Coastal Cram

Question 1

Explain the formation of a headland:

Answer 1

Headlands are formed at discordant coastlines where there are alternating bands of hard rock and soft rock at right angles to the coastline, which means that the soft rock gets eroded faster than the hard rock (since it is less resistant) creating a bay and a protruding headland.

Question 2

Explain the formation of a bay:

Answer 2

Bays are formed at discordant coastlines where there are alternating bands of hard rock and soft rock at right angles to the coastline, which means that the soft rock gets eroded faster than the hard rock (since it is less resistant) creating a bay and a protruding headland.

Question 3

Explain the formation of a cliff:

Answer 3

Cliffs tend to be located on a headland due to erosion from wave action. The base of the cliff is eroded through a number of ways: Hydraulic action, abrasion and corrosion. The rock type will affect cliff gradient or steepness. Cliffs with soft rock are gently sloping while cliffs with hard rock are steep.

Question 4

Explain the formation of a wave cut platform:

Answer 4

• Due to wave action (sea hitting) on the base of the cliff between the high and low water mark, wave-cut notch is formed.
• Abrasion, corrosion and hydraulic action further extend the wave cut notch back into the cliff.
• The undercutting of the cliff leads to instability and collapse of the cliff.
• Backwash of the waves carries away eroded material, leaving behind a wave cut platform.
• Process repeats and cliff continues to retreat.

Question 5

Explain the formation of a cave, arch, stack and stump:

Answer 5

• Found on a headland due to wave action and sub-aerial weathering.
• Weakness in the headland are exploited on both sides by erosional processes of hydraulic action, abrasion and corrosion.
• Cracks begin to widen, abrasion will begin to wear away at the forming cave.
  The cave will become larger and eventually break through the headland to form an arch.
• The base of the arch continually becomes wider and thinner through erosion below and weathering from above.
• Eventually the roof of the arch collapses, leaving behind an isolated column of rock called a stack.
• The stack is undercut at the base by wave action and sub-aerial weathering above until it collapses to form a stump.

Question 6

What are the abiotic features of a coral reef?

Answer 6

• Sunlight: Corals need some sunlight to survive-for photosynthesis.
• Depth: As corals need light, typically corals can be found at 25m under sea level.
• Water Temps: Prefer temperatures of 23-29 degrees Celsius
• Salinity: Corals need salty water (32%-42%)
• Air: Can survive out of water for very short periods of time.
• Water: Need clean and clear water.

Question 7

What are the requirements of Mangroves?

Answer 7

• Water- Need shallow water between 0.5m to 2.5m high
• Humidity- High levels of humidity required (75%-80%)
• Rain- Need (1500-3000mm) rainfall per annum.
• Temperature- Ideal temp required is 27 degrees Celsius.

Question 8

What are some natural causes of coastal flooding?

Answer 8

Storm surges- rapid rise in sea level caused by low-pressure storms.
Storm Tides- Occur when there is a combination of high tide and low-pressure storm.
Tsunamis- Large sea waves due to underwater earthquakes.

Question 9

Explain 2 methods used to help forecast coastal flooding:

Answer 9

1. Past records: Will identify areas at high risk and frequency.
2. Modern Technology: GIS, satellite and computer monitoring.

Question 10

Explain actions that reduces or removes the risk of coastal flooding:

Answer 10

Flood defences
Emergency centres
Early warning systems
Education
Planning
Buffer zones.

Question 11

What are 4 approaches available for coastline management?

Answer 11

Hold the line- hard engineering dominant
Advance the Line- soft and hard engineering used
Managed reallignment- soft engineering dominant
Do nothing

Question 12

What are the advantages and disadvantages of beach replenishment?

Answer 12

• Advantages:
  Beaches absorb wave energy
  Widens beach front
• Disadvantages:
  Has to be repeated regularly- which is expensive
  Can impact sediment transportation down the coast.

Question 13

What are the advantages and disadvantages of managed retreat?

Answer 13

• Advantages:
  No expensive construction costs
  Creates new habitats such as salt marshes
• Disadvantages:
  People’s lands and homes are lost.
  Cost of relocation may be expensive

Question 14

Describe groynes:

Answer 14

Wood,rock or steel piling built at right angles to shore- traps sediment from longshore drift.

Question 15

Describe revetments

Answer 15

Sloping wooden or concrete fence with open plank structure.

Question 16

What are the Advantages and Disadvantages of revetments?

Answer 16

• Advantages:
  Traps beach material behind them.
  Cheaper than sea walls
• Disadvantages:
  Can make beach inaccessible
  Visually unnattractive
  Regular maintenance required

Question 17

Describe sea walls

Answer 17

A wall, usually concrete and curved outwards to deflect the power of waves.

Question 18

Describe gabions

Answer 18

Wire cages filled with stone, concrete, sand etc.