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Beach evolution is a natural process occurring along shorelines where sea, lake, or river water erodes the land. Beaches form as sand accumulates over centuries through recurrent processes that erode rocky and sedimentary material into sand deposits. River deltas contribute by depositing silt carried 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 evolution.

Accretion and erosion

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See also: Beach accretion and erosion

Sudden and rapid processes

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Tsunamis and hurricane-driven storm surges

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Tsunamis can cause significant erosion and sediment displacement. They can strip away years of accumulated sand from beaches and devastate coastal vegetation. These powerful waves can flood inland areas far beyond the typical high-tide mark. Additionally, the swift currents associated with the inundating tsunami can demolish homes and other coastal structures.

A storm surge is an onshore gush of water associated with a low pressure weather system. Storm surges can cause beach accretion and erosion.^[1] Historically notable storm surges occurred during the North Sea Flood of 1953, Hurricane Katrina, and the 1970 Bhola cyclone.

Volcanism and earthquakes related sea-level changes

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Both geological events and the climate can change (progressively or suddenly) the relative height of the Earth’s surface to the sea-level. These events or processes continuously change coastlines.

Volcanic activity can create new islands. For example, Surtsey Island in Iceland which has a diameter of 800 meters (2,600 ft), was created between November 1963 and June 1967.^[2] The island emerged from undersea vents that are part of the Vestmannaeyjar submarine volcanic system.^[3] Although the island has since partially eroded, but it is expected to last another 100 years.

Some earthquakes can create sudden variations of relative ground level and change the coastline dramatically. Structurally controlled coasts include the San Andreas Fault zone in California and the seismic Mediterranean belt (from Gibraltar to Greece).

The Bay of Pozzuoli, in Pozzuoli, Italy experienced hundreds of tremors between August 1982 and December 1984. The tremors, which reached a peak on October 4, 1983, damaged 8,000 buildings in the city center and raised the sea bottom by almost 2 meters (6.6 ft). This rendered the Bay of Pozzuoli too shallow for large craft and required the reconstruction of the harbor with new quays. The photo at the upper right shows the harbor before the uplift while the one on the bottom right shows the new quay.

Gradual processes

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The gradual evolution of beaches often comes from the interaction of longshore drift, a wave-driven process by which sediments move along a beach shore, and other sources of erosion or accretion, such as nearby rivers.^[4]

Deltas

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Deltas are nourished by alluvial systems and accumulate sand and silt, growing where the sediment flux from land is large enough to avoid complete removal by coastal currents, tides, or waves.

Most modern deltas are formed during the last five thousand years, after the present sea-level high stand was attained. However, not all sediment remains permanently in place: in the short term (decades to centuries), exceptional river floods, storms or other energetic events may remove significant portions of delta sediment or change its lobe distribution (pattern in which sediments are deposited across Delta, forming distinct, lobe shaped structures) and, on longer geological time scales, sea-level fluctuations lead to the destruction of deltaic features.

Subsidence and uplift related sea-level changes

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Subsidence is the motion of the Earth’s surface downward relative to the sea level due to internal geodynamic causes, It can occur naturally or due to human activities. The opposite of subsidence is uplift, which increases elevation.

Venice is probably the best-known example of a subsiding location. Built suspended over a coastal lagoon, it experiences periodic flooding when extreme high tides or surges arrive; St Mark’s Square is built only 55 centimeters above sea level.^[5] This phenomenon is caused by the compaction of young sediments in the Po River delta area, magnified by subsurface water and gas exploitation. Man-made works to solve this progressive sinking have been unsuccessful.

Mälaren, the third-largest lake in Sweden, is an example of deglacial uplift. It was once a bay on which seagoing vessels were once able to sail far into the country’s interior, but it ultimately became a lake. Its uplift was caused by deglaciation: the removal of the weight of ice-age glaciers caused rapid uplift of the depressed land. For 2,000 years as the ice was unloaded, uplift proceeded at about 7.5 centimeters (3.0 in)/year. Once deglaciation was complete, uplift slowed to about 2.5 centimeters (0.98 in) annually, and it decreased exponentially after that. Today, annual uplift rates are 1 centimeter (0.39 in) or less, and studies suggest that rebound will continue for about another 10,000 years. The total uplift from the end of deglaciation may be up to 400 meters (1,300 ft).

Beach management

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Main article: Coastal management

See also: Longshore drift, coastal development hazards, and Integrated coastal zone management

Integrated coastal zone management minimizes the negative human impacts on coasts, enhances coastal defense, mitigates the risk associated with the sea level rise and other natural hazards.

The beach erosion is a type of bioerosion which alters the coastal geography through beach morphodynamics. There are numerous incidents of modern recession of beaches, mainly due to the longshore drift and coastal development hazards related to human activities.

Solutions range from “do nothing” to “Move beach seaward” approach which uses the elements of hard and soft engineering. The interventionist methods, such as “Move beach seaward”, combine the hard engineering methods such as constructing structures (accropodes) with the soft engineering methods such as sand dune stabilization. These intervention are aimed at prevention of beach erosion caused by longshore drift and coastal development hazards, as well as facilitation of beach evolution and expansion.

Coastal planning approaches

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Five generic planning approaches involved in coastal defense are:^[6]

• Abandonment of shore: do nothing, let the natural process takeover.
• Managed retreat, also called realignment.
• Hold the shoreline: by using shoreline hardening techniques to create permanent concrete and rock constructions such as groynes.
• Move beach seaward: by using hard and soft intervention techniques usually in areas of high economic significance.
• Limited intervention: usually in areas of low economic significance, often includes the succession of haloseres, including salt marshes and sand dunes.

Coastal engineering

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Coastal engineering techniques can be classified into two categories: hard engineering methods and soft engineering methods

Hard engineering methods

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Hard engineering methods are also called “Structural methods”. “Move towards the sea” beach accretion can be facilitated by the four main type of hard engineering structures, namely seawall, revetment, groyne or breakwater. Most commonly used hard structures are seawall and series of “headland groyne” (breakwater connected to the shore with groyne).

Main types of structures

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Four main types of structures or accropodes are seawalls, groynes, breakwater and revetments. Headland groynes are a combination of breakwater and groyne.

Seawalls

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Seawalls re-direct most of the incident energy in the form of sloping revetments, resulting in low reflected waves and much reduced turbulence. Designs use porous designs of rock or concrete objects such as Tetrapods or Xblocs with flights of steps for beach access. Seawall at Cronulla beach, NSW,^[7] for example, uses concrete wall. Submerged seawalls or structures are constructed to create the underwater reefs to slow down wave energy and beach erosion.

