Evolution of a North Slope barrier island (Narwhal Island, North Arctic Alaska) 1955- 2007
Abstract
In 1955, Narwhal island was a 4 km long and 30 to 200 m wide barrier island, located at 145 30' W; 70 24' N, about 20 km offshore of the North Slope coast by Foggy Island Bay and near Prudhoe Bay, Alaska. According to available aerial photography, by 1979, the island had been breached in 4 locations creating a five island chain. By 1984, the chain consisted of 3 pieces indicating a reformation process. In subsequent years, the chain appears to have gone through a couple more cycles of breakup and reformation. The island is subject to wind waves, sea-ice impacts, and storm surges. Preliminary GIS analysis and recent GPS surveys indicate that, in the past 50 years, the western end of the island had migrated about 200 m to the west consistent with the direction of sea-ice movement and consistent with the frequent east winds during the summer (open water) period. The rate of migration is consistent with the findings of earlier studies. In addition to the island's westward migration, the northern (seaward) side of the island has retreated landward by about 5 m/year during the past decade. Here, the details of the GIS and GPS work are described. In addition, a preliminary wave (SWAN) and sediment transport model is presented that explains the morphodynamic changes. Considering continued sea ice retreat consequent to global warming, we speculate about future morphodynamic changes.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFM.H34B..08R
- Keywords:
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- 1807 Climate impacts;
- 1815 Erosion;
- 1862 Sediment transport (4558);
- 4217 Coastal processes;
- 4534 Hydrodynamic modeling