Skip to main content Accessibility help
×
Home

Controls on the basal water pressure in subglacial channels near the margin of the Greenland ice sheet

  • Andreas P. Ahlstrøm (a1), Johan J. Mohr (a1), Niels Reeh (a1), Erik Lintz Christensen (a1) and Roger LeB. Hooke (a2)...

Abstract

Assuming a channelized drainage system in steady state, we investigate the influence of enhanced surface melting on the water pressure in subglacial channels, compared to that of changes in conduit geometry, ice rheology and catchment variations. The analysis is carried out for a specific part of the western Greenland ice-sheet margin between 66° N and 66°30′N using new high-resolution digital elevation models of the subglacial topography and the ice-sheet surface, based on an airborne ice-penetrating radar survey in 2003 and satellite repeat-track interferometric synthetic aperture radar analysis of European Remote-sensing Satellite 1 and 2 (ERS-1/-2) imagery, respectively. The water pressure is calculated up-glacier along a likely subglacial channel at distances of 1, 5 and 9 km from the outlet at the ice margin, using a modified version of Röthlisberger’s equation. Our results show that for the margin of the western Greenland ice sheet, the water pressure in subglacial channels is not sensitive to realistic variations in catchment size and mean surface water input compared to small changes in conduit geometry and ice rheology.

  • View HTML
    • Send article to Kindle

      To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

      Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

      Find out more about the Kindle Personal Document Service.

      Controls on the basal water pressure in subglacial channels near the margin of the Greenland ice sheet
      Available formats
      ×

      Send article to Dropbox

      To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

      Controls on the basal water pressure in subglacial channels near the margin of the Greenland ice sheet
      Available formats
      ×

      Send article to Google Drive

      To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

      Controls on the basal water pressure in subglacial channels near the margin of the Greenland ice sheet
      Available formats
      ×

