Inundation of a barrier island (Chandeleur Islands, Louisiana, USA) during a hurricane : observed water-level gradients and modeled seaward sand transport
Sherwood, Christopher R.
Long, Joseph W.
Dickhudt, Patrick J.
Dalyander, P. Soupy
Thompson, David M.
Plant, Nathaniel G.
MetadataShow full item record
Large geomorphic changes to barrier islands may occur during inundation, when storm surge exceeds island elevation. Inundation occurs episodically and under energetic conditions that make quantitative observations difficult. We measured water levels on both sides of a barrier island in the northern Chandeleur Islands during inundation by Hurricane Isaac. Wind patterns caused the water levels to slope from the bay side to the ocean side for much of the storm. Modeled geomorphic changes during the storm were very sensitive to the cross-island slopes imposed by water-level boundary conditions. Simulations with equal or landward sloping water levels produced the characteristic barrier island storm response of overwash deposits or displaced berms with smoother final topography. Simulations using the observed seaward sloping water levels produced cross-barrier channels and deposits of sand on the ocean side, consistent with poststorm observations. This sensitivity indicates that accurate water-level boundary conditions must be applied on both sides of a barrier to correctly represent the geomorphic response to inundation events. More broadly, the consequence of seaward transport is that it alters the relationship between storm intensity and volume of landward transport. Sand transported to the ocean side may move downdrift, or aid poststorm recovery by moving onto the beach face or closing recent breaches, but it does not contribute to island transgression or appear as an overwash deposit in the back-barrier stratigraphic record. The high vulnerability of the Chandeleur Islands allowed us to observe processes that are infrequent but may be important at other barrier islands.
Author Posting. © American Geophysical Union, 2014. 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: Earth Surface 119 (2014): 1498–1515, doi:10.1002/2013JF003069.
Showing items related by title, author, creator and subject.
Barrier island breach evolution : alongshore transport and bay-ocean pressure gradient interactions Safak, Ilgar; Warner, John C.; List, Jeffrey H. (John Wiley & Sons, 2016-12-16)Physical processes controlling repeated openings and closures of a barrier island breach between a bay and the open ocean are studied using aerial photographs and atmospheric and hydrodynamic observations. The breach site ...
Complexities in barrier island response to sea level rise : insights from numerical model experiments, North Carolina Outer Banks Moore, Laura J.; List, Jeffrey H.; Williams, S. Jeffress; Stolper, David (American Geophysical Union, 2010-07-09)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 ...
Hein, Christopher J.; FitzGerald, Duncan M.; Carruthers, Emily A.; Stone, Byron D.; Barnhardt, Walter A.; Gontz, Allen M. (2012-02-24)Details of the internal architecture and local geochronology of Plum Island, the longest barrier in the Gulf of Maine, has refined our understanding of barrier island formation in paraglacial settings. Ground-penetrating ...