Subglacial drainage system structure and morphology of Brewster Glacier,New Zealand |
| |
Authors: | Ian Willis Wendy Lawson Ian Owens Bob Jacobel Jenny Autridge |
| |
Institution: | 1. Scott Polar Research Institute, Department of Geography, University of Cambridge, Lensfield Road, Cambridge CB2 1ER, UK;2. Department of Geography, University of Canterbury, Private Bag 4800, Christchurch, New Zealand;3. Department of Physics, St. Olaf College, 1520 St.Olaf Avenue, Northfield, MN 55057, USA |
| |
Abstract: | A global positioning system and ground penetrating radar surveys is used to produce digital elevation models of the surface and bed of Brewster Glacier. These are used to derive maps of subglacial hydraulic potential and drainage system structure using three different assumptions about the subglacial water pressure (Pw): (i) Pw = ice overburden; (ii) Pw = half ice overburden; (iii) Pw = atmospheric. Additionally, 16 dye‐tracing experiments at 12 locations were performed through a summer melt season. Dye return curve shape, together with calculations of transit velocity, dispersivity and storage, are used to infer the likely morphology of the subglacial drainage system. Taken together, the data indicate that the glacier is underlain by a channelised but hydraulically inefficient drainage system in the early summer in which water pressures are close to ice overburden. By mid‐summer, water pressures are closer to half‐ice overburden and the channelised drainage system is more hydraulically efficient. Surface streams that enter the glacier close to the location of major subglacial drainage pathways are routed quickly to the channels and then to the glacier snout. Streams that enter the glacier further away from the drainage pathways are routed slowly to the channels and then to the snout because they first flow through a distributed drainage system. Copyright © 2008 John Wiley & Sons, Ltd. |
| |
Keywords: | glacier hydrology subglacial drainage dye tracing hydraulic potential digital elevation model New Zealand |
|
|