Articles | Volume 17, issue 11
https://doi.org/10.5194/tc-17-4797-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-17-4797-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
15 Nov 2023
Research article |
| 15 Nov 2023
| 15 Nov 2023
The evolution of isolated cavities and hydraulic connection at the glacier bed – Part 1: Steady states and friction laws
Christian Schoof
CORRESPONDING AUTHOR
Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada
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Christian Schoof
The Cryosphere, 17, 4817–4836, https://doi.org/10.5194/tc-17-4817-2023, https://doi.org/10.5194/tc-17-4817-2023, 2023
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The subglacial drainage of meltwater plays a major role in regulating glacier and ice sheet flow. In this paper, I construct and solve a mathematical model that describes how connections are made within the subglacial drainage system. This will aid future efforts to predict glacier response to surface melt supply.
Camilo Andrés Rada Giacaman and Christian Schoof
The Cryosphere, 17, 761–787, https://doi.org/10.5194/tc-17-761-2023, https://doi.org/10.5194/tc-17-761-2023, 2023
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Water flowing at the base of glaciers plays a crucial role in controlling the speed at which glaciers move and how glaciers react to climate. The processes happening below the glaciers are extremely hard to observe and remain only partially understood. Here we provide novel insight into the subglacial environment based on an extensive dataset with over 300 boreholes on an alpine glacier in the Yukon Territory. We highlight the importance of hydraulically disconnected regions of the glacier bed.
Christian Schoof
The Cryosphere, 17, 4817–4836, https://doi.org/10.5194/tc-17-4817-2023, https://doi.org/10.5194/tc-17-4817-2023, 2023
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The subglacial drainage of meltwater plays a major role in regulating glacier and ice sheet flow. In this paper, I construct and solve a mathematical model that describes how connections are made within the subglacial drainage system. This will aid future efforts to predict glacier response to surface melt supply.
Camilo Andrés Rada Giacaman and Christian Schoof
The Cryosphere, 17, 761–787, https://doi.org/10.5194/tc-17-761-2023, https://doi.org/10.5194/tc-17-761-2023, 2023
Short summary
Short summary
Water flowing at the base of glaciers plays a crucial role in controlling the speed at which glaciers move and how glaciers react to climate. The processes happening below the glaciers are extremely hard to observe and remain only partially understood. Here we provide novel insight into the subglacial environment based on an extensive dataset with over 300 boreholes on an alpine glacier in the Yukon Territory. We highlight the importance of hydraulically disconnected regions of the glacier bed.
Related subject area
Discipline: Glaciers | Subject: Glacier Hydrology
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Velocity variations and hydrological drainage at Baltoro Glacier, Pakistan
Seasonal to decadal dynamics of supraglacial lakes on debris-covered glaciers in the Khumbu region, Nepal
A conceptual model for glacial lake bathymetric distribution
The evolution of isolated cavities and hydraulic connection at the glacier bed – Part 2: A dynamic viscoelastic model
The impact of surface melt rate and catchment characteristics on Greenland Ice Sheet moulin inputs
Evaporation over a glacial lake in Antarctica
A local model of snow–firn dynamics and application to the Colle Gnifetti site
Accumulation of legacy fallout radionuclides in cryoconite on Isfallsglaciären (Arctic Sweden) and their downstream spatial distribution
Drainage of an ice-dammed lake through a supraglacial stream: hydraulics and thermodynamics
Development of a subglacial lake monitored with radio-echo sounding: case study from the eastern Skaftá cauldron in the Vatnajökull ice cap, Iceland
Geophysical constraints on the properties of a subglacial lake in northwest Greenland
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Coupled modelling of subglacial hydrology and calving-front melting at Store Glacier, West Greenland
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The Cryosphere, 18, 2487–2507, https://doi.org/10.5194/tc-18-2487-2024, https://doi.org/10.5194/tc-18-2487-2024, 2024
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Water beneath glaciers in Antarctica can influence how the ice slides or melts. Airborne radar can detect this water, which looks bright in radar images. However, common techniques cannot identify the water's size or shape. We used a simulator to show how the radar image changes based on the bed material, size, and shape of the waterbody. This technique was applied to a suspected waterbody beneath Thwaites Glacier. We found it may be consistent with a series of wide, flat canals or a lake.
