what are the causes of beach erosion

What are 3 main causes of beach erosion?

What are the causes and effects of beach erosion?

What are 5 causes of coastal erosion?

What causes erosion?

What causes coastal erosion for kids?

What are the 6 types of erosion?

What are the 4 types of coastal erosion?

What are 4 types of erosion?

Abstract

Before renourishing an eroded beach it is necessary to know why it has been eroded and where the sediment has gone: landward, seaward or alongshore. This chapter deals with the causes of beach erosion, including alterations in processes and sediment supply, along with anthropogenic influences.

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What causes erosion on the beach?

Beach erosion is usually caused by ocean currents and waves. The energy of the moving water pulls sand away from the shore. High winds speed up erosion. Building along the coast can damage sand dunes, which are mounds of sand that separate the lower beach from higher ground.

What causes coastal erosion?

Coastal erosion may be caused by hydraulic action, abrasion, impact and corrosion by wind and water, and other forces, natural or unnatural. On non-rocky coasts, coastal erosion results in rock formations in areas where the coastline contains rock layers or fracture zones with varying resistance to erosion.

What are the causes of beach erosion?

Natural and human-related causes of beach erosion are discussed and illustrated by examples. Sea level rise, trapping of sand by natural inlets and migration of natural inlets are the most pervasive natural causes. Construction of navigation works, followed by reduction in sediment delivery to the coast and subsidence induced by ground fluid extraction are the most prevalent human-related causes. Application of the Bruun Rule to sea level rise is discussed including its limitations and extensions to include beach nourishment and barrier islands. Prediction of shoreline changes caused by natural phenomena on decadal scales can only be accurately calculated with historical data. However, predictions of shoreline and volume changes due to human-induced effects such as construction of a littoral barrier or a beach nourishment project can reasonably be calculated with analytical and numerical models. Societal responses to beach erosion are expensive and limited to: retreat, stabilization with structures, nourishment and combinations of the last two. Each beach is unique thus placing a need to understand the cause of the erosion, develop a prognosis for “without response” conditions and prescribe the best approach for the future. Fortunately, long-term shoreline changes are available in some areas as are the effectiveness of some stabilization projects to guide this process. It is concluded that it will be possible to maintain some highly developed areas for one or two centuries with available technology and resources. Some areas will undoubtedly require abandonment within this period.

How do coastal defences affect erosion?

Coastal defences have long been employed to halt or slow coastal erosion. Their impact on local sediment flux and ecology has been studied in detail through field studies and numerical simulations. The non-local impact of a modified sediment flux regime on mesoscale erosion and accretion has received less attention. Morphological changes at this scale due to defended structures can be difficult to quantify or identify with field data. Engineering scale numerical models, often applied to assess the design of modern defences on local coastal erosion, tend not to cover large stretches of coast and are rarely applied to assess the impact of older structures. We extend previous work to explore the influences of sea walls on the evolution and morphological sensitivity of a pinned, soft-cliff, sandy coastline under a changing wave climate. The Holderness coast of East Yorkshire, UK, is used as a case study, represented both as a defended example with major sea walls included and a natural example where no sea defences exist. Using a mesoscale numerical coastal evolution model, stochastic wave climate data are perturbed gradually to assess the sensitivity of the coastal morphology to changing wave climate for both the defended and natural scenarios. Comparative analysis of the simulated output suggests that sea walls in the south of the region have a greater impact on sediment flux due to the increased sediment availability along this part of the coast. Multiple defended structures, including those separated by several kilometres, were found to interact with each other, producing a complex imprint on coastal morphology under a changing wave climate. Although spatially and temporally heterogeneous, sea walls generally slowed coastal recession and accumulated sediment on their up-drift side.

What are the techniques used to determine low frequency rhythmic patterns in the shoreline?

Time series analysis techniques that include parametric spectra, autocorrelation, and cross correlation are utilized to identify low frequency rhythmic patterns in the shoreline. Nonstationarity and phase shifting of rhythmic patterns is identified via comparison of the shoreline changes for different time intervals. Probability density functions of the shoreline change rates are also investigated and found to be in reasonable accord with Gaussian filtered noise.

