State of the Beach/State Reports/SC/Beach Erosion
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2% of South Carolina's shoreline is critically eroding, according to the report "State Coastal Program Effectiveness in Protecting Natural Beaches, Dunes, Bluffs, and Rock Shores" (T. Bernd-Cohen and M. Gordon), Coastal Management, 27:187-217, 1999.
Following passage of the 1988 Beachfront Management Act, the Coastal Council established a beach-monitoring program at approximately 400 survey benchmarks along the coast. Each benchmark, a metal disk set in concrete, has a known vertical elevation which is used as the starting point for the beach survey. In addition, the horizontal coordinates of each benchmark have been established, so the benchmark can be replaced in the same location if it is ever destroyed. The information from this beach-monitoring program was used to delineate the position of the baseline, set at either the actual dune crest for natural beaches or the theoretical dune crest for armored beaches. With grant support from the US Geological Survey, this monitoring program collects beach profiles at all stations twice a year to a depth of -5 feet, as a surveyor wades into chest-deep water at low tide. In addition, offshore profiles to a depth of -20 feet are collected annually at selected stations, using a submersible survey rig towed by a boat.
As called for under the Beachfront Management Act, all beaches in the state have been classified as standard zones or inlet zones. Inlet zones are regions in close proximity to a tidal inlet, where the presence of the inlet plays a dominant role in erosion or accretion patterns on the beach. Most inlet zones are un-stabilized, meaning the inlet channel is not anchored by jetties or groins, and the surrounding shoreline is often quite dynamic.
South Carolina's annual State of the Beaches reports (not Surfrider's report) summarize changes to South Carolina's beaches within the past year. The reports contain individual summaries for each island or beach in the state. Summaries are presented in a south-to-north progression, from Daufuskie Island to Waites Island. The geographic setting of each beach is discussed, along with any significant long-term trends. A typical beach profile plot is provided, with a location map showing survey monument locations. The 2009 report represents a technological and graphical presentation advance from previous reports, with color graphs of beach profiles, color aerial photographs and benchmark location maps. Unfortunately, these reports have not been produced since 2009.
The surveys are used to help draw construction setback lines along the coast. New lines must be calculated every decade under the state's Beachfront Management Act. The most recent re-draw occurred in 2008-2010.
The 2009 State of the Beaches Report (covering the year 2008) contains the following summary:
The year 2008 had few named tropical systems with any great influence on the coast of South Carolina. In mid-July Bertha brought some larger than normal swell, and then in August and September two tropical storms crossed into South Carolina and a low pressure cell that developed off the coast. Wind speed information was obtained from the SC Climatology Office, and additional information can be obtained from their South Carolina 2008 Weather in Review report. (Here are their 2009, 2010, 2011, 2012 and 2013 reports).
On August 20th, Tropical Storm Fay affected the southern and central coasts with 39 mph gusts that caused breaking wave heights of 6-8 feet and moderate erosion at Hunting Island and Edisto Beach. On September 5th and 6th, Tropical Storm Hanna crossed into the Little River area, producing wind speeds of 53 mph and some erosion along the Grand Strand’s beaches. On September 25th, a low-pressure cell moved onshore with gusts of 46 mph measured at the Myrtle Beach Airport.
Two renourishment projects were conducted in South Carolina in 2008. The Isle of Palms project placed 885,000 cubic yards of sand dredged from an offshore sand source along 2.6 miles of beach, while the Grand Strand project, constructed in three phases, placed 2.9 million cubic yards of sand dredged from an offshore source along 26 miles of shoreline in North Myrtle Beach, Myrtle Beach, Surfside Beach, and Garden City.
In general the inlet zones, those beaches closest to unstabilized tidal inlets, are the most dynamic beaches and may experience the greatest shoreline erosion or accretion. Other sections of beach away from tidal inlets can still experience chronic beach erosion. Regardless of its designation as an inlet zone or standard zone, any section of beach with a sand deficit and a minimal beach width should be considered vulnerable to storm damage, since the dunes and dry-sand beach provide a buffer between the ocean and high-ground development. At present, the beaches most vulnerable to erosion, with sand deficits and a minimal dry-sand beach width at high tide, are listed from south to north as follows:
- Hunting Island – Several cabins on the southwestern end of the island were lost to erosion during 2007 and 2008, and others cabins remain threatened.
- Harbor Island – Chronic erosion in portions of the northeastern end of the island has resulted in ocean water coming up under several houses at high tide.
