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
A year ago the hurricane winds of Storm Xynthia drove the sea over much of the Charente-Maritime and Vendée coastline to devastating effect. Many people lost their lives. France’s Government has set up a new coastal defence plan costing €500 million over six years.
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Bangladesh’s coastal area covers about 20% of the country and over thirty percent of the net cultivable area. The saline sea waters have been pushing up inland and progressively more and more areas are meeting a similar fate.
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The next winter storm is threatening to wash away beach-side homes in Montauk. Concerned residents, however, are not blaming Mother Nature, but rather jetties built by the Army Corps of Engineers about 20 years ago.
The debate about terminal groins, shore-perpendicular structures built at inlets in attempt to slow erosion, is worth keeping an eye on, whether you live in western North Carolina or in a coastal community, because it could cost you and our state a pretty penny.
In Québec, shoreline erosion primarily affects the estuarine regions and the Gulf of St-Lawrence that extends from Québec city to the Magdalen Islands.
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$2 million were spent building a sea wall in an attempt to try to stop beach erosion.
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For Ghana, the real story of coastal erosion is not about what lies at the water’s edge, but what occurs beneath the waves offshore. In the capital city of Accra, an estimated 70 percent of the beach is eroding at rates exceeding 3 feet per year.
The seas around the islands in the Bay of Bengal that support a unique mangrove ecosystem, are rising faster than anywhere else on Earth, and the lives and livelihoods of more than 4 million residents are under threat from rising waters.
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Such costly reef have proved successful in other areas, and it could be the only option to protect the coastline of Old Bar, Australia.
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