Articles | Volume 11, issue 6
The Cryosphere, 11, 2691–2710, 2017
The Cryosphere, 11, 2691–2710, 2017

Research article 21 Nov 2017

Research article | 21 Nov 2017

Rapidly changing subglacial hydrological pathways at a tidewater glacier revealed through simultaneous observations of water pressure, supraglacial lakes, meltwater plumes and surface velocities

Penelope How1,2, Douglas I. Benn3, Nicholas R. J. Hulton1,2, Bryn Hubbard4, Adrian Luckman5,6, Heïdi Sevestre3, Ward J. J. van Pelt7, Katrin Lindbäck8, Jack Kohler8, and Wim Boot9 Penelope How et al.
  • 1Institute of Geography, School of GeoSciences, University of Edinburgh, Edinburgh, UK
  • 2Department of Arctic Geology, University Centre in Svalbard, Longyearbyen, Norway
  • 3School of Geography and Sustainable Development, University of St. Andrews, Fife, UK
  • 4Centre for Glaciology, Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, UK
  • 5Department of Geography, College of Science, Swansea University, Swansea, UK
  • 6Department of Arctic Geophysics, University Centre in Svalbard, Longyearbyen, Norway
  • 7Department of Earth Sciences, Uppsala University, Uppsala, Sweden
  • 8Norwegian Polar Institute, Tromsø, Norway
  • 9Institute of Marine and Atmospheric Research, Utrecht University, Utrecht, the Netherlands

Abstract. Subglacial hydrological processes at tidewater glaciers remain poorly understood due to the difficulty in obtaining direct measurements and lack of empirical verification for modelling approaches. Here, we investigate the subglacial hydrology of Kronebreen, a fast-flowing tidewater glacier in Svalbard during the 2014 melt season. We combine observations of borehole water pressure, supraglacial lake drainage, surface velocities and plume activity with modelled run-off and water routing to develop a conceptual model that thoroughly encapsulates subglacial drainage at a tidewater glacier. Simultaneous measurements suggest that an early-season episode of subglacial flushing took place during our observation period, and a stable efficient drainage system effectively transported subglacial water through the northern region of the glacier tongue. Drainage pathways through the central and southern regions of the glacier tongue were disrupted throughout the following melt season. Periodic plume activity at the terminus appears to be a signal for modulated subglacial pulsing, i.e. an internally driven storage and release of subglacial meltwater that operates independently of marine influences. This storage is a key control on ice flow in the 2014 melt season. Evidence from this work and previous studies strongly suggests that long-term changes in ice flow at Kronebreen are controlled by the location of efficient/inefficient drainage and the position of regions where water is stored and released.

Short summary
This study provides valuable insight into subglacial hydrology and dynamics at tidewater glaciers, which remains a poorly understood area of glaciology. It is a unique study because of the wealth of information provided by simultaneous observations of glacier hydrology at Kronebreen, a tidewater glacier in Svalbard. All these elements build a strong conceptual picture of the glacier's hydrological regime over the 2014 melt season.