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Complexities in barrier island response to sea level rise : insights from numerical model experiments, North Carolina Outer Banks

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dc.contributor.author Moore, Laura J.
dc.contributor.author List, Jeffrey H.
dc.contributor.author Williams, S. Jeffress
dc.contributor.author Stolper, David
dc.date.accessioned 2010-09-02T13:49:14Z
dc.date.available 2011-01-09T09:22:38Z
dc.date.issued 2010-07-09
dc.identifier.citation Journal of Geophysical Research 115 (2010): F03004 en_US
dc.identifier.uri http://hdl.handle.net/1912/3897
dc.description Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 115 (2010): F03004, doi:10.1029/2009JF001299. en_US
dc.description.abstract Using a morphological-behavior model to conduct sensitivity experiments, we investigate the sea level rise response of a complex coastal environment to changes in a variety of factors. Experiments reveal that substrate composition, followed in rank order by substrate slope, sea level rise rate, and sediment supply rate, are the most important factors in determining barrier island response to sea level rise. We find that geomorphic threshold crossing, defined as a change in state (e.g., from landward migrating to drowning) that is irreversible over decadal to millennial time scales, is most likely to occur in muddy coastal systems where the combination of substrate composition, depth-dependent limitations on shoreface response rates, and substrate erodibility may prevent sand from being liberated rapidly enough, or in sufficient quantity, to maintain a subaerial barrier. Analyses indicate that factors affecting sediment availability such as low substrate sand proportions and high sediment loss rates cause a barrier to migrate landward along a trajectory having a lower slope than average barrier island slope, thereby defining an “effective” barrier island slope. Other factors being equal, such barriers will tend to be smaller and associated with a more deeply incised shoreface, thereby requiring less migration per sea level rise increment to liberate sufficient sand to maintain subaerial exposure than larger, less incised barriers. As a result, the evolution of larger/less incised barriers is more likely to be limited by shoreface erosion rates or substrate erodibility making them more prone to disintegration related to increasing sea level rise rates than smaller/more incised barriers. Thus, the small/deeply incised North Carolina barriers are likely to persist in the near term (although their long-term fate is less certain because of the low substrate slopes that will soon be encountered). In aggregate, results point to the importance of system history (e.g., previous slopes, sediment budgets, etc.) in determining migration trajectories and therefore how a barrier island will respond to sea level rise. Although simple analytical calculations may predict barrier response in simplified coastal environments (e.g., constant slope, constant sea level rise rate, etc.), our model experiments demonstrate that morphological-behavior modeling is necessary to provide critical insights regarding changes that may occur in environments having complex geometries, especially when multiple parameters change simultaneously. en_US
dc.description.sponsorship This work was partially supported by the U.S. Geological Survey, Woods Hole Science Center and a sabbatical leave fellowship from Oberlin College to Laura Moore from the Mellon‐8 Consortium. en_US
dc.format.mimetype application/pdf
dc.language.iso en_US en_US
dc.publisher American Geophysical Union en_US
dc.relation.uri http://dx.doi.org/10.1029/2009JF001299
dc.subject Coastal processes en_US
dc.subject Landform evolution en_US
dc.subject Sea level change en_US
dc.title Complexities in barrier island response to sea level rise : insights from numerical model experiments, North Carolina Outer Banks en_US
dc.type Article en_US
dc.identifier.doi 10.1029/2009JF001299


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