• Sea wall in the Netherlands that does allow the tide and organisms through, but brakes wave energy.
• Stone Seawall with cemented walkway, mud revetment stabilized with grass, and gravel riprap armament at the base.

Groynes and Headland groyne

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Groynes are the walls perpendicular to the coastline. Groynes are generally placed in series and the areas between groups of groynes are called groyne fields. To directs the sand towards the shore targeted for sand accumulation, a shorter groyne turned slightly towards downdrift side of the beach is deployed at updrift end of the beach, a longer groyne at the downdrift end of the beach is deployed, a series of groyne are deployed between the two ends. Groynes are often made of gabion, greenharts, concrete, rock or wood. Material builds up on the downdrift side, where littoral drift is predominantly in one direction, creating a wider and a more plentiful beach. Groynes are cost-effective, require little maintenance and are one of the most common defences.^[8]Headland groyne or Bulkhead breakwaterWhen groyne is built to attach a breakwater to shore, the resulting T-structure is called “headland breakwater”, “headland groyne”, “bulkhead groyne” or “bulkhead breakwater”. Use of groynes and headland groyne, accumulates the sand across the beach but it tend to deplete the sand faster from the downdrift end of the beach. This can be mitigated and sand could be accumulated at the downdrift end of the beach also. This is achieved by having a longer “groyne” or “headland groyne” at the end of downdrift side of the beach. To enhance the sand accumulation, this “headland groyne” could have another series of smaller “headland groyne” jutting out of it pointing towards updrift end of the beach in a way that the smaller “headland groyne” are parallel to the shore and perpendicular to main “headland groyne”. This will facilitate gradual natural creation of ayre (sand or gravel filled beach). If there is a near shore island near the downdrift end of the beach and “headland groyne”, then this could be turned into a cuspate foreland headland with the use of the gradual natural creation of ayre (gravel filled beach). Main “headland groyne” at the end of downdrift could be further stabilized by a hard engineered detention basin and grassy mangrovesalt marsh. Salt marsh could be created with the use of soft engineering approach, such as lose stone sills, while leaving a whole in the sill for a seawater channel. Seawater channel could be a cemented open channel or a pipe buried under the beach. This marsh could be designed to taper into a hard engineered sandy beach. Having inland saltwater marsh between the beach and mainland will lower the cost by eliminating the need for filling up the marshy area with the sand, and the mangroves and grasses in the marsh will facilitate gradual built up of sediments.

• Series of cost effective groynes made of wood.
• “Headland groyne” with wood log breakwater and stone filled wooden groyne, an easy to build cost effective option made of cheap and native materials.
• Groyne at Mundesley, Norfolk, UK.
• “Headland groyne” at East Coast Beach in Singapore consists of breakwater parallel to shore and connected to shore by a vertical groyne. Higher mainland is fortified with a low rise mud seawall which has been further stabilized by planting grass and trees.

Breakwater

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Breakwater, also called “offshore breakwater”, are offshore structure constructed parallel to the shore to alter wave direction and tide energy. The waves break further offshore and therefore lose erosive power. This leads to formation of wider beaches, which further absorb wave energy. A series of breakwaters is often deployed across the beach shore.

Revetment

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Revetments are slanted or upright blockades, built parallel to the coast, usually towards the back of the beach to protect the area beyond. The most basic revetments consist of timber slants with a possible rock infill. Waves break against the revetments, which dissipate and absorb the energy. The shoreline is protected by the beach material held behind the barriers, as the revetments trap some of the material. Unless other methods are used in combination, surf progressively erodes and destroys the revetment which requires ongoing maintenance.

Other types of structures

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Riprap / Rock armour

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Rock armour, also called riprap, is basement placed at the sea edge using local material. This could be the protruding foot of a seawall or revetment to reduce maintenance of those. Longshore drift is not hindered.

Cliff stabilization

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Cliff stabilization can be accomplished through drainage of excess rainwater of through terracing, planting and wiring to hold cliffs in place.

Floodgates

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Floodgates prevent damage from storm surges or any other type of natural disaster that could harm the area they protect. They are habitually open and allow free passage, but close under threat of a storm surge. The Thames Barrier is an example of such a structure.

Construction elements

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These construction elements can be incorporated in any of the above structures, either as core element or as a supplementary element to enhance to reduce the cost and maintenance of main structural elements.

Concrete objects

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These are complex reinforced concrete objects, such as A-jack, Akmon, Dolos, Honeycomb sea wall (Seabees), KOLOS, Tetrapod and Xbloc. Simple concrete blocks have been replaced by these complex concrete objects because these objects are more resistant to wave action and require less concrete to produce a superior result. These could be used to build seawalls, groyne, breakwater, and other structures including residential buildings. Tetrapod used at Marine Drive, Mumbai are an example of complex concrete objects.

• Tetrapods, Marine Drive, Mumbai.
• Dolos.
• KOLOS.
• Xblocs.

Gabions

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Gabions are constructed by wiring boulders and rocks into mesh cages and placed in front of areas vulnerable to erosion, sometimes at cliffs edges or at right angles to the beach. When the ocean lands on the gabion, the water drains through leaving sediment, while the structure absorbs a moderate amount of wave energy. Gabions need to be securely tied to protect the structure. They can be used to build seawalls, groynes, breakwaters, revetments, buildings, underwater reefs, etc.,^{[citation needed]}

• Gabion, welded wiremesh filled with stone.

Soft engineering methods

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See also: Beach evolution and Sand dune stabilization

Soft engineering uses a “soft” (non-permanent) structure by creating a larger sand reservoir, pushing the shoreline seaward. It gained popularity because it preserved beach resources and avoided the negative effects of hard structures.

Managed retreat

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Managed retreat means the shoreline is left to erode, while relocating buildings and infrastructure further inland.

Beach evolution

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Beach evolution, also called “beach replenishment” or “beach nourishment”, it involves importing sand from elsewhere and adding it to the existing beach. The imported sand should be of a similar quality to the existing beach material so it can meld with the natural local processes and without adverse effects. Without the groynes or scheme requires repeated applications on an annual or multi-year cycle. Beach nourishment can be used in combination with seaward curving half-moon shaped “headland breakwater” structure, this combining the benefits of breakwater and groyne structures.

Sand dune stabilization

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Sand dune stabilization protects beaches by catching windblown sand, increasing natural beach formation. Fences can allow sand traps to create blowouts and increase windblown sand capture. Plants such as Ammophila (Marram grass) can bind the sediment.

