Arey Lagoon and Island, situated on the Beaufort Sea coast just west of Barter Island and within the Arctic National Wildlife Refuge (ANWR), was selected as a focus site for an in-depth study of coastal processes on a regional to local scale. Arey Lagoon and adjacent areas encompass a barrier island chain, a glacially fed river and delta (Hulahula and Ogpilak Rivers) from the Brooks Range watershed, low-lying tundra with coastal wet sedge, and thermokarst lakes that all may be vulnerable to the effects of changing storm patterns in response to climate change.
Analysis of historical maps and imagery showed that Arey Lagoon mainland coast, partially protected by Arey Island from the direct attack of ocean waves, was slightly erosional (average -0.8 0.3 m/yr, 1947-2009) and, with the exception of three areas, underwent relatively uniform rates of change along the entire coast. Shoreline change calculations showed a weakly significant increase in migration/erosion rates of Arey Island-east during the 1987-2009 time period compared to the 1947-2009 or 1947-1987 time periods. The increase in erosion rates noted for the latter years of available data is likely the result of increased storminess and longer open water season. NARR re-analysis data of sea-ice thickness indicated that the open water season (number of days with no shore-fast ice) has nearly doubled from approximately 80 days in the early 1980s to ~140 days during 2010 in the vicinity of Arey Lagoon. More importantly, fall re-freeze has been occurring later, coincident with higher probability of intense storm events; the onset of shorefast ice and end of the open water season was early to mid-October in the vicinity of the study site during the years of 2005-2010. Results from 5 different GCMs were used to estimate sea-ice extents and start and end of the open-water season for the projected time period of 2010-2100. The models suggest that the pace of increasing open water duration will slow towards the end this century, and that by the year 2100 the open water season will typically end by late November.
Spatial and time-varying wind and pressure fields from re-analysis products and GCMs were applied to a suite of numerical models to hindcast and project storm surge and wave conditions during the open-water season of years 1981 through 2100. Water level, wave, and current measurements - the first of their kind within the study site - were used to assess background conditions and evaluate model skill. Observations and model results indicate that longshore transport is from the east and that although storms from both northwest and northeast directions predominate, only storms from the northwest quadrant are of significance for coastal change at the study site.
Breaching and landward migration of Arey Island-east was evaluated with projected 21st century oceanographic conditions and sediment transport models. The model indicated that while breaching is likely to occur along select sections of the island, some sections will undergo accretion by both cross-shore and long-shore transport process. Landward migration of the barrier is projected to continue at least until the early part of 2030.
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