Breakwater

The Editors of Encyclopaedia Britannica describe breakwater as an “artificial offshore structure protecting a harbor, anchorage, or marina basin from water waves,” and are constructed to “intercept longshore currents and prevent beach erosion" [1]. The name of breakwater comes from the effect that these “offshore shore-parallel structures” have of ‘“breaking” waves,’ and breakwater can be “floating or fixed on the ocean floor,” where these structures can be “attached to the shoreline as headlands or submerged near the shoreline as sills” [2].

In general, breakwater can be utilized to “dissipate wave energy and protect inland sites” [2]. Specifically, breakwater may also serve the purpose of “forming an artificial harbor with a basin protected from the effect of waves to provide safe berthing for fishing vessels.” Major materials to look for in breakwater are “natural rock and concrete, or a combination of the two” which are used to construct breakwaters, “forming 95 percent or more of all breakwaters” [3].

In terms of shape, breakwaters are either triangular or trapezoidal or have directly vertical faces, with an “outer slope that should not be steeper than 1 on 2 and the inner or harbor side slope not steeper than 1 on 1.5” in the case of triangular or trapezoidal breakwaters [3]. In the case of these breakwaters, the outer layer, or the “main armor layer” that is the “primary defense of the breakwater against wave attack” is composed of “stone sizes” in the range of “1 tonne (1000 kilograms) to 3 tonnes (3000 kilograms)" [3]. Breakwaters of this shape often appear as “rubble-mound structures” capable of “absorbing wave energy” [4]. Lastly, for vertical breakwaters, these are only employed “in waters no deeper than 2 meters and not exposed to strong wave action” [3].

References

[1] The Editors of Encyclopaedia Britannica. (2020, January 29). Breakwater. Retrieved (2021, August 3), from https://www.britannica.com/technology/breakwater

[2] National Park Service. (2019, April 5). Breakwaters, Headlands, Sills, and Reefs. Retrieved (2021, August 3), from https://www.nps.gov/articles/breakwaters-headlands-sills-and-reefs.htm

[3] Food & Agriculture Organization. 7. Breakwaters. Retrieved (2021, August 3), from http://www.fao.org/3/i1883e/i1883e07.pdf

[4] PND Engineers, Inc. (2015). Breakwaters Including Partial Penetrating Wave Barriers. Retrieved (2021, August 3), from https://www.pndengineers.com/home/showpublisheddocument/413/636068632346830000