A bulkhead is a

retaining wall Retaining walls are relatively rigid walls used for supporting soil laterally so that it can be retained at different levels on the two sides. Retaining walls are structures designed to restrain soil to a slope that it would not naturally keep to ...

, such as a bulkhead within a ship or a watershed retaining wall. It may also be used in mines to contain flooding. Coastal bulkheads are most often referred to as seawalls, bulkheading, or riprap revetments. These manmade structures are constructed along

shoreline A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, su ...

s with the purpose of controlling

beach A beach is a landform alongside a body of water which consists of loose particles. The particles composing a beach are typically made from Rock (geology), rock, such as sand, gravel, shingle beach, shingle, pebbles, etc., or biological s ...

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 ...

. Construction materials commonly used include wood pilings, commercially developed vinyl products, large

boulder In geology, a boulder (or rarely bowlder) is a rock fragment with size greater than in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others are extremely massive. In ...

s stacked to form a wall, or a seawall built 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 ...

or another hard substance. Coastal property owners typically seek to develop bulkheads in an attempt to slow large

landslide Landslides, also known as landslips, rockslips or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslides ...

erosion caused by

wave In physics, mathematics, engineering, and related fields, a wave is a propagating dynamic disturbance (change from List of types of equilibrium, equilibrium) of one or more quantities. ''Periodic waves'' oscillate repeatedly about an equilibrium ...

action. Studies over recent decades have resulted in public awareness as to potential negative effects that bulkheads may bring to beaches and the interconnected

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

areas of fish, plants, and birds. Many states have enacted laws to protect beaches to allow for future use of the beaches, as well as protect these natural habitats. The term bulkhead is also used in a similar but distinct context to refer to large pressure sealing isolation barriers which can be retroactively installed for temporary or permanent use during maintenance or construction activities.

Effects

While bulkheads may serve their purpose to slow erosion at a bluff or

front, they commonly cause a

domino effect A domino effect is the cumulative effect produced when one event sets off a series of similar or related events, a form of chain reaction. The term is an analogy to a falling row of dominoes. It typically refers to a linked sequence of events ...

of change to the beach profile. The increased

reflection caused by their presence can result in an increased re-suspension of

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

in the water in front of the bulkhead. This can lead to more sand being distributed in the alongshore direction, away from the beach profile. Due to coastal littoral drift, the sand would then instead be distributed toward the ends of the bulkheads, leaving larger

gravel Gravel () is a loose aggregation of rock fragments. Gravel occurs naturally on Earth as a result of sedimentation, sedimentary and erosion, erosive geological processes; it is also produced in large quantities commercially as crushed stone. Gr ...

and sometimes

bedrock In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of bed ...

in place of the once sandy beach. Since sand is a natural habitat for several

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of fish to lay their eggs and is also the only surface in which eelgrass can take root, these natural processes can no longer take place in this now sand-stripped location. The absence of eelgrass means that the

spawning Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...

habitat for

herring Herring are various species of forage fish, belonging to the Order (biology), order Clupeiformes. Herring often move in large Shoaling and schooling, schools around fishing banks and near the coast, found particularly in shallow, temperate wate ...

and the protection for juvenile

salmon Salmon (; : salmon) are any of several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the genera ''Salmo'' and ''Oncorhynchus'' of the family (biology), family Salmonidae, native ...

would no longer be present. This new sand-stripped habitat also encourages other species, such as

kelp Kelps are large brown algae or seaweeds that make up the order (biology), order Laminariales. There are about 30 different genus, genera. Despite its appearance and use of photosynthesis in chloroplasts, kelp is technically not a plant but a str ...

, to move in.

Gallery

Image:NorthPadreIslandfig10LG.jpg, Seawall on North Padre Island constructed in the backbeach to protect condominiums from storm waves and beach erosion. Central Texas Image:USGSseawall-lg.jpg, Seawall protecting homes from storm waves and beach erosion. Northwestern Panhandle of Florida Image:fig10-large.jpg, Hard structures, such as the Galveston seawall, can increase erosion of adjacent beaches. Image:seawall-large.jpg, Seawall protecting homes from storm waves and beach erosion. Eastern Panhandle of Florida

References

Shore Stewards News - Bulkheads and Your Beach - PDFShore Stewards News - Creosote - PDF
*Johannessen, J. 2000. *Alternatives to Bulkheads in the Puget Sound Region: What is Soft Shore Protection & What is Not? In: Proceedings of Coasts at the Millennium, Coastal Society's 17th International Conference. July 2000. In Press. *''*Portions of article information obtained from''
(Soft Shore Protection as an Alternative to Bulkheads—Projects And Monitoring - PDF
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External links

*

* ttp://www.ecy.wa.gov/programs/sea/shorelan.html Washington Department of Ecology Website: Washington State Shorelands & Environmental Assistancebr>Beach Nourishment on Puget Sound: A Review of Existing Projects and Potential Applications – PDFAlternative Shoreline Stabilization Evaluation Project – Final Report, Prepared For:. Puget Sound Action Team. P.O. Box 40900 – PDF
Seawalls

Effects

Gallery

See also

References

External links