Waves, Tides, and Currents

Waves, tides and currents are the principal sources of energy in the coastal system. They drive erosion, transport sediment and create the landforms that define our coastlines. A thorough understanding of these processes is essential for A-Level Geography, as they underpin virtually every other topic in Coastal Systems and Landscapes.

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Wave Formation and Characteristics

Waves are generated by wind blowing over the surface of the sea. The frictional drag of wind on water creates ripples, which grow into waves as energy is transferred from the atmosphere to the ocean surface. The size and energy of waves depend on three factors:

1. Wind speed — stronger winds transfer more energy, producing larger waves
2. Wind duration — winds must blow consistently to build up wave height
3. Fetch — the distance of open water over which the wind blows

Key Definition: Fetch is the uninterrupted distance of ocean over which the wind blows in a constant direction. The longer the fetch, the greater the wave energy. The maximum fetch for waves reaching the west coast of Britain is approximately 5,000 km across the Atlantic Ocean.

Wave Anatomy

Understanding wave terminology is essential: