincial approval last week. The federal permitting decision is expected in November. The suite of three open pits are in close proximity to glaciers, with the ultimate outline of the Mitchell pit intersecting the present extent of Mitchell Glacier. The proponent report filed by Seabridge Gold Inc states: “The current recession rate of the Mitchell Glacier has been estimated by Seabridge geologists at 100 m per year. As mining progresses, melting of the ice is expected to clear the area for the ultimate pit and create space needed for a series of diversion dams and ponds as well as the required debris catch basins upstream of the diversion inlets.” Seabridge is also seeking to excavate a 22 km long haulage tunnel that will convey 120,000 tonnes per day of ore underneath glaciers north of the open pits. A 38 km long glacier road, which ascends Berendon Glacier, crosses a local topographic divide, and descends an unnamed glacier, will provide winter access to the trio of open pits. The Berendon Glacier access road would be close proximity to the Knipple Glacier access road proposed by Pretium Resources Inc to access the nearby Bruce Jack Mine. Presumably the KSM project will be keeping a close eye regional glacier projections!

Controversial Canadian KSM mine gets key govt. permits

KSM (Kerr-Sulphurets-Mitchell) Project: Canadian Environmental Assessment Agency

KSM_glacier_road

Kerr-Sulphurets-Mitchell Project glacier access road during the winter. The road ascends Berendon Glacier in the east, crosses the local topographic divide, and descends an unnamed glacier in the west.

KSM_site_map

Site map of the Mitchell Pit at the Kerr-Sulphurets-Michell gold mine. Purple line denotes haulage tunnel. Dashed black line denotes ultimate extent of Mitchell Pit. White areas denote glacier extent.

 

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Camp TUTO Sixty Year Anniversary

Posted by William Colgan on September 30, 2014
Applied Glaciology, Cold War Science, Glaciology History / 1 Comment

Sixty years ago this month, in September 1954, the US Army Corps of Engineers completed its first summer of construction at Camp TUTO, Greenland. Camp TUTO was tucked against the Greenland ice sheet east of Thule Air Base. The gently sloping ice sheet adjacent to the camp, earmarked for vehicle access to the ice sheet interior, was named Thule Take-Off (or TUTO). Over the summer of 1954, some of the one hundred soldiers stationed at Camp TUTO built a gravel road up the first 1500 meters (4700 feet) of TUTO Ramp. Although that got them above the sometimes bare ice and slush of the lower elevation ice sheet melt zone, it still proved difficult to drive over the soft snow of the higher elevation ice sheet accumulation zone.

In official reports, the US Army Corps of Engineers tested “every off-road military vehicle (probably not excepting Hannibal’s elephants)” in the search for a suitable over-snow vehicle. The M29C Weasel, originally designed as an amphibious vehicle late in the Second World War, had proved disappointing in swampy terrain, but exceptionally nimble on the ice sheet. Although the Weasel was out of production even before construction started at Camp TUTO, it became a beloved backbone of US Army logistics on the Greenland ice sheet for almost two decades.

Constructing TUTO Ramp and adopting the Weasel opened up the interior of the Greenland ice sheet for a wide array of military engineering activities, including the construction of ice sheet runways and under-snow stations, as well as civilian science activities, including recovering the first “deep” ice core and wide-ranging snow and accumulation surveys. An auspicious anniversary of a ground-breaking project in applied glaciology!

(skimmed from my upcoming Cold War science project.)

TUTO_Ramp_in_1954

The view up TUTO Ramp, from the ice margin at Camp TUTO, on to the Greenland ice sheet in 1954. (from Nate Galbreath at thule1954.com)

Weasels_on_the_ice_sheet_in_1954

Modified M29C Weasels in convoy (left) on the Greenland ice sheet in 1954. (from Nate Galbreath at thule1954.com).

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Ice Excavation in an Open Ice Pit

Posted by William Colgan on September 24, 2014
Applied Glaciology, New Research / No Comments

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_velocity_open_ice_pit

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)

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