An investigation of the subglacial environment, Briksdalsbreen, Norway

Abstract

This study uses GPR combined with borehole, video and wireless multisensor probe data to record the temporal changes in englacial and subglacial water and till variability associated with a rapidly retreating glacier. Over a 13 day period, ice radar-wave data varied between 0.129 m/ns and 0.159 m/ns, and water content from 7.7% to 1.44% (using Parens formula). Basal reflection power (BRP) was calculated to categorise the bed into high water content, deforming bed and sticky spots. Then a site on the deforming bed and sticky spots were monitored for 4 days each to record their stability. The results showed that the BRP values for the deforming bed were high and relatively constant, whilst those from the sticky spot were lower and more variable. It is suggested that these changes in englacial storage were caused by the enhanced crevassing generated by the newly floating ice margin which accelerated glacier retreat.