Improving Habitat Classification, Hazard Mitigation and Navigation in Coastal Georgia with a State-of-the-Art Bathymetric Sonar System

The bathymetry, or underwater depth, throughout a coastal region is a critical dataset that impacts many facets of coastal environmental and hazard management. Without a knowledge of depth, the US Army Corps of engineers cannot accurately model hurricane storm inundation, coastal fisheries biologists cannot effectively identify and manage essential fish habitat as required by the Magnuson-Stevens Act, and boaters cannot safely transit our state's recreational waters. The need for managers to identify and manage essential fish habitat is particularly critical and almost impossible to do without the sort of site-specific data that will be provided by this study. This importance has manifested itself in a government-funded series of mapping campaigns that have produced bathymetric data for coastal regions throughout the United States. The last time the bathymetry of coastal Georgia was mapped comprehensively was in the 1930s.These old datasets for most of the sounds in Georgia have been converted to digital datasets. Given the energetic physical environment and anthropogenic activities over the past 80 years, it is unreasonable to assume that any of the bathymetric data for the Georgia coast, outside of that for the Brunswick and Savannah harbors, is reasonably accurate.

This project focused on addressing this critical need for up-to-date bathymetry in coastal Georgia by taking a state-of-the-art, Edgetech 4600 bathymetric sonar system recently acquired by the Skidaway Institute of Oceanography for use on the 90' RV Savannah, and developing its use in estuaries and sounds. One of the advantages to this system is that it collects both bathymetry and sidescan (bottom roughness and character) data simultaneously. Together, these datasources are a powerful combination for evaluating benthic habitats. The goals of this project were to successfully deploy the system from the RV Jack Blanton, a 28' research vessel owned by Skidaway Institute, by constructing an appropriate sonar mount for the vessel and to use it to collect a comprehensive bathymetric dataset for Wassaw Sound as a proof-of-concept for the technique which can be applied to other estuaries and sounds to update bathymetry in coming years.