IGCSE (9-1) Geography - Coasts (CIE)

Summary

This video explains coastal processes and landscapes, including erosional features like cliffs and depositional ones like beaches. Key concepts such as fetch, wave types (constructive and destructive), and the forces shaping the coastline are covered. The video also explores various coastal processes, including hydraulic action, abrasion, attrition, and transportation mechanisms like saltation and suspension. It emphasizes the interaction of waves with the coastline, from their energy transfer to the sediment movement, helping viewers understand the dynamic nature of coastal environments.

Takeaways

• 😀 The coastline consists of the backshore and foreshore, with tidal variations creating the surf zone where waves break.
• 😀 Fetch is the distance over which wind can generate wave energy, influencing wave size and strength.
• 😀 Waves transfer energy from air to water through oscillations, and as they approach the shore, they change shape, eventually breaking.
• 😀 Constructive waves have a long wavelength and small wave height, bringing sediment onto the shore, leading to gradual deposition.
• 😀 Destructive waves are strong, with a short wavelength and large wave height, leading to erosion and creating a steeper beach slope.
• 😀 Erosional processes like hydraulic action, abrasion, and attrition break down the coastline and contribute to landscape changes.
• 😀 Hydraulic action involves waves compressing air into cracks in the coastline, causing them to expand and erode over time.
• 😀 Abrasion occurs when waves carry sediment that erodes the coastline, increasing the rate of erosion.
• 😀 Attrition is the process of sediment colliding with other particles, breaking down into smaller, rounder pieces, contributing to sand formation.
• 😀 Sediment transportation occurs via traction, saltation, suspension, and solution, each describing how sediment moves along the coast.

Q & A

What is the 'fetch' in coastal processes, and how does it influence wave energy?

Fetch refers to the distance over which the wind blows across the surface of the water. A greater fetch allows more wind to pass over the water, which increases the energy transferred into the waves. This leads to higher and more powerful waves as the wind builds up energy over a longer distance.

What are the key differences between constructive and destructive waves?

Constructive waves are gentle, with a long wavelength and low wave height, resulting in a gradual beach slope and deposition of smaller sediment. In contrast, destructive waves have a short wavelength and high wave height, creating steeper beaches and erosion due to stronger backwash.

How does wave energy transfer from the air to the water?

Wave energy is transferred from the air to the water through wind. As the wind blows across the surface of the water, it creates oscillations, which then move in circular patterns. As the waves approach the shore, they become elliptical and eventually break, transferring their energy onto the beach.

What is the process of 'swash' in coastal dynamics?

Swash is the movement of water up the beach after a wave breaks. It is driven by the energy of the wave and typically moves at an angle determined by the direction of the wind. Swash carries sediment onto the shore.

What role does 'backwash' play in coastal processes?

Backwash is the return of water down the beach after the swash. It moves straight back to the sea, influenced mainly by gravity, and is responsible for removing sediment from the shore, particularly in areas where waves are more destructive.

What is hydraulic action in the context of coastal erosion?

Hydraulic action occurs when waves crash against a cliff, compressing air in cracks. This leads to the erosion of the cliff as the pressure causes the cracks to widen and break down the rock, a process known as cavitation.

What is the effect of abrasion on the coastline?

Abrasion happens when the waves, carrying sediment, strike the cliff. The force of the waves, combined with the sediment, grinds down the rock, eroding the coastline. This process increases the rate of erosion.

What is attrition, and how does it affect sediment along the coast?

Attrition is the process where larger particles of sediment collide with each other, breaking down into smaller and rounder pieces over time. This reduces the size of the sediment and contributes to the formation of sand on the beach.

What is the role of 'suspension' in the transportation of sediment?

Suspension occurs when very fine particles, such as sand or silt, are carried in the water column. These small particles are light enough to be lifted and suspended by the wave energy, allowing them to be transported across the coastal area.

How does deposition occur on beaches, and what factors influence it?

Deposition happens when the wave energy decreases, such as when the water's velocity drops below a certain threshold. When the wave can no longer carry sediment, it is deposited on the beach. Factors like wave energy, sediment type, and the slope of the beach determine the location and extent of deposition.