Coasts

Question 1

What does the size and energy of the wave depend on?

Answer 1

-the fetch- how far the wave has travelled
-the strength of the wind
-how long the wind has been blowing for

Question 2

What is the swash and backwash?

Answer 2

A swash is the wave to comes up a beach
A backwash is the water that flows back towards the sea

Question 3

What are the characteristics of destructive waves?

Answer 3

-weak swash and strong backwash
-occurs in stormy conditions, with strong winds
-the strong backwash removes sediment from the beach
-the waves are steep and close together
-tall waves with short wavelength
-they arrive quickly and have a high frequency – a lot of them come in a short period of time

Question 4

What are the characteristics of a constructive wave?

Answer 4

-small waves, with low wave height and long wavelength
-occurs in calm conditions, without much wind
-strong swash and weak backwash
-the strong swash brings sediments to build up the beach
-the backwash is not strong enough to remove the sediment
-the waves are low and further apart

Question 5

What is freeze-thaw weathering?

Answer 5

Freeze-thaw weathering occurs when rocks are porous (contain holes) or permeable

-Water enters cracks in the rock.
-When temperatures drop, the water freezes and expands causing the crack to widen.
-The ice melts and water makes its way deeper into the cracks.
-The process repeats itself until the rock splits entirely.

Question 6

Explain the process of biological weathering

Answer 6

Plant roots can get into small cracks in the rock.
As the roots grow, the cracks become larger.
This causes small pieces of rock to break away.

Question 7

Explain chemical weathering

Answer 7

Rainwater and seawater can be a weak acid. If a coastline is made up of rocks such as limestone or chalk, over time they can become dissolved by the acid in the water.

Question 8

What is mass movement?

Answer 8

the downhill movement of sediment that moves because of gravity

Question 9

What is rock fall?

Answer 9

Bits of rock fall off the cliff face, usually due to freeze-thaw weathering.

Question 10

What is mudflow?

Answer 10

Saturated soil (soil filled with water) flows down a slope.

Question 11

What is a landslide?

Answer 11

Large blocks of rock slide downhill.

Question 12

What is a rotational slip?

Answer 12

Saturated soil slump down a curved surface.

Question 13

What is longshore drift?

Answer 13

Longshore (littoral) drift is the movement of material along the shore by wave action. It happens when waves approach the beach at an angle. The swash (waves moving up the beach) which moves in the prevailing wind direction angle, carries material up and along the beach. The backwash (waves moving back down the beach) carries material back down the beach at right angles due to gravity.

Question 14

What are discordant and concordant coastlines?

Answer 14

Discordant coastline occurs where bands of differing rock type run perpendicular to the coast.
The differing resistance to erosion leads to the formation of headlands and bays.A hard rock type is resistant to erosion and creates a promontory whilst a softer rock type is easily eroded creating a bay.

A concordant coastline occurs where the bands of differing rock types run parallel to the coast.
The outer hard provides a protective barrier to erosion of the softer rocks further inland.

Question 15

How is the wave-cut platform formed?

Answer 15

The sea attacks the base of the cliff between the high and low tide marks.
Erosion processes of hydraulic action and abrasion, create a
wave-cut notch
.
Over time the notch increases in size and the upper cliff is unsupported, while weathering weakens the upper cliff.
These processes cause the
cliff to collapse.
A wave-cut platform is the bedrock that is left behind as the cliff moves backwards.
The backwash carries the rubble towards the sea smoothing the wave-cut platform through abrasion.
The process repeats and the cliff continues to retreat.

Question 16

How do rocks affect erosion?

Answer 16

Soft rock, e.g. sand and clay, erodes easily to create gently sloping cliffs. Hard rock, e.g. chalk, is more resistant and erodes slowly to create steep cliffs.

Question 17

What are headlands?

Answer 17

A headland is a cliff that sticks out into the sea and is surrounded by water on three sides. Headlands are formed from hard rock, that is more resistant to erosion, such as limestone, chalk and granite. Headlands form along discordant coastlines where bands of soft and hard rock outcrop at a right angle to the coastline (see image below). Due to the different nature of rock erosion occurs at different rates. Less resistant rock (e.g. boulder clay) erodes more rapidly than more resistant rock (e.g. chalk).

Question 18

What are bays?

Answer 18

The areas where the soft rock has eroded away, next to the headland, are called bays.

Question 19

How are sea caves formed?

Answer 19

Cracks in the rock erode through abrasion.
Caves occur when waves force their way into cracks in the cliff face. The water contains sand and other materials that grind away at the rock until the cracks become a cave. Hydraulic action and abrasion are the predominant erosion processes.

