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  • Created on: 28-02-10 23:39

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Coastal Erosion from waves
1. Hydraulic Action ­ Sheer force of the waves beating down on the coast. High Pressure.
2. Abrasion ­ Waves carrying sediment which is then used to erode the coast.
3. Attrition ­ Sediment and particles carried down by the river colliding with each other.
4. Solution ­ Rock minerals which can be dissolved by sea water, breaking rocks down.
Sediment Transport by Waves
1. Traction ­ Heavy boulders rolling along the sea bed, brought down by the river.
2. Saltation ­ Small/Medium size sediments bouncing along the sea bed in a leap from motion.
3. Suspension ­ Small/Medium size sediments carried by the waves in the sea water.
4. Solution ­ Rock minerals dissolved by the sea water, breaking rocks down.
Waves are formed by wind blowing over the surface of the water.
They are pulses of energy moving through the sea water.
How do waves break?
As the wave approaches the coast the circular motions of the water particles become slowed down
and distorted. Therefore the wave increases in height and slows down. The water particles at the top
of the wave are quicker than those closer to the sea bed and so it becomes unstable and topples
over; releasing its energy on the coast.
What determines the energy of a wave?
Wind Speed ­ Higher the wind speed, higher the energy of the wave. The frictional drag exerted on
the water has the potential to transfer more energy. (Think storms)
Wind Duration ­ Longer the wind is blowing, the higher the energy. More energy being transferred.
Wave Fetch ­ The fetch is the distance the wave producing winds can blow over open sea. Longer
the fetch, more energy.
Different Waves
Destructive ­ Frequent (11-15 waves per minute). Short, steep waves that is high in relation to
wavelength. Stronger backwash than swash. Drags material back down the beach.
Constructive ­ Infrequent (6-9 waves per minute). Long, shallow waves that is low in relation to
wavelength. Stronger swash than backwash. Carries material up the beach.

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Headlands and Bays
Where the bay has been formed was softer rock. It
has been eroded away from waves, hydraulic
action, attrition abrasion and solution. The
headlands that stick out are made of harder rock
and so they don't erode back.
As waves move towards headlands they focus
maximum energy on the headland increasing
As waves move towards the beach they decrease
in height as friction increases into the bay.…read more

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Human activity on the coast
1. Recreation ­ Dog walking, holiday makers.
2. Industry ­ ports, large ships with trade, tourism.
3. Flooding ­ sea levels rise due to climate or storms. Bad for the houses/buildings/hotels etc.
4. Pollution ­ Litter from tourists, dog mess on beaches and pollution from ships.
5. Erosion ­ Cliff collapse and retreat threatening houses, tourists etc.
6. Conservation ­ Beautiful landscapes and preserved. Protecting rare wildlife.
Coastal Management
Usually done to...
Prevent erosion. (Might reach houses/building etc. dangerous.…read more

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Hard Management Strategies
Sea Wall
Concrete walls built to reflect the wave attack on the coast
preventing erosion of the land behind.
Small Mesh cage filled with small rocks. They are able to move a little by are
strong. They allow water in but absorb the energy of the wave and
dissipate wave energy. Water can move inside to reduce risk of landslide
and mudflows.
Armour Blocks
Large boulders dumped on beach. Very strong and protects coast from
being eroded.…read more


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