Erosion and other Hazards
- What hazards can affect real estate along South Carolina's shorelines?
- What causes shoreline erosion?
- Do South Carolina's ocean beaches experience "long-term" erosion?
- As a buyer of coastal property, will I automatically be informed about erosion and erosion rates?
State Beachfront Jurisdiction
- What is the Beachfront Management Act?
- What is the State's Beachfront Jurisdiction?
- How often do the state jurisdictional lines change?
- How and where are jurisdictional lines drawn?
- How are erosion rates calculated?
- Will state beachfront jurisdictional lines affect my homeowners insurance?
- If I purchase undeveloped oceanfront property, where should I build on the lot?
- What can I build in the setback area?
- Can I build anything seaward of the baseline?
- Can I make additions to an existing beachfront house?
- Can I rebuild or repair my beachfront structure if it is damaged by a hurricane or other coastal storm?
- What does "Destroyed Beyond Repair" or "DBR" mean?
Protection from Erosion and Other Hazards
- What building construction features help reduce or prevent damage from natural events?
- If my oceanfront property becomes threatened by erosion, can I construct a seawall?
- If my oceanfront property becomes threatened by erosion, can I move my house away from the eroding shoreline?
- If my oceanfront property becomes threatened by erosion, can I construct sand dunes?
- If my oceanfront property becomes threatened by erosion, can I place sandbags in front of my home?
What unusual hazards can affect real estate along South Carolina's shorelines?
South Carolina's coastline is constantly changing due to a common coastal hazard- beach erosion. Coastal erosion can be long-term, chronic erosion from a variety of causes, or it may be short-term as the result of a single or series of storm events. In addition to erosion, beachfront homes may also be threatened by high wind and flooding generated by storm surge. And in South Carolina, there is even a threat of earthquakes- the last big one rocked the Charleston area in 1886 and registered 7.6 on the Richter Scale.( Top )
What causes shoreline erosion?
Hurricanes, nor'easters, and other storms cause seasonal fluctuations of the shoreline. Generally, beaches erode more in the stormy fall and winter months than in the calm summer months. Of course, when a beach is hit directly by a hurricane, beachfront erosion can be even more dramatic. Inlets are also affected by seasonal storms and can change configuration rapidly and severely as tremendous amounts of water and sand flow through them. In severe storms, it is even possible for new inlets to form and existing inlets to close. On sandy beaches, erosion associated with storms is often severe because large quantities of sand can be moved quickly offshore from the beach and dunes. This type of erosion is usually called "short-term" erosion because the shoreline may return to its original profile as conditions improve over time. Beaches need time to recover after a storm, so a series of storm events can lead to prolonged erosional conditions. Long-term, chronic erosion can also occur from a variety of causes including shoal bypassing events near inlets or a reduction of sand in the sand-sharing system.( Top )
Yes. Long-term erosion, often called "beach migration," is generally associated with rising sea levels, but can also be caused by a variety of other factors. Sea level in the Charleston area has risen nearly a foot during the last century, causing beaches to migrate landward.
Although this process can cause erosion along the entire oceanfront, areas adjacent to inlets are often the most profoundly affected. Some "migrating inlets" are constantly moving in one direction. Others may stay in the same general location but expand and contract constantly. These inlets are often called "oscillating inlets."
In addition to natural causes, erosion can be set in motion by human activities. For example, a jetty constructed to stabilize an inlet or a structure built to stabilize a beach can trap sand on one side but increase erosion on the other. Such erosion will continue until the structure is removed or adjusted or the beach is renourished.( Top )
As a buyer of coastal property, will I automatically be informed about erosion and erosion rates?
Not necessarily. Purchasers should always research coastal hazards, seeking information on pertinent laws and regulations from local government, DHEC OCRM and your realtor.
Erosion rates vary not only from municipality to municipality, but sometimes even from one stretch of beach to another part of that same beach. If you are working with a licensed real estate agent, the agent has a duty to disclose material facts that she or he knows or reasonably should know. Although real estate agents might not always know the erosion rates for particular oceanfront properties, they should advise you of the possibility of erosion and direct you to available sources of information. If a beachfront property is located, in whole or in part, seaward of the legislated jurisdictional setback line or baseline, a contract of sale or transfer of real property must contain a disclosure statement. The statement must indicate that the property is or could be affected by the legislated lines and the statement must include the local erosion rate most recently made available by DHEC for that zone. The setback line and baseline positions and adopted erosion rates statewide may be accessed through the SC Beachront Jurisdictional Lines Viewer.( Top )
The Coastal Tidelands and Wetlands Act of 1977 was enacted to protect our coastal resources and promote responsible development. This legislation served the beaches well during its first decade, but as South Carolina became a more popular tourist destination, it became apparent that the portion of the Act that dealt with beaches was inadequate. As development crept seaward, seawalls and rock revetments proliferated, damaging public beaches.
