A tetrapod is a form of wave-dissipating concrete block used to prevent erosion caused by weather and longshore drift, primarily to enforce coastal structures such as seawalls and breakwaters. Tetrapods are made of concrete, and use a tetrahedral shape to dissipate the force of incoming waves by allowing water to flow around rather than against them, and to reduce displacement by interlocking.
Tetrapods were originally developed in 1950 by Pierre Danel and Paul Anglès d'Auriac of Laboratoire Dauphinois d'Hydraulique (now Artelia) in Grenoble, France, who received a patent for the design. The name was derived from Greek, with tetra- meaning four and -pode meaning foot, a reference to the tetrahedral shape. Tetrapods were first used at the thermal power station in Roches Noires in Casablanca, Morocco, to protect the sea water intake.
Tetrapods have become popular across the world, particularly in Japan; it is estimated that nearly 50 percent of Japan's 35,000 kilometers (22,000 mi) 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.
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 (South Africa, 1963), the Stabilopod (Romania, 1969), the Seabee (Australia, 1978), the Accropode (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.
- Artificial reef – Human-made underwater structure that functions as a reef
- Breakwater (structure) – Structure constructed on coasts as part of coastal management or to protect an anchorage
- Coastal management – Preventing flooding and erosion of shorelines
- Coastal erosion – Displacement of land along the coastline
- Ocean surface wave – Surface waves generated by wind on open water
- Riprap – Rock or concrete protective armour
- Seawall – Form of coastal defence
- Xbloc – Concrete breakwater element
- KOLOS – Concrete breakwater element
- Dolos – Concrete breakwater element
- Accropode – Concrete breakwater element
- ^ "What are Tetrapods? (Tetrapods Resist Wave Impact and Prevent Beach Erosion)". Brighthub Engineering. Retrieved 2017-08-02.
- ^ Park, Sang Kil; et al. (2014). "Effects of vertical wall and tetrapod weights on wave overtopping in rubble mound breakwaters under irregular wave conditions" (PDF). Retrieved 2 August 2014.
- ^ Pierre Danel and Paul Anglès d'Auriac (1963) Improvements in or relating to artificial blocks for building structures exposed to the action of moving water 
- ^ Danel, Pierre (1953). "TETRAPODS". Coastal Engineering Proceedings. 1 (4): 28. doi:10.9753/icce.v4.28. ISSN 2156-1028.
- ^ Danel, Pierre (1967). "The Tetrapod". Retrieved 2 August 2017.
- ^ a b Hesse, Stephen (2007-07-22). "TETRAPODS". The Japan Times Online. ISSN 0447-5763. Retrieved 2017-08-02.
- ^ Spătaru, A (1990). "Breakwaters for the Protection of Romanian Beaches". Coastal Engineering. Elsevier Science Publishers. 14 (2): 129–146. doi:10.1016/0378-3839(90)90014-N.
- Lagasse, P.F. (2007). Countermeasures to protect bridge piers from scour. Washington, D.C.: Transportation Research Board. ISBN 978-0-309-09909-7.
- Hesse, Stephen. "The Japan Times environment columnist". Don't You Just Love 'Em ... Tetrapods. The Japan Times. Retrieved 13 May 2011.
- Zimmerman, Claus, ed. (2005). Environmentally friendly coastal protection : proceedings of the NATO Advanced Research Workshop on Environmentally Friendly Coastal Protection Structures, Varna, Bulgaria, 25-27 May 2004 (Online-Ausg. ed.). Dordrecht: Springer. ISBN 978-1-4020-3299-8.
- Wijers-HasegawaHesse, Yumi. "Tetrapodistas: Beauty beheld in huge concrete forms". The Japan Times.
- Hesse, Stephen. "Loving and Loathing Japan's Concrete Coasts, Where Tetrapods Reign". The Asia-Pacific Journal: Japan Focus.