Sources of energy in coastal environments: winds, waves (constructive and…

The idea

Coastal systems are driven by multiple energy sources. Winds generate waves and drive surface currents, with fetch determining wave energy. Constructive waves have a strong swash and weak backwash, building up beaches, whereas destructive waves possess a weak swash and strong backwash, eroding material. Tides, driven by gravitational pull, dictate the range of wave action and generate tidal currents in estuaries. High energy coasts, like Cornwall, face strong prevailing winds and long fetches, resulting in destructive waves and erosional landforms such as cliffs. Conversely, low energy coasts, like the Baltic Sea, experience limited fetch and gentle winds, dominated by constructive waves and depositional features like spits and mudflats.

What earns the marks

• Identify wind as the primary energy source that generates waves and influences their magnitude through fetch, duration, and velocity.
• Contrast constructive waves (low frequency, strong swash, net deposition) with destructive waves (high frequency, strong backwash, net erosion).
• Explain the role of tides in shifting the zone of wave action and generating tidal currents that transport sediment, particularly in estuaries.
• Characterise high energy coasts by their exposure to strong prevailing winds, long fetches, and dominant erosional processes and landforms.
• Characterise low energy coasts by their sheltered locations, short fetches, and dominant depositional processes and landforms.

Common mistakes and how to put them right

• Stating that constructive waves have a strong backwash.

  Put it right: Constructive waves have a strong swash and weak backwash, leading to sediment deposition.

• Confusing currents and tides.

  Put it right: Tides are vertical movements of water driven by gravity, while currents are horizontal movements of water driven by wind, temperature, or tidal flows.

• Assuming high energy coasts only experience erosion.

  Put it right: While erosion dominates high energy coasts, deposition still occurs in sheltered bays or during calmer seasonal conditions.

Exam tips

• Link wave types directly to beach profiles, explaining how destructive waves create steep, combed-down winter profiles.
• Use specific geographical examples to contrast high energy (e.g., Atlantic coast of Scotland) and low energy (e.g., Lincolnshire coast) environments.
• When discussing energy sources, explicitly mention how wind fetch and duration control the kinetic energy transferred to waves.