Numerical analysis of rapid water transfer beneath Antarctica
Abstract:We use a simple energy-conservation model and a model based on Röthlisberger's theory for steady-state water flow in a subglacial conduit to model water movement between lakes in the Adventure subglacial trench region of East Antarctica during a 1996–98 jökulhlaup. Using available field evidence to constrain the models suggests that water flow would likely be accommodated in a tunnel with a cross-sectional area of 36 m2 and a value for k (the reciprocal of Manning's roughness parameter) larger than the 12.5 m1/3 s–1 previously calculated. We also use Nye's theory for time-dependent conduit water flow to model the temporal evolution of conduit discharge, cross-sectional area, water pressure and lake draining and filling during the flood. We initially assume one source and one sink lake. We perform sensitivity tests on the input parameter set, matching modeled source- and sink-lake depth changes with measured surface elevation data. Using a simple function for vertical ice deformation in which surface deformation scales linearly to the lake depth change, we find the scaling factor is of the order 4 × 10–3 of the ice thickness. The most likely value of k lies in the range 55–68 m1/3 s–1, and the ratio of source to sink-lake radii is approximately 1 : 1.4. Finally, we experiment using Nye's theory to model water movement between one source and three sink lakes. The model fails to produce the observed patterns of water movement as indicated by the surface deformation data.
Document Type: Research Article
Publication date: September 1, 2009
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- The Journal of Glaciology is published six times per year. It accepts submissions from any discipline related to the study of snow and ice. All articles are peer reviewed. The Journal is included in the ISI Science Citation Index.
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