Beach drainage

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The beach face dewatering lowers the water table locally beneath the beach face. This causes accretion of sand above the drainage system.^[9]

Cost considerations

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The costs of installation, operation and maintenance vary due to:

• system length (non-linear cost elements)
• flow rates (sand permeability, power costs)
• soil conditions (presence of rock or impermeable strata)
• discharge arrangement /filtered seawater utilization
• drainage design, materials selection & installation methods
• geographical considerations (location logistics)
• regional economic considerations (local capabilities /costs, availability of local material and native skilled workforce)
• study requirements /consent process.

An illustrative example

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This Integrated coastal zone management example is based on the “move beach seaward” general planning approach which involves both hard and soft engineering methods. This scenario minimizes the maintenance effort and cost by making optimal use of the coastal geography by incorporating natural coastal geographical features in the engineering design. The cost is kept low by the use of easily available free or cost-effective local material, use of which is already known to or easily acquired by the local workforce. This solution entails beach nourishment (creating recreational area by filling with sand), and further beach expansion and prevention of beach erosion caused by longshore drift and coastal development hazards. The design makes use of a shorter groyne slightly inclined toward the beach in the same direction as downdrift, with a series of “headland groyne” perpendicular to the shore, and a longer “headland groyne” at the end of downdrift side of the beach with smaller “headland groyne” perpendicular to it facing the updrift end of the beach.

This example of tropical setting, part of the sea could be reclaimed by building a seawall with revetment (slope) fortified with armament of honeycomb seebee made of concrete with hexagonal holes, parts of seawall could be made of gabion. Seawall will sit^[10] over gravel or rock. Seawall could be a mix of vertical structures in the areas where more space is needed and tapering revetments (slope) as aesthetic landscaping feature. Revetments could be made of locally available material. Different parts of revetment could have different material and design, such as gabion (welded wire mesh filled with stone, gravel and wood) and honeycomb seebee (made of concrete with hexagonal holes). Honeycomb seebee or gabion could be used in the downdrift areas, though wood groyne would be the cheapest option such as used at Mundesley. Other areas of seawall and revetment could be a mix of cemented low walls, gabion, riprap made of gravel or sand bags. Parts of seawall and revetment could be left exposed especially those made of decorative gabion, and others parts could be covered with low or mid level native plants. Seawall will sit^[10] over gravel or rock base which could be wider than the seawall so that it also acts as the riprap armament.

Reclaimed area could be filled with the sand and stabilized by aesthetic landscaping by growing native trees and plants. A dense layer of native tropical trees could be planted at the mainland side of the reclaimed land with due consideration to the height of the trees that they do not block the view of any construction such as resort or beach house. Reclaimed area would enhance the economical value by creating a sand filled safe recreation area which might house sunbathing areas and inland freshwater or seawater wading pool or lagoon surrounded by bars, restaurants, water sports, etc. Restaurants could have retractable-canopied areas set closer to the seawall greenified with tapering layers of evergreen native tropical plants. Bars could be open air, portable or canopied (thatched roof nipa hut and trellis of native material, pergola or beach parasol) bars with pool and beach seating. Seating could be relaxing-and-sprawling reclined futon type, sunken sand pits, sand filled bean bags on the beach, locally made designer stools/chairs and tables made of native eco-friendly natural material such as bamboo, aged rustic driftwood and abundant low weathering native wood.

• A series of trellises forms the wall of a garden room.
• Creeping groundsel growing on a wooden trellis in Italy.
• Casa Redonda, one of five nipa houses built by the Philippine national hero José Rizal during his exile in Dapitan.^[11]
• The raised bale houses of the Ifugao people.^[12]

Status of beaches

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Historical accretion of beaches

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In the Mediterranean Sea, deltas have been continuously growing for the last several thousand years. Six to seven thousand years ago, the sea level stabilized, and continuous river systems, ephemeral torrents, and other factors began this steady accretion. Since intense human use of coastal areas is a relatively recent phenomenon (except in the Nile delta), beach contours were primarily shaped by natural forces until the last centuries.

In Barcelona, for example, the accretion of the coast was a natural process until the late Middle Ages, when harbor-building increased the rate of accretion.

The port of Ephesus, one of the great cities of the Ionian Greeks in Asia Minor, was filled with sediment due to accretion from a nearby river; it is now 5 kilometers (3.1 mi) from the sea. Likewise, Ostia, the once-important port near ancient Rome, is now several kilometres inland, the coastline having moved slowly seaward.

Bruges became a port during the early Middle Ages and was accessible by sea until around 1050. At that time, however, the natural link between Bruges and the sea silted up. In 1134, a storm flood opened a deep channel, the Zwin, linking the city to the sea until the fifteenth century via a canal from the Zwin to Bruges. Bruges had to use a number of outports, such as Damme and Sluis, for this purpose. In 1907, a new seaport was inaugurated in Zeebrugge.

Modern beach recession

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At the present time, important segments of low coasts are in recession, losing sand and reducing beach dimensions. This loss can occur very rapidly. There are various reasons for beach recession, some more natural than others (degree of anthropization). Examples of this are occurring at Sète, in California, in Poland, in Aveiro (Portugal), and in the Netherlands and elsewhere along the North Sea. In Europe, coastal erosion is widespread (at least 70%) and distributed very irregularly.

California beaches

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California‘s beaches and other shoreline features change according to the availability of beach sand, the wave and current energy impinging on the coast, and other physical processes that affect the movement of sand. A constant supply of sand is necessary for beaches to form and be maintained along this shoreline. Many human activities, including dam construction and river channelization, have reduced the supply of sand that reaches the ocean. This, in turn, has prevented beaches from being replenished and has thus created greater vulnerability for shorelines that have always been subject to varying levels of erosion. There are few practical solutions to improving sand supply from inland sources, so management of shoreline erosion will likely continue to focus at the land/sea interface along the California coastline.

Construction of breakwaters, jetties, or groyne fields to protect harbor entrances, maintain beaches, or protect coastal structures have both helped and harmed the movement of sand along the shoreline. Protective armoring formations trap sand and allow beaches to expand up-coast from the device, but can interrupt the flow of sand to beaches located down-coast.

France

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Atlantic coast

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Some of the coastal defence bunkers of the Atlantic Wall, built by the German soldiers during the Second World War at the top of the dunes were underwater 2/3 of the time 65 years after the war. It shows 200 meters of recession of the beach in 65 years.

