coasts

Question 1

describe a constructive wave

Answer 1

low wave in proportion to length

long wavelength and short fetch

strong swash

weak backwash

deposition on beach

Question 2

describe a destructive wave

Answer 2

high wave in proportion to length

breaks downwards with great force

short wavelength and long fetch

erodes the beach making it steeper

strong backwash

weak swash

Question 3

explain the types of coastal erosion

Answer 3

Attrition - rocks smash against each other and become smaller, rounder and smoother.

Abrasion - rocks are smashed against the cliff wearing it away.

Solution - rocks are dissolved

Hydraulic action - the power of the wave forces air and water into cracks making them bigger.

Question 4

what does concordant mean

Answer 4

when the geology (rocks) are arranged parallel to the coastline.

Question 5

what does discordant mean

Answer 5

when the geology (rocks) are at 90 degrees to the coastline.

Question 6

what does fetch mean

Answer 6

the distance which the wind has blown over the sea.

Question 7

what does geology mean

Answer 7

the different rocks and their resistance and permeability.

Question 8

explain the process of a plunge pool

Answer 8

hard rock is not eroded. As the lower, softer layer erodes the plunge pool will develop. The harder, more resistant rock will begin to extend out or produce an overhang. The weight of this heavier, more resistant rock will eventually succumb to gravity and collapse to the plunge pool below. When this occurs the waterfall will migrate or move upstream extending the canyon and begin this process again.

Question 9

how are bays and headlands formed

Answer 9

waves attack a section of cliff
cliff made up of different types of geology
soft rock is less resistant and therefore erodes faster retreating backwards creating a bay
hard rock is more resistant and therefore remains, forming headlands

Question 10

what are the stages of how a stump is created

Answer 10

waves attack a cliff and a crack/crevice forms
hydraulic action causes the crack to widen and form a cave
corrasion/abrasion punches hole in back of the cave to form an arch
top of the arch is unsupported and falls to create a stack
waves weaken the bottom of the stack, it falls over forming a stump

Question 11

describe the formation of a spit

Answer 11

longshore drift carries material along the coastline, where the coastline changes direction deposition of material takes place forming a piece of land jutting out into the sea.

Question 12

describe the process of longshore drift

Answer 12

Waves approach the coast at an angle. Swash carries sediment up the beach at an angle. Backwash carries sediment down the beach with gravity – at right angles to the beach.

Question 13

What are the impacts of longshore drift on the coastline?

Answer 13

can destroy a beach by removing all the material from it

can change the shape of a beach

can create landforms such as spits

can make estuaries used as harbours too shallow because of deposited material

Question 14

What 3 factors affect the rate of landform change?

Answer 14

Geology:

Climate:

Humans:

Question 15

For two contrasting coastlines explain the factors affecting rate of landform change

Answer 15

Holderness
Boulder clay is less resistant.
Rock groyne stopped longshore drift and narrowed the beach.
Sea wall and granite rip-rap at Withernsea to slow down erosion.
The removal of sediment offshore has made the coastline more vulnerable
Frequently subjected to powerful destructive waves from the North Sea.

Jurassic coastline
Discordant coastline created Swanage Bay and Headlands of Durlston and Ballard Point which have Old Harry’s stack.
Concordant coastline has hard limestone parallel to coastline and in one place has punched through the outer layer and created Lulworth Cove from the less resistant clays and sands.
Weight of buildings on cliff top e.g. The Grand Hotel in Swanage increase landslides.
The construction of 19 timber groynes, restoration of the sea wall, beach replenishment with 160,000 tonnes, cliff regrading - reduced rate.

Question 16

what is cost/benefit analysis

Answer 16

weighing up the costs of protecting the coastline against the benefits of protecting the coastline

Question 17

what is rotational slumping

Answer 17

caused by water entering dry cracks in the cliff and saturates the soil so it becomes too heavy for the cliff and it slides down

Question 18

what is soil creep

Answer 18

slow downhill movement of soil

Question 19

what is weathering

Answer 19

the breakdown of rock in-situ

Question 20

what are the types of weathering

Answer 20

Physical - water gets into cracks, freezes and expands over night widening cracks or rock heated during day, expands and at night cools and contracts - layers peel off (onion skin weathering)

Biological - roots get into cracks and as plant grows, roots expand widening the cracks.

Chemical - acidic rain reacts with alkaline
rock e.g. limestone and breaks it down

Question 21

What are the different options for managing the coastline?

Answer 21

1. Hold the line - coastline held at present place by building or maintaining defences
2. Advance the line - build new defences to build up the coast into the sea;
3. Retreat the line (managed retreat):- allow the coastline to retreat by not maintaining defences or punching hole in defences;
4. Do nothing:- take no action including the maintenance or removal of defences.