Anna Wendleder, Jasmin Bramboeck, Jamie Izzard, Thilo Erbertseder, Pablo d'Angelo, Andreas Schmitt, Duncan J. Quincey, Christoph Mayer, and Matthias H. Braun
The Cryosphere, 18, 1085–1103, https://doi.org/10.5194/tc-18-1085-2024, https://doi.org/10.5194/tc-18-1085-2024, 2024
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This study analyses the basal sliding and the hydrological drainage of Baltoro Glacier, Pakistan. The surface velocity was characterized by a spring speed-up, summer peak, and autumn speed-up. Snow melt has the largest impact on the spring speed-up, summer velocity peak, and the transition from inefficient to efficient drainage. Drainage from supraglacial lakes contributed to the fall speed-up. Increased summer temperatures will intensify the magnitude of meltwater and thus surface velocities.
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The Cryosphere, 18, 525–541, https://doi.org/10.5194/tc-18-525-2024, https://doi.org/10.5194/tc-18-525-2024, 2024
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In this study we developed methods for automatically identifying supraglacial lakes in multiple satellite imagery sources for eight glaciers in Nepal. We identified a substantial seasonal variability in lake area, which was as large as the variability seen across entire decades. These complex patterns are not captured in existing regional-scale datasets. Our findings show that this seasonal variability must be accounted for in order to interpret long-term changes in debris-covered glaciers.
Taigang Zhang, Weicai Wang, and Baosheng An
The Cryosphere, 17, 5137–5154, https://doi.org/10.5194/tc-17-5137-2023, https://doi.org/10.5194/tc-17-5137-2023, 2023
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Detailed glacial lake bathymetry surveys are essential for accurate glacial lake outburst flood (GLOF) simulation and risk assessment. We creatively developed a conceptual model for glacial lake bathymetric distribution. The basic idea is that the statistical glacial lake volume–area curves conform to a power-law relationship indicating that the idealized geometric shape of the glacial lake basin should be hemispheres or cones.
Christian Schoof
The Cryosphere, 17, 4817–4836, https://doi.org/10.5194/tc-17-4817-2023, https://doi.org/10.5194/tc-17-4817-2023, 2023
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The subglacial drainage of meltwater plays a major role in regulating glacier and ice sheet flow. In this paper, I construct and solve a mathematical model that describes how connections are made within the subglacial drainage system. This will aid future efforts to predict glacier response to surface melt supply.
Tim Hill and Christine F. Dow
The Cryosphere, 17, 2607–2624, https://doi.org/10.5194/tc-17-2607-2023, https://doi.org/10.5194/tc-17-2607-2023, 2023
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Water flow across the surface of the Greenland Ice Sheet controls the rate of water flow to the glacier bed. Here, we simulate surface water flow for a small catchment on the southwestern Greenland Ice Sheet. Our simulations predict significant differences in the form of surface water flow in high and low melt years depending on the rate and intensity of surface melt. These model outputs will be important in future work assessing the impact of surface water flow on subglacial water pressure.
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The evaporation over an ice-free glacial lake was measured in January 2018, and the uncertainties inherent to five indirect methods were quantified. Results show that in summer up to 5 mm of water evaporated daily from the surface of the lake located in Antarctica. The indirect methods underestimated the evaporation over the lake's surface by up to 72 %. The results are important for estimating the evaporation over polar regions where a growing number of glacial lakes have recently been evident.
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Eyjólfur Magnússon, Finnur Pálsson, Magnús T. Gudmundsson, Thórdís Högnadóttir, Cristian Rossi, Thorsteinn Thorsteinsson, Benedikt G. Ófeigsson, Erik Sturkell, and Tómas Jóhannesson
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We present a unique insight into the shape and development of a subglacial lake over a 7-year period, using repeated radar survey. The lake collects geothermal meltwater, which is released in semi-regular floods, often referred to as jökulhlaups. The applicability of our survey approach to monitor the water stored in the lake for a better assessment of the potential hazard of jökulhlaups is demonstrated by comparison with independent measurements of released water volume during two jökulhlaups.
Ross Maguire, Nicholas Schmerr, Erin Pettit, Kiya Riverman, Christyna Gardner, Daniella N. DellaGiustina, Brad Avenson, Natalie Wagner, Angela G. Marusiak, Namrah Habib, Juliette I. Broadbeck, Veronica J. Bray, and Samuel H. Bailey
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In the last decade, airborne radar surveys have revealed the presence of lakes below the Greenland ice sheet. However, little is known about their properties, including their depth and the volume of water they store. We performed a ground-based geophysics survey in northwestern Greenland and, for the first time, were able to image the depth of a subglacial lake and estimate its volume. Our findings have implications for the thermal state and stability of the ice sheet in northwest Greenland.
