HR: 14:35h
AN: C12B-04    [PDF]
TI: The role of hydrologically-driven ice fracture in drainage system evolution on an Arctic glacier
AU: * Boon, S
EM: sboon@ualberta.ca
AF: Dept. of Earth & Atmospheric Sci., 1-26 Earth Sci. Bldg. University of Alberta, Edmonton, AB T6G 2E3 Canada
AU: Sharp, M
EM: martin.sharp@ualberta.ca
AF: Dept. of Earth & Atmospheric Sci., 1-26 Earth Sci. Bldg. University of Alberta, Edmonton, AB T6G 2E3 Canada
AB: Observations from Ellesmere Island suggest that a connection between surface and subglacial drainage on a predominantly cold glacier is made abruptly in spring by hydrologically-driven propagation of fractures from the ice surface to the glacier bed. Where ice is 150 m thick, water ponded to a depth of 6.9 m within a supraglacial stream system before a permanent connection to the bed was established. Multiple premonitory drainage events preceded the final drainage of the ponded water, implying that fracturing is necessary, but insufficient, to establish a permanent link between the surface and subglacial drainage systems. Refreezing of water that penetrates the first fractures to form may reseal the connection, while flow resistance within the subglacial system may delay the onset of continuous through-flow. A large volume of ponded water seems to be required to enlarge fractures sufficiently by melting to maintain continuous drainage, while feedbacks between subglacial hydrology and ice dynamics may assist in maintaining the connection and initiating subglacial outflow.
UR: http://arctic.eas.ualberta.ca/sarah/resume.html\#publicns
DE: 1857 Reservoirs (surface)
DE: 1863 Snow and ice (1827)
DE: 9315 Arctic region
SC: Cryosphere [C]
MN: 2003 Fall Meeting