Flashcards in ✅126.96.36.199 - Coastal Management Deck (53)
How many people lived within the coastal zone in 1999?
How much of UK manufacturing lies close to the coast?
How much of coastal land is built on?
What are the reasons for coastal management?
Failure of previous defences
What is hold the line?
Maintain current defences
What is advance the line?
Build new defences seaward of existing line
What is managed retreat?
Allow the coastline to retreat due to flooding and erosion but closely manage the rate and location of the retreat
What is 'do nothing'?
Low value areas left to natural coastal processes as not deemed viable to spend on defences
What are the social factors taken into account?
Number of residents
Use of the land
Who is impacted if it is damaged
Effect of downdrift land
What are the economic factors taken into account?
Value of land
Coast of defences
Cost of maintenance
Value of business and connections in the area
What are the environmental factors taken into account?
Impact on surrounding land
Current state of the coast
Habitats and environment concerned
What are the political factors taken into account?
What are the alternatives?
Likelihood of success
Taking into account opinions of stakeholder
What is tangible cost benefit analysis?
When costs and benefits are known and can be given as a value
What is intangible cost benefit analysis?
Where costs may be difficult to assess but are important (eg visual impact)
What are the steps in cost benefit analysis?
Where is the issue?
What are causes and effects?
Who is affected?
What should be done?
Is solution technically viable and environmentally acceptable?
What is cost benefit?
What are sea walls?
Concrete or stone walls at the foot of a cliff, or at the top of a beach. Usually have a curved face to reflect waves back to sea
What are the advantages of sea walls?
Protects high value land
Can prevent flooding
What are the disadvantages of sea walls?
Eyesore to the locals and tourists
Expensive to build and maintain
Produce strong backwash, undercutting it
What are groynes?
Timber or rock structures built at right angles to coast. Trap sediment being moved along the coast by longshore drift, building up beach
What are the advantages of groynes?
Very effective for building beach
Prevents sediment moving by LSD
Allows a natural defence to build up
What are the disadvantages of groynes?
Remove a lot of sediment from downdrift
Other beaches left vulnerable to erosion
What are gabions?
Bundles of rock in mesh cages at base of cliff to reduce impact of waves and prevent cliffs being undercut
What are the advantages of gabions?
Cheap to build and maintain
Difficult to erode
What are the disadvantages of gabions?
Not very effective
Unsightly, unnatural appearance
Ongoing maintenance required
What are revetments?
Sloping wooden, concrete or rock structures placed the the front of a beach. Break up the waves energy
What are the advantages of revetments?
Effective in reducing erosion
Little maintenance once built
What are the disadvantages of revetments?
Expensive to build
What are barrages eg. the Thames Barrier?
Big, retractable walls built across estuaries that can be used as floodgates to prevent storm surges
What are the advantages of barrages?
Can be used to generate energy for commercial use