Sète

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The coast recession near Sète is related with coastal drift sand supply interruption due to growth of the Rhone delta, which (like most deltas) is becoming independent of the rest of the coast. The present lido shoreline is 210 meters away from the Roman lido.

Netherlands

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The Dutch coast consists of sandy, multi-barred beaches and can be characterised as a wave-dominated coast. Approximately 290 km of the coast consists of dunes and 60 km is protected by structures such as dikes and dams. With the melting of the ice at the end of the last ice age, the coastline shifted eastward until about 5000 years ago the present position of the Dutch coastline was reached. As the sea level rise stagnated, the sand supply decreased and the formation of the beach ridges stopped, after which when the sea broke through the lines of dunes during storms, men started to defend the land by building primitive dikes and walls. The dunes, together with the beach and the shoreline, offer a natural, sandy defence to the sea. About 30% of the Netherlands lies below sea level.

Over the last 30 years, approximately 1 million m³ sand per year has been lost from the Dutch coast to deep water. In most northern coastal sections, erosion occurs in deep water and also in the nearshore zone. In most southern sections, sedimentation occurs in the nearshore zone and erosion in deep water. Structural erosion is due to sea-level rise relative to the land and, in some spots, it is caused by harbour dams. The Dutch coast looked at as a single unit shows erosive behaviour. Approximately 12 million m³ of sand is transferred annually from the North Sea to the Wadden Sea as a result of relative rising sea level and coastal erosion.

Poland

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During the last glaciation, the Baltic Polish area was covered in ice and associated morainal sediments. Deglaciation left a substantial amount of unconsolidated sediment. Currently, these unconsolidated sediments are strongly eroded and reworked by the sea.

Portugal

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The North Portuguese coast and its beaches were fed by large Iberian rivers. The massive building of dams in the Douro River basin has cut the sediment supply to the Aveiro coast, resulting in its recession. Hard protective works have been done all along.

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, such as sand, gravel, shingle, pebbles, etc., or biological sources, such as mollusc shells or coralline algae. Sediments settle in different densities and structures, depending on the local wave action and weather, creating different textures, colors and gradients or layers of material.

Though some beaches form on inland freshwater locations such as lakes and rivers, most beaches are in coastal areas where wave or current action deposits and reworks sediments. Erosion and changing of beach geologies happens through natural processes, like wave action and extreme weather events. Where wind conditions are correct, beaches can be backed by coastal dunes which offer protection and regeneration for the beach. However, these natural forces have become more extreme due to climate change, permanently altering beaches at very rapid rates. Some estimates describe as much as 50 percent of the earth’s sandy beaches disappearing by 2100 due to climate-change driven sea level rise.^[1]

Sandy beaches occupy about one third of global coastlines.^[1] These beaches are popular for recreation, playing important economic and cultural roles—often driving local tourism industries. To support these uses, some beaches have human-made infrastructure, such as lifeguard posts, changing rooms, showers, shacks and bars. They may also have hospitality venues (such as resorts, camps, hotels, and restaurants) nearby or housing, both for permanent and seasonal residents.

Human forces have significantly changed beaches globally: direct impacts include bad construction practices on dunes and coastlines, while indirect human impacts include water pollution, plastic pollution and coastal erosion from sea level rise and climate change. Some coastal management practices are designed to preserve or restore natural beach processes, while some beaches are actively restored through practices like beach nourishment.

Wild beaches, also known as undeveloped or undiscovered beaches, are not developed for tourism or recreation. Preserved beaches are important biomes with important roles in aquatic or marine biodiversity, such as for breeding grounds for sea turtles or nesting areas for seabirds or penguins. Preserved beaches and their associated dune are important for protection from extreme weather for inland ecosystems and human infrastructure.^[1]

Location and profile

Although the seashore is most commonly associated with the word beach, beaches are also found by lakes and alongside large rivers.

Beach may refer to:

• small systems where rock material moves onshore, offshore, or alongshore by the forces of waves and currents; or
• geological units of considerable size.

The former are described in detail below; the larger geological units are discussed elsewhere under bars.

There are several conspicuous parts to a beach that relate to the processes that form and shape it. The part mostly above water (depending upon tide), and more or less actively influenced by the waves at some point in the tide, is termed the beach berm. The berm is the deposit of material comprising the active shoreline. The berm has a crest (top) and a face—the latter being the slope leading down towards the water from the crest. At the very bottom of the face, there may be a trough, and further seaward one or more long shore bars: slightly raised, underwater embankments formed where the waves first start to break.

The sand deposit may extend well inland from the berm crest, where there may be evidence of one or more older crests (the storm beach) resulting from very large storm waves and beyond the influence of the normal waves. At some point the influence of the waves (even storm waves) on the material comprising the beach stops, and if the particles are small enough (sand size or smaller), winds shape the feature. Where wind is the force distributing the grains inland, the deposit behind the beach becomes a dune.

These geomorphic features compose what is called the beach profile. The beach profile changes seasonally due to the change in wave energy experienced during summer and winter months. In temperate areas where summer is characterised by calmer seas and longer periods between breaking wave crests, the beach profile is higher in summer. The gentle wave action during this season tends to transport sediment up the beach towards the berm where it is deposited and remains while the water recedes. Onshore winds carry it further inland forming and enhancing dunes.

Conversely, the beach profile is lower in the storm season (winter in temperate areas) due to the increased wave energy, and the shorter periods between breaking wave crests. Higher energy waves breaking in quick succession tend to mobilise sediment from the shallows, keeping it in suspension where it is prone to be carried along the beach by longshore currents, or carried out to sea to form longshore bars, especially if the longshore current meets an outflow from a river or flooding stream. The removal of sediment from the beach berm and dune thus decreases the beach profile.

If storms coincide with unusually high tides, or with a freak wave event such as a tidal surge or tsunami which causes significant coastal flooding, substantial quantities of material may be eroded from the coastal plain or dunes behind the berm by receding water. This flow may alter the shape of the coastline, enlarge the mouths of rivers and create new deltas at the mouths of streams that had not been powerful enough to overcome longshore movement of sediment.

The line between beach and dune is difficult to define in the field. Over any significant period of time, sediment is always being exchanged between them. The drift line (the high point of material deposited by waves) is one potential demarcation. This would be the point at which significant wind movement of sand could occur, since the normal waves do not wet the sand beyond this area. However, the drift line is likely to move inland under assault by storm waves.^[3]

Formation

See also: Beach evolution

Beaches are the result of wave action by which waves or currents move sand or other loose sediments of which the beach is made as these particles are held in suspension. Alternatively, sand may be moved by saltation (a bouncing movement of large particles). Beach materials come from erosion of rocks offshore, as well as from headland erosion and slumping producing deposits of scree. A coral reef offshore is a significant source of sand particles. Some species of fish that feed on algae attached to coral outcrops and rocks can create substantial quantities of sand particles over their lifetime as they nibble during feeding, digesting the organic matter, and discarding the rock and coral particles which pass through their digestive tracts.

