BEACH MORPHOLOGY AND SEDIMENTOLOGY IN NORTHERN PALM BEACH COUNTY, FLORIDA, USA: A BRIEF UPDATE

Coastal erosion of sandy beaches is a global problem that threatens ecosystems and coastal communities. Beach nourishment is one of the commonly implemented mitigation strategies, using beach compatible sediment from various borrow sources that is placed on beaches and back in the littoral system. However, the geotechnical properties of sediment from different borrow sources can vary. Sediment characteristics influence post-nourishment equilibration, beach slope, substrate temperatures for incubating sea turtles, and morphologic response to storms. Although many regulatory agencies have policies requiring that the borrow source sediment closely matches, or is compatible with, the native beach sediment, placement of sediment from various borrow sources could result in sediment properties that deviate from the native material over time due to selective transport processes. This study is a brief update on the results of Brown and Briggs (2020) on the sediment properties and beach morphology of nourished and non-nourished beaches in northern Palm Beach County, FL, USA. Nourished beaches using various borrow sources were similar in sedimentology and slope to non-nourished beaches. Foreshore slopes on local beaches were most similar to predicted slopes for protected beaches, likely due to reduced fetch from the Bahamian archipelago. The proximity to hard structures appears to have an important influence on foreshore slopes and sediment properties and requires further analysis.