This refers to the construction of seawalls, jetties, offshore breakwaters and groins intended to hold shorelines in place. Although it is well understood by scientists that armoring beaches destroys beaches on a decadal time scale, this fact is still widely unrecognized by the general public or ignored by coastal developers and engineers. The demand for armoring will become even more widespread as the rate of sea-level rise and shoreline retreat increases. A few political entities (North Carolina, USA, North Sea Coast of Holland) have outlawed armoring (with moderate success) and more should be urged to do so. There are large numbers of salesmen with “unique” types of seawalls and groins (Holmberg Device) that need to be refuted.
Definitions of Shoreline Armoring Terms
- The addition of sand to a beach allowing it to widen and build out seaward.
- Groin is a structure built perpendicular to the shoreline usually of rock or metal designed to trap sand that moves in the long shore current
- Hardened beach structures
- A general term referring to groins, jetties, offshore breakwaters, sea walls, tombolos, or any other engineered
- A jetty is a hardened structure built at an inlet usually made of rock or metal designed to keep navigation channels from filling in with sediment
- Longshore drift
- Long shore drift carries sand and sediment parallel to the shore and serves as the sand source for many beaches. On the east coast of the US, the long shore current is from the north to the south.
- Offshore breakwaters
- An engineered structure placed offshore and parallel to the beach. Breakwaters mimic sandbars to cause waves to break, lessening erosion on the beach behind the breakwater, but interrupting the longshore drift.
- Shoreline armoring
- The use of groins, jetties, offshore breakwaters, sea walls, tombolos or other hardened beach structures on the shore
- Sea wall
- A sea wall is designed to protect the land from erosion particularly during storms and usually made of metal, wood, or rock. One of the most famous seawalls is the Galveston seawall in Galveston, TX built after the 1900 hurricane killed 6,000 people on the island.
- Tombolos are a special type of groin built perpendicular to the shore to trap sand, but with an end parallel to the shore designed to reduce wave energy.
Surfing in / Shoreline Armoring
Battling the beach erosion in places like Greenbackville, Va is nothing short of team effort. The Chincoteague Bay Field Station (CBFS) has been working to fight erosion using living shorelines, and now the Environmental Protection Agency (EPA) has stepped in to help them out with a $91,000 grant.
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Experimental removable seawalls have been ordered to be taken down in front of erosion-imperiled condos and houses.
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As sea levels rise along U.S. coasts, it may soon get easier for people and local governments to obtain federal permits to build what are known as “living shorelines,” natural or nature-based structures designed to protect communities and infrastructure from extreme storms and flooding even as they protect habitat.
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As Louisiana’s wetlands continue to disappear at an alarming rate, a new study has pinpointed the human-made structures that disrupt the natural water flow and threaten these important ecosystems. The findings have important implications for New Orleans and other coastal cities that rely on coastal wetlands to serve as buffer from destructive extreme weather events.
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Natural and undeveloped beaches should not be armored or modified with “nourishment,” as the sand-sharing system moves deposits from dune to beach in storms and back again. Normally following storms, beach sands are gradually returned to reform dunes.
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For centuries, large bulkheads have been used to help control erosion along coastlines. More recent research suggests that a natural approach may be a better alternative. Having nature on your side, especially during a storm or hurricane, is proven to provide better protection from coastal erosion.
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Decisions about terminal groins are being made in towns throughout the southern N.C. coast after the N.C. General Assembly in 2011 repealed a nearly 30-year-old ban on hardened beach erosion control structures. Legislators changed the law in 2015 to allow for up to six terminal groins.
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Impacts associated with shoreline armoring can scale up to have cumulative, large-scale effects on the characteristics of shorelines and the diversity of life they support, new research shows.
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More than 14,000 miles – 14 percent of continental U.S. coastline — has been armored with hardened structures. Hardened structures cause elevated rates of erosion on the shoreward side of the structure.
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