The composition of the beach depends upon the nature and quantity of sediments upstream of the beach, and the speed of flow and turbidity of water and wind. Sediments are moved by moving water and wind according to their particle size and state of compaction. Particles tend to settle and compact in still water. Once compacted, they are more resistant to erosion. Established vegetation (especially species with complex network root systems) will resist erosion by slowing the fluid flow at the surface layer. When affected by moving water or wind, particles that are eroded and held in suspension will increase the erosive power of the fluid that holds them by increasing the average density, viscosity, and volume of the moving fluid.

Coastlines facing very energetic wind and wave systems will tend to hold only large rocks as smaller particles will be held in suspension in the turbid water column and carried to calmer areas by longshore currents and tides. Coastlines that are protected from waves and winds will tend to allow finer sediments such as clay and mud to precipitate creating mud flats and mangrove forests. The shape of a beach depends on whether the waves are constructive or destructive, and whether the material is sand or shingle. Waves are constructive if the period between their wave crests is long enough for the breaking water to recede and the sediment to settle before the succeeding wave arrives and breaks.

Fine sediment transported from lower down the beach profile will compact if the receding water percolates or soaks into the beach. Compacted sediment is more resistant to movement by turbulent water from succeeding waves. Conversely, waves are destructive if the period between the wave crests is short. Sediment that remains in suspension when the following wave crest arrives will not be able to settle and compact and will be more susceptible to erosion by longshore currents and receding tides. The nature of sediments found on a beach tends to indicate the energy of the waves and wind in the locality.

Constructive waves move material up the beach while destructive waves move the material down the beach. During seasons when destructive waves are prevalent, the shallows will carry an increased load of sediment and organic matter in suspension. On sandy beaches, the turbulent backwash of destructive waves removes material forming a gently sloping beach. On pebble and shingle beaches the swash is dissipated more quickly because the large particle size allows greater percolation, thereby reducing the power of the backwash, and the beach remains steep. Compacted fine sediments will form a smooth beach surface that resists wind and water erosion.

During hot calm seasons, a crust may form on the surface of ocean beaches as the heat of the sun evaporates the water leaving the salt which crystallises around the sand particles. This crust forms an additional protective layer that resists wind erosion unless disturbed by animals or dissolved by the advancing tide. Cusps and horns form where incoming waves divide, depositing sand as horns and scouring out sand to form cusps. This forms the uneven face on some sand shorelines. White sand beaches look white because the quartz or eroded limestone in the sand reflects or scatters sunlight without significantly absorbing any colors.

Sand colors

The composition of the sand varies depending on the local minerals and geology.^[4] Some of the types of sand found in beaches around the world are:

• White sand: Mostly made of quartz and limestone, it can also contain other minerals like feldspar and gypsum .^[4][5]
• Light-colored sand: This sand gets its color from quartz and iron,^[4] and is the most common sand color in Southern Europe^[6] and other regions of the Mediterranean Basin, such as Tunisia.^[4]
• Tropical white sand: On tropical islands, the sand is composed of calcium carbonate from the shells and skeletons of marine organisms, like corals and mollusks, as found in Aruba.^[4]
• Pink coral sand: Like the above, is composed of calcium carbonate and gets its pink hue from fragments of coral, such as in Bermuda and the Bahama Islands.^[4]
• Black sand: Black sand is composed of volcanic rock, like basalt and obsidian, which give it its gray-black color.^[4] Hawaii‘s Punaluu Beach, Madeira‘s Praia Formosa and Fuerteventura‘s Ajuy beach are examples of this type of sand.^[4]
• Red sand: This kind of sand is created by the oxidation of iron from volcanic rocks.^[5] Santorini‘s Kokkini Beach or the beaches on Prince Edward Island in Canada are examples of this kind of sand.^[5]
• Orange sand: Orange sand is high on iron. It can also be a combination of orange limestone, crushed shells, and volcanic deposits.^[5] Ramla Bay in Gozo, Malta or Porto Ferro in Sardinia are examples of each, respectively.^[4]
• Green sand: In this kind of sand, the mineral olivine has been separated from other volcanic fragments by erosive forces.^[4] A famous example is Hawaii’s Papakolea Beach, which has sand containing basalt and coral fragments.^[4] Olivine beaches have a high potential for carbon sequestration, and artificial greensand beaches are being explored for this process by Project Vesta.^[7]

Types of beach sand

• Fine, white sand made up of pure quartz in Hyams Beach, New South Wales, Australia.
• Yellow-colored sand in Castelldefels beach, Spain.
• One of Bermuda’s pink-sand beaches at Astwood Park.
• Ajuy‘s beach black sand.
• Red sand from Santorini‘s Kokkini beach.
• Orange sand from Ramla Bay, Malta
• Close view of Papakolea Beach‘s green sand.
• Grey sand at Carters Beach, New Zealand

Erosion and accretion

Natural erosion and accretion

Causes

Beaches are changed in shape chiefly by the movement of water and wind. Any weather event that is associated with turbid or fast-flowing water or high winds will erode exposed beaches. Longshore currents will tend to replenish beach sediments and repair storm damage. Tidal waterways generally change the shape of their adjacent beaches by small degrees with every tidal cycle. Over time these changes can become substantial leading to significant changes in the size and location of the beach.

Effects on flora

Changes in the shape of the beach may undermine the roots of large trees and other flora. Many beach adapted species (such as coconut palms) have a fine root system and large root ball which tends to withstand wave and wind action and tends to stabilize beaches better than other trees with a lesser root ball.

Effects on adjacent land

Erosion of beaches can expose less resilient soils and rocks to wind and wave action leading to undermining of coastal headlands eventually resulting in catastrophic collapse of large quantities of overburden into the shallows. This material may be distributed along the beach front leading to a change in the habitat as sea grasses and corals in the shallows may be buried or deprived of light and nutrients.

Humanmade erosion and accretion

Coastal areas settled by man inevitably become subject to the effects of human-made structures and processes. Over long periods of time, these influences may substantially alter the shape of the coastline, and the character of the beach.