- Sullivans Island – Similar to Harbor Island, chronic erosion at the northeastern end of the island, near Breach Inlet, has also resulted in ocean water coming up under several houses at high tide.
- Pawleys Island – Many houses on the southern end of the island, near Pawleys Inlet, have minimal protection. The parking area, which provides most of the public beach access in Georgetown County, is in jeopardy.
A newspaper article discussing the 2009 State of the Beaches Report can be found here.
The South Carolina Beachfront Jurisdiction web application was developed to enable efficient access to key information by coastal stakeholders and decision-makers. Users of the application can quickly navigate to specific beaches or properties, view state jurisdictional line locations and adopted long-term erosion rates. Technical users of the site may also download beachfront survey information packets, which contain jurisdictional line coordinates, adopted long-term erosion rates and survey monument locations.
Coastal Carolina University's Online Profile Management system provides the coastal community with information critical to understanding temporal and spatial variability in coastal systems. Tools are available for logging into the system; loading, viewing, analyzing, and managing regional profile data; creating new benchmarks; and exporting the data into comma-delimited or RMAP files. The program has collected approximately 500 beach profiles on public beaches throughout the state of South Carolina for over a decade, providing an invaluable data set to analyze beach and nearshore change. Profiles are available from Daufuskie Island at the SC/GA border to Waites Island at the SC/NC border. The profile data is used by OCRM to write the annual State of the Beaches Report for the state of South Carolina. Data collection methods have advanced from a theodolite and cart with a 30’ boom to a Real-Time Kinematic (RTK) GPS system with motion compensation instrumentation and a single beam fathometer for nearshore surveys. Support has been provided by the S.C. Office of Coastal Resources Management (OCRM), S.C. Sea Grant, U.S. Army Corps of Engineers, U.S. Geological Survey, Coastal Carolina University, and local towns and municipalities. The profiles are available at gis.coastal.edu in an on-line profile management database directed by M. Scott Harris (CCU) with support provided by the Army Corps of Engineers, OCRM, SC Sea Grant, USGS and Coastal Carolina University. The database features graphical representations of profiles over time, several methods to calculate volume change, mapping tools to locate profiles, and recent photographs at each profile where available.
The USGS Woods Hole Science Center is conducting a South Carolina Coastal Change project. Understanding the processes that control local sediment fluxes is critical in evaluating regional vulnerability to coastal erosion. The geologic framework component of the South Carolina Regional Coastal Erosion Study (SCCES) identified an elongated sediment shoal aligned obliquely to the coast offshore of Singleton Swash in North Myrtle Beach, South Carolina. The shoal is a Holocene marine deposit that consists of fine to medium, clean sand and represents a potential source for aggregate material needed for ongoing beach nourishment activities in the Myrtle Beach area. The influences that this feature may have on the along-shore distribution of wave power and local sediment transport are not clear due to a lack of observation data and numerical modeling of the region. Mining the shoal could disrupt important mechanisms controlling beach vulnerability to coastal erosion. This project task involves the analysis of observational data collected as part of the SCCES, and additional coastal process modeling for the Grand Strand region. Modeling based on the physical oceanographic observations will increase our understanding of the hydrodynamic and sediment transport processes responsible responsible for shaping the shoal and adjacent shoreline. Both the observational data and numerical models will be used to understand the circulation dynamics and to predict sediment transport patterns around the shoal and in the nearshore (surf zone).
South Carolina Sea Grant is another source of information on beach erosion and coastal hazards issues in South Carolina.
Morris Island has an average erosion rate of 30 ft/year and some sections of the beach experience erosion rates up to 50 feet/year. This extreme erosion is evident at the Morris Island Lighthouse. The shoreline has retreated 1600 feet inland past the lighthouse. The lighthouse stands partially submerged in the ocean. Here is a link to a brief history of the lighthouse with references to the erosion rate: http://www.savethelight.org/briefhistory.html
An article in the The Post and Courier in September 2012 discussed plans to rebuild Folly Beach County Park after huge waves from passing Hurricane Irene in August 2011 tore through the dunes and crossover boardwalks. Since then, surf erosion has progressively destroyed park features.
An article in The State in April 2012 discussed erosion in the area of Haig Point Lighthouse. In response, the local community hired Myrick Marine Contracting to place a quarter-mile-long revetment to bolster the beachfront against further erosion. At the same time, the firm will solidify 350 feet of shoreline along Beach Road. The private community will pay for the nearly $700,000 project with its reserves and contributions from homeowners.