In many areas with seawalls and revetments, there was little or no beach left at high tide. In some areas, there was no beach at low tide, either. In 1988 and again in 1990, South Carolina's legislators took action to amend and strengthen the state's coastal regulations. The resulting Beachfront Management Act protects South Carolina's sandy shores by increasing the state's jurisdiction and encouraging soft solutions to erosion like beach renourishment.( Top )
What is the State's Beachfront Jurisdiction?
The higher the erosion rate, the farther landward the state's jurisdiction. To find the boundaries of this jurisdiction, staff from DHEC must first locate the baseline , which is typically the crest of the primary oceanfront sand dune in standard zones and stabilized inlet zones. Where there are no dunes, the agency uses scientific methods to determine where the natural dune would lie if natural or man-made occurrences had not interfered with nature's dune building process. In unstabilized inlet zones, the baseline is set at the most landward point of erosion in the last 40 years, as determined by analysis of historical aerial photographs. The setback line is the most landward boundary and is measured from the baseline based on long-term erosion rates. To find the distance between the baseline and setback line, the beach's annual erosion rate is calculated using the best available data and multiplied by 40. For example, if the erosion rate is one foot per year, the results will be a setback zone that stretches 40 feet from the baseline. The setback line is always located a minimum distance of 20 feet landward of the baseline. The setback line and baseline positions and adopted erosion rates statewide may be accessed through the SC Beachfront Jurisdictional Lines Viewer.
If any portion of your property falls seaward of the setback line, talk with DHEC OCRM’s Beachfront Permitting Project Manager before beginning construction. Failure to do so may result in a fine and/or the removal of the structure at the property owner's expense.
The Folly Beach Exception
Folly Beach in Charleston County is the only beach without a setback line. The Charleston Harbor jetties, a federal project built in the late 1800s, are a major contributing factor of erosion on Folly Beach. To compensate property owners for their loss, the General Assembly set Folly Beach's baseline along the beach's erosion control structures. There is no setback area on Folly Beach, thus the state's jurisdiction is seaward of the baseline, except in cases where the beaches critical area extends landward of the baseline.( Top)
DHEC is mandated by the Beachfront Management Act (48-39-280-C) to review the position of the beachfront baseline and 40-year setback line, the state's beachfront jurisdictional lines, every 7 to 10 years. The next line review cycle will begin no earlier than 2024.( Top )
State beachfront jurisdictional lines are determined depending on the classification of the beach zone:
Within a standard erosion zone (a segment of shoreline which is subject to essentially the same set of coastal processes, has a fairly constant range of profiles and sediment characteristics and is not directly influenced by tidal inlets or associated inlet shoals) the baseline is established at the location of the crest of the primary oceanfront sand dune in that zone. In a standard erosion zone in which the shoreline has been altered naturally or artificially by the construction of erosion control devices, groins, or other man-made alterations, the baselines must be established by DHEC using the best scientific and historical data, as where the crest of the primary ocean front sand dune for that zone would be located if the shoreline had not been altered.
Unstabilized Inlet Zones
Within an unstabilized inlet zone (inlets that have not been stabilized by jetties, terminal groins, or other structures) the baseline must be determined by DHEC as the most landward point of erosion at anytime during the past forty years, unless the best available scientific and historical data of the inlet and adjacent beaches indicate that the shoreline is unlikely to return to its former position. In collecting and utilizing the best scientific and historical data available for the implementation of the preservation policy, DHEC, among other factors, must consider: historical inlet migration, inlet stability, channel and ebb tidal delta changes, the effects of sediment bypassing on shorelines adjacent to the inlets, and the effects of nearby beach restoration project on inlet sediment budgets.
