Subglacial processes at Bondhusbreen, Norway: preliminary results.

Abstract

Subglacial hydrology, sediment transport, pressure, and temperature have been studied beneath c.160 m of ice at Bondhusbreen, an outlet glacier from Folgefonni in SW Norway. The volume of the mean annual water discharge passing through the study area is about 60x106m3. The discharge of eroded material is about 7600 tonnes. a-1. Of this, roughly 90% is transported by running water. Pressure gauges and thermistors were installed at two sites under the glacier. At one location, about 20 m up- glacier, non-hydrostatic differential pressures of up to 30 bar were recorded across an artificial dome-shaped obstacle. A boulder 0.3 m3 in size passed over the obstacle, destroying one of the pressure sensors. This sensor recorded a pressure of 90 bar before failing. Temperature measurements suggest that the difference in temperature across this obstacle was less than 0.03 deg, or an order of magnitude less than expected. -from Authors