Hydrologic Properties Of A Highly Permeable Firn Aquifer In The Wilkins Ice Shelf, Antarctica

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 x 10(-4) m s(-1), equivalent to permeability of 2.6 +/- 2.2 x 10(-11) m(2). A borehole dilution test indicates an average specific discharge value of 1.9 +/- 2.8 x 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.