Destruction of flora

Beachfront flora plays a major role in stabilizing the foredunes and preventing beach head erosion and inland movement of dunes. If flora with network root systems (creepers, grasses, and palms) are able to become established, they provide an effective coastal defense as they trap sand particles and rainwater and enrich the surface layer of the dunes, allowing other plant species to become established. They also protect the berm from erosion by high winds, freak waves and subsiding floodwaters.

Over long periods of time, well-stabilized foreshore areas will tend to accrete, while unstabilized foreshores will tend to erode, leading to substantial changes in the shape of the coastline. These changes usually occur over periods of many years. Freak wave events such as tsunami, tidal waves, and storm surges may substantially alter the shape, profile and location of a beach within hours.

Destruction of flora on the berm by the use of herbicides, excessive pedestrian or vehicle traffic, or disruption to freshwater flows may lead to erosion of the berm and dunes. While the destruction of flora may be a gradual process that is imperceptible to regular beach users, it often becomes immediately apparent after storms associated with high winds and freak wave events that can rapidly move large volumes of exposed and unstable sand, depositing them further inland, or carrying them out into the permanent water forming offshore bars, lagoons or increasing the area of the beach exposed at low tide. Large and rapid movements of exposed sand can bury and smother flora in adjacent areas, aggravating the loss of habitat for fauna, and enlarging the area of instability. If there is an adequate supply of sand, and weather conditions do not allow vegetation to recover and stabilize the sediment, wind-blown sand can continue to advance, engulfing and permanently altering downwind landscapes.

Sediment moved by waves or receding floodwaters can be deposited in coastal shallows, engulfing reed beds and changing the character of underwater flora and fauna in the coastal shallows.

Burning or clearance of vegetation on the land adjacent to the beach head, for farming and residential development, changes the surface wind patterns, and exposes the surface of the beach to wind erosion.

Farming and residential development are also commonly associated with changes in local surface water flows. If these flows are concentrated in stormwater drains emptying onto the beach head, they may erode the beach creating a lagoon or delta.

Dense vegetation tends to absorb rainfall reducing the speed of runoff and releasing it over longer periods of time. Destruction by burning or clearance of the natural vegetation tends to increase the speed and erosive power of runoff from rainfall. This runoff will tend to carry more silt and organic matter from the land onto the beach and into the sea. If the flow is constant, runoff from cleared land arriving at the beach head will tend to deposit this material into the sand changing its color, odor and fauna.

Creation of beach access points

The concentration of pedestrian and vehicular traffic accessing the beach for recreational purposes may cause increased erosion at the access points if measures are not taken to stabilize the beach surface above high-water mark. Recognition of the dangers of loss of beach front flora has caused many local authorities responsible for managing coastal areas to restrict beach access points by physical structures or legal sanctions, and fence off foredunes in an effort to protect the flora. These measures are often associated with the construction of structures at these access points to allow traffic to pass over or through the dunes without causing further damage.

Concentration of runoff

Beaches provide a filter for runoff from the coastal plain. If the runoff is naturally dispersed along the beach, water borne silt and organic matter will be retained on the land and will feed the flora in the coastal area. Runoff that is dispersed along the beach will tend to percolate through the beach and may emerge from the beach at low tide.

The retention of the freshwater may also help to maintain underground water reserves and will resist salt water incursion. If the surface flow of the runoff is diverted and concentrated by drains that create constant flows over the beach above the sea or river level, the beach will be eroded and ultimately form an inlet unless longshore flows deposit sediments to repair the breach.

Once eroded, an inlet may allow tidal inflows of salt water to pollute areas inland from the beach and may also affect the quality of underground water supplies and the height of the water table.

Deprivation of runoff

Some flora naturally occurring on the beach head requires freshwater runoff from the land. Diversion of freshwater runoff into drains may deprive these plants of their water supplies and allow sea water incursion, increasing the saltiness of the groundwater. Species that are not able to survive in salt water may die and be replaced by mangroves or other species adapted to salty environments.

Inappropriate beach nourishment

Beach nourishment is the importing and deposition of sand or other sediments in an effort to restore a beach that has been damaged by erosion. Beach nourishment often involves excavation of sediments from riverbeds or sand quarries. This excavated sediment may be substantially different in size and appearance to the naturally occurring beach sand.

In extreme cases, beach nourishment may involve placement of large pebbles or rocks in an effort to permanently restore a shoreline subject to constant erosion and loss of foreshore. This is often required where the flow of new sediment caused by the longshore current has been disrupted by construction of harbors, breakwaters, causeways or boat ramps, creating new current flows that scour the sand from behind these structures and deprive the beach of restorative sediments. If the causes of the erosion are not addressed, beach nourishment can become a necessary and permanent feature of beach maintenance.

During beach nourishment activities, care must be taken to place new sediments so that the new sediments compact and stabilize before aggressive wave or wind action can erode them. Material that is concentrated too far down the beach may form a temporary groyne that will encourage scouring behind it. Sediments that are too fine or too light may be eroded before they have compacted or been integrated into the established vegetation. Foreign unwashed sediments may introduce flora or fauna that are not usually found in that locality.

Brighton Beach, on the south coast of England, is a shingle beach that has been nourished with very large pebbles in an effort to withstand the erosion of the upper area of the beach. These large pebbles made the beach unwelcoming for pedestrians for a period of time until natural processes integrated the naturally occurring shingle into the pebble base.

Use for recreation

History

Even in Roman times, wealthy people spent their free time on the coast. They also built large villa complexes with bathing facilities (so-called maritime villas) in particularly beautiful locations. Excavations of Roman architecture can still be found today, for example on the Amalfi Coast near Naples and in Barcola in Trieste.^[8]

The development of the beach as a popular leisure resort from the mid-19th century was the first manifestation of what is now the global tourist industry. The first seaside resorts were opened in the 18th century for the aristocracy, who began to frequent the seaside as well as the then fashionable spa towns, for recreation and health.^[9] One of the earliest such seaside resorts, was Scarborough in Yorkshire during the 1720s; it had been a fashionable spa town since a stream of acidic water was discovered running from one of the cliffs to the south of the town in the 17th century.^[9] The first rolling bathing machines were introduced by 1735.

The opening of the resort in Brighton and its reception of royal patronage from King George IV, extended the seaside as a resort for health and pleasure to the much larger London market, and the beach became a centre for upper-class pleasure and frivolity. This trend was praised and artistically elevated by the new romantic ideal of the picturesque landscape; Jane Austen‘s unfinished novel Sanditon is an example of that. Later, Queen Victoria‘s long-standing patronage of the Isle of Wight and Ramsgate in Kent ensured that a seaside residence was considered as a highly fashionable possession for those wealthy enough to afford more than one home.