How many houses are affected by erosion?

erosion may claim one out of four houses within 500 feet of the U. S. shoreline.” Many

Where is aragonite sand used?

In the first full-scale use in the United States of imported aragonite sand for beach restoration, approximately 23 000 m³ of fill were barged from the Bahamas, placed by truck, and stabilized by seven rock structures along 620 m of shoreline at Fisher Island, Florida. The structures emulate a Mediterranean-style design and are "tuned' to the incident wave field to minimize fill losses and impacts to nearshore sea grass beds. Six-month monitoring results suggest that the project is performing as per predictions. No adverse impacts nor physical decay of the aragonite have been observed to date. -Authors

Which natural causes the most pervasive natural causes?

migration of natural inlets are the most pervasive natural causes. Construction of

Can shore-based predictions be accurately calculated?

only be accurately calculated with historical data. However, predictions of shore-

How does beach erosion occur?

Beach erosion can be manifested by the complete overwash of the subaerial beach, usually associated with high tides and large wave set-ups. With lower water levels and short period waves, near-vertical cuts or scarps can be formed (Dean and Dalrymple, 2004; Anthony, 2009; Buynevich et al., 2011 ). Straight beach scarps have been observed along eroding dissipative beaches and can also form along embayments of highly rhythmic shorelines on intermediate beaches ( Short, 2001 ). These features can be detected from measured cross-shore beach profiles, and their spatio-temporal evolution will depend on the incoming wave energy and water levels ( Ruiz de Alegria-Arzaburu et al., 2013; De Schipper et al., 2017 ). While these features are indicative of erosive conditions, they can be very temporary, and disappear as beach erosion continues. Thus, on a seasonal scale, erosive conditions are better represented by high-energy morphodynamic beach states that denote a significant subaerial beach volume loss (see Fig. 20.4 ).

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.

What are groins in beach landforms?

Groins are shore perpendicular structures designed to trap sand moving alongshore ( Fig. 15.16 ). By blocking longshore transport of sediment (see Chapter 2 ), they create differences in beach widths with accretion on the updrift sides and erosion downdrift. Use of groins has tended to decrease relative to shore-parallel structures and beach nourishment, in part because of accelerated erosion on their downdrift sides, yet new groins are still being constructed, often to designs that allow for some bypass of sediment.

What are sandbars in surf zone?

Sandbars are very dynamic morphological features that result from the wave action across the surf zone. They are generally perceived as amplifications on the intertidal or submerged beach profile and contain large amounts of sediment (10s m 3 m −1) that contribute significantly to the sediment balance across the beach ( Holman and Bowen, 1982; Aagaard et al., 2013 ). In an idealised winter erosion sequence commencing with a reflective beach, sandbars form near the shoreline as a low tide terrace (LTT) at the beginning of the high-energy wave season, and their cross-shore movement related to the incoming wave energy. Generally, these features move offshore during high-energy waves, onshore during lower-to-nonbreaking wave conditions and during low-energy conditions can weld to the intertidal beach ( Shepard, 1950; Short, 1999 ). Surfzone sandbars can be remotely detected from video-data ( Holman and Stanley, 2007) or extracted from field measurements ( Vidal-Ruiz and Ruiz de Alegría-Arzaburu, 2019 ), and their cross-shore position and alongshore variability are indicative of the seasonal imprint of the morphodynamics of the beach.

Why are breakwaters important?

Breakwaters are shore-parallel structures built offshore to reduce wave energy or hold beach sand in place ( Fig. 15.16 ). They are more common where wave energy levels and tidal ranges are limited and their size and construction costs can be kept low. Shore-parallel structures built landward of the beach provide a barrier between the dynamic beach and sites of human development. They truncate the landward portion of the beach that would be reworked by storms and restrict or prevent exchanges of sediment and biota between the beach and dunes. These structures prevent the beach from migrating landward in response to sea-level rise or reductions in the sediment budget. They also allow human structures to survive closer to the water than would normally be the case. Unlike groins that rearrange sediment which is being transported by natural processes, shore-parallel structures are designed to resist natural processes and are less environmentally friendly than groins.

How did the Holocene cause erosion?

