The main causes of beach erosion are as follows:
- Reduction in sediment supply from eroding cliffs.
- Reduction of fluvial sediment supply to the coast.
- Reduction of sediment supply from the sea floor.
- Reduction of sand supply from inland dunes.
What is beach erosion and how does it occur?
Beach Erosion. Erosion is the removal of soil and sand by the forces of wind and water and it has occurred for as long as land has met water. Erosion is a continual natural process; material is constantly being shifted around to change the shape of a stream, riverbank, or beach. Today, when much available land bordering the ocean (coastlines)...
What happens to a beach when there is a storm?
Storm waves carry more energy than calm waves, and can quickly wear away beach material. For all the sand lost from a beach, the action of the waves also brings an equal amount of sand ashore. Thus, although the shape of a beach will change, the beach itself will remain.
What geologic formation is a beach?
A beach is a geologic formation that is located along a large body of water, including lakes, rivers, and oceans. Beaches are characterized by the presence of tiny pieces of organic sediment. The sediments may be composed of sand, rock, shell, algae, or pebbles. Natural beaches may take thousands of years to evolve,...
How can we prevent beach erosion?
A strategy that scientists are evaluating to reduce erosion is to build up the bottom of the ocean farther out from the beach, creating an off-shore ridge with sand and materials such as steel from aircraft and ships, or stone. Incoming waves break over the ridge of piled up material instead of breaking on the beach.
How do beaches get eroded?
Coastal erosion occurs when the waves that lap at the coast slowly wear away at the shoreline. As these waves wash over the shore, they carry sand and sediment with them and redistribute it to the ocean floor or to other areas. Erosion can be worsened by factors such as high winds, wave currents, and tidal currents.
What are 3 main causes of beach erosion?
The main causes of beach erosion are as follows:Reduction in sediment supply from eroding cliffs.Reduction of fluvial sediment supply to the coast.Reduction of sediment supply from the sea floor.Reduction of sand supply from inland dunes.Submergence and increased wave attack.More items...•
Are beaches eroding?
Leatherman cites U.S. Environmental Protection Agency estimates that between 80 and 90 percent of the sandy beaches along America's coastlines have been eroding for decades. In many of these cases, individual beaches may be losing only a few inches per year, but in some cases the problem is much worse.
Do beaches erode naturally?
Although erosion is a natural process and does not completely remove a beach, scientists are concerned about beach erosion because human activities have altered the way erosion occurs. Coastlines are attractive places and many people want to live or visit there.
Which is most likely to cause beach erosion?
Storm surge and high waves are likely to cause beach erosion along nearly 80% of sandy beaches and overwash about 50% of the dunes from Florida through North Carolina.
Why do beaches disappear?
A problem that has plagued most coastal regions is the fast rate of erosion. This problem has been hastened by climate change, prompting stronger and more frequent storms that cause more sand to retreat into the ocean. According to a 2020 study, half of the beaches worldwide will disappear by the end of the century.
Why do beaches lose sand?
Often, they change drastically during the year, depending upon the frequency of storms. Ultimately, a beach erodes because the supply of sand to the beach can not keep up with the loss of sand to the sea. Most sand is transported from inland via rivers and streams.
What are the impacts of beach erosion?
Beach erosion is one of the most common impacts of extreme storm events, as elevated wave energy, in combination with winds, currents and elevated water levels drive sediment offshore from shallow to deeper waters.
Why is passive erosion common on armored beaches?
Passive erosion occurs on armored beaches and, because seawalls arrest the landward retreat of the shoreline in the face of erosion, the beach seaward of the structure is frequently drowned ( Hall and Pilkey, 1991; Griggs, 2005 ).
What causes groundwater to be salinized?
This can cause salinization of the groundwater, which may be intensified by the hardening of surfaces, so that surface water from rain is diverted to storm water drains, instead of sinking into the soil.
What are the impacts of intertidal seawalls?
