A Tetrapod is a form of
wave-dissipating concrete block
A wave-dissipating concrete block is a naturally or manually interlocking concrete structure designed and employed to minimize the effects of wave action upon shores and shoreline structures, such as quays and jettys.
Examples include such propr ...
used to prevent
erosion caused by
weather
Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmosphere, the t ...
and
longshore drift, primarily to enforce coastal structures such as
seawall
A seawall (or sea wall) is a form of coastal defense constructed where the sea, and associated coastal processes, impact directly upon the landforms of the coast. The purpose of a seawall is to protect areas of human habitation, conservatio ...
s and
breakwaters
A breakwater is a permanent structure constructed at a coastal area to protect against tides, currents, waves, and storm surges. Part of a coastal management system, breakwaters are installed to minimize erosion, and to protect anchorages, h ...
. Tetrapods are made of
concrete, and use a
tetrahedral
In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the ...
shape to
dissipate the force of incoming waves by allowing water to flow around rather than against them, and to reduce displacement by
interlocking.
Invention
Tetrapods were originally developed in 1950 by Pierre Danel and Paul Anglès d'Auriac of Laboratoire Dauphinois d'Hydraulique (now
Artelia
Artelia is a French design firm specializing in engineering, project management, and consultancy. Launched in 2010, Artelia is active building construction, water, energy, environment, industry, maritime operations, transportation, urban develo ...
) in
Grenoble,
France, who received a
patent for the design. The name was derived from
Greek, with ''tetra''- meaning four and -''pode'' meaning
foot
The foot ( : feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made ...
, a reference to the
tetrahedral
In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the ...
shape. Tetrapods were first used at the
thermal power station in
Roches Noires in
Casablanca
Casablanca, also known in Arabic as Dar al-Bayda ( ar, الدَّار الْبَيْضَاء, al-Dār al-Bayḍāʾ, ; ber, ⴹⴹⴰⵕⵍⴱⵉⴹⴰ, ḍḍaṛlbiḍa, : "White House") is the largest city in Morocco and the country's econom ...
,
Morocco, to protect the
sea water intake.
Adoption
Tetrapods have become popular across the world, particularly in
Japan; it is estimated that nearly 50 percent of Japan's coastline has been covered or somehow altered by tetrapods and other forms of concrete. Their proliferation on the island of
Okinawa, a popular vacation destination in Japan, has made it difficult for tourists to find unaltered beaches and shoreline, especially in the southern half of the island.
Similar designs
The tetrapod inspired many similar concrete structures for use in breakwaters, including the Modified Cube (United States, 1959), the
Stabit (
United Kingdom, 1961), the
Akmon (
The Netherlands, 1962), the
Dolos
A dolos (plural: dolosse) is a wave-dissipating concrete block used in great numbers as a form of coastal management. It is a type of tetrapod. Weighing up to , dolosse are used to build revetments for protection against the erosive force of ...
(
South Africa, 1963), the
Stabilopod (
Romania, 1969),
the Seabee (
Australia, 1978), the
Accropode
Accropode blocks are wave-dissipating concrete blocks designed to resist the action of waves on breakwaters and coastal structures.
History
The Accropode is a single-layer artificial armour unit developed by Sogreah in 1981. Accropode concret ...
(France, 1981), the Hollow Cube (
Germany, 1991), the
A-jack (United States, 1998), and the
Xbloc (The Netherlands, 2001), among others. In Japan, the word ''tetrapod'' is often used as a generic name for wave-dissipating blocks including other types and shapes.
See also
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References
Further reading
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{{coastal management
Coastal engineering
Wave-dissipating concrete blocks