Select your language

Suggested languages for you:
Log In Start studying!
StudySmarter - The all-in-one study app.
4.8 • +11k Ratings
More than 3 Million Downloads
Free
|
|

All-in-one learning app

  • Flashcards
  • NotesNotes
  • ExplanationsExplanations
  • Study Planner
  • Textbook solutions
Start studying

Coastal Erosion and Deposition

Save Save
Print Print
Edit Edit
Sign up to use all features for free. Sign up now
Coastal Erosion and Deposition

Waves, winds, currents, tides, and storms are the major forces on the coastline. The results of these actions and interactions by natural forces on the shoreline and near-shore seabed are coastal processes, which include erosion and deposition.

What factors are involved in coastal erosion and deposition?

There are several factors involved in coastal erosion and deposition. The main processes are:

Shaping coastlines

Waves are the primary drivers in shaping coastlines. Destructive waves (waves that have a stronger backwash) are the most common types of waves that cause erosion . These waves occur during stormy conditions and are characterised by big, strong waves that have high energy. Constructive waves (with a limited backwash) occur during calmer weather, have low energy, and cause deposition rather than erosion. Because of their characteristics, destructive waves can erode the coastlines in several ways:

  • Hydraulic action – air in cracks in the cliff is compressed when waves crash in. The pressure caused by this action breaks off pieces of rocks.
  • Attrition – bits of rock in water smash against each other and break into smaller pieces.
  • Abrasion – bits of rock and sediment transported by the waves, smash and grind against rocks and cliffs, breaking bits off and smoothing the surface.
  • Corrosionsoluble rocks get gradually dissolved by the seawater.

Coastal formations

The principle marine processes responsible for shaping the coastline are erosion , transportation , and deposition. Erosion is where the force of waves breaks down the land. Transportation is when waves and tides transfer the broken material somewhere else. Meanwhile, deposition is when waves and tides lose their energy, cease transporting the eroded material, and deposit it. Each coastline has its balance between the processes of erosion, transportation, and deposition.

Erosional coastal formations include:

  1. Headlands and bays.
  2. Cliffs and wave-cut platforms.
  3. Stacks and stumps.
  4. Shoreline platforms.

Coastal Erosion and Deposition Stacks and Stumps StudySmarterDuncansby Stacks Image: Bill C CC BY-SA 3.0

When waves no longer have any energy left to transport the sediment, deposition occurs. What features are formed by the sediment will depend on how and where the sediment is deposited.

Depositional coastal formations include:

  1. Spits.
  2. Beaches.
  3. Offshore bars and tombolos.
  4. Cuspate forelands.
  5. Salt marshes and estuarine mudflats.
  6. Sand dunes.

Sediment transportation

The energy provided by waves, tides, and currents transport the eroded material. There are four main processes involved in sediment transportation:

  • Solution – substance that is dissolved and carried along in the water.
  • Saltation – larger particles are too heavy to be carried, so they are bounced along the sea bed.
  • Suspension – this is where very fine material is carried along in the water.
  • Traction – enormous particles are pushed along the sea bed by the force of the water.

These processes can transport sediment along the shore; this is known as longshore drift or littoral drift .

Sediment is moved along the coast in sediment cells. Within each cell, the sediment moves between the beach, cliffs, and the sea through the process of erosion, transportation, and deposition. Any action taken in one place has an impact elsewhere in the cell. Each cell operates between physical barriers that prevent the sediment from moving any further along the coast. There are 11 principal cells along the coastline of England and Wales.

Sub-aerial processes

Sub-aerial processes are land-based processes that alter the shape of the coastline. The main sub-aerial processes are weathering and mass movement.

Weathering

The gradual breakdown of rocks in situ at or close to the ground surface is known as weathering. This can be divided into three different types - mechanical, chemical and biological.

Types of Weathering
Mechanical (physical)Freeze-thaw (frost shattering) Salt weathering (salt crystallisation) Wetting and drying (sea weathering)
Chemical Carbonation
BiologicalPlants WaterMicrobes

Mass movement

This is the movement of materials downslope at a range of speeds. Water acts as the common lubricant involved in mass movement.

Types of mass movement are:

  • Soil creep

  • Solifluction

  • Earth and mudflows

  • Rock falls

  • Rock / debris slides

  • Slumps

Coastal Erosion and Deposition - Key takeaways

  • Constructive and destructive waves are the primary drivers in shaping the coastline.

  • Constructive waves are depositional.

  • Destructive waves are erosive.

  • Destructive waves can erode the coastlines through hydraulic action, corrosion, attrition, abrasion, and corrosion.

  • The four main processes involved in transporting material are solution, saltation, suspension, and traction.

  • The sub-aerial processes involved in shaping the coastline are weathering and mass movement.

