A NEW BEACH-DUNE CYCLE OF FOREDUNE EVOLUTION, GULF OF MEXICO, FLORIDA

This study examined the relationship between foredunes with a wide range of long-term erosion and accretion rates and exposure to different wave and wind energy. The purpose of this study was to quantitatively increase our understanding of beach-dune interactions and enhance current conceptual models and develop a new model for Gulf County, Florida. Topographic and vegetation surveys were conducted on coastal foredunes in this relatively undeveloped region of the Florida panhandle. Historical profile surveys and aerial photography were utilized to help understand changes to these profiles. Foredune vegetation diversity increased with foredune height, and in Gulf County, the tallest foredunes were found on shorelines with low erosion rates, and therefore allowed time for mature species development. These established foredunes’ greatest sediment source was from antecedent foredunes which were developed when the spit was initially prograding beyond these sites. Rapidly prograding locations had marked differences in vegetation and those were the locations where multiple new foredune ridges were forming, with sediment derived from the prograding beach, and can be anticipated to be a precursor to larger foredunes. Evidence from Gulf County demonstrates that incorporation of event synchronization, vegetation, and the antecedent geology are crucial additions to current beach-dune models. A new quantitatively supported conceptual model of foredune evolution is presented for Gulf County, with potential implications for universal beach-dune models.