Coasts

Question 1

Attrition

Answer 1

When rocks carried by the sea bang together making them smaller

Question 2

Solution

Answer 2

Rocks are vulnerable to being dissolved by water. Found in areas of limestone and chalk. Water mixes with the lime stone creating an acid solution.

Question 3

Hydraulic power

Answer 3

The sheer force of waves against the cliff

Trapped air gets into the cracks of the cliff causing them to weaken and get bigger

Question 4

Solution

Answer 4

Dissolved chemicals often derived from limestone or chalk

Question 5

Suspension

Answer 5

Particles carried within the water

Question 6

Traction

Answer 6

Large pebbles rolled along he seabed

Question 7

Saltation

Answer 7

Bouncing motion of particles alone sea bead that are too heavy to be suspended

Question 8

Formation of a sea stack

Answer 8

A stack is formed over a long period of time, primarily caused by a fault in a resistant rock. Abrasion (corrasion) and hydraulic action of waves widen the weakness in the cliff to eventually form a cave. Caves formed on both sides of the headland eventually form an arch due to waves cutting through and continually widening the base. Eventually the roof of the arch become too heavy to be supported and collapses, leaving a stack.

Question 9

Shoreline management plan

Answer 9

Plans for management of a length of coast, including the natural processes, human and environmental needs

Question 10

Why does erosion occur on the Norfolk coast ?

Answer 10

It occurs primarily because of heavy rainfall and destructive waves. Lack of coastline protection allows for more erosion at the base of cliffs, producing wave cut notches. Rising sea levels due to global warming also contribute to coastal erosion and also high levels of hydraulic action

Question 11

Why is coastal erosion on the Norfolk coast a problem ?

Answer 11

Because many buildings, including houses, schools, shops and areas of land are being lost to the sea. This affects tourism (especially in Norfolk broads where £5m+ is brought in).

The Thames barrier is also a problem (currently protecting £80bn of buildings) as it will need to be replaced within 30-50 years or there will be risk of flooding

Rising sea levels mean erosion rates are likely to increase threatening coastal settlements such as Overstrand and flappisburgh - current sea defences will need strengthening = £££

Question 12

Abrasion

Answer 12

Waves carry small particles of rock and sand that rub against the coastline wearing it away

Question 13

Formation of a wave cut platform (and cliff erosion)

Answer 13

1. Weather weakens the top of the cliff
2. Through the process of hydraulic action and abrasion causes the base of the cliff to be eroded away to form a wave cut notch
3. The notch increases in size causing the cliff to collapse
4. Backwash carries rubble from cliff towards the sea forming a wave cut platform
5. The process repeats and the cliff continues to retreat

Question 14

Constructive wave

Answer 14

• smaller in height
• weak backwash ; little erosion
• strong swash ; pushes material up the beach

Question 15

Destructive wave

Answer 15

• larger in height
• weak swash ; little beach building
• sting backwash ; scours the beach, pulling sand and shingle down the beach (erosion)

Question 16

How do waves form ?

Answer 16

1) circular orbit in open water
2) friction with the seabed distorts the circular orbital motion
4) increasing elliptical orbit - crest of wave moves faster
5) wave begins to break and water rushes up the beach - swash
6) water from previous wave returns - backwash

Question 17

What is hard engineering and some examples

Answer 17

Building artificial structures/barriers which control the power of the sea and prevent erosion. They can be expensive and need maintaining.

Eg: sea walls, revetments, rock armour, gabions, offshore breakwater and groynes

Question 18

What is soft engineering and some examples

Answer 18

A sustainable approach to managing the coast without using artificial structures. They can revise or rework existing materials or leave natural processes to take place

Eg : beach nourishment, beach replenishment, beach regeneration, managed retreat

Question 19

Beach nourishment (and advantages and disadvantages)
(Soft)

Answer 19

The addition of sand or shingle to an existing beach to make it higher/broader. Sediment is usually locally attained to blend in with existing beach

Advantages : relatively cheap and easy to maintain (£3000 per metre)
Blends in with existing beach
Increases tourist potential bc. of bigger beach

Disadvantages : needs constant maintenance unless structures are built to retain the beach

Question 20

Beach replenishment (advantages and disadvantages) 
(Soft)

Answer 20

Replaces material lost by erosion each year

Advantages : VERY cheap (£3 per m)
Disadvantages : regular replacement is needed

Question 21

Beach regeneration (soft)

Answer 21

Sand dunes are effective buffers to the sea yet they are easily damaged and destroyed. Marram grass can be planted to stabilise the dunes and help them to develop - areas can be fenced off (£2000 per m)

