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Below is a false color image of the southern extent of Folly Island, where the colors on the image represent the data values — in this case, elevation. The term "false color" simply means that the image is not a photograph, and that you should use the color bar on the image to interpret what the colors mean. On the land-ward side of the island, tidal creeks are visible. There is a light blue sand bar just off shore. Looking towards the center of the island, structures, displayed in red, begin to become apparent to the viewer. You can make a similar image using the BeachMapper software application provided on the second volume of this CD-ROM set. For more information about the BeachMapper Application, click here.
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Portable Document Format (PDF) maps have been created to show LIDAR data for South Carolina's beaches and islands. PDF maps will allow you to zoom in on the data and print the maps at better resolution. However, because of the intense density of the data, the PDF files will not draw properly from your browser. If you have Adobe Acrobat Reader® software installed on your computer, you can view the maps by navigating to the pdf/islands directory on this CD-ROM and double click on a file. A directory of maps is available in the readme.txt file. Adobe Acrobat Reader software has been provided on this CD-ROM.
To learn more about PDF documents and installing the software need to view them, click here.
In Charleston County, Stono and Lighthouse Inlets bound Folly Island to the west and east. One of Charleston’s oldest beach communities, the island has a long history of rapid erosion exacerbated by construction of the Charleston Harbor jetties in the 1890s. The 3-mile long rock jetties block the southerly drift of beach sand carried by longshore currents. Sand that would naturally move on to the beachfront is trapped on the updrift side of the north jetty. Today, nearly all of Folly’s shoreline is armored and contains groin fields. Due to the impact of the federal navigation project, Folly Island is excluded from part of the Beachfront Management Act. Under the exemption, seawalls on the island may be rebuilt if destroyed.
Prior to 1993, chronic sand loss left the beach eroded to the point that there was no visible beach at high tide. In 1989 Hurricane Hugo destroyed or heavily damaged oceanfront houses, along with their protective revetments and seawalls. Storm surge greater than 12 feet above sea level carried and deposited sand over 250 feet inland. Several years of negotiation preceded the 1993 U.S. Army Corps of Engineers renourishment project. As a result, 85% of the $15.3 million renourishment effort was federally funded. 2.5 million cubic yards (cy) of sand were hydraulically pumped from the Folly River behind the southern end of the island and spread over a 5.3 mile stretch of shoreline. Since the 1993 renourishment the upper beach has lost a significant amount of sand. In particular, the county park located at the west end of Folly has eroded drastically and plans for renourishment are underway.
Beach profile surveys are conducted in the spring and fall at approximately 400 monitoring stations throughout the State of South Carolina. Various agencies participate in the beach profile collection, including The South Carolina Department of Health and Environmental Control (SCDHEC) Office of Ocean and Coastal Resource Management (OCRM), Coastal Carolina University, and the College of Charleston. The results of the surveys provide a snapshot of the beach face. Over time, these surveys can be compiled to determine if and how the profile of the beach is changing. Below is a map of the stations and a sample of the profiles that can be extracted from the data. The beach profile data compiled by OCRM is provided on the second volume of this CD-ROM set.
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| *South Carolina Department of
Health and Environmental Control Office of Ocean and Coastal Resource Management |
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For more information about South Carolina beach profiles see: South
Carolina's Annual State of the Beaches Report, April 1998,
SCDHEC OCRM, 1362 McMillian Ave. Suite 400, Charleston, SC 29405.
| Beach | Folly Island |
| Construction Dates | January - May 1993 |
| Completion Date | 5/1993 |
| Volume of Sand (cy) | 2,500,000 cy |
| Unit Area Volume(cy/ft) | 88.6 cy/ft |
| Source of Sediment | Folly River (shoal #4)to rear of Charleston County Park; hydraulic pipeline dredge w/ booster plant |
| Grain Size Characteristics Native Sediment/Fill | Native=0.12 mm - 0.21 mm Borrow=0.10 mm - 0.28 mm (both well sorted) |
| Previous Nourishments | 1979 construction of Folly River navigation project; material from shoal 4 ~305,562 cy - 325,000 cy spoiled on west end of Folly |
| Length of project (Coverage) | 28,200 ft (5.34 miles) |
| % Sacrificial Fill | (1.15cy/1cy) 13% |
| Total Cost | $12.52 M |
| Cost of Components | $9.893 M -Fill and groins $1.78 M -Engineering and design |
| Cost per Unit ($/cy) | $5.00/cy |
| Funding | $1.88M State, through City of Folly Beach (15%) $10.64M Federal (85%) |
| Significant Storms | Northeaster, March 13, 1993 ("The Storm of the Century") |
| Storm Results | Storm occurred during the construction of the project; visual checks indicate that considerable sand was lost |
| Action Taken | Additional sand was applied to the project so that at completion 2.5M cy were placed on the beach |
| Monitoring | U.S. Army Corps of Engineers during project; Coastal Carolina University |
| Engineer and Contractor | U.S. Army Corps of Engineers / T.L. James |
| Projected/Actual Lifespan | 8 years; designed for 5 year frequency storm event/N/D |
| Historic Erosion Rates | 1854-1977: -9 ft/yr. -east end; -15 ft/yr. west end; 57% attributed to federal navigation project |
| Beach Stabilization Structures | Between 1949-1970 48 groins installed; almost entire shoreline is armored; 9 groins restored in project |
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