Hannah R. Field, William H. Armstrong, and Matthias Huss
The Cryosphere, 15, 3255–3278, https://doi.org/10.5194/tc-15-3255-2021, https://doi.org/10.5194/tc-15-3255-2021, 2021
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The growth of a glacier lake alters the hydrology, ecology, and glaciology of its surrounding region. We investigate modern glacier lake area change across northwestern North America using repeat satellite imagery. Broadly, we find that lakes downstream from glaciers grew, while lakes dammed by glaciers shrunk. Our results suggest that the shape of the landscape surrounding a glacier lake plays a larger role in determining how quickly a lake changes than climatic or glaciologic factors.
Chloé Scholzen, Thomas V. Schuler, and Adrien Gilbert
The Cryosphere, 15, 2719–2738, https://doi.org/10.5194/tc-15-2719-2021, https://doi.org/10.5194/tc-15-2719-2021, 2021
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We use a two-dimensional model of water flow below the glaciers in Kongsfjord, Svalbard, to investigate how different processes of surface-to-bed meltwater transfer affect subglacial hydraulic conditions. The latter are important for the sliding motion of glaciers, which in some cases exhibit huge variations. Our findings indicate that the glaciers in our study area undergo substantial sliding because water is poorly evacuated from their base, with limited influence from the surface hydrology.
Andreas Kellerer-Pirklbauer, Michael Avian, Douglas I. Benn, Felix Bernsteiner, Philipp Krisch, and Christian Ziesler
The Cryosphere, 15, 1237–1258, https://doi.org/10.5194/tc-15-1237-2021, https://doi.org/10.5194/tc-15-1237-2021, 2021
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Present climate warming leads to glacier recession and formation of lakes. We studied the nature and rate of lake evolution in the period 1998–2019 at Pasterze Glacier, Austria. We detected for instance several large-scale and rapidly occurring ice-breakup events from below the water level. This process, previously not reported from the European Alps, might play an important role at alpine glaciers in the future as many glaciers are expected to recede into valley basins allowing lake formation.
Christian Schoof
The Cryosphere, 14, 3175–3194, https://doi.org/10.5194/tc-14-3175-2020, https://doi.org/10.5194/tc-14-3175-2020, 2020
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Glacier lake outburst floods are major glacial hazards in which ice-dammed reservoirs rapidly drain, often in a recurring fashion. The main flood phase typically involves a growing channel being eroded into ice by water flow. What is poorly understood is how that channel first comes into being. In this paper, I investigate how an under-ice drainage system composed of small, naturally occurring voids can turn into a channel and how this can explain the cyclical behaviour of outburst floods.
Samuel J. Cook, Poul Christoffersen, Joe Todd, Donald Slater, and Nolwenn Chauché
The Cryosphere, 14, 905–924, https://doi.org/10.5194/tc-14-905-2020, https://doi.org/10.5194/tc-14-905-2020, 2020
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This paper models how water flows beneath a large Greenlandic glacier and how the structure of the drainage system it flows in changes over time. We also look at how this affects melting driven by freshwater plumes at the glacier front, as well as the implications for glacier flow and sea-level rise. We find an active drainage system and plumes exist year round, contradicting previous assumptions and suggesting more melting may not slow the glacier down, unlike at other sites in Greenland.
Camilo Rada and Christian Schoof
The Cryosphere, 12, 2609–2636, https://doi.org/10.5194/tc-12-2609-2018, https://doi.org/10.5194/tc-12-2609-2018, 2018
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We analyse a large glacier borehole pressure dataset and provide a holistic view of the observations, suggesting a consistent picture of the evolution of the subglacial drainage system. Some aspects are consistent with the established understanding and others ones are not. We propose that most of the inconsistencies arise from the capacity of some areas of the bed to become hydraulically isolated. We present an adaptation of an existing drainage model that incorporates this phenomena.
Cited articles
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Short summary
Computational models that seek to predict the future behaviour of ice sheets and glaciers typically rely on being able to compute the rate at which a glacier slides over its bed. In this paper, I show that the degree to which the glacier bed is
hydraulically connected(how easily water can flow along the glacier bed) plays a central role in determining how fast ice can slide.
Computational models that seek to predict the future behaviour of ice sheets and glaciers...
