EVALUATION OF LOCAL OFFSHORE SEDIMENTS FOR COASTAL RESTORATION PROJECTS IN PALM BEACH COUNTY, FL, USA

Open-coast beach-dune environments are vulnerable to erosion, such as from storms or interruption of littoral drift. Although protected from event-driven wave energy, backbarrier shorelines are also susceptible to erosion, due to tidal currents and boat wakes. A common response to mitigate erosion is to place sediment and restore the environment. For placement on beaches, a significant effort has been made to identify offshore resources available; however, offshore resources have seldom been considered for dune or backbarrier shoreline restoration. This study evaluates the geotechnical sediment properties of offshore sediments in proven borrow areas for beach nourishment and reclassifies them for placement in dunes and along the backbarrier in Palm Beach County, Florida. Two different methods calculate volume of offshore resources available for dune or backbarrier projects, including numerical calculations and interpolation of volume through SURFER. Because existing proven borrow areas are delineated for beach nourishment, less volume of sediment available in these areas for other coastal environments. The results of this study suggest that identifying offshore sediment sources for lower-energy environments would not adversely impact sediment needed for beach nourishment. As coastal environments are increasingly threatened by climate change and sea level rise, sediment resources become scarcer, the need to efficiently and effectively use sediments will be of utmost importance for scientists, engineers, and managers in their efforts to protect coastal habitat and communities.