Crowded Coasts, Unit 2 Edexcel Geography Revision notes

Crowded Coasts, Unit 2 Edexcel Geography Revision notes 

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Unit 2 ­ Coastal environments
Coasts are systems ­ they have inputs, processes and outputs
1. INPUTS ­ river sediment, sediment from cliffs that have been eroded or suffered landslides and sediment that
has been transported by waves from offshore (out at sea)
2. PROCESSES ­ wave action, tidal movement, erosion, weathering, transportation, deposition.
3. OUTPUTS ­ sediment washed out to sea, or deposited further along the coast.
Coastal sediment cells (littoral cells) ­ lengths of coastline that are pretty much entirely selfcontained for the
movement of sediment. Each one is a coastal system so processes occurring in one cell don't affect the movement of
sediment in another cell.
Waves are responsible for erosion and deposition of beach sediment
1. Waves are created by the wind blowing over the surface of the sea. The size and effect of the wave is
determined by the fetch and wind speed of the wave.
2. Constructive Waves ­ low frequency (68 waves per minute). They're low and long which gives them more
elliptical cross profile. This powerful swash carries material up the beach and deposits it.
3. Destructive Waves ­ high and steep, with a more circular cross profile. They have a higher frequency
(1014 waves per minute). The strong backwash removes material from the beach.
Tide affects where waves break ­ the area of land between maximum high tide and minimum low tide is where
landforms are created and destroyed.
Subaerial weathering occurs along the coastline
1. Describes coastal processes that are not linked to the action of the sea. It includes freezethaw
weathering and salt weathering. Weathering weakens cliffs and makes them more vulnerable to erosion.
2. Throughflow (flow of water through cliffs) and runoff (flow of water over land) caused by heavy rain can
also make cliffs more unstable and increase the likelihood of mass movement.
3. Mass movement is the movement of material downhill due to gravity. It includes landslides, slumping and
rockfalls.
Five main ways to erode the coastline
1. Abrasion/corrasion ­ bits of rock and sediment transported by the waves smash and grind against rocks and
cliffs, breaking bits off and smoothing surfaces.
2. Hydraulic action ­ Air in cracks is compressed when waves crash in. The pressure exerted by the
compressed air breaks off rock pieces
3. Quarrying ­ the energy of a wave as it breaks against a cliff is enough to detach bits of rock.
4. Corrosion/solution ­ soluble rocks (e.g. limestone, chalk) get gradually dissolved by the seawater and other
chemicals dissolved in the oceans.
5. Attrition ­ bits of rock in the water smash against each other and break into smaller bits.
Rate at which a stretch of coastline is eroded depends on several factors
1. The width of the beach
2. The breaking point of waves
3. The aspect ­ if the coastline faces the dominant wind and wave direction, erosion will be faster.
4. The fetch of the waves
5. Rock type (geology)
6. Relief of the land (hills, etc)
7. Human activities
8. Ecosystems
9. Longshore drift processes
10. Rainfall and temperature

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Storms/surges
Currents transport sediment
1. Current ­ general flow of water in one direction
2. They move material along the coast ­ this is called longshore drift
3. Swash carries sediment (e.g. shingle, pebbles) up the beach, parallel to prevailing wind. Backwash carries
sediment back down the beach, at right angles to the shoreline.
4. When there's an angle between the prevailing wind and the shoreline, a few rounds of swash and backwash
move along the shoreline.…read more

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Sea level changes are either Eustatic or Isostatic
EUSTATIC (Eeverywhere GLOBAL) ISOSTATIC (I ­ inside only local)
Caused by vertical movements of the land relative to the
Caused by a change in the volume of water in the sea, or sea.…read more

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Management of river systems ­ some management strategies (e.g. dams) trap sediment and so reduce the
amount being deposited at the river's mouth. This causes deltas and salt marshes to shrink, providing less
protection against high tides and storm surges.
2. Management of coastal systems ­ some management strategies alter sediment movement, reducing the
amount of protective beach material further along the coast. E.g.…read more

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Only some parts of the coast are managed with the aim of the protection being to protect homes, businesses and
the environment from erosion and flooding. This is because flooding and erosion of the coastline can have severe
social, economic and environmental impacts. All coastal settlements want to be defended, but the amount of
money available is limited so not everywhere can be defended. Choosing which places are defended (and how) is
based on costbenefit analysis.…read more

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Controlled release of
water through turbines in the dam at
low tide generates electricity. They
also prevent flooding from storm
surges
Soft Engineering defences involve coaxing natural processes along
1. Beach nourishment ­ sand and shingle added to beaches from elsewhere (dredged for example offshore).
This creates wide beaches, which reduce erosion of cliffs.
2. Beach stabilisation ­ can be done by reducing the slope angle and planting vegetation, or by sticking stakes
and old tree trunks in the beach to stabilise the sand.…read more

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Beaches are created with the deposition of eroded material
5. Flood plains are generally wide, flat valley floors that become regularly flooded by a river.
6. Deltas form at a river mouth when sediment is deposited faster than the sea can remove it.
7. Certain ecosystems, such as mangrove swamps, are valuable natural environments, providing important
breeding grounds for many species of fish.
Different types of development can be found on a variety of coastal environments
Dramatic scenery of some coastlines attracts tourists, e.g.…read more

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