Frequently Asked Questions about Coastal Erosion and Deposition

Both coastal erosion and deposition are caused by the action of waves. There are two main types of waves responsible for this, destructive waves and constructive waves

Coastal erosion is the wearing away of land by destructive waves, currents, and wind. As a result of coastal erosion, the shoreline will retreat causing land loss. Globally, this is a massive issue. Deposition happens when the sea loses energy and it drops the sand, rock particles, and pebbles it has been carrying. Constructive waves are responsible for this as the swash is stronger than the backwash.

The four processes of coastal erosion are corrosion, abrasion, attrition, and hydraulic power.

The most significant danger to coastal areas comes from natural events such as hurricanes, coastal storms (storm surge), tsunamis, and landslides (mass movement), as well as longer-term risks of coastal erosion and sea-level rise.

 The negative effects of coastal erosion are the damage it can cause to transport and infrastructure through storm surges and mass movement. In addition, changes to the soil structure result from seawater contaminating the farming land through flooding, causing economic loss and the destruction of property.


Final Coastal Erosion and Deposition Quiz

Question

Waves are responsible for shaping the coastline. There are two types: what are they?

Show answer

Answer

Constructive and destructive waves.

Show question

Question

What are the characteristics of a constructive wave?

Show answer

Answer

They have a low frequency and a weak backwash.

Show question

Question

What are the characteristic of a destructive wave?

Show answer

Answer

They are high and deep, have a high frequency and they have a strong backwash and a weak swash.

Show question

Question

Erosional coastal formations include what?

Show answer

Answer

Headlands and bays, Cliffs and wave-cut platforms, Stacks and stumps, and Shoreline platforms

Show question

Question

Depositional coastal formations include what? 


Show answer

Answer

Spits, beaches, offshore bars and tombolos, cuspate forelands, salt marshes, estuarine mudflats, and sand dunes.

Show question

Question

There are four processes whereby the waves transport material; what are they?


Show answer

Answer

Solution, saltation, suspension, and traction.

Show question

Question

Add the missing words to the following sentences.  

Solution  - Substance that is ……….. and ………... along in the water.

Saltation  - Larger particles are ………. to be carried, so they are ……….. along the sea bed. 

Suspension  - This is where very ……….. is ……….. along in the water.

Traction  - …………. particles are ………… ... the sea bed by the force of the water.


Show answer

Answer

Solution - Substance that is dissolved and carried along in the water.

Saltation - Larger particles are too heavy to be carried, so they are bounced along the sea bed. 

Suspension - This is where very fine material is carried along in the water.

Traction - Enormous particles are pushed along the sea bed by the force of the water.

Show question

Question

What are the main sub-aerial processes?

Show answer

Answer

The main sub-aerial processes are weathering and mass movement.


Show question

Question

What is weathering?


Show answer

Answer

The gradual breakdown of rocks, in situ, at or close to the ground surface.

Show question

Question

Weathering can be divided into three different types. What are they?


Show answer

Answer

Mechanical, chemical, and biological.

Show question

Question

 What is mass movement?


Show answer

Answer

This is the movement of materials downslope, because of gravity, at a range of speeds. Water acts as the common lubricant involved in mass movement.

Show question

Question

What are the types of mass movement?


Show answer

Answer

Types of mass movement are soil creep, solifluction, earth and mudflows, rock falls, rock / debris slides, and slumps.

Show question

Question

How are waves produced?

Show answer

Answer

Waves are produced by friction between the wind and water, resulting in an energy transfer from the wind to the sea. Ripples are created; these ripples will become waves if the wind is sustained.

Show question

Question

When do waves move forward?

Show answer

Answer

Waves move up and down – there is no horizontal movement. It is only when the water enters shallower areas that the water itself moves forward.

Show question

Question

What is the highest point of a wave called?


Show answer

Answer

wave crest

Show question

Question

What is the distance between trough and crest called?

Show answer

Answer

The wave height.

Show question

Question

Explain wave refraction.

Show answer

Answer

As a result of the coastal feature, the depth of water around a coast varies. As the wave approaches a coast, its progress is modified due to friction from the seabed, halting the motion of waves. In addition, as waves approach a coast, they are refracted so that their energy is concentrated around headlands but reduced around bays.

Show question

Question

What are the two types of waves?


Show answer

Answer

Constructive and destructive waves.

Show question

Question

Describe a constructive wave.


Show answer

Answer

They are also called spilling or surging waves. They are gentle, flat waves with a strong swash and a weak backwash; as a result, constructive waves build beaches. As the wave breaks, it carries material up the beach in its swash. Beach material is deposited as a bridge of sediment (berm) at the top of the beach. The relatively gentle profile of the beach with a steep ridge at the top of the beach means that the backwash soaks into the sand or slowly drains away. When the following wave breaks, its swash will deposit more material without it being 'captured' by the backwash of the preceding wave.