Copyright

References

Hide All
Ahlstrøm, A.P. 2003. Ice sheet ablation assessed by observation, remote sensing and modelling. (PhD thesis, University of Copenhagen.)
Ahlstrøm, A.P. and 6 others. 2002 Mapping of a hydrological ice-sheet drainage basin on the West Greenland ice-sheet margin from ERS-1/-2 SAR interferometry, ice-radar measurement and modelling. Ann. Glaciol., 34, 309314.
Alley, R.B. and Bindschadler, R.A. eds. 2001. The West Antarctic ice sheet: behavior and environment. Washington, DC, American Geophysical Union. (Antarctic Research Series 77.)
Ambach, W., Rehwald, W., Blumthaler, M., Eisner, H. and Brunner, P.. 1988 Correspondence. Chernobyl fall-out on glaciers in the Austrian Alps. J. Glaciol., 34(117), 255256.
Arnold, N., Richards, K., Willis, I. and Sharp, M.. 1998 Initial results from a distributed, physically based model of glacier hydrology. Hydrol. Process., 12, 191219.
Björnsson, H. 1982 Drainage basins on Vatnajökull mapped by radio echo soundings. Nord. Hydrol., 13(4), 213232.
Boon, S. and Sharp, M.. 2003 The role of hydrologically-driven ice fracture in drainage system evolution on an Arctic glacier. Geophys. Res. Lett., 30(18), 1916. (10.1029/2003GL018034.)
Carr, J.R. 1995. Numerical analysis for the geological sciences. Englewood Cliffs, NJ, Prentice-Hall.
Christensen, E.L., Reeh, N., Forsberg, R., Jørgensen, J.H., Skou, N. and Woelders, K.. 2000 A low-cost glacier-mapping system. J. Glaciol., 46(154), 531537.
Cutler, P.M. 1998 Modelling the evolution of subglacial tunnels due to varying water input. J. Glaciol., 44(148), 485497.
Dahl-Jensen, D. and Gundestrup, N.S.. 1987 Constitutive properties of ice at Dye 3, Greenland. International Association of Hydrological Sciences Publication 170 (Symposium at Vancouver 1987 – The Physical Basis of Ice Sheet Modelling), 3143.
Dahl-Jensen, D. and Johnsen, S.J.. 1986 Palaeotemperatures still exist in the Greenland ice sheet. Nature, 320(6059), 250252.
Flowers, G.E. and Clarke, G.K.C.. 1999 Surface and bed topography of Trapridge Glacier, Yukon Territory, Canada: digital elevation models and derived hydraulic geometry. J. Glaciol., 45(149), 165174.
Flowers, G.E., Björnsson, H. and Pálsson, F.. 2003 New insights into the subglacial and periglacial hydrology of Vatnajökull, Iceland, from a distributed physical model. J. Glaciol., 49(165), 257270.
Gogineni, S. and 9 others. 2001 Coherent radar ice thickness measurements over the Greenland ice sheet. J. Geophys. Res., 106(D24), 33,76133,772.
Hagen, J.O., Etzelmüller, B. and Nuttall, A.M.. 2000 Runoff and drainage pattern derived from digital elevation models, Finster-walderbreen, Svalbard. Ann. Glaciol., 31, 147152.
Hock, R. 2003 Temperature index melt modelling in mountain areas. J. Hydrol., 282(1–4), 104115.
Hock, R. and Hooke, R.L.B.. 1993 Evolution of the internal drainage system in the lower part of the ablation area of Storglaciären, Sweden. Geol. Soc. Am. Bull., 105(4), 537546.
Hooke, R.LeB., Laumann, T. and Kohler, J.. 1990 Subglacial water pressures and the shape of subglacial conduits. J. Glaciol., 36(122), 6771.
Hubbard, B. and Nienow, P.. 1997 Alpine subglacial hydrology. Quat. Sci. Rev., 16(9), 939955.
Huybrechts, P., Letréguilly, A. and Reeh, N.. 1991 The Greenland ice sheet and greenhouse warming. Palaeogeogr., Palaeoclimatol., Palaeoecol., 89(4), 399412.
Iken, A. and Truffer, M.. 1997 The relationship between subglacial water pressure and velocity of Findelengletscher, Switzerland, during its advance and retreat. J. Glaciol., 43(144), 328338.
Iken, A., Echelmeyer, K., Harrison, W. and Funk, M.. 1993 Mechanisms of fast flow in Jakobshavns Isbræ, West Greenland: Part Measurements I. of temperature and water level in deep boreholes. J. Glaciol., 39(131), 1525.
Kamb, B. 1987 Glacier surge mechanism based on linked cavity configuration of the basal water conduit system. J. Geophys. Res., 92(B9), 90839100.
Krabill, W.B. and 9 others. 2000 Greenland ice sheet: highelevation balance and peripheral thinning. Science, 289(5478), 428430.
Ohmura, A. 2001 Physical basis for the temperature-based melt-index method. J. Appl. Meteorol., 40(4), 753761.
Paterson, W.S.B. 1994. The physics of glaciers. Third edition. Oxford, etc., Elsevier.
Röthlisberger, H. 1972 Water pressure in intra- and subglacial channels. J. Glaciol., 11(62), 177203.
Shreve, R.L. 1972 Movement of water in glaciers. J. Glaciol., 11(62), 205214.
Thomas, R.H., Abdalati, W., Frederick, E., Krabill, W.B. Manizade, S. and Steffen, K.. 2003 Investigation of surface melting and dynamic thinning on Jakobshavn Isbræ, Greenland. J. Glaciol., 49(165), 231239.
Thomsen, H.H. and Olesen, O.B.. 1990 Continued glaciological investigations with respect to hydropower and ice-climate relationships, at Pâkitsoq, Jakobshavn, West Greenland. Rapp. Grønl. Geol. Undersøgelse 148, 8386.
Thomsen, H.H., Thorning, L. and Braithwaite, R.J.. 1988 Glacier-hydrological conditions on the Inland Ice north-east of Jacobshavn/Ilulissat, West Greenland. Rapp. Grønl. Geol. Undersøgelse 138.
Thorning, L. and Hansen, E.. 1987 Electromagnetic reflection survey 1986 at the Inland Ice margin of the Pâkitsoq basin, central West Greenland. Rapp. Grønl. Geol. Undersøgelse 135, 8795.
Van de Wal, R.S.W. 1992. Ice and climate. (PhD thesis, Utrecht University.)
Walder, J.S. and Fowler, A.. 1994 Channelized subglacial drainage over a deformable bed. J. Glaciol., 40(134), 315.

Controls on the basal water pressure in subglacial channels near the margin of the Greenland ice sheet

  • Andreas P. Ahlstrøm (a1), Johan J. Mohr (a1), Niels Reeh (a1), Erik Lintz Christensen (a1) and Roger LeB. Hooke (a2)...

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed