Costal Transport- Longshore Drift

Question 1

What is longshore drift?

Answer 1

Longshore drift is the movement of sediment carried along the coastlines by wave actions. More specifically, waves approach the beach at an angle determined by the prevailing wind, the swash carries material up and along the beach and the backwash transports material at a right angle due to gravity, this results a zigzag motion as sediment is transported from the coastline. From time to time, the beach can change shape as it influences by longshore drift.

Question 2

What coastal management is used to prevent longshore drift?

Answer 2

Groynes are a low concrete wall or a barrier built from a beach to prevent erosions. This can be build to interrupt the flow of longshore drift and limits the movement of sediment. However, some sand and gravel can still escape.

Question 3

What is a swash?

Answer 3

Waves that rushes up the beach

Question 4

What is a backwash?

Answer 4

Waves that flows back towards the sea

Question 5

What are the size and energy of the wave depends on?

Answer 5

The fetch - how far the wave has travelled
The strengths of the wind
How long the wind has been blowing for

Question 6

What are the two waves type?

Answer 6

Constructive and destructive

Question 7

What are the characteristics of a destructive wave?

Answer 7

Weak swash and strong backwash
The strong backwash removes sediment from the beach
The waves are steep and close together

Question 8

What are the characteristics of a constructive wave?

Answer 8

Strong swash hand weak backwash
The strong swash brings sediments to build up the beach
The backwash is not strong enough to bring the sediments back to the sea
The waves are low and further apart