Coastal Management Flashcards
Why manage the coast? (3 stars)
- 23% total land area lies within 10km of the coast
- 21 million people live within the coastal zone
- 40% of UK manufacturing industry lies close to the coast
Reasons for management
Coastal erosion
Coastal flooding
Failure of former defences
Possible management stategies
Hold the line
Advance the line
Retreat the line (managed retreat)
Do nothing
Hold the line
Maintain current defences or build new ones to ensure coastline stays where it is
Advance the line
Build new defences seaward of existing line - often unnatural and expensive
Retreat the line (managed retreat)
Allow the coastline to retreat due to flooding and erosion but closely manage the rate and location of this retreat
Do nothing
Low value areas left to natural coastal processes as not deemed viable to spend on defences
Only some parts of the coast
Are defended
The aim of coastal management is to protect…
Homes, businesses and the environment from erosion and flooding
The amount of money available is _________ and so not everywhere can be defended.
We use a ____-________ analysis to chose which places are defended.
Limited
Cost-benefit
The money available is usually used to protect…
Large settlements and industrial sites, rather than smaller settlements
Name factors affecting the approach taken (5)
- Likelihood of success?
- Cost of defence?
- Value and land use
- Would it affect locations elsewhere?
- Alternatives?
CBA
Cost benefit analysis
Tangible factors
Where costs and benefits are known and can be given a monetary value
E.g house prices
Intangible factors
Where costs may be difficult to assess but are important
E.g visual impact
Tangible factors that need consideration for an accurate CBA…
Land value Business values House prices Infrastructure value Transport networks value Population
Intangible factors that need consideration for an accurate CBA…
Social attachment Visual impact Emotional impact Peoples emotional connections Historic value Ecology
Issues caused by not using CBA
Impact on locations further down coast
Waste of money
Wrong location
The steps taken by the government in organising defences
- What is the issue
- Causes and effects
- Who affected
- What done
- Environmentally acceptable?
- CBA
- Décision makers
- Effects of proposition
- Who and what affected
- Gains/losses
- What is the issue
Hard engineering
Making a physical change to the coastline using man made materials and/or structures
Soft engineering
Works with nature and natural systems to protect the coast
Hard engineering strategies (9)
Sea wall Groynes Gabions Revetments Riprap/Rock armour Tidal Barrages Tidal Barriers Offshore reefs/Breakwaters Earth Bank
Soft engineering techniques (7)
Beach nourishment Beach stabilisation Dune regeneration Managed retreat Land-use management Creating marshland Do nothing
Sea wall
Outline
Pros
Cons
Cost
Curved wall reflects wave energy + barrier to flooding
Often have a promenade for walking on
Reflect//absorbing wave energy + unnatural
£6000/m
Groynes
Outline
Pros
Cons
Cost
Timber structures built at right angles to the coast, trapping sediment being moved by LSD
Works with processes and increases tourism potential
Starves beaches along the coastline of sediment
£5000-£10,000 each
Gabions
Outline
Pros
Cons
Cost
Rock filled cages built at foot of cliff. They absorb wave energy reducing erosion
Cheaper than other types
Can break easily
X
Revetments
Outline
Pros
Cons
Cost
Sloping wooden/concrete/rock structures at foot of cliff or top of beach - absorb wave energy
Inexpensive to maintain
Unnatural looking
Up to £4,500/m
Riprap/Rock armour
Outline
Pros
Cons
Cost
Boulders piled along the coast, they reduce wave energy
Used for recreation - fishing
Can look out of place if rocks are not local
£300,000/100m
Tidal barriers
Outline
Pros
Cons
Cost
Partially submerged structures built across river estuaries. Contain flood gates that can be raised to prevent flooding
More consistent water level
Environmental impacts
X
Tidal barrages
Outline
Pros
Cons
Cost
Dams built across river estuaries that generate electricity and prevent flooding too
Very expensive and disrupt sediment flow
X
Offshore reefs/Breakwaters
Outline
Pros
Cons
Cost
Old tyres and cement used to create off-shore reefs to encourage waves to break offshore
Reduced erosive power
Difficult to install
X
Earth bank
Outline
Pros
Cons
Cost
Mounds of earth act as a barrier to prevent flooding
Can be eroded
Quite expensive
Beach nourishment
Outline
Pros
Cons
Cost
The addition of sand/pebbles to an existing beach to make it higher/wider. The sediment is usually dredged from the nearby seabed
Looks natural
Requires constant maintenance
£3000 per 100m
Dune regeneration
Outline
Pros
Cons
Cost
Marram grass can be planted to stabilise dunes. Areas can be fenced in it to keep people off newly planted dunes.
Habitats
Time-consuming
£200-£2000 per 100m
Managed retreat
Outline
Pros
Cons
Cost
Allowing low lying coastal areas to be flooded by the sea
Creates a natural buffer to powerful waves
Agricultural land is lost
Cost of compensation (depends on land value)
Land-use management
Outline
Pros
Cons
Cost
Process of managing the use and development of land resources
Sustainable approach
Restricts development
X
Beach stabilisation
Outline
Pros
Cons
Cost
Reducing the slope angle And planting vegetation, or by sticking steaks and old tree trunks in the beach to stabilise the sand
Creating marshland
Outline
Pros
Cons
Cost
Planting appropriate vegetation which stabilises the sediment, and the stems and leaves help to reduce the speed of the waves
Less flooding
Do nothing
Outline
Pros
Cons
Cost
Dealing with the effects of flooding and erosion as they come or just ignoring them
No money lost
There may be a more effective approach
Cost - potentially councils sewed for damages
Management strategies for the future must be
Sustainable
