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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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