Intertidal seawalls and other structures that reflect wave energy and constrain the natural landward migration of the shoreline have unplanned environmental impacts, such as flanking erosion of shorelines adjacent to those protected by engineering structures ( Hall and Pilkey, 1991; Griggs, 2005 ).
How does damming rivers affect erosion?
Damming of rivers is resulting in increased rates of coastal erosion by depriving estuaries and shorelines of natural fluvial input of sediment. In 1950 there were 5270 large dams in the world, whereas there are currently almost 60,000 ( ICOLD, 2017 ).
What are the different types of coral reefs?
Coral reef ecosystems usually exist in clear water and can be classified to show different forms of coral reef, dead coral, coral rubble, algal cover, and sand lago ons and different densities of seaweeds, for example. SAV may grow in more turbid waters, thus it is more difficult to map.
What is suspended sediment?
Suspended sediment is considered a portion of sediment matter that includes sand, silt, clay, and such from discharges of coastal and inland sources that are mixed and transported to various parts of the shoreline through littoral currents, waves, tides, winds, and other hydrodynamic processes ( Nair et al., 1993; Jennerjahn et al., 2008; Narendra Babu et al., 2010; Tripathy et al., 2018 ). In general, the large amount of suspended sediments accumulates more within the shallow depth of nearshore than offshore region and influences morphological changes in the coastal and marine environment ( Carpenter and Carpenter, 1983; Mertes et al., 1993; Qu, 2014; Larson et al., 2018; Kaliraj et al., 2019a, b ). In the coastal systems, suspended sediments transporting and dispersing is regulated mainly through hydrodynamic processes including littoral current, tidal fluctuation, wave height, and wind direction, and it tends to create erosion and accretion processes ( Forget and Ouillon, 1998; Doxaran et al., 2002; Wackerman et al., 2017 ). Suspended sediments provide input sources for physical, chemical, and biological activities, and for regulating nutrient availability and formation of coastal landforms.
What are beach deposits?
Beach deposits predominantly consist of sand particles that can be easily eroded by waves. These deposits comprise terrestrial sediment delivered to the coast by rivers, sediment produced by the erosion of coastal landforms by waves, and marine sediment that has been reworked from offshore deposits onto the coast.
What causes erosion of dunes?
2. Climate change related to global warming. An increase in the frequency of major coastal storms or a rise in relative sea level can accelerate shoreline erosion and also trigger the erosion of dunes immediately behind the beach.
What are the cycles of erosion and accretion?
Natural cycles of erosion and accretion. Sandy beaches are dynamic sedimentary systems that naturally experience phases of erosion and accretion that operate over a range of time intervals 3. Frequent short-term changes are seasonal – erosion mostly occurs in seasons when storms that generate erosional wave regimes are more frequent.
Why is the volume of fluvial sediment supplied to beaches, however, may be quite small compared to the volume
The volume of fluvial sediment supplied to beaches, however, may be quite small compared to the volume being moved to the coast because sediment is often trapped in tide-dominated and wave-dominated estuaries, which act as sediment sinks.
What are the long term trends in beach morphology?
Long term trends in beach morphology are also related to changes in sea level, which can induce phases of erosion (rising sea level) and accretion (falling sea level).
How is sand transported along the coast?
In contrast, in regions with a more regular coastline, sand can be transported many hundreds of kilometres along the coast by oblique waves and shore parallel currents, forming a corridor of sediment transportation ( e.g. northern coast of NSW, SE Queensland). Photo 1.
How long does it take for a beach to recover from a storm?
Beach accretion, however, is generally a much slower process than beach erosion. For example, it may take several years for a beach to return to its pre-storm condition after one major storm or several smaller storms in quick succession 3.
What causes erosion on the beach?
Factors that can increase beach erosion: 1 Increased wave action due to armor on neighboring property 2 Removal of beach vegetation 3 Onsite beach armoring causing scouring
What factors increase beach erosion?
Factors that can increase beach erosion: On beaches, native plants and drift logs help dissipate wave energy. Without the interference of bulkheads and seawalls, beaches will usually erode gradually but will also be replenished by sand and sediment from nearby bluffs and beaches.