Question 20

How are arches formed?

Answer 20

If the cave is formed in a headland, it may eventually break with erosion like abrasion through to the other side forming an arch.

Question 21

How are stacks and stumps formed?

Answer 21

The arch will continue to be eroded (attrition) and will gradually become bigger until it can no longer support the top of the arch. When the arch collapses, it leaves the headland on one side and a stack (a tall column of rock) on the other.
The stack will be attacked at the base in the same way that a wave-cut notch is formed. This weakens the structure and it will eventually collapse to form a stump.

Question 22

What is a beach?

Answer 22

Beaches
are a common feature of a coastline. Beaches are made up of eroded material that has been transported from elsewhere and deposited by the sea.Constructive
waves help to build up beaches. The material found on a beach depends on the geology of the area and wave energy.

The material found on a beach varies in size and type as you move further away from the shoreline. The smallest material is deposited near the water and larger material is found nearer to the cliffs at the back of the beach.

Large material is deposited at the back of the beach in times of high energy, for example during a storm. Most waves break near the shoreline, so sediment near the water is more effectively broken down by attrition.

Question 23

What is a shingle beach?

Answer 23

This is a beach where strong swash waves will be assisted by windy and stormy conditions to throw larger pieces of shingle further up the beach. Shingle beaches will usually contain many different ridges across their profile.

The smallest material will be found on the beach face and larger pieces of shingle/ pebble will be thrown to the back of the beach. Shingle beaches usually have much steeper profiles. This is because the wave will percolate through the shingle, making the backwash too weak to remove the material.

Question 24

How is a spit formed?

Answer 24

When longshore drift transports material along the coast, it sometimes comes across an estuary or a change in the direction of the coastline.

In either case, the transport process tends to carry on moving the material in the same direction.

Over time, a ridge of material will build up into the deeper water.

This will form a spit.

Eventually the spit may form a substantial feature, many miles long with sand dunes and plants, possibly even buildings on it.

Many spits show a series of hook or recurved spit end which relate to material moved by winds creating waves from a different direction.

Question 25

What happens behind the spit?

Answer 25

In the low-energy environment behind the spit, deposition of fine silt and mud will occur and salt marsh forms.

Question 26

How are bars and tombolos formed?

Answer 26

Over time, spits may move inland and many are regularly broken by storms and reform in subsequent years.

If longshore drift carries material across a bay, it may form a bay barrier or bar.

Such bars rarely form across estuaries as the power of the river erodes material from the ends of the spit if the gap becomes very narrow. If longshore drift transports material across to a nearby island, then it forms a tombolo linking the island to the mainland.

Question 27

How do estuaries influence spits?

Answer 27

The river current will prevent the spit from reaching across the bay and forming a bar.

Question 28

What are the advantages and disadvantages of soft engineering method beach nourishment?

Answer 28

Beaches are made higher and wider by importing sand and shingle to an area affected by longshore drift to increase its height and width to provide protection from erosion or flooding by absorbing wave energy.
Advantages:
The approach is cheap and retains the natural appearance of the beach. Beaches are a natural defence against erosion. Additionally, the beach is a valuable amenity for tourism, bringing economic benefits to the area.
Disadvantages:
Offshore dredging of sand and shingle increases erosion in other areas and affects the marine ecosystem. Large storms will require further beach replenishment, increasing costs.

Additionally, people may be prevented from using the beach for several weeks during the year during maintenance.

Question 29

What are the advantages and disadvantages of soft engineering method managed retreat?

Answer 29

This is when areas of the coast are allowed to erode. This is usually in areas where the land is of low value.
Advantages:
Managed retreat retains the natural balance of the coastal system. Eroded material encourages the development of beaches and salt marshes. Creates new habitats and it is cheap.
Disadvantages:
People lose their livelihood, e.g. farmers. These people will need to be compensated. It is difficult to predict the sea’s movements

Question 30

What are the advantages and disadvantages of soft engineering method Dune regeneration?

Answer 30

Dune regeneration involves taking action to build up dunes and increase vegetation. This helps to strengthen the dunes and prevent coastal retreat. New sand dunes can be created to protect from coastal flooding. Often, marram grass is planted to hold the dunes together. Wooden boardwalks can be built to encourage people not to walk on the dunes.
Advantages:
Dune regeneration provides a barrier between land and sea, absorbs wave energy, and provides cheap stabilisation. It also maintains a natural-looking coastline.

Dune regeneration can increase biodiversity by providing a greater range of natural habitats for plants, animals and birds.
Disadvantages:
During dune regeneration, the land must be carefully managed so that any new vegetation planted is appropriately protected from trampling by humans. This could involve temporarily fencing off the dunes or providing wooden walkways. Storm waves can also damage dunes.