Stabilized Inlet Zones
Within a stabilized inlet zone (inlets which are stabilized by jetties, terminal groins, or other
structures) the baseline location must be determined in the same manner as provided for in a standard erosion zone. However the actual location of the crest of the primary oceanfront sand dune of that erosion zone is the baseline of that zone, not the location if the inlet had remained unstabilized.
A setback line must be established landward of the baseline a distance which is forty times the average annual erosion rate or not less than twenty feet from the baseline for each erosion zone based upon the best historical and scientific data (48-39-280).( Top )
Long-term erosion rates are determined by analyzing historical shoreline positions and calculating annual erosion rates based on beach survey data. Each year, DHEC monitors over 400 survey monuments on state beaches.( Top )
Will state jurisdictional lines directly affect my homeowners insurance?
No. State beachfront jurisdictional lines only affect what can be built or rebuilt seaward of the baseline and within the setback area.( Top )
Building location is influenced by the setback line, which is established by using a mathematical formula based on the 40-year erosion rate in that area. Seaward of the setback line, new habitable structures must be built as far landward as possible and are limited to a maximum of 5,000 square feet of heated space. Special permits must be obtained to build seaward of the baseline. Among other requirements, the structure (usually a house) must be built as far landward as possible and have no impact on the primary sand dune or active beach area. If the beach erodes and the permitted structure becomes situated on the active beach, the property owner, at his or her own expense, must remove the structure if so ordered by DHEC OCRM.
The Federal Emergency Management Agency (FEMA) provides additional information on where to site residential structures on coastal property in their Coastal Construction Manual (FEMA 55 - 6/2000). A copy of the publication can be requested by contacting FEMA at 1-800-480-2520. ( Top )
The setback area is not a no-build area. If you have an existing home located in the setback area, regardless of size, you can keep your existing home. If your home receives impacts and is damaged beyond repair you can rebuild your home up to the total square footage of the original structure. New homes may be built up to 5,000 square feet of heated space within the setback area.
Within the setback area, you can keep an existing pool. If your pool is damaged or destroyed, it can be rebuilt to pre-existing dimensions with DHEC OCRM authorization. New or reconstructed pools are not permitted, unless they are located landward of an existing functional erosion control structure, such as a seawall or revetment and receive prior written approval from DHEC OCRM. To help fully understand the allowable structures and necessary authorizations for building within the beachfront jurisdiction, please contact DHEC OCRM for assistance. ( Top)
If your home is partially or fully seaward of the baseline, you can keep your existing home. If your home receives impacts, but is Not Damaged Beyond Repair and is not located on the active beach, it can be repaired with a special permit to its pre-existing square and linear footage. If your home is Damaged Beyond Repair and is not located on the active beach, it can be rebuilt with a special permit up to the heated square footage size of other similar homes in the neighborhood.
Seaward of the baseline, if you have an existing pool, you can keep it. If your pool is Damaged Beyond Repair, it can be rebuilt if it is landward of an existing functional erosion control structure; however, no new pools can be permitted seaward of the baseline. To help fully understand the allowable structures and necessary authorizations for building within the beachfront jurisdiction, please contact DHEC OCRM for assistance. ( Top )
Can I make additions to an existing beachfront house?
Additions located entirely or partially in the setback area are allowed, provided that the addition and the existing structure together do not exceed 5,000 square feet of heated space. The additions, including decks, must also be located no farther seaward than the existing structure. The linear footage of the structure, parallel to the coast, cannot be increased. Additions made totally landward of the setback area do not require any notice to DHEC OCRM. Additionally, you must contact your local floodplain administrator and building permit official for local floodplain management regulations and code requirements. Also keep in mind that if the cost of modifying a structure, because of damage or otherwise, exceeds 50% of the value of the structure, the entire structure must be brought up to current code requirements. ( Top )
Yes. A habitable structure that has been destroyed beyond repair due to a natural cause and that is wholly or partially in the setback area may be replaced or rebuilt provided all of the following requirements are met:
- The total square footage of the replaced structure seaward of the setback line does not exceed the total footage of the original structure seaward of the baseline;
- The linear footage of the replaced structure parallel to the coast does not exceed the original linear footage parallel to the coast;
- The replacement structure is no farther seaward than the original structure;
- Where possible, the replaced structure is moved landward of the setback line or if not possible, then as far landward as practicable, considering local zoning and parking regulations;
- Meets the requirements for new construction as defined in the local community's flood damage prevention ordinance.