Seaside resorts for the working class

The extension of this form of leisure to the middle and working classes began with the development of the railways in the 1840s, which offered cheap fares to fast-growing resort towns. In particular, the completion of a branch line to the small seaside town of Blackpool from Poulton led to a sustained economic and demographic boom. A sudden influx of visitors, arriving by rail, led entrepreneurs to build accommodation and create new attractions, leading to more visitors and a rapid cycle of growth throughout the 1850s and 1860s.^[10]

The growth was intensified by the practice among the Lancashire cotton mill owners of closing the factories for a week every year to service and repair machinery. These became known as wakes weeks. Each town’s mills would close for a different week, allowing Blackpool to manage a steady and reliable stream of visitors over a prolonged period in the summer. A prominent feature of the resort was the promenade and the pleasure piers, where an eclectic variety of performances vied for the people’s attention. In 1863, the North Pier in Blackpool was completed, rapidly becoming a centre of attraction for upper class visitors. Central Pier was completed in 1868, with a theatre and a large open-air dance floor.^[11]

Many of the popular beach resorts were equipped with bathing machines, because even the all-covering beachwear of the period was considered immodest. By the end of the century the English coastline had over 100 large resort towns, some with populations exceeding 50,000.^[12]

Expansion around the world

The development of the seaside resort abroad was stimulated by the well-developed English love of the beach. The French Riviera alongside the Mediterranean had already become a popular destination for the British upper class by the end of the 18th century. In 1864, the first railway to Nice was completed, making the Riviera accessible to visitors from all over Europe. By 1874, residents of foreign enclaves in Nice, most of whom were British, numbered 25,000. The coastline became renowned for attracting the royalty of Europe, including Queen Victoria and King Edward VII.^[13]

Continental European attitudes towards gambling and nakedness tended to be more lax than in Britain, so British and French entrepreneurs were quick to exploit the possibilities. In 1863, Charles III, Prince of Monaco, and François Blanc, a French businessman, arranged for steamships and carriages to take visitors from Nice to Monaco, where large luxury hotels, gardens and casinos were built. This area of Monaco was then renamed Monte Carlo after prince Charles III.^[14]

Commercial sea bathing spread to the United States and parts of the British Empire by the end of the 19th century. The first public beach in the United States was Revere Beach, which opened in 1896. During that same time, Henry Flagler developed the Florida East Coast Railway, which linked the coastal sea resorts developing at St. Augustine, FL and Miami Beach, FL, to winter travelers from the northern United States and Canada on the East Coast Railway. By the early 20th century surfing was developed in Hawaii and Australia; it spread to southern California by the early 1960s. By the 1970s cheap and affordable air travel led to the growth of a truly global tourism market which benefited areas such as the Mediterranean, Australia, South Africa, and the coastal Sun Belt regions of the United States.

Today

Beaches can be popular on warm sunny days. In the Victorian era, many popular beach resorts were equipped with bathing machines because even the all-covering beachwear of the period was considered immodest.^[15] This social standard still prevails in many Muslim countries. At the other end of the spectrum are topfree beaches and nude beaches where clothing is optional or not allowed. In most countries social norms are significantly different on a beach in hot weather, compared to adjacent areas where similar behavior might not be tolerated and might even be prosecuted.^{[clarification needed]}

In more than thirty countries in Europe, South Africa, New Zealand, Canada, Costa Rica, South America and the Caribbean, the best recreational beaches are awarded Blue Flag status, based on such criteria as water quality and safety provision. Subsequent loss of this status can have a severe effect on tourism revenues.

Beaches are often dumping grounds for waste and litter, necessitating the use of beach cleaners and other cleanup projects. More significantly, many beaches are a discharge zone for untreated sewage in most underdeveloped countries; even in developed countries beach closure is an occasional circumstance due to sanitary sewer overflow. In these cases of marine discharge, waterborne disease from fecal pathogens and contamination of certain marine species are a frequent outcome.

Artificial beaches

Some beaches are artificial; they are either permanent or temporary (For examples, see Copenhagen, Hong Kong, Manila, Monaco, Nottingham, Paris, Rotterdam, Singapore, Tianjin, and Toronto).

The soothing qualities of a beach and the pleasant environment offered to the beachgoer are replicated in artificial beaches, such as “beach style” pools with zero-depth entry and wave pools that recreate the natural waves pounding upon a beach. In a zero-depth entry pool, the bottom surface slopes gradually from above water down to depth. Another approach involves so-called urban beaches, a form of public park becoming common in large cities. Urban beaches attempt to mimic natural beaches with fountains that imitate surf and mask city noises, and in some cases can be used as a play park.

Beach nourishment involves pumping sand onto beaches to improve their health. Beach nourishment is common for major beach cities around the world; however the beaches that have been nourished can still appear quite natural and often many visitors are unaware of the works undertaken to support the health of the beach. Such beaches are often not recognized by consumers as artificial. A famous example of beach nourishment came with the replenishment of Waikīkī Beach in Honolulu, Hawaii, where sand from Manhattan Beach, California was transported via ship and barge throughout most of the 20th century in order to combat Waikiki’s erosion problems. The Surfrider Foundation has debated the merits of artificial reefs with members torn between their desire to support natural coastal environments and opportunities to enhance the quality of surfing waves. Similar debates surround beach nourishment and snow cannon in sensitive environments.

Restrictions on access

Further information: Freedom to roam

Public access to beaches is restricted in some parts of the world.^[16][17] For example, most beaches on the Jersey Shore are restricted to people who can purchase beach tags.^[18] Many beaches in Indonesia, both private and public, require admission fees.^[19] Some beaches also restrict dogs for some periods of the year.^[20]

Private beaches

Main article: Intertidal zone § Legal issues

Some jurisdiction make all beaches public by law. Some allow private ownership (for example by owners of abutting land or neighborhood associations) to the mean high tide line or mean low tide line. In some jurisdictions, the public has a general easement to use privately-owned beach land for certain purposes. Signs are sometimes posted where public access ends.

