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Question 7 Coasts Paper 1

Waves- how are they formed and how do they affect the coast?

Waves are caused by friction between the wind and water causing the water to swell.
The size and energy of a wave is influenced by:

how long the wind has been blowing

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Coastal processes- weathering

When rocks and surface materials are broken down through the actions of the atmosphere
we call it weathering. Weathering weakens rocks at the coast and makes them more likely
to be affected by mass movement and erosion

It is a sub aerial process
Chemical: when weak acids…

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When the sea loses energy, it drops the beach material / sediment, rock particles and
pebbles it has been carrying. This is called deposition.

Deposition happens when the swash is stronger than the backwash and is associated with
constructive waves.

Deposition is likely to occur when:
waves enter an area…

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Cliff erosion and wave cut platforms
Cliffs and wave-cut platforms
The process of cliff erosion.
1. Weather weakens the top of the cliff.
2. The sea attacks the base of the cliff forming a wave-cut notch through abrasion and
hydraulic action.
3. As erosion continues the notch increases in size…

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1) Longshore drift moves material along the coastline.
2) There is a sharpe change in direction of the coast e.g. river
or bay.
3) A spit forms when the material is deposited.
4) Over time, the spit grows and develops a hook if the
prevailing wind changes direction.

Waves cannot…

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The extra weight/pressure acting on the cliff causes it to move.

The clay flows down towards the sea as part of a mud or debris flow

As it moves it rotates

CASE STUDY: The impact of rising sea levels: The Maldives

Located in the Indian Ocean
Small country made…

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16km stretch of coastline. Difficult to protect it all.
Tourism is big business and provider of jobs.
Densely populated with resorts such as Barton-on-sea.

Why is it eroding rapidly?
1- Marine processes weaken base of cliff. Hydraulic action and abrasion.

2- Sub aerial processes attack cliff top ­ weathering, slumping,…

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A wall built on the edge of the coastline. Protects the base of cliffs, land and buildings
against erosion. Can prevent coastal flooding
in some areas. Strong and durable. Made of
reinforced concrete.

Expensive to build. £10k per metre. Curved
sea walls reflect the energy of the waves

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The main advantage is that beaches are a natural defence against erosion and coastal
flooding. Beaches also attract tourists.
It is a relatively inexpensive option but requires constant maintenance to replace the
beach material as it is washed away.

Managed retreat
Areas of the coast are allowed to erode and…

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The Environment Agency took charge to protect the area.
Opened in September 2006 and is one of the largest flood storage schemes in
Europe .
It allows flood water from the Humber estuary to spill out of the river during the
highest tides to fill the low lying land.


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