Remember, if the cost of modifying or repairing a structure exceeds 50% of the value of the structure, the entire structure must be brought up to current code requirements. ( Top )
For habitable structures, destroyed beyond repair means more than sixty-six and two-thirds percent of the replacement value of the habitable structure has been destroyed. See R.30-14(D)(3)(a) for more information.
For pools, destroyed beyond repair means more than sixty-six and two-thirds percent of the replacement value of the pool has been destroyed. See R.30-14(D)(3)(b) for more information.
For seawalls, bulkheads and revetments damage must be judged on the percentage of the structure remaining intact at the time of the damage assessment. Destroyed beyond repair means more than fifty percent above grade has been destroyed. See R.30-14(D)(3)(c) for more information. ( Top )
What building construction features help reduce or prevent damage from natural events?
Several features can prevent or substantially reduce the likelihood of damage from severe storms, erosion, or earthquakes. Pilings raise the first floor above expected flood elevations and waves. In many areas, embedding the tip of pilings deeper than ten feet below sea level can help a building stand during severe erosion. Any first floor walls constructed between pilings should be designed to break away when hit by waves to prevent damage to the elevated portion of the building.
Elevating a building to protect it from storm surge and flood increases its exposure to storm winds. The key to reducing storm wind damage lies in the quality of the building's design and construction. If you are building a new home on the beach, consider employing the services of a professional engineer to help ensure an adequate structural design. If you are buying an existing home, a professional engineer can help you assess the structure's strengths and weaknesses, as well as suggest structural and non-structural modifications which may help make the house more damage resistant.
Modifications may include:
- adding "hurricane clips" to improve the roof's ability to withstand uplift forces of high winds
- installing storm window protection to protect window and door openings from wind-driven rain and debris
- replacing asphalt roof shingles
- reinforcing gable end roofs
- reinforcing the attachment of plywood roof decking to roof rafters with additional nails, screws or adhesives
- reinforcing the attachments of porches and decks to a house's main structure
Remember, however, no home is disaster-proof. There are inherent and unavoidable dangers associated with building homes along the beach. Because of the substantial cost of coastal property, a professional engineering analysis could be a wise investment.
Note: Sand dunes are natural features that also provide significant protection during the most severe storms. You can protect and enhance frontal dunes by keeping vehicles and people off them, planting additional dune grasses, and installing sand fences. Keep in mind, however, that dunes protect against short-term erosion caused by very severe, infrequent storms but offer little protection from long-term erosion.
FEMA's Coastal Construction Manual (FEMA 55 - 6/2000) provides guidance for the design and construction of coastal residential buildings that will be more resistant to the damaging effects of natural hazards. A copy of the publication can be requested by contacting FEMA at 1-800-480-2520. (Top )
If my oceanfront property becomes threatened by erosion can I construct a seawall?
No. Erosion control structures represent the greatest threat to the preservation of the beach. On an erosional beach, seawalls and rock revetments may actually accelerate erosion, effectively destroying the beach. South Carolina applies a strict regulatory position where these structures are concerned. No new erosion control structures are allowed seaward of the setback line. Functional erosion control structures may not be enlarged, strengthened or rebuilt, but may be maintained in their present condition. If destroyed, the structure must be removed at the owner's expense. ( Top )
If my oceanfront property becomes threatened by erosion, can I move my house away from the eroding shoreline?
Yes. House-moving is an allowable and generally a cost-effective means of getting a structure out of harm's way. If space allows, a structure may be moved landward on the same lot; otherwise, it can be relocated to new property. Regardless of where the building is moved, it must meet any existing setback requirements. ( Top )
If my oceanfront property becomes threatened by erosion, can I construct sand dunes?
Yes. Sand dunes provide some of the best protection against high tides and minor storms. DHEC OCRM's " How to Build A Dune " is a helpful guide for creating and preserving sand dunes. Contact DHEC OCRM to inquire about permitting requirements for constructing sand dunes on your property. ( Top )
If my oceanfront property becomes threatened by erosion, can I place sandbags in front of my home?
Maybe. If an emergency situation is caused by a significant storm event, such as a named tropical storm or hurricane, and a building is severely threatened by beach erosion with erosion within 20 feet of the structure, then DHEC or the local government may issue an emergency order allowing sand scraping, minor beach renourishment, or the temporary use of sandbags to provide protection. ( Top )