| Summary: | © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Lai, C.-Y., Stevens, L. A., Chase, D. L., Creyts, T. T., Behn, M. D., Das, S. B., & Stone, H. A. Hydraulic transmissivity inferred from ice-sheet relaxation following Greenland supraglacial lake drainages. Nature Communications, 12(1), (2021): 3955, https://doi.org/10.1038/s41467-021-24186-6. Surface meltwater reaching the base of the Greenland Ice Sheet transits through drainage networks, modulating the flow of the ice sheet. Dye and gas-tracing studies conducted in the western margin sector of the ice sheet have directly observed drainage efficiency to evolve seasonally along the drainage pathway. However, the local evolution of drainage systems further inland, where ice thicknesses exceed 1000 m, remains largely unknown. Here, we infer drainage system transmissivity based on surface uplift relaxation following rapid lake drainage events. Combining field observations of five lake drainage events with a mathematical model and laboratory experiments, we show that the surface uplift decreases exponentially with time, as the water in the blister formed beneath the drained lake permeates through the subglacial drainage system. This deflation obeys a universal relaxation law with a timescale that reveals hydraulic transmissivity and indicates a two-order-of-magnitude increase in subglacial transmissivity (from 0.8 ± 0.3 mm3 to 215 ± 90.2 mm3) as the melt season progresses, suggesting significant changes in basal hydrology beneath the lakes driven by seasonal meltwater input. C.-Y.L. and L.A.S thank Lamont-Doherty Earth Observatory for funding through the Lamont Postdoctoral Fellowships. D.L.C acknowledges support from the National Science Foundation (NSF) Graduate Research Fellowship. T.T.C. was supported by NSF’s Office of Polar Programs (NSF-OPP) through OPP-1643970, the National Aeronautics and Space Administration (NASA) through NNX16AJ95G, and a grant ...
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