Comparison of the spatiotemporal variability of dredge material at two inletadjacent beaches

This study analyzed two different inlet management strategies being utilized in Palm Beach County and compared how the downdrift beaches were affected by those strategies throughout the year. Cross-sectional beach profiles, Digital Elevation Model comparisons, and subaerial volumetric change were analyzed for patterns in postplacement beach morphology. Trends in cross- and alongshore grainsize were also analyzed. In Boca Raton the inlet was dredged multiple times a month depending on the level of infilling and the material was placed on the beach immediately downdrift of the inlet. The downdrift beach of the Boca Raton inlet underwent a cycle of shoreline advance in the summer and shoreline retreat in the winter. It was dominated by seasonal processes and its morphologic change was the direct result of shifts in the wind and waves without having a beach more than 60 to 80 meters over the course of the study. In Jupiter, the inlet was dredged on a near annual basis and the material was placed 600m south of the inlet. The size and scope of the larger one-time annual nourishment project resulted in beach widths upwards of 120 meters. The equilibration process that followed in both the cross- and alongshore are what dominated the morphological trends experienced at the site. The results of this study should help coastal managers without current inlet management strategies, compare and overview two different successful inlet management options. For future studies, researchers should extend the monitoring period and extend profiles to the depth of closure to capture. Sediment is a valuable resource, and it’s important for best management practices to maximize benefits and protect downdrift beaches for long-term resiliency of coastal communities.