Beach Nourishment Studies
As development of South Carolina’s coastline continues, erosion presents a major problem especially on our barrier islands which support valuable residential properties and a large portion of the state’s tourism industry. Beach nourishment, the placement of sand onto eroding beaches, provides protection for beachfront property and restores the recreational value of beaches, but its impact on coastal ecosystems remains a bit of a contentious point amongst researchersy. Our staff have monitored a number of beach nourishment projects since 1990 and are currently monitoring the progress of projects on Folly Beach, Hilton Head and Kiawah Island. As an example, the “Study to Evaluate the Effects of Beach Nourishment at Folly Beach” began in May 2005 and is nearing completion. Prior to construction, ERS staff sampled the bottom-dwelling communities living within the sediments both at the offshore sand borrow areas (where dredging equipment collects sand) and on the intertidal beach (where the sand is deposited). Borrow area sampling focused on characterizing the condition and composition of the entire bottom-dwelling invertebrate community, whereas the beach surveys are confined to ghost crabs and ghost shrimp. These efforts established a baseline for monitoring the recovery process within the two habitats. Additional sampling was conducted in 2006 to evaluate the impacts and recovery rates of this project.
Ocean Disposal Area Studies
An essential practice to construct and maintain navigational channels and ports is to remove and relocate sediments. Dredging and disposal of dredged sediments are among the most important activities affecting valuable wetlands, estuaries and associated fisheries along the coastal areas of the United States. Ocean disposal of dredged material is only permitted at Ocean Dredged Material Disposal Sites (ODMDS) which are designated by the US Environmental Protection Agency. There are several ODMDS’s along US coastlines designated to receive dredged materials from approved projects. Many of these areas are not closely monitored and remain largely unstudied in the effects they have on the surrounding seafloor. The ODMDS in Charleston, South Carolina, is a repository for uncontaminated sediments dredged from Charleston Harbor shipping and entrance channels. A monitoring program of the physical and biological condition of bottom habitats within and surrounding the Charleston ODMDS was completed after the conclusion of disposal activities associated with the 1999-2002 Charleston Harbor Deepening Project (Adobe PDF). The placement of disposal material into the Charleston ODMDS from the Charleston Harbor Deepening Project, and from ongoing maintenance dredging, has resulted in a number of physical and biological impacts to the areas surrounding the disposal zone, as well as anticipated impacts within the disposal area.
Additionally, to determine if migrating sediments were negatively affecting invertebrate and/or finfish communities at reef areas around the disposal area, a comprehensive study involving scientists from SCDNR, Coastal Carolina University, and the University of Georgia monitored three study sites and three reference sites proximal to the disposal area biannually from 2000-2005 (Adobe PDF). The results of this study suggest that surficial sediment depths and changes observed in grain size at sites do not appear to be related to movement of sediments from the disposal area. The trends observed in the hard bottom reef communities in the vicinity of the disposal site do not indicate that reef fishes or invertebrate communities have been negatively affected by disposal activities. However, this study started after disposal activities had already begun, and impacts might have happened before sampling. The Environmental Research Section will continue to be involved with activities to evaluate the effects of open water disposal of sediments, as the DNR has recommended some additional monitoring of the disposal site to evaluate longer-term impacts.
Adobe® Reader® is required to open the files and is available as a free download from the Adobe® Web site.