Relation Between Water Drainage and Short-term Strain/velocity Events on Storglaciaren, Sweden, and Geomorphic Implications

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There is an overdeepening in the bed of Storglaciaren, a predominantly temperate valley glacier in northern Sweden. In the overdeepening the glacier is, at least locally, underlain by a layer of water-saturated deformable till, the glacial drainage system is englacial, and water pressures are consistently high. Here also, diurnal variations in water input appear to result in long, low waves in the water table. These waves seem to become amplified as they move downglacier, resulting in a local diurnal uplift of the glacier surface. Downglacier from the overdeepening the drainage is subglacial and there are large (often 7 b) diurnal variations in water pressure. Here, peak velocities seem to occur during rising and falling water pressures, rather than during the peak pressure. Tracer experiments and measurements of surface tilt, strain, velocity, internal deformation, and water pressure will be undertaken to study these phenomena. The results are expected to not only clarify their causes, but also to contribute to a general understanding of the response of glaciers to variations in water pressure. The results are also expected to shed light in a classical problem of glacial geology: the origin of cirques and overdeepening in glacier beds. As part of the study of this problem, a post- doctoral research associate will be investigating processes of glacial quarrying.