Question 22

Using named examples, explain what are the social and economic reasons why some coastlines are protected and others are not?

Answer 22

Happisburgh-
Cost of defences (sea wall, rip rap and groynes) - £6m
Benefit of defences - £6m protected (Agricultural land worth £1m, 20-35 properties worth £4-7m, Grade 1 & 2 listed buildings, and a Caravan park)
Defences would reduce sediment transport along the coast.
Buy and demolish scheme would cost less than the defences.
Therefore - retreat the line (managed retreat).

Sea Palling-
Cost of defences (9 offshore reefs, 150,000 tonnes of rip rap, 1.4million m3 of sand) - £20m
Benefit of defences - £345m e.g. Norfolk Broads National Park - £18m in biodiversity, £310m in recreation and £17 million providing drinking water
Will provide protection for all assets behind beach e.g. several sites of special scientific interest and 6000ha of farmland and other settlements.
Recharge will help to supply sediment to other areas along the coast
Therefore - hold the line

Question 23

what is soft engineering examples

Answer 23

beach replenishment (where sand is placed on the beach), cliff regrading (where angle of cliff is reduced), managed retreat (where areas are allowed to flood)

Question 24

hard engineering examples

Answer 24

rip rap (large boulders placed on beach) recurved seawall (to absorb energy of waves), groynes (barriers at 90 degrees to stop longshore drift), offshore reef (causes waves to break out at sea)

Question 25

advantages of soft engineering

Answer 25

cheap, easily available, fewer environmental impacts

Question 26

disadvantages of soft engineering

Answer 26

Doesn’t last very long, can be flimsy and ineffective, uses up land (managed retreat)

Question 27

advantages of hard engineering

Answer 27

permanent, effective, reduces wave energy

Question 28

disadvantages of hard engineering

Answer 28

Expensive, ugly, needs constant maintenance

Question 29

physical factors that increase vulnerability

Answer 29

Storm surges, tropical storms etc Narrowing of the land between Britain and Europe funnels water Low lying areas with no coastal defences e.g. Bangladesh Climate change and sea level rise

Question 30

How do social and economic factors increase vulnerability?

Answer 30

Areas of large % of people who have long-term health problem or disability means they will find it difficult to move. Low levels of educational achievement means they may not be aware Large proportion of the population who are elderly and do not want to move Low levels of income mean they are unable to afford to move Large population Low income countries who do not have the ability to defend themselves Location of key services e.g. hospitals, transport routes, water treatment plants, power plants.

Question 31

How do severe weather events and climate change increase vulnerability to coastal flooding in one named location?

Answer 31

London Storm surges in the North Sea off the East coast of Britain being funnelled towards Thames estuary e.g. winter storms of 2013/14 If this coincides with a high tide or spring tide sea level will be even higher Isostatic recovery - the South East is sinking by 1.5mm a year raising sea levels. Sea levels also rising due to climate change

Question 32

How can the risk of coastal flooding be reduced?

Answer 32

Monitoring and forecasting extreme events e.g. Met Office and Environment agency Online hazard mapping - awareness of which areas are at risk Emergency planning - prepared with actions before, during and after can avoid loss of life

Question 33

Using named examples explain why some coastal communities are at greater risk in the future than others?

Answer 33

Maldives Over 1000 small islands Most of the land is no more than 1m above sea level An increase in sea levels of up to 59cm by 2100 is predicted. Islands are at greater risk from the effects of hurricanes Is ranked 119th out of 228 in the world for GDP London Whilst London is at risk it has the £535m (£1.6 billion in today’s money) Thames Barrier completed in 1982 It protects 1.25 million people, £200 billion worth of property, tube network, historic buildings, power supplies, hospitals and schools. It has been used just under 200 times.

Question 34

impacts of rising sea levels in a named location

Answer 34

Maldives Most of the Maldives will be washed away in 30 years 3 of the 200 inhabited islands have already been evacuated As sea levels rise, the coral reef habitat which forms the islands, is being destroyed - fishing yields have halved and is the second biggest industry. Tourists will stop coming and over 90% of government income comes from tourist taxes. The 400,000 residents will be forced to leave Tidal surges flood homes regularly and cause salinisation preventing crops from growing. Bangladesh Environmental refugees, already people are migrating to Dhaka leading to overcrowding

Question 35

How are governments dealing with the problem of rising sea levels?

Answer 35

Maldives Hulhumale reclaimed island from the sea - 2m above sea level The capital Male has a 3m sea wall surrounding the island Floating golf courses to enable tourism to continue Houses being built on stilts on the highest ground Plans to relocate the population to a new territory such as in Sri Lanka, India or Australia - environmental refugees UK The Thames Flood Barrier costing £535m, opened in 1982 Increasing expectation that individuals and communities should help themselves to prepare