The impact of Hurricane Sandy on the shoreface and inner shelf of Fire Island, New York : large bedform migration but limited erosion
Goff, John A.
Flood, Roger D.
Austin, James A.
Schwab, William C.
Browne, Cassandra M.
Denny, Jane F.
Baldwin, Wayne E.
MetadataShow full item record
We investigate the impact of superstorm Sandy on the lower shoreface and inner shelf offshore the barrier island system of Fire Island, NY using before-and-after surveys involving swath bathymetry, backscatter and CHIRP acoustic reflection data. As sea level rises over the long term, the shoreface and inner shelf are eroded as barrier islands migrate landward; large storms like Sandy are thought to be a primary driver of this largely evolutionary process. The “before” data were collected in 2011 by the U.S. Geological Survey as part of a long-term investigation of the Fire Island barrier system. The “after” data were collected in January, 2013, ~two months after the storm. Surprisingly, no widespread erosional event was observed. Rather, the primary impact of Sandy on the shoreface and inner shelf was to force migration of major bedforms (sand ridges and sorted bedforms) 10’s of meters WSW alongshore, decreasing in migration distance with increasing water depth. Although greater in rate, this migratory behavior is no different than observations made over the 15-year span prior to the 2011 survey. Stratigraphic observations of buried, offshore-thinning fluvial channels indicate that long-term erosion of older sediments is focused in water depths ranging from the base of the shoreface (~13-16 m) to ~21 m on the inner shelf, which is coincident with the range of depth over which sand ridges and sorted bedforms migrated in response to Sandy. We hypothesize that bedform migration regulates erosion over these water depths and controls the formation of a widely observed transgressive ravinement; focusing erosion of older material occurs at the base of the stoss (upcurrent) flank of the bedforms. Secondary storm impacts include the formation of ephemeral hummocky bedforms and the deposition of a mud event layer.
© The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution.. The definitive version was published in Continental Shelf Research 98 (2015): 13-25, doi:10.1016/j.csr.2015.03.001.
The following license files are associated with this item:
Showing items related by title, author, creator and subject.
Inner-shelf circulation and sediment dynamics on a series of shoreface-connected ridges offshore of Fire Island, NY Warner, John C.; List, Jeffrey H.; Schwab, William C.; Voulgaris, George; Armstrong, Brandy; Marshall, Nicole (Springer, 2014-10-24)Locations along the inner-continental shelf offshore of Fire Island, NY, are characterized by a series of shoreface-connected ridges (SFCRs). These sand ridges have approximate dimensions of 10 km in length, 3 km spacing, ...
Predicting seabed burial of cylinders by wave-induced scour : application to the sandy inner shelf off Florida and Massachusetts Trembanis, Arthur C.; Friedrichs, Carl T.; Richardson, Michael D.; Traykovski, Peter A.; Howd, Peter A.; Elmore, Paul A.; Wever, Thomas F. (IEEE, 2007-01)A simple parameterized model for wave-induced burial of mine-like cylinders as a function of grain-size, time-varying, wave orbital velocity and mine diameter was implemented and assessed against results from inert ...
Geologic framework of the northern North Carolina, USA inner continental shelf and its influence on coastal evolution Thieler, E. Robert; Foster, David S.; Himmelstoss, Emily A.; Mallinson, David J. (Elsevier, 2013-11-20)The inner continental shelf off the northern Outer Banks of North Carolina was mapped using sidescan sonar, interferometric swath bathymetry, and high-resolution chirp and boomer subbottom profiling systems. We use this ...