Wave Action on Coasts
Geography: Edexcel IGCSE, topic 1.2.7
Types of Wave
Constructive and destructive waves are the two main types of wave. The characteristics of these waves are described below:
What are constructive waves?
- Constructive waves are not very tall.
- When the sea's waves are constructive, we say that the sea is calm.
- Constructive waves have a longer wavelength than destructive waves which means individual waves are spread quite far apart.
- Constructive waves have a low frequency (about 7-10 waves arrive at the beach each minute).
- Constructive waves deposit material onto coastlines because they have strong swash and weak backwash. This means that more material is deposited onto the beach than the weak backwash can drag material away.
What are destructive waves?
- Destructive waves are taller and more frequent than constructive waves.
- Destructive waves have a high frequency. They have around 10-15 waves per minute.
- Destructive waves cause most of the erosion of coastlines.
- Destructive waves have a stronger backwash than swash, meaning they drag more material away from the coastline than is deposited on the shore.
What is deposition?
- Deposition describes the sea putting (depositing) solid material from the sea onto the land on the coastline.
- Constructive waves deposit material on coastlines because their swash depositing things on the beach is stronger than their backwash dragging things from the beach.
How do destructive waves erode the coast?
- Destructive waves erode the coast using 3 erosional processes:
- Hydraulic power: The force of wave actually breaks the rock itself.
- Abrasion: The material and rock being carried by the sea damages the coastal rock.
- Attrition: The bedload collides with itself, eroding it.
Test yourself on Wave Action on Coasts
Which 3 erosional processes cause the rock on the coastline to retreat?
What are the main types of waves?
Which of the following is not a category of wave?
Which of the statements below are characteristics of destructive waves?