1 Dec 2022

Ship-Induced Waves at Tybee Island, Georgia

Abstract: Commercial vessels transiting the Savannah entrance channel intermittently generate large wake events at Tybee Island, Georgia, creating a potential hazard for beachgoers. However, not all commercial vessels generate large wakes, and the relationship between vessel dimensions, operating conditions, wake height, and drawdown magnitude is unclear. This study evaluates bathymetric data, high-frequency wave and vessel wake measurements, and broadcast vessel identification over a 4-month period with the goal of providing a quantitative characterization of vessel wake conditions at Tybee Island. Data from 1,386 cargo vessel passages and 202 tanker passages indicate that vessel dimensions (length and beam) are positively correlated with drawdown magnitude and secondary wake height, although large vessels do not consistently generate large wakes. Container ships, which tended to travel faster than tankers, corresponded to the largest wakes in the dataset. A further hypothesis is that tidally modulated energy dissipation may favor smaller vessel wake uprush at low tide and larger uprush at high tide, but this idea cannot be confirmed without additional measurements to quantify nonlinear wave propagation on the beach face. Based on the collected data, the study concludes with four recommendations for reducing risk to beachgoers.

27 Apr 2020

PUBLICATION NOTICE: Benefits of Engineered Habitats to Seasonal Bird Communities on the Savannah Harbor Navigation Project, Dredged Material Containment Areas, 1994-2012

Abstract: This report presents the results of a long-term habitat and trend analyses of bird community data from a monitoring effort conducted on five Dredged Material Containment Areas (DMCAs) from 1994 to 2012. The USACE Savannah District developed and implemented a Long-Term Management Strategy (LTMS) for the DMCAs in 1996 to mitigate lost wetland habitat due to maintenance operations in the Savannah Harbor, and to provide habitat for the floral and faunal communities that otherwise would be available if not for the urban and economic development of the area. Bimonthly surveys were conducted from 1994 to 2012 to assess the effectiveness of the LTMS to provide seasonal habitat for the bird community. Archived quarterly satellite imagery was collected and analyzed from 2001 to 2011 to assess year-round seasonal habitat availability. All bird community data collected were fitted to a negative binomial (mean abundance) or Poisson distribution (mean species richness) and used to assess trends for 180 individual species and 12 species groups for spring, summer, fall, and winter seasons from 1994 to 2012. Results indicate that the Savannah DMCAs support stable to increasing populations of most species and species groups during each season, including many species ranked as regional priority species.

14 Apr 2020

PUBLICATION NOTICE: Update to: Use of Engineering With Nature® Concepts on the Savannah Harbor Navigation Project, Dredged Material Containment Areas, Savanna, GA

 NOTE: A new PDF for this report was uploaded on 2/20/2020 to correct an error that was in the previous version. The link to the report on Knowledge Core will still remain the same. If you have downloaded a version of the report prior to now please replace it with the new version now available.Link: http://dx.doi.org/10.21079/11681/35353  Report

3 Feb 2020

PUBLICATION NOTICE: Use of Engineering With Nature® Concepts on the Savannah Harbor Navigation Project, Dredged Material Containment Areas, Savanna, GA

 Link: http://dx.doi.org/10.21079/11681/35353 Report Number: ERDC/TN EWN-20-1Title: Use of Engineering With Nature® Concepts on the Savannah Harbor Navigation Project, Dredged Material Containment Areas, Savanna, GA By Michael P. Guilfoyle, J. Stevan Calver, Mary E. Richards, and Richard A. Fischer Approved for Public Release; Distribution is