Managing Coasts - hard engineering

• Why do coasts need to be managed?

  To maintain a balance between the forces of nature and the demands of people.
• What is a primary reason for managing coasts?

  To protect people living or working at the coast from erosion and flooding.
• What future challenge is mentioned regarding coastal management?

  Sea levels are expected to rise, making coastal defenses more expensive.
• What might happen if the costs of coastal defenses outweigh the benefits?

  Coastlines may be left undefended.
• What are the three different management strategies for defending the coast?

  • Hard engineering
  • Soft engineering
  • Managed retreat
• What is hard engineering in coastal management?

  Using artificial structures such as sea walls to control natural processes.
• What is soft engineering in coastal management?


  Less intrusive, more environmentally-friendly methods that work with natural processes.
• What does managed retreat involve in coastal management?

  Enabling the controlled retreat of the coastline, allowing the sea to flood over low-lying land.
• What are some common hard engineering structures used in coastal management?


  Sea walls, groynes, rock armour, and gabions.
• What is the function of groynes in coastal management?

  They trap sediment moved by longshore drift and enlarge the beach.
• What is the cost of timber groynes?

  £150,000 each at every 200m.
• What are the advantages and disadvantages of groynes?

  Advantages:

  • Create a wider beach, popular with tourists
  • Useful for fishing
  • Not too expensive

  
  

  Disadvantages:

  • Starve beaches further along the coast
  • Unnatural appearance
• What is the description of a sea wall?

  Concrete or rock barriers placed at the foot of cliffs or a beach to reflect waves back into the sea.
• What is the cost range for sea walls?

  £5,000 to £10,000 per metre.
• What are the advantages and disadvantages of sea walls?

  Advantages:

  • Effective at stopping the sea
  • Often includes a walkway or promenade

  
  

  Disadvantages:

  • Obtrusive and unnatural appearance
  • Very expensive and high maintenance
• What is the problem caused by groynes in coastal management?

  They starve beaches further along the coast, leading to increased rates of erosion elsewhere.
• What is rock armour used for in coastal management?

  Piles of large boulders dumped at the foot of a cliff to absorb wave energy and protect the cliffs.
• What is the cost of rock armour?

  £200,000 per 100m.
• What are the advantages and disadvantages of rock armour?

  Advantages:

  • Relatively cheap and easy to maintain
  • Provides interest to the coast
  • Often used for fishing

  
  

  Disadvantages:

  • Rocks may come from distant locations
  • Can be expensive to transport
  • May not fit in with local geology
• What are gabions in coastal management?

  Wire cages filled with rocks that can support a cliff or provide a buffer against the sea.
• What is the cost of gabions?

  Up to £50,000 per 100m.
• What are the advantages and disadvantages of gabions?

  Advantages:

  • Cheap to produce and flexible in design
  • Can improve drainage of cliffs
  • Will eventually become vegetated

  
  

  Disadvantages:

  • Look unattractive initially
  • Cages last only 5-10 years before rusting
• If a local council wishes to defend a 1 km stretch of coastline, what would be the comparative cost for sea walls?

  $Cost =$$1000 \text{ m} \times £5000 \text{ to } £10000 =$$£5,000,000 \text{ to } £10,000,000$
• If a local council wishes to defend a 1 km stretch of coastline, what would be the comparative cost for rock armour?

  $Cost =$$1000 \text{ m} \times £2000 =$$£2,000,000$
• If a local council wishes to defend a 1 km stretch of coastline, what would be the comparative cost for groynes?

  $Cost =$$\frac{1000 \text{ m}}{200 \text{ m}} \times £150,000 =$$£750,000$
• If a local council wishes to defend a 1 km stretch of coastline, what would be the comparative cost for gabions?

  $Cost =$$\frac{1000 \text{ m}}{100 \text{ m}} \times £50,000 =$$£500,000$