Coasts

Question 1

Erosion

Answer 1

When waves wear away rocks at the coast eg abrasion, attrition, hydraulic action, corrosion

Question 2

Weathering

Answer 2

The breakdown of material in situ eg salt crystal growth, biological weathering

Question 3

Mass movement

Answer 3

The collapse of rock due to gravity eg slumping, rockfall

Question 4

Hydraulic action

Answer 4

The force of water hitting off the cliff and squeezing air into the cracks

Question 5

Attrition

Answer 5

Material carried by waste becomes smaller and rounder as it collides with other material and the sharp edges are knocked off

Question 6

Abrasion

Answer 6

Stones carried by waves are hurled and scrape across the cliff, causing it to erode away

Question 7

Corrosion

Answer 7

Rocks and minerals are dissolved by weak chemicals in the sea water

Question 8

Salt crystal growth

Answer 8

A type of chemical weathering, water left behind from when waves have sprayed over rocks evaporates, leaving behind salt, grow and expands, forms salt crystals

Question 9

Biological weathering

Answer 9

Tree roots grow into cracks in rocks, causing the rock to collapse and break apart

Question 10

How waves are created

Answer 10

Wind blows across the surface of the sea
Friction created produces a swell in the water
Energy of wind causes water particles to rotate inside the swell, moving the wave forward to the coast

Question 11

Constructive wave

Answer 11

Build beaches
Deposits sand 
Less than 10 per min
Strong swash
Weak backwash
Short

Question 12

Destructive wave

Answer 12

Erodes beaches 
Removes sand 
More than 10 per min
Strong backwash
Weak swash
Tall

Question 13

Factors affecting cliff recession

Answer 13

Rock type- more resistant eg granite, erosion occurs at a slower rate
Rock structure- rocks which are well-jointed eg limestone will erode more quickly as the wave will exploit these lines of weaknesses
Beach type- the steeper the beach , the faster the rate of coastal erosion
- the more narrow the beach , the faster the rate of erosion
Fetch - the distance over which the wind has travelled
- Longer the fetch the stronger the wind, more powerful he wave, meaning erosion occurs at a quicker rate

Question 14

Effects of coastal recession - Happisburgh

Answer 14

Social - 100 homes lost, 25 since 1995
- lifeboat launching station lost
- houses on Beach Road valued at £1
Environmental - golf courses eroded
- 50cm of land lost per year
- nests destroyed
- beaches littered with bricks

Question 15

Effects of coastal recession - Dawlish

Answer 15

Social - 30 residents evacuated
- fronts of several houses destroyed
Environmental - 3000 tonnes of sea wall collapsed

Question 16

Managing coastal erosion- North Norfolk coastline

Answer 16

Cromer- 6.5 m high sea wall, dissipates wave’s energy
- cliffs have been regraded and vegetated to reduce the chances of slumping
- wooden groynes put in place
Happisburgh- 5000 tonnes of granite rip-rap placed at thee base of the cliff in 2006, nothing else installed due to it not being cost effective

Question 17

Hard engineering strategies- rock armour

Answer 17

Igneous rocks placed at the foot of the cliff
Adv - effective for many years
- dissipates wave energy
Disadv- unattractive
- can make beach inaccessible for tourists

Question 18

Hard engineering strategies-sea wall

Answer 18

Concrete walls built at the base of a cliff, modern ones have a recurved face
Adv- effective for many years
- visible, makes tourists feel safe
Disadv- ugly
- expensive (£3000 per m)

Question 19

Hard engineering strategies- groynes

Answer 19

Wooden or rock fences which stretch from the coastline into the sea
Adv- prevents LSD
- builds wide beaches for tourists
Disdv- ugly
- expensive (£5000) each

Question 20

Hard engineering strategies-gabions

Answer 20

Wire cages filled with stones, cages are stacked to form wall at the base of the cliff
Adv- rock cages absorb waves energy, reducing erosion
- cheap
Disadv- not as effective
- wire cages may break

Question 21

Hard engineering strategies- offshore reefs

Answer 21

Huge concrete blocks/ natural boulders sunk offshore to alter wave direction and dissipate the energy of the waves and tides
Adv- wide beaches develop which protects the cliff from erosion
- wave break at barrier, reducing erosion
Disadv- may be remove by heavy storms
- expensive (£1950 to build)

Question 22

Hard engineering strategies- revetments

Answer 22

Slated wooden or concrete structures built at the base of a cliff
Adv- cheaper alternative to sea wall (£1200 per m)
- dissipates wave energy
Disadv - expensive
- require constant maintenance

Question 23

Soft engineering strategies - beach replenishment

Answer 23

Sand dredged from offshore/imported from somewhere else and added to the beach
Adv- beach in place for tourism
- look natural
Disadv - needs to be replaced every few years
- sea will continue to erode it

Question 24

Soft engineering strategies - managed retreat

Answer 24

Allowing the sea to gradually erode cliffs and flood land
Adv- cheap
- no threat to human safety
Disadv- people’s lives and businesses are disrupted
- compensation may need to be aid out

Question 25

Soft engineering strategies - cliff regarding

Answer 25

A cut-back cliff or a gentle slope put in place in order to prevent slumping from taking place Adv- cheap - likelihood of mass movement reduced Disadv- properties may need to be demolished - other methods may need to be put in place in order to prevent erosion from steepening the cliff again

Question 26

Effects of flooding- Great Flood

Answer 26

``` 24,000 homes damaged 30,000 evacuated 13,000 evacuated from Canvey Island, death toll of 59 177 lost their lives in fishing boats Land made infertile by salty water ```

Question 27

How the effects of coastal flooding can be reduced

Answer 27

Thames Barrier- cost £1billion to build, £16,000 to raise the bars each time, protects all area downstream incl Houses of Parliament , should prevent £250 billion worth of damage Metal kitchens so water does not damage flooring Move plug sockets higher up to prevent electrical damage Lift housing in Bangladesh- move houses up on stilts so flooring is not damaged, appropriate as the stilts are made of recycled plastic bottles EA create a liv food map so people can type in their post codes and see how at risk their local area is of flooding