Spatial and temporal variations in glacier hydrology on Storglaciaeren, Sweden

The purpose of this report is to summarize the experimental work on glacier hydrology and basal hydraulic conditions performed on Storglaciaren, northern Sweden, during the years 2003–2005. The aim of the project has been to provide a framework of real conditions within which to interpret theory and extrapolate conditions beneath a future ice sheet over Fennoscandia. Surface fed subglacial hydrological systems are extremely dynamic because the input rates of rain and temperature-contolled surface melt fluctuate and the geometry of flow paths is constantly changing due to ice deformation which tends to close the flow paths. The hydrological system of a glacier is unique since water is flowing through conduits made of its solid phase (ice). A possible analogy is lava flowing through rock of the same composition. Hence understanding the expected dynamic range of the glacier hydrological system is best studied by in situ measurements. The processes studied on Storglaciaren can be expected to apply to ice sheet scale, albeit on different spatial scales. Since Storglaciaren is a polythermal glacier with a large fraction of ice below freezing and at the melting point and with a surface-fed hydrological system of conduits and tunnels, results apply to the margins (ablation zone) of the past Fennoscandian Ice Sheet, at least along its southern margin. In this report we discuss the measurements made to assess the subglacial conditions that provide an analogue for conditions under the Fennoscandian Ice Sheet. We have also included a large quantity of unpublished data from Storglaciaren from different research projects conducted since 1990. Together these data provide a good picture of the temporal and spatial water pressure conditions in and under Storglaciaren. The report is the first comprehensive analysis of these subglacial water pressure records.