Numerical Methods for Nearshore-Berm Evaluation, St. Johns County, Florida.
Abstract
Stable and unstable nearshore berms are investigated as shore protection features for mitigation of coastal storm damage to upland properties and to reduce shoreline erosion Nearshore berm placement on existing beach profiles can initiate offshore wave breaking, decreasing wave energy at the shore and reducing storm impacts. Estimates of annual beach recession rates, project renourishment rates, and storm-related recession distance are required for economic evaluation of a nearshore berm project This information is site-specific and varies for different shoreline protection options. In support of the St Johns County Shore protection Project under the jurisdiction of U.S. Army Engineer District, Jacksonville, the U.S. Army Engineer Waterways Experiment Station developed methods for addressing storm-related recession and renourishment Predictions were made for the existing profile at St Johns County, Florida, and several engineered design templates for nearshore berm alternatives were superimposed on the existing profile. The study utilized climatic information and numerical models to predict relative storm-related recession and storm-related renourishment for the nearshore berm profiles. Results from this study indicate nearshore berms could provide significant shoreline protection from storm events. By initiating wave breaking on the berm, a less energetic wave re-forms in the lee, resulting in lower wave runup and reduced shoreline erosion. When compared to the without-berm profile, shoreline recession estimates decreased by as much as 70 m per event as the result of placing an engineered nearshore berm on the profile. Following with-project and without-project numerical simulations, recession estimates may be used as input for event frequency correlation and economic evaluation.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1998
- Accession Number
- ADA345034
Entities
People
- Cheruly E. Pollock
- Hans R. Moritz
- William R. Curtis