APPLYING KARST HYDROLOGIC TECHNIQUES TO CALCULATE ENGLACIAL TUNNEL DISCHARGE, BERING GLACIER, ALASKA

A technique originally developed for use in limestone caves has been modified to estimate paleo-discharge through abandoned englacial tunnels at Bering Glacier, Alaska. As water moves in contact with tunnel wall irregularities, turbulent flow leads to uneven melting thus resulting in the formation of a scallop pattern. Scallop asymmetry indicates paleo-flow direction and scallop wavelength may be used to yield velocity. Paleo-flow velocity is estimated using a modified version of the Curl (1974) equation as follows:

Rn = [(r v l)/m] = 21,000

where Reynolds Number (Rn anticipated at ~2100), fluid density (r), and fluid viscosity (m) remain constant, thus establishing scallop wavelength (l) to be entirely dependant on velocity (v). Although air currents may also move though a tunnel, they have no significant influence on scallop formation. Scallop studies in conjunction with multi-year mapping of tunnel expression on a continually declining surface offer new potential for defining and understanding the scale and magnitude of meltwater movement within glacial ice.