Olsen Associates, a consulting firm hired by the Town of Hilton Head Island, conducted a survey of the island's beaches in October 2004. The survey showed that approximately 4 million cubic yards of sand placed on the beach during beach fill projects in 1990 and 1997 has ended up on the lower parts of the beach under the waterline. The dry beach width near the Port Royal beach house in Port Royal Plantation decreased from about 100 feet in April 2004 to 70 to 80 feet in October, presumably as a result of the 2004 hurricanes.
A article by Daniel Brownstein that appeared in islandpacket.com on February 16, 2009 discussed the disappearing sand at Port Royal Plantation. In 1996, sand at this location was accumulating so much that some homeowners wanted the town to remove sand. Now the ocean has reversed course and about 120,000 cubic yards of sand per year are disappearing. In 1999, the average low watermark was about 1,350 feet from the seaward edge of the private properties. By 2006, the distance was 750 feet. In early 2009 it was about 500 feet. In response, the Town Council in 2008 approved moving forward with an estimated $11.4 million plan to build a rock groin and fill the beach with at least 550,000 cubic yards of sand along a 2,000-foot strtch of beach. The project was tentatively scheduled for 2011, although a funding source had yet to be secured.
During the past 25 years, erosion has claimed about 1,200 acres from four primary barrier islands in the Cape Romain National Wildlife Refuge nature north of Charleston, according to statistics provided in late 2013 by the Fish and Wildlife Service. Those include Bulls Island, the refuge’s signature land formation. Islands in the 66,000-acre Cape Romain refuge provide important nesting habitat for loggerhead sea turtles, federally protected reptiles that deposit their eggs in sand dunes for protection. But many of the dunes are washing away.
Erosion monitoring stations were installed in 2004 at Folly Beach and off Springmaid Pier in Myrtle Beach by the University of South Carolina. This work, funded by federal grants, is being done as part of the SouthEast Atlantic Coastal Ocean Observing System. The collected data will help the Department of Health and Environmental Control's office of Ocean and Coastal Resource Management better understand ocean currents and the associated movement of offshore sand.
An WMBF news report in July 2015 stated:
Coastal Carolina University researchers calculate about 200,000 cubic yards of sand were lost when Tropical Storm Ana hit in North Myrtle Beach. Most of the sand was lost in Cherry Grove. Beach renourishment projects involve construction, bringing in sand to replenish the shoreline. The federal projects are done every 10 years for the entire Grand Strand region. With the tide sweeping in and out and nature taking its course, beachfront disappears and erodes into the ocean, especially at high tide. You're hard pressed to find a spot on the sand that doesn't get overtaken by waves. As you can imagine, this is a problem if you're trying to go to the beach. The last renourishment was in 2008, so there are a few more years until the next project starts. In the meantime, North Myrtle Beach has had to go so far as bulldozing from one place to another to move sand around, which is very costly and entirely at the expense of the local government, but also necessary considering the alternative.
The Coastal and Marine Geology Program of the U.S. Geological Survey has generated a comprehensive database of digital vector shorelines and shoreline change rates for the U.S. Southeast Atlantic Coast (Florida, Georgia, South Carolina, North Carolina). These data were compiled as part of the U.S. Geological Survey's National Assessment of Shoreline Change Project.
South Carolina has not assessed the impact of sea level rise on coastal communities and critical habitats such as coastal wetlands. An analysis of South Carolina beachfront and estuarine shorelines is necessary to determine the risk level.
DHEC-OCRM has several ongoing initiatives to improve data acquisition and planning for coastal hazards. These include:
- Information on coastal hazards will be collected as part of NOAA performance measure tracking efforts.
- DHEC-OCRM is acquiring a comprehensive data set for the Critical Area that will include tidal creeks, stormwater ponds, docks, bridges, piers, and marsh vegetation. These data will be acquired from high-resolution aerial photography obtained by both the DNR and DHEC-OCRM, and can be used for improved assessments of shoreline change.
The Heinz Center's Evaluation of Erosion Hazards report mentioned below notes that many beach and dune impacts—as well as costs—were experienced after Hurricane Hugo in 1989. The storm caused serious beach and dune erosion along 65 miles of South Carolina's coast. As a result of the beach flattening, the beach widened to nearly 500 feet in some locations, more than twice its normal width. With such a flat profile and lack of dunes, many properties that were not destroyed by Hugo were considered at high risk after the storm. This situation provided the impetus for an emergency beach and dune restoration program to provide immediate protection for threatened inland properties and, eventually, efforts to restore the recreational beach.
