BackwardForwardHomeExit BackwardForwardHomeExit I. What are the major processes operating along coasts? 1.1 What is wave generation? Download Flash Player.

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I. What are the major I. What are the major processes operating along processes operating along coasts?coasts?

1.1 What is wave 1.1 What is wave generation?generation?

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Parts of a waveParts of a wave

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1.2 What are the 1.2 What are the characteristics of wave characteristics of wave generation?generation?

1. Fetch1. Fetch

Fetch is the maximum distance in one Fetch is the maximum distance in one

direction across an open body of water direction across an open body of water

that wind can blow.that wind can blow.

Wind

Land

Fetch

The maximum distance a wave can travel

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• The longer the fetch, the larger the The longer the fetch, the larger the

wave.wave.

• Areas with longest fetch potentially Areas with longest fetch potentially

receive the highest energy waves. receive the highest energy waves.

Cornish Coast in Cornish Coast in

the southwestern the southwestern

part of England part of England

receives receives

maximum fetch maximum fetch

because it is because it is

exposed to the exposed to the

Atlantic OceanAtlantic Ocean

Fetch

Atlantic Ocean

Cornish Coast

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2. Energy2. Energy

The size and energy of waves are affected by:The size and energy of waves are affected by:

• How long the wind has been blowing- How long the wind has been blowing-

The longer the time, the stronger the wavesThe longer the time, the stronger the waves

• The strength of the wind - The strength of the wind -

The stronger the wind, the stronger the The stronger the wind, the stronger the

waveswaves

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• The The fetch fetch - -

The longer the fetch, the stronger the The longer the fetch, the stronger the waveswaves

• Wave height - Wave height -

The higher the wave, the greater the wave The higher the wave, the greater the wave energyenergy

The size and energy of waves are affected by:The size and energy of waves are affected by:

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Change in wave forms when it Change in wave forms when it approaches the coastapproaches the coast

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1.3 What are constructive 1.3 What are constructive waves?waves?

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1.3 What are destructive 1.3 What are destructive waves?waves?

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What are constructive and What are constructive and destructive waves?destructive waves?

Wave height

Wave length

Wave size

Wave frequency

Offshore gradient

Higher

Shorter

Bigger

12-14 waves per minute

Steeper

Constructive wave

Lower

Longer

Smaller

6-8 waves per minute

Gentler

Destructive wave

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What are constructive and What are constructive and destructive waves?destructive waves?

Constructive wave Destructive wave

Swash

Backwash

Relationship between swash and backwash

Coastal process

Stronger

Weaker

Swash > Backwash

Deposition

Weaker

Stronger

Backwash > Swash

Erosion

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1.4 What are the erosion 1.4 What are the erosion processes along coasts?processes along coasts?

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1.5 What are the 1.5 What are the transportation processes transportation processes along coasts?along coasts?

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Longshore drift Longshore drift

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1.6 What are the deposition 1.6 What are the deposition processes along coasts?processes along coasts?

What is deposition?What is deposition?

When waves lose their energy, they When waves lose their energy, they will drop the materials they are will drop the materials they are carrying such as sand, rock particles carrying such as sand, rock particles and pebbles. and pebbles.

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Deposition takes place inDeposition takes place in

• sheltered areas with low-energy sheltered areas with low-energy waves waves

• Input exceeds output, with abundant Input exceeds output, with abundant supply of sedimentssupply of sediments

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