Oyster Bed Multibeam & Sidescan Sonar Surveys
Geodynamics was contracted to conduct high-resolution hydrographic surveys of the seafloor at four proposed oyster sanctuary sites in the Pamlico Sound, NC. Prior to the placement of any oyster reef material at each proposed site, each location was surveyed to determine the presence or absence of existing structure, identify potential submerged cultural sites, and to delineate Submerged Aquatic Vegetation (SAV). To ensure the appropriate placement of reef making material, Geodynamics also collected the water depths at each site and identified the bottom substrate.
Both multibeam and sidescan sonar data were collected in order to accurately assess the seafloor of ~3,000 acres of proposed oyster sanctuary with depths ranging from 6ft to 20ft. Multibeam data was collected using a Kongsberg EM3002-D dual-head system in accordance with USACE standards for navigation and dredging requirements to provide accurate seafloor elevations. Sidescan data was collected using an Edgetech 4200-HD towfish. Although there are no available NOAA tide zone files available for this area, a separation model was acquired from NOAA to accurately transform the ellipsoid heights to Chart Datum MLLW. To appropriately use this separation model, the Applanix POS-MV data was post-processed in POSPac to incorporate GPS tides; the health and status of the NC CORS network for the nearest basestations were monitored daily.