Energy at the Coastline Back
What is the coastline?
The coastline marks the meeting point between the land and sea. This area is dynamic and constantly changing in nature due to the processes of erosion, transport and deposition that take place here (see the coastal system for a summary). The extent of these processes are dependent on the amount of energy available. At the coastline the energy source is the wind which transfers its energy to the water creating waves.
How is energy transferred to create waves?
- Wind creates friction on the waters surface;
- Frictional drag between the wind and the waters surface causes water particles to rotate and energy is transferred forward;
- When the wave reaches shallow water, it slows down due to friction between the base of the wave and the sea bed. The shape of the wave becomes increasingly elliptical;
- The top of the wave continues to move forward as it is unaffected by the friction with the sea bed. It becomes steeper and steeper and eventually breaks;
- Water moves up the beach as the swash;
- Water then returns back down the beach as the backwash.
There are two main types of waves:
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Constructive Waves |
Destructive Waves | ||||||||||||||||
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What determines how much energy waves have?
- Wind speed
- Wind duration (length of time for which wind blows)
- The Fetch of the wave (distance of open sea over which the wind has blown)