AQA GCSE Geography A the coastal zone

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How do waves shape our coastline?
How do waves form?
Waves are usually formed by the wind blowing over the sea. Friction with the surface of the water
causes ripples to form and these develop into waves. The stretch of water over which the wind
blows is called the fetch. The longer the fetch, the more powerful the waves become.
Waves can also be formed more dramatically when earthquakes or volcanic eruptions shake the
seabed. These are called tsunamis.
When waves reach the coast
In the open sea there is
little horizontal transfer of
water, it is only when the
waves approach the shore
that there is forward
movement as waves break
and wash up the beach. As
the sea becomes shallower,
the circular motion becomes
more elliptical. This causes the crest of the wave to rise up and then eventually topple onto the
beach. The water that rushes up the beach is called the swash and the water that flows back; the
backwash.
Types of waves found at the coast

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Which land processes shape our coastline?
Weathering
Processes of weathering affect rocks exposed at coast. At coast,
freeze-thaw weathering is particularly effective if the rock
exposed is porous and permeable. Freezethaw weathering can lead
to rock fall.
Mass movement
Mass movement is when a lot of material is removed from the
coastline at one time. It causes a large retreat in the coastline too.
There are two types ­ slides and slumps. Slides are when material
slides off the coast in a straight line.…read more

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Which marine processes shape our coastline?
Coastal erosion
o Hydraulic power - trapped air blasted into rocks by sheer power of waves.
o Corrosion ­ the effect of rocks being flung at the cliff by powerful waves.
o Abrasion ­ this is the `sandpapering effect of pebbles grinding over a rocky
platform, often causing it to become smooth.
o Solution ­ some rocks are vulnerable to being dissolved by seawater. This is
particularly true of limestone and chalk which forms cliffs.…read more

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What are the distinctive landforms resulting
from erosion?
Headlands and bays
Cliffs rarely erode at an even pace.
Sections of cliff that are particularly
resistant to erosion stick out to form
headlands. Weaker sections are easily
eroded to form bays. Headlands are the
most vulnerable to the power of the
wave, which explains the presence of
erosional features such as cliffs and wave
cut platforms. In contrast, bays are often
much more sheltered so this is why sandy
beaches are common.…read more

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What are the distinctive landforms resulting from
deposition?
Beaches
Beaches are accumulations of sand and shingle found where deposition occurs at the coast. Sandy
beaches are often found in sheltered bays, where they are called head beaches. When waves enter
these bays, they tend to mirror the shape of the coast. This is called refraction. The way the water
gets shallower as the waves enter the bay causes this to happen.…read more

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Coastal deposition at Hurst Castle, Hampshire
Case study: Hurst Castle in Hampshire
A popular tourist destination for one of the most famous spits in England. It is located on the
Hampshire coast, close to the city of Southampton. Its formation is complex, but longshore drift has
actively been shaping the landform for hundreds of years. Henry VIII built a castle near the tip of the
spit to help defend England from possible invasions.…read more

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Political:
Sea defences will be expensive. `Managed retreat' may cause controversy.
Case study (2): Bangladesh
Political: Natural:
A decrease in production of cash crops Salt industry ruined (high unemployment).
= decrease in GDP. Land quality degraded.
Increase in poverty. Mangrove forest and it unique habitat at
Migration to India resulting in conflict risk.
between two governments. 8000km² land loss.
Social: Economic:
People will become homeless. Food and water supplies wrecked.
Infrastructure and houses destroyed. Loss of jobs.
20 million people at risk from flooding.…read more

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Usually the decision is made to `hold the line' however sometimes planners decide to `advance the
line' for greater protection by things such as increasing beach size.
Hard engineering schemes
Hard Description Cost Advantages Disadvantages
engineerin
g
Sea wall Concrete or rock Up to £6 Effective at Looks obtrusive.
barrier. Curved million stopping sea. Expensive.
face to reflect per km. Often makes High
waves back. 3-5m walkway. maintenance.
high.
Groynes Timber or rock £10,000 Makes a bigger Interrupting
structures built each at beach.…read more

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Managed retreat
Allowing the controlled flooding of low-lying coastal area where the value of the land is low.
Case study: coastal defences at Minehead, Somerset
Minehead is on the north coast of Somerset and is one of the regions premier tourist resorts.
In the early 1990's it became clear that the current sea defences were going to become inadequate.
Storm damage was estimated to be £21 million if nothing was done. The Environment Agency
developed a plan to develop the town.…read more

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A more deposition occurs the mud begins to break the surface to form
mug flats. Salt-tolerant plants such as cord grass soon start to colonise the mud flats. They are called
pioneer plants. Cord grass has long roots to stop it being swept away and stabilise it. However its
tangled roots also trap sediment and stabilise mud. As mid level rises there is less water. Rain washes
some of the salt away improving fertility. Plant species start to colonise.…read more

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can't use it in 2003 word.

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