IGCSE Geography 0460 - 2. The Natural Environment

2.3 Coasts: Processes, Landforms & Management

This section explores the dynamic nature of coastlines, focusing on the processes that shape them, the resulting landforms, and the strategies used to manage coastal hazards.

Coastal Processes

Coastal processes are the forces that shape and modify the coastline. The primary processes are:

• Erosion: The wearing away and removal of coastal material by waves, tides, and wind.
• Deposition: The dropping of eroded material in a new location, forming new landforms.
• Longshore Drift: The movement of sediment along the coastline, parallel to the shore, caused by waves approaching at an angle.

Wave Action: Waves are the most powerful agent of coastal erosion. The energy of a wave depends on its height (wave height) and length (wavelength). Larger waves carry more energy and cause greater erosion. The process of wave erosion involves:

1. Hydraulic Action: The force of water entering cracks and crevices in the rocks, compressing air and causing the rocks to break apart.
2. Abrasion (Corrasion): The wearing away of rocks by sediment carried in the waves.
3. Attrition: The breaking down of rocks and pebbles as they collide with each other in the waves.
4. Solution (Corrosion): The dissolving of soluble rocks like chalk by seawater.

Tides: Tides are the rise and fall of sea level caused by the gravitational pull of the Moon and the Sun. High tides occur when the Moon and Sun are aligned, and low tides occur when they are at right angles. Tides contribute to coastal erosion and can transport significant amounts of sediment.

Wind: Wind can erode sand dunes and transport sand inland, creating features like sand dunes and spits.

Coastal Landforms

Coastal processes create a variety of distinctive landforms:

Landform	Description	Process(es) Involved
Cliffs	Steep, vertical rock faces formed by wave erosion.	Wave action (erosion), weathering
Wave-Cut Platform	A flat, rocky area at the base of cliffs, formed by abrasion.	Wave action (abrasion), hydraulic action
Sea Caves	Hollows in cliffs formed by wave erosion.	Hydraulic action, abrasion, solution
Arches	Natural bridges formed when a sea cave erodes through a headland.	Hydraulic action, abrasion
Stacks	Isolated rock pillars left behind when an arch collapses.	Wave action (erosion)
Spits	Long, narrow ridges of sand or shingle that project from the land into the sea.	Longshore drift, deposition
Sand Dunes	Hills of sand formed by the deposition of sand carried by the wind.	Wind, deposition
Bay	A recessed area of coastline.	Deposition, reduced wave energy
Headland	An area of coastline that juts out into the sea.	More exposed to wave action, greater erosion

Coastal Management Strategies

Coastal management aims to protect people, property, and the environment from coastal hazards. Strategies can be broadly divided into:

• Hard Engineering: Structures built to defend the coastline from erosion. Examples include:
  • Sea Walls: Solid walls built parallel to the shore to protect the coastline from wave attack.
  • Groynes: Structures built perpendicular to the shore to trap sediment and prevent erosion.
  • Breakwaters: Offshore structures built to reduce wave energy reaching the shore.
  • Revetments: Sloping structures built parallel to the shore to absorb wave energy.

  Advantages of Hard Engineering: Can be effective in the short term. Disadvantages: Can be expensive, disrupt natural coastal processes, and may cause erosion further down the coast.

• Soft Engineering: Strategies that work with natural coastal processes. Examples include:
  • Dune Systems: Encouraging the growth of sand dunes to provide a natural barrier against coastal erosion.
  • Beach Nourishment: Adding sand to the beach to replace eroded material.
  • Managed Realignment: Relocating coastal defenses to a more sustainable position.

  Advantages of Soft Engineering: More sustainable, works with natural processes. Disadvantages: May not be as effective as hard engineering in the short term.

• Managed Retreat: The deliberate withdrawal of coastal defenses to allow the coastline to naturally erode. This is often a long-term strategy used in areas where coastal erosion is inevitable.

The choice of coastal management strategy depends on a variety of factors, including the nature of the coastal hazard, the cost of the strategy, and the environmental impact.