Show question

Question

Describe a destructive wave.

Show answer

Answer

These waves are also known as plunging waves. Not surprisingly, destructive waves destroy beaches. As the wave approaches the coast, it gains height and drops onto a steep beach. As a result, it does not travel far up it. The swash of a destructive wave is much weaker than its backwash. This means that these waves transport beach material back into the sea, lowering the height of a beach. The more the waves crash onto the beach, the more sediment is washed out to sea. Because the waves are so frequent, the backwash has less time to soak into the sand. During a storm, the most common waves are destructive.

Show question

Question

The following are facts about constructive waves. Add in the missing words

Their wavelength is …….and a….. frequency (8-10 waves per minute).

They have a….... gradient, typically under ………. in height.

They have low ……. and an …... orbit.

Have a larger ……. than ………..

Show answer

Answer

Their wavelength is long and a low frequency (8-10 waves per minute).

They have a low gradient, typically under one meter in height.

They have low energy and an elliptical orbit.

Have a larger swash than backwash

Show question

Question

The following are facts about destructive waves. Add in the missing words.

Destructive waves are usually ……. over 1m.

They have a more ……… .cross profile.

They are most common where …… .. is short.

They have a mainly circular orbit, a …… .. gradient, 

These act as agents of erosion because their ………. is greater than their .......

They are more common in ……. than in summer

Show answer

Answer

Destructive waves are usually very high, over 1m.

They have a more circular cross profile.

They are most common where fetch is short.

They have a mainly circular orbit, a steep gradient.

These act as agents of erosion because their backwash is greater than their swah.

They are more common in winter than in the summer

Show question

Question

There are four processes involved in the eroding coastlines. What are they?

Show answer

Answer

Hydraulic action, attrition, abrasion, and corrosion.

Show question

Question

What is hydraulic action?

Show answer

Answer

This is where waves approach the cliff; air may become trapped and compressed in joints and cracks along a cliff face. Then when the wave retreats, the compressed air expands again. This continual process can weaken the joints and cracks in the cliff, causing pieces of rock to break off.

Show question

Question

What is abrasion?


Show answer

Answer

Bits of rock and sand that the waves have picked up are thrown against the cliff face. The sediment acts as a tool on the cliff, chiselling away at the surface and gradually wearing it down by removing small particles.

Show question

Question

What is attrition?


Show answer

Answer

When a wave breaks upon the shore, rocks and pebbles that are being carried collide with each other breaking them and eventually making them smaller and smoother. The net result is that the sediment gets smaller and smaller over time.

Show question

Question

What is corrosion?


Show answer

Answer

Corrosion is also known as solution. It is where salts and acids within the seawater will gradually dissolve some types of rock found along the coast. This process happens over thousands of years.

Show question

Question

For populated coastlines, the risks associated with flooding are more significant than the risk of erosion. Why in that case do people live in such an area?

Show answer

Answer

Because it is economically beneficial, for example, through tourism, as people love to visit the coast, through trade as deltas and estuaries make ideal ports, and as a result of agriculture, they have fertile soil.

Show question

Question

The causes of flooding at the coast can be linked to what?

Show answer

Answer

The height of land above sea level, the degree of erosion and subsidence, deforestation and vegetation removal and storm surges.

Show question

Question

 Give an example of a low lying coastal area vulnerable to coastal flooding?

Show answer

Answer

 The mega-deltas of Asia.

Show question

Question

Erosion and subsidence at the coast are affected by human activities. Can you give any examples?


Show answer

Answer

Through the drainage of saturated sediment/soil for agriculture, e.g. Fens of East Anglia. The weight of coastal towns and cities and built environment can also compress sediment, leading to subsidence, e.g. Venice. And through land reclaimed from the sea, the Netherlands.

Show question

Question

 How does the removal of vegetation affect coastal flooding?


Show answer

Answer

Vegetation intercepts the rainfall, slowing down its movement by removing it. As a result, infiltration and interception are reduced and surface run-off increases. The vegetation also stabilises existing sediment and traps new sediment, raising the height of the land above sea level. In addition, it absorbs wave energy, reducing wave impact and erosion, and reduces the distance waves travel onshore before the energy is exhausted.

Show question

Question

What is a storm surge?


Show answer

Answer

They are a short term change in sea level caused by intense low-level pressure systems from depressions (a low-pressure weather system) and tropical cyclones (hurricanes, typhoons).

Show question

Question

Storm surges can be exacerbated through various factors, such as?


Show answer

Answer

They can be exacerbated through land subsidence, the removal of natural vegetation, and global warming.

Show question

Question

Can you give an example of a recent storm surge in the UK?


Show answer

Answer

Storm Xaver, December 2013.

