Coastal Change

Question 1

Define weathering

Answer 1

Weathering is the breakdown of rock at or near the surface by the weather

Question 2

List and define the 3 main types of weathering

Answer 2

1. Mechanical weathering – wearing down of rock caused by changing temperatures between day and night e.g. freeze thaw action, onion skin weathering. 2. Chemical weathering – breakdown of rock caused by a chemical reaction between calcium carbonate in rocks and water. 3. Biological weathering – breakdown of rock caused by roots of vegetation growing in cracks.

Question 3

Define erosion

Answer 3

Wearing away of rocks by water, weather or ice

Question 4

List and define the 4 main types of erosion

Answer 4

1. Hydraulic action – water being forced into cracks in the rock and breaking it up. 2. Abrasion – loose rocks (sediment) are thrown against the cliff by waves. This wears away at the cliff and chips bits of rock off. 3. Attrition – loose sediment that has been knocked off the cliff is swirled around by waves, colliding with other pieces wearing them into smaller smoother pieces. 4. Solution – Seawater dissolves material from the rock.

Question 5

What is mechanical weathering?

Answer 5

Mechanical weathering is caused by physical changes such as changes in temperature, freezing and thawing, and the effects of wind, rain and waves.

Question 6

Describe the process of chemical weathering?

Answer 6

The weathering of rocks by chemicals is called chemical weathering. Rainwater is naturally slightly acidic because carbon dioxide from the air dissolves in it. Minerals in rocks may react with the rainwater, causing the rock to be weathered.

Question 7

What is mass movement?

Answer 7

Mass movement is when cliffs at the coast collapse. This happens when water can build up in soils and add weight to it. The material moves down slope along a curved surface, leaving behind an exposed scarp face below the head of the slump, and producing a hummocky toe at the foot

Question 8

How do waves erode the coast by hydraulic action?

Answer 8

Destructive waves erode the coastline through Hydraulic action is when air may become trapped in joints and cracks on a cliff face. When a wave breaks, the trapped air is compressed which weakens the cliff and causes erosion.

Question 9

Which waves are associated with coastal erosion?

Answer 9

Destructive Waves

Question 10

Describe how a wave-cut platform is formed.

Answer 10

Weather weakens the top of the cliff. The sea attacks the base of the cliff forming a wave-cut notch. The notch increases in size causing the cliff to collapse. The backwash carries the rubble towards the sea forming a wave-cut platform. 5. The process repeats and the cliff continues to retreat.

Question 11

Can you label a diagram of longshore drift?

Answer 11

Question 12

Label a diagram of mass movement?

Answer 12

Question 13

What is deposition?

Answer 13

When the sea loses energy, it drops the sand, rock particles and pebbles it has been carrying. This is called deposition. Deposition happens when the swash is stronger than the backwash and is associated with constructive waves.

Question 14

Describe the characteristics of destructive waves?

Answer 14

• Destructive waves are created in storm conditions.
• They are created from big, strong waves when the wind is powerful and has been blowing for a long time.
• They occur when wave energy is high and the wave has travelled over a long fetch.
• They tend to erode the coast.
• They have a stronger backwash than swash.
• They have a short wave length and are high and steep.

Question 15

Describe how a spit is formed?

Answer 15

1. Longshore drift moves material along the coastline
2. A spit forms when the material is deposited.
3. Over time the spit grows and develops a hook as wind blows off the sea.
4. Waves cannot get past the spit and a sheltered area develops behind it where silt is deposited to create mud flats and salt marshes

Question 16

Where do spits form?

Answer 16

• Where there is a bend in the coastline.
• Long shore Drift can only travel in straight lines and it does not bend around corners therefore it continues straight out to sea.
• Forming a spit overtime.

Question 17

Explain how beaches are formed?

Answer 17

• Beaches are made up of eroded material that has been transported from elsewhere anddeposited by the sea.
• Constructive waves help to build up beaches. The material found on a beach (ie sand or shingle) depends on the geology of the area and wave energy.

Question 18

Give two economic impacts of coastal flooding?

Answer 18

• Loss of tourism
• Damage repair
• Loss of agricultural land- the high salt content in sea water can reduce soil fertility.

Question 19

Give two social impacts of coastal flooding.

Answer 19

• Deaths
• Water supplies can become contaminated with salt or sewage.
• Loss of housing
• Loss of jobs

Question 20

Using a case study explain why some places are more at risk of coastal erosion?

Answer 20

The Holderness coast is in the north east of England. This is one of the most vulnerable coastlines in the world and it retreats at a rate of one to two metres every year.

The problem is caused by:

• Strong prevailing winds creating longshore drift that moves material south along the coastline.
• The cliffs are made of a soft boulder clay. It will therefore erode quickly, especially when saturated.

Question 21

Describe a political impact of coastal flooding in the Maldives?

Answer 21

• The government has to make policies to reduce the impacts of future flooding.
• They might need to build better coastal defences.
• They have made agreements with neighbouring countries to each take in environmental refugees from the Maldives.
• Try to getting other countries to agree to a global commitment to reducing the impacts of climate change.

Question 22

Give two main reasons for rapid erosion along a named coastine?

Answer 22

The Holderness coast is in the north east of England.

• Strong prevailing winds creating longshore drift that moves material south along the coastline.
• The cliffs are made of a soft boulder clay. It will therefore erode quickly, especially when saturated.

Question 23

Give some details on a case study under threat from cliff erosion?

Answer 23

• The village of Mappleton, perched on a cliff top on the Holderness coast, has approximately 50 properties. Due to the erosion of the cliffs, the village is under threat.
• In 1991, the decision was taken to protect Mappleton. A coastal management scheme costing £2 million was introduced involving two types of hard engineering - placing rock armour along the base of the cliff and building two rock groynes.

Question 24

What have been the impacts of cliff management at Mappleton?

Answer 24

The rock groynes have stopped beach material being moved south from Mappleton along the coast. However, this has increased erosion south of Mappleton. Benefits in one area might have a negative effect on another.

Question 25

What are hard engineering strategies?

Answer 25

Hard engineering options tend to be expensive, short-term options. They may also have a high impact on the landscape or environment and be unsustainable.

Question 26

Name three hard engineering strategies?

Answer 26

–Groynes,

–Sea walls

–Gabions

–Rock armour

Question 27

What are the benefits of soft engineering strategies?

Answer 27

Soft engineering options are often less expensive than hard engineering options. They are usually more long-term and sustainable, with less impact on the environment.

Question 28

Describe the advantages of beach management?

Answer 28

–This replaces beach or cliff material that has been removed by erosion or longshore drift.

–The main advantage is that beaches are a natural defence against erosion and coastal flooding. Beaches also attract tourists.

–It is a relatively inexpensive option but requires constant maintenance to replace the beach material as it is washed away.

Question 29

Describe the advantages of managed retreat?

Answer 29

–Areas of the coast are allowed to erode and flood naturally. Usually this will be areas considered to be of low value - eg places not being used for housing or farmland.

–The advantages are that it encourages the development of beaches(a natural defence) and salt marshes (important for the environment) and cost is low.

–Managed retreat is a cheap option, but people will need to be compensated for loss of buildings and farmland.

Question 30

Explain a disadvantage of using groynes as a coastal defence?

Answer 30

• Can be seen as unattractive.
• Costly to build and maintain.
• Can have knock-on effects further down the coast.