In some places, such as Florida, it is not always clear which parts of a beach are public or private.^[21]

Public beaches

The first public beach in the United States opened on 12 July 1896, in the town of Revere, Massachusetts, with over 45,000 people attending on the opening day. The beach was run bay the Metropolitan Parks Commission and the new beach had a bandstand, public bathhouses, shade pavilions, and lined by a broad boulevard that ran along the beach.^[22]

Public access to beaches is protected by law in the U.S. state of Oregon, thanks to a 1967 state law, the Oregon Beach Bill, which guaranteed public access from the Columbia River to the California state line, “so that the public may have the free and uninterrupted use”.^[23] Public access to beaches in Hawaii (other than those owned by the U.S. federal government) is also protected by state law.^[24]

Access design

Beach access is an important consideration where substantial numbers of pedestrians or vehicles require access to the beach. Allowing random access across delicate foredunes is seldom considered good practice as it is likely to lead to destruction of flora and consequent erosion of the fore dunes.

A well-designed beach access should:

• provide a durable surface able to withstand the traffic flow;
• aesthetically complement the surrounding structures and natural landforms;
• be located in an area that is convenient for users and consistent with safe traffic flows;
• be scaled to match the traffic flow (i.e. wide and strong enough to safely carry the size and quantity of pedestrians and vehicles intended to use it);
• be maintained appropriately; and
• be signed and lit to discourage beach users from creating their own alternative crossings that may be more destructive to the beachhead.

Concrete ramp or steps

A concrete ramp should follow the natural profile of the beach to prevent it from changing the normal flow of waves, longshore currents, water and wind. A ramp that is below the beach profile will tend to become buried and cease to provide a good surface for vehicular traffic. A ramp or stair that protrudes above the beach profile will tend to disrupt longshore currents creating deposits in front of the ramp, and scouring behind. Concrete ramps are the most expensive vehicular beach accesses to construct requiring use of a quick-drying concrete or a cofferdam to protect them from tidal water during the concrete curing process. Concrete is favored where traffic flows are heavy and access is required by vehicles that are not adapted to soft sand (e.g. road registered passenger vehicles and boat trailers). Concrete stairs are commonly favored on beaches adjacent to population centers where beach users may arrive on the beach in street shoes, or where the foreshore roadway is substantially higher than the beach head and a ramp would be too steep for safe use by pedestrians. A composite stair ramp may incorporate a central or side stair with one or more ramps allowing pedestrians to lead buggies or small boat dollies onto the beach without the aid of a powered vehicle or winch. Concrete ramps and steps should be maintained to prevent a buildup of moss or algae that may make their wet surfaces slippery and dangerous to pedestrians and vehicles.

Corduroy (beach ladder)

A corduroy road or beach ladder (or board and chain) is an array of planks (usually hardwood or treated timber) laid close together and perpendicular to the direction of traffic flow, and secured at each end by a chain or cable to form a pathway or ramp over the sand dune. Corduroys are cheap and easy to construct and quick to deploy or relocate. They are commonly used for pedestrian access paths and light duty vehicular access ways. They naturally conform to the shape of the underlying beach or dune profile, and adjust well to moderate erosion, especially longshore drift. However, they can cease to be an effective access surface if they become buried or undermined by erosion by surface runoff coming from the beach head. If the corduroy is not wide enough for vehicles using it, the sediment on either side may be displaced creating a spoon drain that accelerates surface runoff and can quickly lead to serious erosion. Significant erosion of the sediment beside and under the corduroy can render it completely ineffective and make it dangerous to pedestrian users who may fall between the planks.

Fabric ramp

Fabric ramps are commonly employed by the military for temporary purposes where the underlying sediment is stable and hard enough to support the weight of the traffic. A sheet of porous fabric is laid over the sand to stabilize the surface and prevent vehicles from bogging. Fabric Ramps usually cease to be useful after one tidal cycle as they are easily washed away, or buried in sediment.

Foliage ramp

A foliage ramp is formed by planting resilient species of hardy plants such as grasses over a well-formed sediment ramp. The plants may be supported while they become established by placement of layers of mesh, netting, or coarse organic material such as vines or branches. This type of ramp is ideally suited for intermittent use by vehicles with a low wheel loading such as dune buggies or agricultural vehicles with large tyres. A foliage ramp should require minimal maintenance if initially formed to follow the beach profile, and not overused.

Gravel ramp

A gravel ramp is formed by excavating the underlying loose sediment and filling the excavation with layers of gravel of graduated sizes as defined by John Loudon McAdam. The gravel is compacted to form a solid surface according to the needs of the traffic. Gravel ramps are less expensive to construct than concrete ramps and are able to carry heavy road traffic provided the excavation is deep enough to reach solid subsoil. Gravel ramps are subject to erosion by water. If the edges are retained with boards or walls and the profile matches the surrounding beach profile, a gravel ramp may become more stable as finer sediments are deposited by percolating water.

Longest beaches

Amongst the world’s longest beaches are:

• Praia do Cassino (240 kilometres [150 mi]) in Brazil;^[25]
• Eighty Mile Beach (220 kilometres [140 mi]) in north-west Australia;
• The Jersey Shore (204 kilometres [127 mi]) in New Jersey;
• Padre Island beach (about 182 kilometres [113 mi]) in the Gulf of Mexico, Texas.
• Ninety Mile Beach, Victoria (151 kilometres [94 mi]) in Victoria, Australia;
• Cox’s Bazar, Bangladesh (150 kilometres [93 mi]) in Bangladesh;
• Naikoon Provincial Park (100 kilometres [62 mi]) in the north-east of Haida Gwaii, Canada;
• Playa Novillera beach (about 90 kilometres [56 mi]) in Mexico.
• 90 Mile Beach (88 kilometres [55 mi]) in New Zealand;
• Fraser Island beach (about 65 kilometres [40 mi]) in Queensland, Australia;
• Troia-Sines Beach (63 kilometres [39 mi]) in Portugal;
• Long Beach, Washington (which is about 40 kilometres [25 mi]).

Wildlife

Main article: Seashore wildlife

A beach is an unstable environment that exposes plants and animals to changeable and potentially harsh conditions. Some animals burrow into the sand and feed on material deposited by the waves. Crabs, insects and shorebirds feed on these beach dwellers. The endangered piping plover and some tern species rely on beaches for nesting. Sea turtles also bury their eggs in ocean beaches. Seagrasses and other beach plants grow on undisturbed areas of the beach and dunes.

Ocean beaches are habitats with organisms adapted to salt spray, tidal overwash, and shifting sands. Some of these organisms are found only on beaches. Examples of these beach organisms in the southeast US include plants like sea oats, sea rocket, beach elder, beach morning glory (Ipomoea pes-caprae), and beach peanut, and animals such as mole crabs (Hippoidea), coquina clams (Donax), ghost crabs, and white beach tiger beetles.^[3]