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Protection and Prevention

Breakwater, Groins, and Wave Attenuators

Breakwater, Groins, and Wave Attenuators are a part of Coastal management to defend against flooding and erosion, and techniques that stop erosion to claim lands


Breakwaters are structures constructed near the coasts to protect an anchorage from the effects of both weather and longshore drift. Breakwaters reduce the intensity of wave action in inshore waters and thereby reduce coastal erosion or provide safe harborage. Breakwaters may also be small structures designed to protect a gently sloping beach and placed 100–300 feet offshore in relatively shallow water.


Groins are walls perpendicular to the coastline, often made of greenhearts, concrete, rock or wood. Material builds up on the downdrift side, where Longshore drift is predominantly in one direction, creating a wider and a more plentiful beach, thereby protecting the coast because the sand material filters and absorbs wave energy. However, there is a corresponding loss of beach material on the updrift side, requiring another groin there. Groinsare cost-effective, require little maintenance and are one of the most common defenses. 


Wave Attenuatorsminimize wave energy and decrease wave height, thereby protecting watercraft and facilities from potential damage and reducing shoreline erosion. Floating wave attenuators have been used for many years and come in various forms, from hollow concrete structures to floating docks. 

Coastal Management

Coastal management is defense 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. 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.