Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
Coastal Erosion Along the Alaskan Beaufort Sea Coast and Regional Estimates of Carbon Yields
Torre Jorgenson1, Jerry Brown2
1ABR, Inc., PO Box 80410, Fairbanks, AK, 99708, USA, Phone 907-455-6777, Fax 907-455-6781, tjorgenson@abrinc.com
2International Permafrost Association, Woods Hole, MA, 02543, USA, jerrybrown@igc.org
The Arctic Coastal Dynamics program has established a methodology for estimating organic and sediment fluxes from coastal erosion of the circumarctic seas. Rapid erosion of ice-rich permafrost is a major contributor to these fluxes. A regional classification of shoreline segments along the Alaskan Beaufort Sea Coast was developed as the basis for regional quantification of coastal morphology, lithology, and sediment characteristics.
We delineated 48 segments along the coast using the 1:250,000-scale World Vector Shoreline that totaled 1957 km of mainland coast and 1334 km of spits and islands. We differentiated the mainland coasts into five broad classes, exposed bluffs (12 segments, 313 km), bays and inlets (6 segments, 235 km), lagoons with barrier islands (13 segments, 546 km), tapped basins (3 segments, 171 km) and deltas (14 segments, 691 km). Sediments of most segments are silts and sands, and uncommonly gravel. Bank heights generally are 2–4 m high for most erosional areas and <1 m in depositional areas such as deltas. Mean annual erosion rates (MAER) by coastline type varied from 0.7 m/yr (maximum 10.4 m/yr at Elson Lagoon) for lagoons to 2.4 m/yr for segments along exposed bluffs (maximum 16.7 m/yr at Cape Halkett North Coast).
When considering dominant soil texture, MAER was much higher in silty soils (3.2/yr) than in sandy (1.2 m/yr) to gravelly (-0.3 m/yr) soils. Soil organic carbon stocks along eroding shorelines (excluding deltas) are estimated to range from 50 to 159 kg C/m2 of bank surface down to the water line. When accounting for segregated and wedge ice, the mean annual carbon flux for eroding shorelines (1265 km in 34 segments) is highly variable, ranging from 16 to 818 Mg (metric tons) C/km of shoreline. We assume carbon flux away from deltas is negligible because they are mainly depositional environments. Across the entire Alaskan Beaufort Sea coast, mean annual carbon input from eroding shorelines is estimated to be 149 Mg C/km of shoreline and total 1.7_105 Mg C/yr. Mean annual mineral input from eroding shorelines (deltas excluded) is estimated to be 2743 Mg/km of shoreline and total 3.1_106 Mg/yr.
Abstract Categories: Coastal Processes
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