Show question

Question

What can be the effects of a storm surge on coastal areas?


Show answer

Answer

As a direct result of the storm, there will be some deaths and injuries to people through drowning or collapsing buildings. Infrastructure such as roads, railways, ports, and airports will be flooded or destroyed. There will be damaged water pipes, electricity transmission lines and sewage systems; as a result, there is likely to be no power or water. Homes will be destroyed, homes on marginally low lying land (slums and shantytowns) will be more vulnerable. Businesses (factories) causing an interruption of raw material delivery and agricultural land contaminated - crop harvest lost.

Show question

Question

Why is the Bay of Bengal extremely vulnerable to flooding?


Show answer

Answer

Most of the area is low lying; storm surges often meet the outgoing river discharges from the rivers resulting in the river and coastal flooding; most of the coastline is made up of unconsolidated sediment from the deltas, which is easily eroded. Intense rainfall is associated with cyclones and the shallow and conical shape of the Bay near Bangladesh.

Show question

Question

Human activities exacerbated the problems in the bay of Bengal; can you explain?


Show answer

Answer

Land that was forested initially has now been cleared and used for growing rice, and 4000km of barriers has been built along the coast. This prevented the natural deposition of sediment used to maintain the island's height. Also, the mangrove forests have been removed, they stabilize the coastline against erosion, collect nutrient-rich sediment, protect extreme weather events such as tsunamis, and absorb and disperse tidal surges.

Show question

Question

When did the IPCC release its report?

Show answer

Answer

2014.

Show question

Question

It had a high degree of confidence in two things happening. What were they? 


Show answer

Answer

Sea levels will rise by between 28 - 98cm by 2100, with the most likely rise being 55cm by 2100. And that the world's significant deltas risk of coastal flooding was likely to increase by 50 per cent.

Show question

Question

What is the solution to coastal flooding? 


Show answer

Answer

There is no solution, but there are two possible approaches for dealing with the risk associated with adaptation and mitigation.

Show question

Question

What is a tectonic factor which can influence sea-level change at the coast?

Show answer

Answer

A coastal region experiencing seismicity (earthquakes) can encounter land being shifted upwards (uplift) or downwards (downthrust) as the geological pressures are released and the adjacent rocks adjust at fault lines. This will cause a rapid change in the sea levels. 


Show question

Question

Give an example of tectonic activity which has affected sea-level changes?

Show answer

Answer

Following the Tohoku earthquake in 2011, more than 200miles of the eastern coastline of Honshu, norther Japan, fell by 0.6 m. A destructive tsunami then followed.


Show question

Question

What do you understand by the term Isostatic? 


Show answer

Answer

A change in the local coastline of land height relative to the sea level.

Show question

Question

What is a post-glacial adjustment?


Show answer

Answer

It is when the ice sheet melts, the land surface is released and slowly rebounds upwards over thousands of years. 


Show question

Question

In the UK, two different isostatic changes have occurred since the last ice age. What were they?

Show answer

Answer

  1. Land in the north and west, which was covered by ice sheets during the last ice age, is still rising due to the recent isostatic recovery. 
  2. Land in the south and east (not covered by the ice sheet)is sinking. As a result, rivers pour water and sediment into the Thames estuary. The weight of this caused the crust to drop there and relative sea levels to rise. Resulting in an increased flooding risk due to isostatic change and rising sea levels caused by global warming.

Show question

Question

What do you understand by the term Eustatic?

Show answer

Answer

Global changes to sea levels.

Show question

Question

What is a submergent coastline? 


Show answer

Answer

A coastline that is sinking relative to the sea level of the time.

Show question

Question

Where would you find examples of a submergent coastline? 


Show answer

Answer

Examples of these can be found along the south coast of England and the east coast of America.

Show question

Question

What is the most common feature of a submergent coastline?


Show answer

Answer

A Rias.

Show question

60%

of the users don't pass the Coastal Erosion and Deposition quiz! Will you pass the quiz?

Start Quiz

Discover the right content for your subjects

No need to cheat if you have everything you need to succeed! Packed into one app!

Study Plan

Be perfectly prepared on time with an individual plan.

Quizzes

Test your knowledge with gamified quizzes.

Flashcards

Create and find flashcards in record time.

Notes

Create beautiful notes faster than ever before.

Study Sets

Have all your study materials in one place.

Documents

Upload unlimited documents and save them online.

Study Analytics

Identify your study strength and weaknesses.

Weekly Goals

Set individual study goals and earn points reaching them.

Smart Reminders

Stop procrastinating with our study reminders.

Rewards

Earn points, unlock badges and level up while studying.

Magic Marker

Create flashcards in notes completely automatically.

Smart Formatting

Create the most beautiful study materials using our templates.

Sign up to highlight and take notes. It’s 100% free.