Following Hugo, South Carolina and the federal government joined in a beach and dune system restoration that had three phases: beach scraping and dune shaping, beach fill, and dune re-vegetation. This effort cost $9.8 million, comparable to the cost of all South Carolina beach fill projects combined between 1980 and 1988 (Kana, 1990). The state covered approximately 60% of these costs, with the federal government (Federal Emergency Management Agency, U.S. Army Corps of Engineers, and taxpayers nationally) picking up the rest. The return on investment is likely to be high. By comparison, the annual benefits of coastal tourism in South Carolina are estimated at $5 billion annually (Kana, 1990), and beaches are one of the principal attractions.
A number of lessons can be learned from South Carolina's experience with beach and dune erosion and subsequent restoration. Some of these relate to beach processes. Major storms such as Hugo are rare, but they intensify or accelerate normal processes, causing permanent coastal changes. However, much of the erosion observed after storms reflects a temporary shift of sand to offshore bars. Most of that sand will likely return to the beaches, although some may be lost permanently, either down-drift or offshore. With respect to shoreline development, one of the lessons from Hugo (as well as chronic, less powerful storms) is that judicious construction setbacks, elevation of buildings above expected storm surge heights, and soft stabilization can protect inland property while preserving options for beach and dune protection and post-storm restoration (Kana, 1990). The Heinz Report states that average erosion rates are 2-3 ft/year in Georgetown, SC.
The Heinz Center's Evaluation of Erosion Hazards, conducted for the Federal Emergency Management Agency (FEMA), studied the causes of coastal erosion hazards and proposed a variety of national and regional responses. The study, published in April 2000, concentrates on the economic impacts of erosion response policies as well as the cost of erosion itself to homeowners, businesses, and governmental entities.
A NOAA website that has graphs of sea level data for many coastal locations around the country over the last 40 to 50 years and projections into the future is Sea Levels Online.
NOAA Shoreline Website is a comprehensive guide to national shoreline data and terms and is the first site to allow vector shoreline data from NOAA and other federal agencies to be conveniently accessed and compared in one place. Supporting context is also included via frequently asked questions, common uses of shoreline data, shoreline terms, and references. Many NOAA branches and offices have a stake in developing shoreline data, but this is the first-ever NOAA Website to provide access to all NOAA shorelines, plus data from other federal agencies. The site is a culmination of efforts of NOAA and several offices within NOS (including NOAA’s Coastal Services Center, National Geodetic Survey, Office of Coast Survey, Special Projects Office, and Office of Ocean and Coastal Resource Management) and other federal agencies to provide coastal resource managers with accurate and useful shoreline data.
A related site launched in 2008 is NOAA Coastal Services Center's Digital Coast, which can be used to address timely coastal issues, including land use, coastal conservation, hazards, marine spatial planning, and climate change. One of the goals behind the creation of the Digital Coast was to unify groups that might not otherwise work together. This partnership network is building not only a website, but also a strong collaboration of coastal professionals intent on addressing coastal resource management needs. Website content is provided by numerous organizations, but all must meet the site’s quality and applicability standards. More recently, NOAA Coastal Services Center has developed a Sea Level Rise and Coastal Flooding Impacts Viewer as part of its Digital Coast website. Being able to visualize potential impacts from sea level rise is a powerful teaching and planning tool, and the Sea Level Rise Viewer brings this capability to coastal communities. A slider bar is used to show how various levels of sea level rise will impact coastal communities. Completed areas include Mississippi, Alabama, Texas, Florida, and Georgia, with additional coastal counties to be added in the near future. Visuals and the accompanying data and information cover sea level rise inundation, uncertainty, flood frequency, marsh impacts, and socioeconomics.
Erosion Contact Info
South Carolina Department of Health and Environmental Control
Ocean and Coastal Resource Management
1362 McMillan Ave, Suite 400
Charleston, SC 29405
(843) 744-5838 x120
South Carolina Department of Health and Environmental Control
Ocean and Coastal Resource Management
Dr. Scott Harris
Department of Geology and Environmental Geosciences
College of Charleston
Dr. Paul T. Gayes
Center for Marine and Wetland Studies
Coastal Carolina University
Coastal Carolina University
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