Meredith G. Kratzmann

Quantifying Anthropogenically Driven Morphologic Changes on a Barrier Island: Fire Island National Seashore, New York

Abstract KRATZMANN, M.G. and HAPKE, C.J., 2012. Quantifying anthropogenically driven morphologic changes on a barrier island: Fire Island National Seashore, New York. Beach scraping, beach replenishment, and the presence of moderate development have altered the morphology of the dune–beach system at Fire Island National Seashore, located on a barrier island on the south coast of Long Island, New York. Seventeen communities are interspersed with sections of natural, nonmodified land within the park boundary. Beach width, dune elevation change, volume change, and shoreline change were calculated from light detection and ranging (LIDAR), real-time kinematic global positioning system (RTK GPS), and beach profile data sets at two ∼4 km long study sites. Each site contains both modified (developed, replenished, and/or scraped) and nonmodified (natural) areas. The analysis spans 9 years, from 1998 to 2007, which encompasses both scraping and replenishment events at Fire Island. The objectives of this study were to quantify and compare morphological changes in modified and nonmodified zones, and to identify erosional areas within the study sites. Areas of increased volume and shoreline accretion were observed at both sites and at the western site are consistent with sand replenishment activities. The results indicate that from 1998 to 2007 locations backed by development and that employed beach scraping and/or replenishment as erosion control measures experienced more loss of volume, width, and dune elevation as compared with adjacent nonmodified areas. A detailed analysis of one specific modification, beach scraping, shows distinct morphological differences in scraped areas relative to nonscraped areas of the beach. In general, scraped areas where there is development on the dunes showed decreases in all measured parameters and are more likely to experience overwash during storm events. Furthermore, the rapid mobilization of material from the anthropogenic (scraped) dune results in increased beach accretion downcoast. National park lands are immediately adjacent to developed areas on Fire Island, and even relatively small human-induced modifications can affect park resources and beach–dune response to storms. This study is the first to conduct a systematic analysis on how anthropogenic modifications affect resources at Fire Island National Seashore and provides essential information for effective management and preservation of coastal resources within the park.

National Assessment of Shoreline Change: A GIS compilation of Updated Vector Shorelines and Associated Shoreline Change Data for the Southeast Atlantic Coast

Sandy ocean beaches in the United States are popular tourist and recreational destinations and constitute some of the most valuable real estate in the country. The boundary between land and water along the coastline is often the location of concentrated residential and commercial development and is frequently exposed to a range of natural hazards, which include flooding, storm effects, and coastal erosion. In response, the U.S. Geological Survey (USGS) is conducting a national assessment of coastal change hazards. One component of this research effort, the National Assessment of Shoreline Change Project, documents changes in shoreline position as a proxy for coastal change. Shoreline position is an easily understood feature representing the historical location of a beach position through time. This report is an update to the original Southeast Atlantic (Morton and Miller, 2005) assessment and includes revised rate-of-change calculations based on additional shoreline position data, improved rate metrics, and application of a proxy-datum bias correction that quantifies potential bias and errors associated with integrating shorelines referenced to different proxies. To be consistent with previous work, the Southeast Atlantic study areas were organized by state for analysis.