Coastal processes and features

Coastal processes and features

Coastal Processes

• Erosional Processes: There are four main types of erosional processes that occur at coastlines: hydraulic action, abrasion, attrition, and solution.
  • Hydraulic action is the force of waves crashing against the cliffs, causing the air in the cracks to become compressed and damage the rocks.
  • Attrition occurs when rock fragments carried by the sea grind against each other, becoming smoother and smaller.
  • ** Abrasion** (also known as corrasion) is the process of rocks thrown by waves scraping and scoring at cliffs.
  • Solution (also known as corrosion) involves the sea water’s chemical action dissolving some types of rock, such as limestone and chalk.

• Depositional Processes: It’s the process in which sediment is left or deposited within the coastline. This often happens when the water carrying the sediment slows down so it no longer has the energy to carry it.

• Transportation Processes: There are four types of coastal transportation: traction, saltation, suspension, and solution.
  • Traction is where pebbles and larger sediment roll along the river bed.
  • Saltation involves smaller particles bouncing along the seabed, lifted and dropped by the flow of the water.
  • Suspension involves small particles carried by the flow of water.
  • Solution involves dissolved chemicals being carried by water and deposited elsewhere due to decrease in water velocity.

Coastal Features

• Cliffs and wave cut platforms: Formed through erosional processes which can alter the land form over time.

• Caves, arches, stacks, and stumps: These are formed by the erosional processes particularly in areas where there are weaknesses in the rock, such as cracks.

• Beaches, spits and bars: These are depositional features that have accumulated over time due to transportation of materials by waves.

• Sand dunes: Sand dunes are formed on large sandy beaches when the wind blows dry sand into ridges.

Coastal Management

• Hard engineering includes man-made structures built to control the flow of seas and reduce flooding and erosion. Examples are sea walls, groynes, revetments and gabions.

• Soft engineering includes practices that work with the existing environment in a more natural way. Examples are beach nourishment, managed retreat, and dune stabilization.

• Adaptive management involves monitoring, assessment and adjustment of management strategies in response to observed changes, maintaining flexibility to adjust responses in a changing environment.

Remember: strategy employed in managing coasts varies depending on array of factors including budget, nature of the coastline, and perceived value of the land at risk.