HR: 0800h
AN: C21C-1124    [Abstracts]
TI: Modeling Proglacial Stream Discharge Based on Climate and Stable Isotopes in Pituffik, Greenland, 76 N 68 W
AU: * Hagedorn, B
EM: hagedorn@u.washington.edu
AF: University of Washington Earth & Space Sciences, Box 351310, Seattle, WA 98195 United States
AU: Sletten, R S
EM: sletten@u.washington.edu
AF: University of Washington Earth & Space Sciences, Box 351310, Seattle, WA 98195 United States
AU: Whorton, E N
EM: ewclimb@u.washington.edu
AF: University of Washington Earth & Space Sciences, Box 351310, Seattle, WA 98195 United States
AB: Greenland extends from 60 to 80 N and its ice sheet is the largest freshwater reservoir in the Arctic, and northern hemisphere, with a total volume of approximately 3x10⁶ km³. Changes in the ice sheet mass balance are of critical concern for oceanic and atmospheric circulation; however, estimates of the mass balance are afflicted with large uncertainties including the melt water runoff. The study area is located near Thule Air Base where continuous weather records since 1978 indicate an annual increase in air temperature of 0.06 C and precipitation of 2 mm water. A melt water discharge model is developed for two streams based on continuous records of discharge, water chemistry, and climate. The investigated streams, North River and South River, originate on the Greenland Ice Sheet and also drain a periglacial area of 100 and 150 km², respectively, before reaching the ocean. Each stream has an annual discharge of 10⁷ to 10⁸ m³, average water temperature of 2-3 C, and total ion concentration of 3-7 mg L^-1. Stream discharge is strongly correlated to air temperature and incoming solar radiation. Rain events also increase discharge; however, this increase is poorly correlated to total rainfall. The hydrograph was separated into various water sources using the stable isotopes δ¹⁸O and δD in the stream, snow, glacial melt water, and summer precipitation. This allows quantification of stream water sources and improves the parameterization of the discharge model. The discharge model, calibrated with modern air temperature and precipitation, may be used to reconstruct past run-off since the 1978 climate records. Flooding occurred during both years of this investigation and was a threat to facilities at the Air Base. The floods were caused by heavy rain or by slush flows from the ice sheet and are difficult to model; however, the stable isotope signatures may identify the water sources and help to better predict flood events in the future.
UR: http://depts.washington.edu/icylands/
DE: 0700 CRYOSPHERE (4540)
DE: 0702 Permafrost (0475)
DE: 0744 Rivers (0483, 1856)
DE: 0762 Mass balance (1218, 1223)
DE: 0798 Modeling
SC: Cryosphere [C]
MN: Fall Meeting 2005