High-energy and low-energy coasts

In this section, you will learn about:

• the characteristics of high-energy and low-energy coastal environments
• how differences in energy influence coastal processes and landforms
• the role of fetch, wind direction and shelter in shaping coastlines

Introducing coastal energy environments

The amount of energy reaching a coastline determines whether it is dominated by erosion or deposition. This energy mainly comes from waves generated by wind. As explored in the previous section, factors such as fetch, wind strength and duration influence how powerful waves become.

Coastlines can therefore be broadly classified into:

• high-energy coasts, where wave energy is strong, and erosion dominates
• low-energy coasts, where wave energy is weaker and deposition is more important

These contrasting environments help explain why coastal landscapes vary so much around the world.

High-energy coasts

High-energy coasts are exposed to powerful waves, often generated over long distances of open water (a long fetch). They are typically found on coastlines facing large oceans.

Key characteristics

• Strong, frequent, destructive waves
• High rates of erosion
• Sediment is removed faster than it is deposited
• Coastlines are often rocky and steep
• Beaches tend to be narrow or absent

Typical landforms

• Cliffs
• Headlands
• Wave-cut platforms
• Caves, arches and stacks

UK examples

• Atlantic-facing coasts such as Cornwall and north-west Scotland
• Areas exposed to prevailing south-westerly winds
• These environments are shaped by the continuous input of energy, which drives erosion and prevents significant sediment accumulation.

Low-energy coasts

Low-energy coasts develop where wave energy is reduced. This may be due to short fetch, shelter from prevailing winds, or offshore features that absorb wave energy.

Key characteristics

• Dominated by constructive waves
• Low rates of erosion
• Deposition exceeds erosion
• Coastlines are often low-lying and gently sloping
• Beaches are typically wide and sandy

Typical landforms

• Beaches
• Spits
• Bars
• Mudflats and salt marshes

UK examples

• Sheltered areas such as estuaries and bays
• Parts of the east and south coast of England, including Lincolnshire
• These coasts act as sediment stores, where material transported from elsewhere is deposited.

Why do these differences occur?

The contrast between high- and low-energy coasts can be explained by variations in:

• Fetch
• Long fetch → high-energy waves
• Short fetch → low-energy waves
• Wind direction
• Prevailing winds determine which coasts receive the most energy
• Coastal orientation
• Coastlines facing dominant winds experience higher energy
• Sheltered coasts receive less wave energy
• Geology and coastal shape
• Headlands may be exposed to high energy
• Bays may be protected, creating lower-energy conditions

A dynamic system

Coastlines are not fixed as high- or low-energy environments. Instead, they exist within a dynamic system:

• Storm events can temporarily increase energy levels
• Seasonal changes can alter wave types (constructive in summer, destructive in winter)
• Sediment supply can modify beach profiles and energy absorption
• This means that coastal environments are constantly adjusting towards a state of dynamic equilibrium.

Link to coastal processes

The energy level of a coastline controls:

• the rate of erosion
• the amount of transport (e.g. longshore drift)
• the extent of deposition
• In high-energy environments, erosion dominates, and landscapes are rugged.
• In low-energy environments, deposition dominates, and landscapes are more gently sloping and sediment-rich.