HR: 0800h
AN: G51A-0136    [Abstracts]
TI: Combining Geological, Geodetic, and Tide-Gauge Data to Estimate Coastal Subsidence and Flooding Hazards in the Mackenzie Delta, Western Arctic Canada
AU: * Forbes, D L
EM: dforbes@nrcan.gc.ca
AF: Geological Survey of Canada, Natural Resources Canada, Box 1006, Dartmouth, NS B2Y 4A2, Canada
AU: * Forbes, D L
EM: dforbes@nrcan.gc.ca
AF: ArcticNet, Memorial University of Newfoundland, Elizabeth Avenue, St. John's, NL A1B 3X9, Canada
AU: Craymer, M
EM: craymer@nrcan.gc.ca
AF: Geodetic Survey Division, Natural Resources Canada, 615 Booth Street, Ottawa, ON K1A 0E9, Canada
AU: Henton, J
EM: jhenton@nrcan.gc.ca
AF: Geodetic Survey Division, Natural Resources Canada, 615 Booth Street, Ottawa, ON K1A 0E9, Canada
AU: Herron, T
EM: herront@dfo-mpo.gc.ca
AF: Canadian Hydrographic Service, Fisheries and Oceans Canada, Box 5050, Burlington, ON L7R 4A6, Canada
AU: Kokelj, S
EM: kokeljsv@inac.gc.ca
AF: Water Resources Division, Indian and Northern Affairs Canada, Box 1500, Yellowknife, NT X1A 2R3, Canada
AU: Lapelle, E
EM: elapelle@nrcan.gc.ca
AF: Geodetic Survey Division, Natural Resources Canada, 615 Booth Street, Ottawa, ON K1A 0E9, Canada
AU: Manson, G K
EM: gmanson@nrcan.gc.ca
AF: Geological Survey of Canada, Natural Resources Canada, Box 1006, Dartmouth, NS B2Y 4A2, Canada
AU: Marsh, P
EM: philip.marsh@ec.gc.ca
AF: National Hydrology Research Centre, Environment Canada, 11 Innovation Boulevard, Saskatoon, SK S7N 3H5, Canada
AU: Mazzotti, S
EM: smazzotti@rncan.gc.ca
AF: Geological Survey of Canada, Natural Resources Canada, Box 6000, Sidney, BC V8L 4B2, Canada
AU: Piraszewski, M
EM: mpirasze@nrcan.gc.ca
AF: Geodetic Survey Division, Natural Resources Canada, 615 Booth Street, Ottawa, ON K1A 0E9, Canada
AU: Solomon, S M
EM: ssolomon@nrcan.gc.ca
AF: Geological Survey of Canada, Natural Resources Canada, Box 1006, Dartmouth, NS B2Y 4A2, Canada
AU: Whalen, D
EM: dwhalen@nrcan.gc.ca
AF: Geological Survey of Canada, Natural Resources Canada, Box 1006, Dartmouth, NS B2Y 4A2, Canada
AB: Relative sea-level trends across the Canadian Arctic are highly variable, in part because of the strong imprint of postglacial isostatic adjustment. In many parts of the central Arctic, ongoing uplift exceeds the rate of regional sea-level rise, resulting in continued coastal emergence. In peripheral areas such as the western Arctic coastal plain, models and geological evidence point to ongoing subsidence, adding to relative sea-level (RSL) rise in the Beaufort-Mackenzie region. Additional sources of subsidence in the Mackenzie Delta include long-term sediment loading and sediment compaction, as well as thaw subsidence where thermal changes such as deeper seasonal thaw lead to melting of excess ground ice. Compaction is reduced in ice-bonded sediments and the thickness of ice bonding varies with the depth of permafrost, which ranges from 0 to 100 m in the main body of the Holocene delta and >500 m in areas outside the main valley fill. Ice-bonding is reduced or absent in thaw taliks beneath deep lakes and channels. Differential subsidence rates may play a role in maintaining or expanding lake area on the delta plain and in promoting delta-front erosion. Beginning in 2001, we have established an Arctic network of continuous GPS (CGPS) stations, including CGPS co-located with tide gauges at Tuktoyaktuk and Ulukhaktok. Fixed monuments for episodic GPS observations have been established and occupied repeatedly in the Mackenzie Delta and we are currently developing a network of fixed reflectors for persistent-scatterer InSAR. Velocities from the North American Reference Frame Working Group (consistent with rates from JPL and SOPAC) indicate positive values (uplift) at all CGPS stations, even in the Beaufort-Mackenzie region. However, the long-term tide-gauge record at Tuktoyaktuk shows a 45-year rising RSL trend (1961-2006) of +3.5±1.3 mm/a. If sea-level rise in the Beaufort Sea has been comparable to the global mean trend during this interval, the implied motion at Tuktoyaktuk is about -1.7±1.8 mm/a (subsidence). Preliminary GPS results from the Mackenzie Delta indicate natural subsidence ranging from 0 to 20 mm/a. These results are being used in the environmental review of proposed natural gas production and transportation facilities. Impacts of natural and potential induced subsidence on nesting waterfowl habitat are being assessed by simulating effects on flooding frequency using high-resolution digital elevation models derived from scanning airborne laser altimetry (LiDAR).
DE: 0475 Permafrost, cryosphere, and high-latitude processes (0702, 0716)
DE: 1211 Non-tectonic deformation
DE: 1225 Global change from geodesy (1222, 1622, 1630, 1641, 1645, 4556)
DE: 1641 Sea level change (1222, 1225, 4556)
DE: 1821 Floods
SC: Geodesy [G]
MN: 2007 Fall Meeting