Waves and Erosion
What are the two types of waves?
Destructive and constructive waves.
How is sediment transported across a beach?
Long-shore drift.
a. Broken down b. Transported c. Dropped
C. Dropped
Name one coastal landform of erosion.
Headlands and bays.
Name three different human uses along the coast.
Food supply, transport, recreation.
What is one difference between constructive and destructive waves?
Constructive: Low energy, low frequency, short fetch, strong swash, flat and low, deposition.
Destructive: High energy, high frequency, long fetch, strong backwash, tall and high, erosion.
What is swash?
When waves move up a beach.
Name two reasons sediment would be deposited.
Sheltered area, low energy waves, water is shallow.
Name one landform of coastal deposition.
Spit
Name one positive and negative of food supply.
People get income
Overfishing --> Less fish, other animals lose food source, negative impact on food chain.
Name four processes of erosion.
Hydraulic action, abrasion, attrition, solution, compressed air.
What is backwash?
When waves move down a beach.
Sea wall, gabion, groynes, rock armour.
How does a headland and bay form?
Forms at a discordant coastline, which means there are alternating bands of hard and soft rock. The soft rock erodes more rapidly than the hard rock. The part that juts out is the headland and the the indent is the bay. Now, most energy is concentrated on the headlands which causes them to be eroded faster (wave refraction). A beach can also form in the sheltered bay.
Name one positive and negative of transport.
Transport goods
Sea pollution --> Less fish, other animals lose food source, negative impact on food chain.
Explain hydraulic action.
When the force of the waves erodes the coast as they crash against it.
What pattern does longshore drift have?
Zig zag.
How do sea walls work?
Reflect waves back into sea, slowing erosion.
Describe how a spit forms.
The prevailing wind moves waves up the coast at an angle (swash). Sediment then moves back down the coast (backwash), this is longshore drift. Longshore drift continues across the coast. Sediment can continue to be transported past the headland and deposited in a sheltered bay. This causes a spit to form. If there is a secondary wind then a hook can form on the spit.
Name one positive and negative of recreation.
Increases tourism
Litter --> Animals can eat this, less fish, other animals lose food source, negative impact on food chain.
Explain Abrasion.
When eroded material (load) in the waves crashes against the coastline.
Explain longshore drift.
Waves move up the beach at an angle, carrying sediment (swash). The waves then move back down the beach (backwash) in a straight line. This zig zag pattern is repeated and transports sediment across the beach.
What is a positive of sea walls?
Slow down erosion.
What is one negative of sea walls?
Very expensive.
How does one coastal management strategy impact coastal processes?
Groynes - Stop transportation, longshore drift. Slow down erosion.
Sea wall - Slows down erosion, can increase mass movement.