HR: 0800h
AN: H41B-0498    [Abstracts]
TI: Influence of Beach Scraping on Beach Profile Morphology: Fire Island, New York
AU: * Kratzmann, M
EM: mkratzmann@mail.uri.edu
AF: University of Rhode Island, Department of Geosciences, Kingston, RI 02881, United States
AU: Hapke, C
EM: chapke@usgs.gov
AF: U.S. Geological Survey, Department of Geosciences University of Rhode Island, Kingston, RI 02881, United States
AB: Fire Island is part of a barrier island system located just south of Long Island, New York. The island is 50 km long, oriented southwest-northeast, and varies in width from 150 meters to 1 kilometer. Established communities on Fire Island are part of Fire Island National Seashore (FIIS) which is managed by the National Park Service. The island is densely populated, and thus mitigating coastal erosion caused by large-scale storm waves has become an important issue. Severe nor'easter storms in 1991, 1992, and 1993 caused substantial erosion and property damage. This prompted communities within FIIS to conduct a pilot study in which the preventative, non-structural practice of beach scraping was employed as a method of erosion control. Beach scraping is the anthropogenic movement of sand from the berm to the back beach creating an artificial foredune. Currently, there is no published research that explores the morphologic influence of beach scraping on Fire Island, although the practice is still in place today for a number of communities. This study assesses changes caused by beach scraping using a temporally robust beach profile dataset of over 150 profiles, spanning thirteen years. Three study areas were chosen based on location (western, central, and eastern parts of Fire Island) and data availability in scraped and adjacent control areas. Analyzed characteristics include beach width, beach volume, slope (dune, beachface, global), berm crest elevation, and dune crest elevation. Initial results indicate a detectable difference in the behavior of the beach between scraped and control areas. Seasonal signals show beach width decreasing substantially westward from the scraped profile location, which is in the direction of net littoral transport. Anthropogenic relocation of berm material to the foredune zone during scraping places sediment in the back beach area that might otherwise be mobilized by storm waves, therefore depriving downcoast beaches of sediment. Longer-term comparisons (decadal) indicate that the beach is both widening and increasing in volume in the western study area (by 30-50%), which corresponds spatially to a persistent accretional cell that has been identified in current studies along this section of Fire Island.
DE: 1815 Erosion
DE: 4217 Coastal processes
SC: Hydrology [H]
MN: 2007 Fall Meeting