A groyne is a rigid hydraulic structure built perpendicularly from an ocean shore or a river bank, interrupting water flow and limiting the movement of sediment. It is usually made out of wood, concrete, or stone. In the ocean, groynes create beaches, prevent beach erosion caused by longshore drift where this is the dominant process and facilitate beach nourishment. There is also often cross-shore movement which if longer than the groyne will limit its effectiveness. In a river, groynes slow down the process of erosion and prevent ice-jamming, which in turn aids navigation.
Beach nourishment describes a process by which sediment, usually sand, lost through longshore drift or erosion is replaced from other sources. A wider beach can reduce storm damage to coastal structures by dissipating energy across the surf zone, protecting upland structures and infrastructure from storm surges, tsunamis and unusually high tides. Beach nourishment is typically part of a larger integrated coastal zone management aimed at coastal defense. Nourishment is typically a repetitive process since it does not remove the physical forces that cause erosion but simply mitigates their effects.
A seawall 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 and leisure activities from the action of tides, waves, or tsunamis. As a seawall is a static feature it will conflict with the dynamic nature of the coast and impede the exchange of sediment between land and sea. The shoreline is part of the coastal interface exposed to a wide range of erosional processes arising from flowing water sources, wind and terrestrial sources, meaning that a combination of denudational processes will work against a seawall.
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, helping isolate vessels within them from marine hazards such as prop washes and wind-driven waves. A breakwater, also known in some contexts as a jetty, may be connected to land or freestanding, and may contain a walkway or road for vehicle access.
Riprap, also known as rip rap, rip-rap, shot rock, rock armour or rubble, is human-placed rock or other material used to protect shoreline structures against scour and water, wave, or ice erosion. Ripraps are used to armor shorelines, streambeds, bridge abutments, foundational infrastructure supports and other shoreline structures against erosion. Common rock types used include granite and modular concrete blocks. Rubble from building and paving demolition is sometimes used, as well as specifically designed structures called tetrapods.
Coastal management is defence against flooding and erosion, and techniques that stop erosion to claim lands. Protection against rising sea levels in the 21st century is crucial, as sea level rise accelerates due to climate change. Changes in sea level damage beaches and coastal systems are expected to rise at an increasing rate, causing coastal sediments to be disturbed by tidal energy.
A dolos is a wave-dissipating concrete block used in great numbers as a form of coastal management. Weighing up to 80 tonnes, dolos are used to build revetments for protection against the erosive force of waves from a body of water. The dolos was invented in 1963, and was first deployed in 1964 on the breakwater of East London, a South African port city.
Accropode blocks are wave-dissipating concrete blocks designed to resist the action of waves on breakwaters and coastal structures.
Hard engineering involves the construction of hydraulic structures to protect coasts from erosion. Such structures include seawalls, gabions, breakwaters, groynes and tetrapods.
Regarding the civil engineering of shorelines, soft engineering is a shoreline management practice that uses sustainable ecological principles to restore shoreline stabilization and protect riparian habitats. Soft Shoreline Engineering (SSE) uses the strategic placement of organic materials such as vegetation, stones, sand, debris, and other structural materials to reduce erosion, enhance shoreline aesthetic, soften the land-water interface, and lower costs of ecological restoration.
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.
An Xbloc is a wave-dissipating concrete block designed to protect shores, harbour walls, seawalls, breakwaters and other coastal structures from the direct impact of incoming waves. The Xbloc model was designed and developed by the Dutch firm Delta Marine Consultants, now called BAM Infraconsult, a subsidiary of the Royal BAM Group in 2001 and has been subjected to extensive research by several universities.
Reef Ball Foundation, Inc. is a 501(c)(3) non-profit organization that functions as an international environmental non-governmental organization. The foundation uses reef ball artificial reef technology, combined with coral propagation, transplant technology, public education, and community training to build, restore and protect coral reefs. The foundation has established "reef ball reefs" in 59 countries. Over 550,000 reef balls have been deployed in more than 4,000 projects.
Beach evolution occurs at the shoreline where sea, lake or river water is eroding the land. Beaches exist where sand accumulated from centuries-old, recurrent processes that erode rocky and sedimentary material into sand deposits. River deltas deposit silt from upriver, accreting at the river's outlet to extend lake or ocean shorelines. Catastrophic events such as tsunamis, hurricanes, and storm surges accelerate beach erosion.
Artificial reefs are used to increase sustainable fishing activities on the coastline of Japan, which depends heavily on the sea for food.
A multi-purpose reef, also commonly known as an artificial surfing reef or surf reef, is a structure located offshore designed to induce wave breaking in a manner that creates a wave suitable for surfing or body boarding. Artificial surfing reefs can exist in many different configurations and be built from a variety of different materials. To date there have been fewer than ten attempts worldwide to build such structures.
KOLOS is a wave-dissipating concrete block intended to protect coastal structures like seawalls and breakwaters from the ocean waves. These blocks were developed in India and were first adopted for the breakwaters of the Krishnapatnam Port along the East coast of India.
Living shorelines are a relatively new approach for addressing shoreline erosion and protecting marsh areas. Unlike traditional structures such as bulkheads or seawalls that worsen erosion, living shorelines incorporate as many natural elements as possible which create more effective buffers in absorbing wave energy and protecting against shoreline erosion. The process of creating a living shoreline is referred to as soft engineering, which utilizes techniques that incorporate ecological principles in shoreline stabilization. The natural materials used in the construction of living shorelines create and maintain valuable habitats. Structural and organic materials commonly used in the construction of living shorelines include sand, wetland plants, sand fill, oyster reefs, submerged aquatic vegetation, stones and coir fiber logs.
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.
An electric reef is an artificial reef made from biorock, being limestone that forms rapidly in seawater on a metal structure from dissolved minerals in the presence of a small electric current. The first reefs of this type were created by Wolf Hilbertz and Thomas J. Goreau in the 1980s. By 2011 there were examples in over 20 countries.