Advantages : maintains a natural coastal environment that is popular with tourists

Disadvantages : time consuming to plant grass
Can be damaged by storms
People may not respond well to bing prohibited from areas

Question 22

Managed retreat (soft)

Answer 22

This involves allowing low-lying coastal areas to be flooded by the sea to become salt marshes. Salt marshes are effective barriers to the sea
(Arable land = £5000 - £10000 per hectare)

Advantages : cheap option compared to maintains expensive sea defences that might be protecting relatively low value land
Creates much needed habitat for wildlife

Disadvantages : land will be list as it is flooded by sea water
Farmers or landowners will need to be compensated

Question 23

Formation of headlands and bays

Answer 23

Headlands are formed when the sea attacks a section of coast with alternating bands of hard and soft rock.

The bands of soft rock, such as sand and clay, erode more quickly than those of more resistant rock, such as chalk. This leaves a section of land jutting out into the sea called a headland. The areas where the soft rock has eroded away, next to the headland, are called bays.

Question 24

Sea wall (hard)

Answer 24

This a 3-5m concrete or rock barrier built at the foot of a cliff or at the top of the beach. It aims to reflect back the waves in hope of trying to prevent the chances of erosion. It is effective, but very expensive (up to 1 million per km)

Question 25

Revetments (hard)

Answer 25

A sloping concrete (£2000 per metre) or wooden (much cheaper) wall that slopes along the coast. The wooden walls have open structures which absorb the wave energy but allows sediment to build up beyond as well. They are more effective than sea walls but are environmentally ugly.

Question 26

Rock armour (hard)

Answer 26

These are piles of large boulders placed at the foot of a cliff that force the waves to break their energy. It costs between £1,000-£4,000 a metre but are relatively easy to maintain. However, they are environmentally ugly, obtrusive and expensive to transport.

Question 27

Offshore breakwater

Answer 27

A wall made of interlocking material or concrete just below the water mark that protects the shore from all waves. It costs around £5000 per metre (expensive!) It is effective as it decreases the strength of hydraulic power, but if the tide is out, it is ugly, obtrusive and dangerous to swim around.

Question 28

Gabions

Answer 28

These are steel mesh cages filled with small rocks in order to absorb wave energy they are fairly cheap, more effective than sea walls- but environmentally ugly.

Question 29

Groynes

Answer 29

These are narrow walls built out into the sea to prevent longshore drift and erosion. They are £10,000 each and need to be placed every 200 metres in order for it to be effective. However, they are often spaced too far apart and ugly.

Question 30

Hold the line

Answer 30

Maintaining the existing coast by building defences

Question 31

Advance the line

Answer 31

Build more defects outwards into the sea

Question 32

Managed retreat

Answer 32

Allowing the land to flood and construct a new line of defence inland

Question 33

No intervention

Answer 33

Allowing natural processes to shape the coastline

Question 34

Happisburgh case study

Answer 34

Home to 850 people
No less than 18 listed buildings 
Houses costing as little as £1 
Happisburgh protects the Norfolk broads 
(Agricultural =67%, residential = 22%, public = 6%, tourism = 4%, commercial = 1%)

If erosion continues : 1000’s of tonnes of cliff material lost
(40ft lost per year)
Many houses will be lost to sea (30 already)
Economy and tourist industry severely damaged

SMP: - Originally timber revetments in 1950’s but destroyed by waves and by 2000 little defence remained

• A rock bund was created in front of cliff in 2002 using 4000 tonnes of boulders
• In 2006 the SMP said the area should enforce managed retreat

Question 35

Sea Palling case study

Answer 35

• Home to 488 people
• Significant tourist industry
• Beaches have blue flag status encouraging watersports
• Sand dunes protect 6000 acres of the Norfolk broads -behind Sea Palling
• Beaches have built up considerably due to sea defences

If erosion continues ; lifeboat station will be lost
6000 acres of Norfolk broads lost - has a land value of £345 million and £500,000

SMP : -Sea wall built in 1953

• 100,000 tonnes of boulders placed in front of sea wall
• 1 million cubic metres of sand brought in to replenish beach
• 4 offshore reefs built parallel to coast - a second set later added to the south (reefs break waves before they reach the beach + absorb storm energy)

Question 36

Hurst castle spit

Answer 36

Hurst castle spit is a spit in Hampshire caused by waves approaching the beach in the direction of North East, transporting sediment. The spit is roughly 2km long and has a width of 150m.