What are sand spits made of?
Sand spits, which are made of fine sediment deposited by the currents , can also be subject to heavy erosion and flooding. Photo: Hugh Shipman Enlarge 1 of 3. Photo: Hugh Shipman Enlarge 2 of 3. Photo: Hugh Shipman Enlarge 3 of 3.
What happens when waves reflect off a beach?
And when waves reflect off a bulkhead, they scour the area at its base and on adjoining beaches. Over time, an entire stretch of beach will become coarser, with less sediment and more gravel. The bulkhead could also eventually crack, tilt, or collapse.
What can a coastal professional do to protect your property?
A qualified coastal professional can evaluate erosion risk on your beach and suggest measures you can take to protect your property. “The onsite visit was a real eye-opener. You can read about shoreline management and even study about it, but unless things are physically pointed out nothing really changes.
Do bulkheads cause erosion?
Ironically, bulkheads can lead to more rapid erosion of beaches in some cases. While these structures can provide some erosion protection on your property, they contribute to overall beach loss by reducing the sediment supply.
What is beach erosion?
Beach”) of the National Healthy Beaches Campaign, beach erosion is defined by the actual removal of sand from a beach to deeper water offshore or alongshore into inlets, tidal shoals and bays.
How much did Miami spend on adding sand to the beach?
In the early 1980s, the city of Miami spent some $65 million adding sand to a 10-mile stretch of fast-eroding shoreline.
How much did Miami spend on sand?
In the early 1980s, the city of Miami spent some $65 million adding sand to a 10-mile stretch of fast-eroding shoreline. Not only did the effort stave off erosion, it helped revitalize the tony South Beach neighborhood and rescue hotels, restaurants and shops there that cater to the rich and famous.
How does rainfall affect the ocean?
Changes in rainfall may alter when and how much sediment washes down rivers to the sea. Changes in sea level, seawater temperature, and other ocean dynamics may change how much the ocean contributes to the erosion of beaches.
What are the factors that influence sand delivery?
Sand delivery is influenced by a variety of oceanic conditions, including wave strength and direction, storms, and the shape of the seafloor. It also is influenced by streams and rivers, which carry sediment from inland sources to the beach.
Why do we need to remove dams from coastal waterways?
Removing dams from coastal waterways is a management action that will help replenish sandy beaches eroding due to sea level rise. Rivers and streams carry sediment from the land to the sea, naturally replenishing beaches.
What are beaches made of?
Beaches are composed of deposited sediments including sand, rocks, shells, algae, or pebbles. A beach is a geologic formation that is located along a large body of water, including lakes, rivers, and oceans. Beaches are characterized by the presence of tiny pieces of organic sediment. The sediments may be composed of sand, rock, shell, algae, ...
Why are beaches in recession?
Additionally, these storms take out most of the vegetation along shorelines that normally helps keep sand in place. Rising sea levels, that occur as a result of global climate change, also result in beach recession. Human activity may also contribute to beach recession.
How does urban development affect the amount of erodible land found near bodies of water?
Urban development, dam projects, and rerouting rivers may reduce the amount of erodible land found near bodies of water. As these human activities progress, the sediment found suspended in the waves is reduced. With less sediment in the water, fewer particles are deposited along the beach, resulting in recession.
How does human activity contribute to beach recession?
This means that waves require access to material that can be eroded and turned into sediment that can later be deposited along coastlines.
Why are sandy beaches different from rocky beaches?
Sandy beaches are often characterized by their slowly sloping profile, whereas rocky beaches tend to exhibit more extreme slope angles. This difference in slope is because of the difference in particle size. The larger particles on rocky beaches, for example, cause the waves to lose their power more quickly.
Why is sediment found closer to the water?
For example, finer sediment is found closer to the water. This is partially because the moving water constantly breaks down the particles located here. As the beach moves further inland, the particles along its surface grow in size.
