Hydrologic Properties of a Highly Permeable Firn Aquifer in the Wilkins Ice Shelf, Antarctica
Lynn Montgomery, C. Miège, Julie Z. Miller, T. A. Scambos, Bruce Wallin, Olivia Miller, D. Kip Solomon, R. R. Forster, L. Koenig
Abstract
Abstract We present measurements of the density, hydraulic conductivity, and specific discharge of a widespread firn aquifer in Antarctica, within the Wilkins Ice Shelf. At the field site, the aquifer is 16.2 m thick, starting at 13.4 m from the snow surface and transitioning from water‐saturated firn to ice at 29.6 m. Hydraulic conductivity derived from slug tests show a geometric mean value of 1.4 ± 1.2 × 10 −4 m s −1 , equivalent to permeability of 2.6 ± 2.2 × 10 −11 m 2 . A borehole dilution test indicates an average specific discharge value of 1.9 ± 2.8 × 10 −6 m s −1 . Ground‐penetrating radar profiles and a groundwater flow model show the aquifer is draining laterally into a large nearby rift. Our findings indicate that the firn aquifer in the vicinity of the field site is likely not in a steady state and its presence likely contributed to past ice shelf instability.