2b.5A

Question 1

What is sediment transportation influenced by

Answer 1

Sediment transportation is influenced by the angle of wave attack, tides and currents and the process of longshore drift

Question 2

State 4 types of transportation

Answer 2

Traction, saltation, suspension, solution

Question 3

Describe traction

Answer 3

Where large, heavy load items are rolled along the sea bed,
e.g. boulders, cobbles and pebbles

Question 4

Describe Saltation

Answer 4

1) Where lighter sediment bounces along
2) Sand particles are usually transported this way
3) Sand can be saltated by wind as well as waves
+ On a dry, windy day, there can be a layer of saltating sand 2-10 cm above the beach

Question 5

Describe suspension

Answer 5

1) Where very light sediment is carried aloft within a body of water or air
2) E.g. silt or clay particles
3) Suspended clay particles, give the sea a cloudy, muddy brown colour on soft-rock coasts, e.g. Holderness

Question 6

Describe solution

Answer 6

Where sediment is carried dissolved within the water

Question 7

How does the angle of attack affect sediment transportation

Answer 7

​- This is the main determinant of the direction of sediment transport (in the foreshore zone).
- Where the wind is blowing directly onshore, the incoming swash transports the material direction up the beach at 90’ to the coastline.
- Backwash then transports sediment perpendicularly back down to the beach to its original starting position.
- Sediment is moved up and down the beach, but there is no net lateral movement

Question 8

How does the tides affect sediment transportation

Answer 8

Tides are changes in sea level produced by the gravitational pull of the moon and the Sun.
- The incoming and ebbing tide can create tidal currents in the nearshore and offshore zones that transport sediment

Question 9

How does the current affect sediment transportation

Answer 9

• This is the flow of water in a particular direction, and they can transport sediment in the nearshore and offshore zones.
• They can be driven by winds, or initiated by differences in water density, temperature or salinity.

Question 10

How do currents transport sediment over a variety of spatial and temporal scales:

Answer 10

• The global thermohaline circulation connects four oceans and takes 500 years for one complete circuit.
• Rip currents on the beach transport sediment a few metres out to sea for a few hours when the wind is blowing direcly onshore with the right strength

Question 11

Describe LSD

Answer 11

• Incoming swash transports sediment up the beach at an angle (movement contains an up-beach component and a lateral component)
• Gravitational backwash then transports sediment back down the beach at 90’ to the coastline.
• A sediment particle comes to rest some distance along the beach from the original starting point due to net lateral movement.
• Particle moves in a zig-zag fashion along the beach with each incoming wave.

Question 12

What wave angle gives the strongest LSD movement

Answer 12

A wave angle 30