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SPRI Review 1998: Glacier Hydrology Group

Glacier Hydrology Group

Dr N. Arnold

Dr G. de Q. Robin, Dr I. Willis (Department of Geography), Dr D. Mair (Department of Geography), D. Rippin

This year has seen the expansion of the Glacier Hydrology Group's activities into high Arctic environments, with a NERC funded PhD studentship, held by David Rippin, and supervised by Drs Arnold and Willis. This studentship aims to expand the successful field-based and modelling-based strategy used in the group's previous work in Switzerland to a high Arctic environment. Glaciers in such regions are believed to behave quite differently from those in more temperate climates, as the ice within them is often below the melting point (rather than at the melting point as in temperate glaciers). This will affect the hydrology of the glacier, as the cold ice may form an impermeable layer that prevents summer meltwater from penetrating to the glacier bed. The focus of Rippin's research is to discover intra-annual and inter-annual motion patterns on a high Arctic glacier that could be linked to seasonal changes in the glacier hydrological system. This field-based work is linked to theoretical reconstructions of the possible subglacial hydrological system, using digital elevation models of the glacier surface and bed surface to define subglacial hydraulic potentials, which are believed to govern the flow of subglacial water. This is linked to a radio echo sounding program on the glacier to investigate both the ice thickness distribution, and possible changes in the distribution of temperate ice.

The first six-week field-trip took place in the summer of 1998. Dr Arnold and Rippin were based at the NERC Arctic Research Station at Ny-Alesund, Svalbard. The glacier under investigation is Midre Lovenbreen, a small valley glacier some 40 minutes walk from the base. The fieldwork and research was conducted in collaboration with Dr Andrew Hodson of Sheffield University, a glacial hydrologist with particular interest in meltwater chemistry. Initial results from the field season are very promising. Although the radio echo sounder failed, it has proved possible to obtain ice thickness distributions from two other sources, Dr John Moores and Dr Helgi Bjornsson. These data have been used to reconstruct a possible drainage network, which can be compared with the results of the successful programme of velocity measurements made on the glacier during the summer. These data are still being processed. Season-long meteorological data were also obtained, which will be used in the distributed, energy-balance model developed by the group to enable water-balance estimates to be made. These can then be compared with any velocity events, to investigate the possibility that water storage could affect glacier flow.

The modelling work for Haut Glacier d'Arolla in Valais, Switzerland, has continued. Early in 1998, the results of a linked hydrology-sediment transport model for this glacier were presented at the University of Leeds at a joint International Glaciology Society/British Geomorphological Research Group/British Quaternary Association conference on glacier sediment transport processes. This paper is to be published in Quaternary Proceedings.

Dr. Arnold's work for the Stage Three Project, an international, interdisciplinary group based in the Department of Earth Sciences, Cambridge, was completed for the current phase of the project. The project aims to reconstruct the climate of Europe during Oxygen Isotope Stage 3, a warmer period during the last Glacial Period, around 40,000 years ago. Dr Arnold's input was a modelling-based study of the possible extent of the Scandinavian Ice Sheet at this time, for use as a boundary condition in a global climate model. The intensive climate modelling phase, by Dr Eric Barron and his research group at Pennsylvania State University, is now underway. These initial results will be presented at the International Quaternary Association Meeting in Durban, South Africa, in mid-1999. The ice sheet modelling results are also being linked with a comprehensive Earth model, developed by Professor Kurt Lambeck of the Australian National University, to reconstruct patterns of isostatic adjustment in Europe during the last glacial period. Dr Arnold is also working with Dr David Pollard of Penn State to develop the ice sheet model from two-dimensional to three-dimensional.

Planned work also includes expanding the Arctic research programme, to include hydrological modelling, as well as new data collection programmes, including the spatial variability of glacier surface characteristics, which are an important control on glacier mass balance.