Natural reduction in sediment supply, driven by global climate change through the Holocene, established a very long-term pattern of beach erosion. In the past this was partly balanced by deforestation for cultivation, grazing, and construction of settlements — which resulted in delivery of vast quantities of sediment to coasts by streams. However, the damming of rivers — which was widespread in the twentieth century — dramatically reversed this trend, resulting in increased rates of erosion. The damming of rivers deprives estuaries and the shoreline of natural fluvial input of sediment. In 1950, there were 5,270 large dams in the world, whereas there are currently more than 36,000 (World Resources Institute 1998). Construction of dams has been a significant cause of coastal erosion in many locations throughout the world. It is diificult, however, to determine the magnitude of this impact or to distinguish between the effects of the dams and effects of associated activities such as quarrying, land reclamation, urbanization, aforestation, and agricultural use (Nordstrom 2000, Shesma et al. 2002).

How does water abstraction affect the water table?

In addition to pollution of groundwater, water abstraction from dunes commonly results in a lowering of the water table. One such activity is the drawing off of water for domestic or agricultural purposes. 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. Lowering of the water table can have serious adverse effects on the dune ecosystem, which in turn may affect the intertidal beach. Whereas flooding or raising the water table hastens beach erosion, extraction of groundwater can lead to subsidence, local increases in sea-level rise, and increased rates of beach loss ( Nicholls and Leatherman, 1996) or even accretion. Artificial recharge with water from other sources may add nutrients and disturb the circulation of ground water, leading to unnatural water table fluctuations. Recharge can also occur from watering lawns. Watering and waste water disposal above coastal bluffs can add weight to weaken cliff materials (by solution in some cases) and lubricate surfaces along which slides develop.

What is beach erosion?

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) ...

Why are scientists concerned about beach 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 want to live or visit there. Many beaches are now completely lined by buildings, parking lots, and roads.

How do waves affect beach erosion?

Over a very long period of time, all these tiny events add up to the rearrangement of the beach. Sometimes, beach erosion occurs at a faster rate, as storms bring larger waves that crash more forcefully onto the beach. Storm waves carry more energy than calm waves, and can quickly wear away beach material.

Why did erosion claim so much land?

One of the reasons that erosion claimed so much land was a manmade attempt to stop the process. In the 1970s the United States Navy built two groynes just north of the lighthouse. The groynes were put there to protect a building. Unfortunately, they accelerated the erosion downstream to the point where moving the lighthouse was necessary to save it.

How does wave action affect the ocean?

Wave action can cause erosion that can remove the support for a house, causing it to tumble into the ocean. Along the 80,000 miles (128,748 kilometers) of coastline in the United States, beach erosion has become a big problem. While erosion is a natural process, humans have caused the rate of erosion to increase.

Why did the lighthouse get moved?

To preserve the structure, engineers picked up the lighthouse, put it on a movable treadmill similar to the ones used to transport Apollo spacecraft to the launch pad in the 1970s , and moved the lighthouse further inland. One of the reasons that erosion claimed so much land was a manmade attempt to stop the process.

What is the rocky area where the land meets the ocean?

A beach is the rocky or, most often, sandy zone where the land meets the lake or ocean. This wind also moves the water towards the land, pushing the water to form waves. As the depth of the water decreases towards the beach, the waves change shape. Eventually, the top of the wave crashes over and down onto the beach. Then the water is pulled back out as the next wave makes its way towards the coastline.

What causes sand erosion?

One phenomenon that causes sand erosion is energetic waves that cause turbulence to move the sand below the wave base. In effect, this movement of sand narrows beach width. Another factor affecting the deterioration of sand is “submarine canyons”.

How does a beach evolve?

The primary formation and evolution of a beach comes from the longshore current. These currents run parallel to the shore, causing the waves to strike the beach at an angle. When theses waves break, they drag the sand grains up, then down in a zigzag motion, finally carrying the sand away.

What are the rocks that make up the beach?

The beach is made up of tiny stones and sediments (quartz, granite, feldspar, hornblende, and mica) that are washed from our mountains by wind and weather. These stones and sediments are brought to the beaches by streams, creeks, and rivers. Once the stones and sediments arrival at the beach, they participate in a constant rotation ...