Question 31

What are the advantages and disadvantages of hard engineering method
of groynes?

Answer 31

Groynes are wooden barriers constructed at right angles to the beach to retain the material. The beach material, including sand and pebbles, are trapped between groynes and cannot be transported away by longshore drift. Groynes encourage a wide beach which helps absorb energy from waves, reducing the rate of cliff erosion. The photograph below illustrates the difference in how far waves travel inland when sediment is trapped by a groyne raising the height of the beach.
Advantages:
-keeps the beach in place for tourist industry
-effective for a long time
Disadvantages:
-disrupt natural processes continues erosion below where the groynes are place
-unattractive and makes it difficult to walk on the beach.

Question 32

What are the advantages and disadvantages of hard engineering method of rip rap (large boulders piled)?

Answer 32

Rock armour(rip rap) is a barrier of large boulders placed in front of a cliff or sea wall to absorb wave energy and reduce backwash by encouraging percolation.
Advantages:
-dissipates wave energy and is effective for many years
-can be cheap depending on rock type
Disadvantages:
-makes beach inaccessible
-unattractive
-doesn’t work in storm conditions.

Question 33

What are the advantages and disadvantages of hard engineering method
of Sea Walls?

Answer 33

Seawalls are usually built along the front of cliffs to protect settlements or another land of high economic importance. They are often recurved which means waves are reflected back on themselves. This can cause the erosion of material at the base of the seawall
Advantages:
-visible making residents feel safe
- very effective for many years
Disadvantages:
-ugly and very expensive
-wave scouring

Question 34

What are the advantages and disadvantages of hard engineering method
offshore reef?

Answer 34

A man made structure of rocks or concrete built from the coastline
Advantages:
-allow build up of sand
-break the waves further removes their erosive power
Disadvantages:
-difficult to install
-may be removed by heavy storms

Question 35

What are hard engineering method
revetments.

Answer 35

Traditionally these have been wooden slatted barriers constructed towards the rear of beaches to protect the base of cliffs. Energy from waves is dissipated by them breaking against the revetments.

Question 36

Holderness coast case study:

Answer 36

The Holderness Coastline is located on the East Coast of Yorkshire
From Flamborough Head in the north down to Spurn Head (61km), where it meets the Humber Estuary
It is the fastest eroding coastline in Europe at 2 m per year
The rock type is mainly soft boulder clay
Easily eroded and vulnerable to slumping
The coastline has naturally narrow beaches, which give less protection as wave power is not reduced
Longshore drift is the dominant process due to North Sea waves
Waves along the coastline have a long fetch, which increases wave energy
Human activity
Bridlington is protected by a 4.7 km long sea wall
Gabions have been built at Skipsea
Hornsea is a popular tourist destination where the cliffs are formed from soft boulder clay.
It has a number of sea defences including:
Wooden groynes at a cost of £5.2 m
Concrete sea wall
Stone and steel gabion along with a concrete revetment have been built south of Hornsea, helping to protect the caravan park
At Mappleton, riprap at a cost of £2 m, groynes and beach nourishment help to maintain a sandy beach
Withernsea has a sea wall, groynes, riprap and beach nourishment in an effort to widen the beach and so reduce wave energy
2.25% of all UK gas comes through the gas terminal at Easington and £4.5 m was spent on riprap, but the scheme protects the terminal and not the village
Spurn Head is protected with groynes and rock armour

Coastal changes
Due to the use of groynes at Mappleton, sediment has been prevented from moving south which has increased erosion at Great Cowden
Erosion has destroyed farms along with the loss of 100 chalets at the Golden Sands Holiday Park
Spurn Head is at risk of losing habitats due to a lack of sediment to maintain the spit

Question 37

Impacts of coastal flooding:

Answer 37

Coastal flooding is something that can happen anywhere along a coastline. Especially the last few decades have proven to be significant as not only does it appear to happen more often, but coastal areas seem to attract more people, tourists and locals alike. The latter could potentially lead to more casualties when coastal flooding happens.

Coastal flooding does not only impact people directly, as in injured or dead, but it can also damage or destroy houses, businesses, infrastructure, and agriculture (including the death of livestock).

Question 38

Effects of coastal erosion:

Answer 38

Coastal erosion is the process by which rising sea levels, storms, and other phenomena wear down or carry away the rocks, land, and sand making up a coastline.
This process causes the loss of tens of thousands of acres of land in the UK. each year, as well as millions of pounds in property damage.
Coastal erosion also has an impact on tourism, shipping, fishing, agriculture, and other industries dependent upon coastlines.