Waves influence erosion through both constructive and destructive processes. Constructive waves gently build up beaches by spilling water up the shore, while destructive waves strongly erode beaches by crashing waves that remove material. Waves are formed by wind blowing across the surface of the ocean, transferring its energy to the water. As waves approach shore, they steepen and eventually break, providing energy to erode, transport, and deposit coastal materials.

1. How do waves
influence erosion?
Key questions:
• What are constructive +
destructive waves?
• How do waves influence
erosion?

2. How do waves work?
What causes waves?

3. How do waves work?
• Waves are created by wind
• The friction of the wind makes the sea
swell and rise up
• The energy of the wind causes water
particles inside the sea to rotate and
this movement pushes the wave forward
• The waves get bigger until they reach
the coast where they break

4. Waves

5. Coastal processes
• Bitesize coastal processes

6. Geog.GCSE
• P88
• Make a large, neat copy of the diagram
on p88.
• Add short labels

7. The sea drains back down
the beach.
This is called backwash.
This process moves
material back down the
beach.
Within each individual
wave, the water particles
all move in a circular
motion. A constant circle
back to their starting
points.
When a wave moves in to
shallow water near the
coastline it starts to
rear up and distort until
it breaks.
Out at sea, sometimes
thousands of miles away,
the wind is blowing.
As the wind blows across
the surface of the sea it
creates friction.
It tugs across the sea
and causes the wave
shape to move forwards.
Once the wave breaks,
there is energy moving
and also water crashing
forwards.
This provides the energy
for erosion and
deposition.
Water from the sea
rushes up the beach.
This is called the swash.
This process moves
material up the beach.

8. The sea drains back down
the beach.
This is called backwash.
This process moves
material back down the
beach.
Within each individual
wave, the water particles
all move in a circular
motion. A constant circle
back to their starting
points.
When a wave moves in to
shallow water near the
coastline it starts to rear
up and distort until it
breaks.
Out at sea, sometimes
thousands of miles away,
the wind is blowing.
As the wind blows across
the surface of the sea it
creates friction.
It tugs across the sea and
causes the wave shape to
Once the wave breaks,
there is energy moving and
also water crashing
forwards.
This provides the energy
for erosion and deposition.
Water from the sea
rushes up the beach.
This is called the swash.
This process moves
material up the beach.
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1
2 3
4 5

9. Waves keywords
• Swash = the wave washing up the beach.
• Backwash = the wave pulling back down the
beach by gravity.
• The crest = is the top of the curling wave,
the wave at its highest point.
• The fetch = is the distance a wave travels
before it crashes on to the coastline.
• A constructive wave = helps to build a beach.
• A destructive wave = erodes a beach.

10. Why are some waves stronger
than others?
Geog.gcse p88. Complete these Qs in sentences.
1. The height and strength of waves depend on
i)................ii)................iii)...................
2. What is the ‘fetch’?
3. What winds affect our south coast in Britain?
4. South-westerly winds produce ....................... waves
because ...........................
5. South-easterly winds produce ..............................
waves because ...........................
6. What is more important, fetch or wind speed?

11. Fetch
Brazil
Atlantic
Ocean
France
English
channel

12. Why do waves break?
• Why do you think waves break when
they reach a beach?

13. Characteristics of Waves
crest
Fetch

14. Waves
• There are two main types of waves:
• Constructive vs Destructive

15. Constructive vs Destructive
• Geog.gcse p89 or Tomorrow’s Geog p5
• Copy the diagrams of the two types.
• You must include the information too

16. Constructive Waves
Gently sloping
wave
Wave crests
far apart
Breaking wave
spills, does
not crash
Gentle beach

17. Destructive Waves Steeply
sloping wave
Breaking wave
plunges + crashes
Waves close
together

18. Quick test
• Which waves builds up the beach?
• Which wave has a stronger backwash?
• Which wave has low wave height?
• Constructive waves usually happen on
gentle or steep slope beaches? Why?
• Destructive waves are ‘spilling’ or
‘breaking’?

19. Waves + the coast
• Not only do waves erode the coast, they
also transport and deposit the material
that they erode to different places
• Southsea beach may have been eroded
and transported there from France
• How do waves transport material?

20. Long-shore drift (LSD)

22. Exam Q
1) Describe and explain how constructive
and destructive waves work. Use
keywords or examples where possible.
[4marks]
2) Apart from the strength of waves,
what other factors can effect how
quickly a coastline erodes? [3marks]