Question 37

Formation of a spit

Answer 37

A spit is a long finger of land along the coastline, jutting out into the sea, where sediment has been deposited due to longshore drift. The angle at which the swash of the waves hits the beach due to prevailing winds transports sediment along the coast until the coastline changes it direction or meets a river mouth. As more and more sediment is deposited the spit extends into the sea and eventually the tip curves round due to prevailing winds to form a hook

Question 38

Barton-on-sea (case study)

Answer 38

Where : Christchurch Bay, Hampshire
What : Coastal erosion and cliff collapse –> buildings lost to the sea - eroding 2m per year
Who : Local people and businesses, tourist industry, wildlife and the landscape
Why : 1) Rocks are weak sand and clays which are easily eroded by the sea and have little strength to resist collapse
2) Arrangement of rocks (Permeable sands on top of impermeable clay) causes the water to ‘pond-up’, increasing the weight of the cliffs (Increase in water pressure) encouraging collapse
3) This stretch of coastline faces the direct force of prevailing south-westerly wind. With a long fetch the waves approaching barton-on-sea are powerful causing a lot of erosion
4) Small dreams flow towards the coast but are stopped by permeable sands before they reach the sea –>adding to the amount of water in the cliffs
5) Buildings on the top of the cliff increase weight upon the cliffs –> more venerable to collapse (also interfere with drainage)

Question 39

Formation and succession of a salt marsh

Answer 39

1) A salt march begins when mud and silt begin to collect at a sheltered part of the coastline, where deposition can be deposited, but the area is too sheltered for the tide to pull it away
2) Deposited silt builds up in layers over time, to form mudflats that break through the surface of the water
3) Some plants begin to grow the first is cordgrass Pioneer plant). It is tolerant to sea water (a halophyte) and has long roots the help keep mud and sediment together.

As the mudflats rise, they are no longer covered by high-tides and this allows the rain and any fresh water from rivers to wash out the salt. Lower salt concentration = more plants that grow due to more fertile soil - such as sea asters (second generation) and eventually bigger and hardier plants such as trees = VEGETATION SUCCESSION

Question 40

Key haven marshes (case study)

specialties, threats and management

Answer 40

Key haven salt marsh is retreating by up to 6m a year

Specialties of Keyhaven ;

1) special species of plant and animal e.g cordgrass, oyster catcher, sea lavender, rigid plover, common blue butterfly and wold spider
2) SSSI (Site of special scientific interest)

Threats to Keyhaven :

1) Sea levels are rising = squeezing of salt marshes because of presence of sea walls
2) Storm events can erode the spit ; In 1989 the spit was breached by a storm, exposing the salt marsh to the sea. Destructive waves eroded 50-80m of salt marsh in 3 months
3) Tourists e.g walkers cause erosion to the mudflats and possibly the spit –> rubbish, cars, anchors mooring within the wetlands

Management of key haven :

• In 1996 rock armour and beach nourishment were added to the spit, to increase its height and width in attempt to stop breaching (this caused waves to break early and stop erosion of shingle)
• Designated area of SSSI - laws and restrictions to protect it –> central car park to contain effects + designate paths for visitors, to make sure most areas are left untouched, preventing erosion

Question 41

What are the environmental effects of Sea level rise in East Anglia?

Answer 41

Settlements such as King’s Lynn may be under threat as sea levels rise and valuable agricultural land such as the Fens will be at greater risk from flooding.

As sea levels rise, erosion rates are likely to increase- threatening the coastal settlements such as Overstrand and Happisburgh. This will mean that current sea defences will need strengthening, which is expensive.

Question 42

What are the social effects of Sea level rise in East Anglia?

Answer 42

In 1953, East Anglia suffered terribly from a storm surge that killed 300 people. People are worried that such an event may happen again so people do not come.

Question 43

What are the economic effects of Sea level rise in east Anglia?

Answer 43

As a result of the Fens flooding, farmers may not have another source of income - could be badly affected by the flooding.

The Thames barrier currently protects buildings worth £80bn. It will probably need to be replaced in the next 30-50 years. As sea levels rise, large areas of the lower Thames estuary will be at risk from flooding, affecting housing, industry and farmland.

The Norfolk boards are a popular tourist destination , bringing £5m pounds to the area. Sea level rise would flood the broads, destroying the economy of the area.

Question 44

What are the political effects of Sea level rise in east Anglia?

Answer 44

Low lying mudflats and marshes in Essex are particularly vulnerable to sea level rise. Areas of salt marsh are being squeezed in between sea walls and rising sea. Some 22% of salt marshes could be lost by 2050- so in some places, managed retreat will break sea walls to allow deliberate flooding so that salt marshes can reform. This is politically controversial.