A tetrapod is a form of wave-dissipating concrete block used to prevent

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

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 cloud cover, cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmo ...

and

longshore drift Longshore drift from longshore current is a geological process that consists of the transportation of sediments (clay, silt, pebbles, sand, shingle, shells) along a coast parallel to the shoreline, which is dependent on the angle of incoming w ...

, 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, conservation, ...

s and

breakwaters A breakwater is a permanent structure constructed at a coastal area to protect against tides, currents, waves, and storm surges. Breakwaters have been built since antiquity to protect anchorages, helping isolate vessels from marine hazards ...

. Tetrapods are made of

concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...

, and use a

tetrahedral In geometry, a tetrahedron (: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular Face (geometry), faces, six straight Edge (geometry), edges, and four vertex (geometry), vertices. The tet ...

shape to

dissipate In thermodynamics, dissipation is the result of an irreversible process that affects a thermodynamic system. In a dissipative process, energy ( internal, bulk flow kinetic, or system potential) transforms from an initial form to a final form, wh ...

the force of incoming waves by allowing water to flow around rather than against them, and to reduce displacement by

interlock An interlock is a feature that makes the state of two mechanisms or functions mutually dependent. It may consist of any electrical or mechanical devices, or systems. In most applications, an interlock is used to help prevent any damage to the mac ...

ing.

Invention

Tetrapods were originally developed in 1950 by Pierre Danel and Paul Anglès d'Auriac of Laboratoire Dauphinois d'Hydraulique (now Artelia) in

Grenoble Grenoble ( ; ; or ; or ) is the Prefectures in France, prefecture and List of communes in France with over 20,000 inhabitants, largest city of the Isère Departments of France, department in the Auvergne-Rhône-Alpes Regions of France, region ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

, who received a

patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an sufficiency of disclosure, enabling discl ...

for the design. The French invention was named , derived from

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

and , a reference to the

shape. Tetrapods were first used at the

thermal power station A thermal power station, also known as a thermal power plant, is a type of power station in which the heat energy generated from various fuel sources (e.g., coal, natural gas, nuclear fuel, etc.) is converted to electrical energy. The heat ...

in Roches Noires in

Casablanca Casablanca (, ) is the largest city in Morocco and the country's economic and business centre. Located on the Atlantic Ocean, Atlantic coast of the Chaouia (Morocco), Chaouia plain in the central-western part of Morocco, the city has a populatio ...

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

, to protect the

sea water Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximate ...

intake.

Adoption

Tetrapods have become popular across the world, particularly in

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

; 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 most commonly refers to: * Okinawa Prefecture, Japan's southernmost prefecture * Okinawa Island, the largest island of Okinawa Prefecture * Okinawa Islands, an island group including Okinawa itself * Okinawa (city), the second largest city in th ...

, 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.

Invention

Adoption

Similar designs

See also

References

Further reading