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32nd Annual Arctic Workshop Abstracts
March 14-16, 2002
INSTAAR, University of Colorado at Boulder

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ASSESSING HYDROLOGIC IMPACTS OF ICE SHEET EXTENT IN NORTHERN EURASIA

AUTHORS

LAMMERS, RICHARD B.. University of New Hampshire.
Forman, Steven L.. University of Illiniois at Chicago.
Vorosmarty, Charles J.. University of New Hampshire.

Dramatic changes in the hydrology of Eurasia occurred during the last glaciation. Discharge of many rivers was probably reduced reflecting colder and dryer climates of the Siberian lowlands. Potentially, some large drainages were dammed by advancing ice sheets, diverting discharge from the Arctic Ocean to the Black Sea. Uncertainty persists on the eastern and northern margin of the Eurasian ice sheet, where small changes in extent (10s to 100s km) would progressively impound more northerly river flow. Ice sheet configurations are based on modifications of the Peltier ice sheet reconstruction with data defensible margins. Minimum, intermediate, and maximum configurations are represented by an eastern ice sheet limit in the Kara Sea, Taymyr Peninsula coast and western North Siberian Lowland, respectively. Topographic grid is provided by a contemporary 5-minute resolution global data set, which is regridded to 30-minute resolution. The river network configuration was derived from automated network delineation methods working off the digital terrain data.

The minimum ice sheet forms a proglacial lake that fills the Kara Sea with drainage to the north. This proglacial lake and concentrated runoff at the eastern-most margin may have limited expansion of the ice sheet. The intermediate ice sheet configuration forms a large proglacial lake equal in volume to of the Caspian Sea. The Ob' and Yenisey rivers are indirectly blocked with the presence of a contiguous ice sheet between Franz Josef Land, Svernaya Zemlya and the Taymyr Peninsula. Most drainage is routed to the east into the Laptev Sea. The maximum ice sheet extent directly blocks the Ob' and Yenisey rivers forming a massive proglacial lake, equivalent in volume to two Caspian Seas. Drainage is shifted to the south resulting in expansion of the Aral, Caspian and Black seas. These simulations show the importance of the eastern and northern ice sheet margins between Franz Josef Land, Svernaya Zemlya and the Taymyr Peninsula in diverting freshwater flow from the Arctic Ocean.

 

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