What are the most beautiful beaches in Los Angeles?

Los Angeles County holds some of the most beautiful and popular beaches in the world. They feature cliffs, tidepools, marine life, and hold many recreational opportunities for the millions of people who visits the vast coastline each year. These beaches share a common ecological danger of sand erosion. Due to waves, currents and man-made structures, such as storm drains, the natural process of sand replenishment is hindered.

What are the causes of erosion?

Rain and sheetwash (unconfined flow over the ground surface after rainfall) are important causes of erosion for sloped landforms such as bluffs. Raindrops strike and disturb upland soil particles, which are moved by the flow of water over the slope. Sheetwash progresses and becomes concentrated, potentially forming grooves and rills, (shallow channels) which then widen into gullies. Runoff from these flow channels can reach higher velocities than sheetwash, dislodging and carrying away larger particles.

How does ice affect erosion?

While anchored or stabilized ice can form a protective barrier from erosion, thawed and/or detached ice can be moved onshore or along the shore by wind and waves. This can cause scouring and can damage erosion control structures. Ice can also form impermeable dams along or within coastal landforms, impeding groundwater and surface flow. In addition, ice and moisture can enter cracks of a landform and widen these crevices, allowing additional water to enter. This reduces the landform’s stability and potentially causing slumps and slides along cracks.

What is the transport of sediments in the nearshore?

Littoral (intertidal zone) transport is the movement of sediments in the nearshore by wave action and currents. A lack of sediment within the littoral system contributes to erosion. The quantity, energy and direction of waves and currents along the shore, in proportion to the size and weight of available sediment, determine the capacity of the system to transport littoral sediment.

Why is groundwater seepage important?

Groundwater seepage is an important factor for sloped landforms such as bluffs. Water can fill in voids, adding weight to the landform and potentially causing the sediment to flow from its own and/or accumulated weight. The flow of water throughout a landform can cause seep zones (dark bands of moist soil) and springs, which may lead to rill and gully erosion.

What are the environmental impacts of erosion?

Environmental impacts. Erosion leads to huge deposition of sediments into drains. This may cause drainage problems. Water sources such as rivers, streams, and lakes can be polluted through extensive inputs of pesticides, nitrogen and phosphorous. READ: Water Erosion: Types, Examples and Facts.

How does water affect rock erosion?

Water plays a significant role in rock erosion since it’s able to move these weathered materials from one point to another. Moving water such as currents in oceans or rivers plays a significant role in erosion because they move materials from their primary source to a separate location.

How does erosion work?

Erosion is the wearing away of the earth’s surface by the action of natural forces, for example, water, wind and glacial ice. The loose and dissolved materials move from one location to another. Erosion should not be confused with weathering. Weathering is where rock is broken down and dissolved into tiny particles by chemical, physical and biological processes. Think of weathering as the process of breaking down rock using a hammer. Erosion moves the weathered rock particles to another location by the action of water, wind, ice and gravity. Transport renders the erosion process complete since it’s the part that entails movement of weathered materials and other particles from the source to other locations.

How does erosion move weathered rock?

Erosion moves the weathered rock particles to another location by the action of water, wind, ice and gravity. Transport renders the erosion process complete since it’s the part that entails movement of weathered materials and other particles from the source to other locations.

What is the effect of erosion on transportation?

Erosion leads to massive deposition of sediments on roads, and railways. This may cut off transportation lines. Costs will be incurred in regards to clearing away the deposition on the transport lines to allow transportation to resume.

Why do rivers discolor?

Erosion may discolor rivers as they snake through the valleys to oceans or seas. This is due to the huge amount of sediment deposited by the process of erosion. Once these eroded materials are settled and piled up in a new location, it is referred to as deposition.

What is erosion in science?

What is Erosion? When you stand at a vantage point of space, you’ll be treated to an array of breathtaking landforms. However, these beautiful pieces of nature can only qualify as landforms if nature created them. This means human-made dams, vehicles, and buildings cannot be called landforms. Mountains, hills, plains, plateaus, beaches, sea stacks ...