29 Mar 2022

Evaluating Cross-Shore Sediment Grain Size Distribution, Sediment Transport, and Morphological Evolution of a Nearshore Berm at Fort Myers Beach, Florida

Abstract: Navigation channels are periodically dredged to maintain safe depths. Dredged sediment was historically placed in upland management areas or in offshore disposal areas. Florida state law prohibits placement of beach fill sediment that contains more than 10% by weight of silt and clay, which is typically a characteristic of dredged material. An alternative is placement in a nearshore berm. Some potential benefits of nearshore berms include wave energy dissipation, reduced cost of dredging and shore protection, and possible onshore movement of the berm material. This study considers sediment distribution, morphological evolution, sediment transport, and shoreline trends along Fort Myers Beach, Florida, related to the nearshore berm constructed in August 2016. Due to timing of the field study, this report also includes information on the influence of a major hurricane that impacted the area. The overall conclusion of this study is that the dredge-sourced sediment in the berm performed as expected. Within 2 years, the berm adjusted to the shoreface environment, maintained a large part of its original volume, and contributed to protection of the beach and shoreline. The impact of Hurricane Irma included a shift in sediment textures and a large but temporary increase in shoreface sediment volumes.