SPATIAL VARIABILITY OF SEDIMENT ON A NOURISHED AND NON-NOURISHED BEACH IN SOUTHEAST FLORIDA

Sediment placement on Florida’s beaches is a common strategy for increasing storm resilience, providing habitat, and supporting the tourist economy. Sediment borrow sites include inlets (typically for navigational maintenance), offshore, and upland mines. State regulations require that sediment closely match the native grain size distribution and composition. However, sediment characteristics can vary alongshore, cross-shore, and with depth. The objective of this study is to quantify sediment properties on a frequently nourished barrier island beach and an adjacent non-nourished beach located south of the Jupiter Inlet, in Palm Beach County, Florida. Six transects were sampled at the surface and at 75 cm depth at the dune toe, mid-beach, and mean high water line. Sediment samples were analyzed for Munsell color, bulk grain size distribution and statistics (using the Moment Method), percent carbonate, and non-carbonate grain size distribution and statistics. The mineralogy of both the bulk and non-carbonate fraction were evaluated with a standard binocular microscope. The 3D spatial variability of sediment characteristics on the nourished and non-nourished beach will be presented and discussed, including influence of inlet proximity and selective transport patterns. Results of this study should provide information on the spatiotemporal variability of sediment placed on beaches and help determine best management practices for coastal projects.