What are the two types of waves that prevent erosion?
Constructive waves, which are those that allow the water to recede and the beach particles to stop moving between waves, result in compacted sediment. This firm beach surface prevents future erosion. Destructive waves, which are fast forming and do not allow the water to recede between waves, result in a near-constant state ...
Problems Caused by Erosion
- Although erosion is a natural process and does not completely remove a beach, scientists are concerned about beach erosion because human activities have altered the way erosion occurs. Coastlines are attractive places and many people wantto live or visit there. Many beaches are no…
Carolina Outer Banks
- The Outer Banks are series of dunes that stretch for 130 miles (209 kilometers) in the sea off the coast of North Carolina. Among the well-known attractions of the Outer Banks is Kitty Hawk, site of Orville and Wilbur Wright's famous 1903 flight, and a series of distinctive lighthouses. The Cape Hatteras lighthouse is also an example of the power of erosion. When the lighthouse was built i…
Development and Erosion
- The desire for a home right on the ocean has lead many people to literally build their houses on top of sand dunes, which are hills of sand heaped up by the wind. Dunes are not permanent structures; they naturally wear away. To attempt to reduce erosion, people have built structures like seawalls and narrow stripsthat jut out into the water (a groyne). These structures break the …
Coastal Development Laws and Acts
- The need to protect coastlines from erosion and overdevelopment has lead the United States to enact various rules and regulations. In 1972 the federal governmentcreated the Coastal Zone Management Act. This voluntary program helped encourage coastal states to make changes that would help protect beaches by sharing the cost of some of this development. In the years since …
Reducing Beach Erosion
- Many areas have passed laws to prevent the destruction of sand dunes, which serve as a natural protective barrier against erosion during storms. Where sand dunes are destroyed by humans or erosion, artificial barriers of wire or tree limbs secured in dune-forming areas help to speed their formation. Protected dunes along seashores are rich in plant life, which serves to further strengt…
For More Information
- Books
Cambers, Gillian. Coping with Beach Erosion. Paris: United NationsEducational, Scientific and Cultural Organization, 1998. Douglas, Scott L. Saving America's Beaches: The Causes of and Solutions to Beach Erosion.Singapore: World Scientific Publishing Company, 2002. Steele, Philip … - Websites
DeVitt, Terry. "Beach Erosion." The Why Files.http://whyfiles.org/091beach/credits.html(accessed on September 7, 2004).
Geological Background
Natural Cycles of Erosion and Accretion
- Sandy beaches are dynamic sedimentary systems that naturally experience phases of erosion and accretion that operate over a range of time intervals3. Frequent short-term changes are seasonal – erosion mostly occurs in seasons when storms that generate erosional wave regimes are more frequent. Rapid erosional episodes may also be produced by high-magnitude storms, such as tr…
Relevant Indicators
- Changes in the following parameters may indicate that a beach is being eroded or is at risk for erosion: 1. a reduction in beach and dune areas(measured by remote sensing techniques); 2. a reduction in protective vegetation on dunes9; The cost of beachrehabilitation can be estimated from: 1. the number and dollar costs of beach nourishment programs9; and 2. the number and a…
More Information
- NSW Government. Office of Environment & Heritage – Coastal Management, 2003. Western Australia Government, 2003. https://catalogue.data.wa.gov.au/. UNESCO, 2003, Coping with beach erosion. USGS, 2003. News and information on El Nino. Landform and Stability module More information on habitat removal/disturbance.
Author
- Brendan Brooke, Geoscience Australia 1. Roy, P.S., Cowell, P.J, Ferland, M.A. and Thom, B.G., 1994. Wavedominated coasts. In: Carter, R.W.G. and Woodroffe, C.D., (Eds.), Coastal Evolution. Cambridge University Press, Cambridge, pp 121-186 2. Murray-Wallace, C.V., Banerjee, D., Bourman, R.P., Olley, J.M., and Brooke, B.P., 2002. Optically stimulated luminescence dating of H…