Coasts- Coastal Management Flashcards
Reasons for coastal management
- coastal erosion
- coastal flooding
- failure of former defences
Why are coastal defences becoming increasingly more important?
- global warming- sea level rise
- high sea levels increase risk of flooding
- increasing population- more people living there increases value of land
- failure of past defences- some areas now starved of sediment and more exposed to erosion
Definition of ‘hold the line’
Maintain current defences or build new ones to ensure the coastline stays where it is
Definition of ‘advance the line’
Build new defences seaward if existing line
Definition of ‘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
Define ‘do nothing’ as a management strategy
Low value areas of land left to natural coastal processes as not deemed valuable enough to spend money on defences
Social factors which may dictate the chosen management strategy
- number of people directly impacted
- history/culture
- employment
Economic factors which may dictate the chosen management strategy
- value of infrastructure and housing
- value of businesses
- cost of the defences
Environmental factors which may dictate the chosen management strategy
- value of ecosystem
- how common the ecosystem is
- pollution to ecosystem
Political factors which may dictate the chosen management strategy
- who will fund the project eg. local council
- voter opinion/importance
- relationship with other areas
What is a Cost Benefit Analysis?
- a cost benefit analysis is carried out before a coastal management project is given the go ahead
- costs are forecast and then compared with the expected benefits
- a project where cost exceeds benefit is unlikely to be given permission to go ahead
What are ‘tangible’ costs and benefits?
Where costs and benefits are known and can be given a monetary value
What are ‘intangible’ costs and benefits?
Where costs may be difficult to assess but are important (eg. visual impact)
What is beach nourishment?
The addition of sand/pebbles to an existing beach to make it higher or wider
The sediment is usually dredged from the nearby seabed
Advantages and disadvantages of beach nourishment
ADVANTAGES-
-relatively cheap and easy to maintain
-looks natural and blends in with existing beach
-increases tourist potential by creating a bigger beach
DISADVANTAGES-
-needs constant maintenance because of the natural processes of erosion and longshore drift
What is dune regeneration?
Marram grass can be planted to stabilise dunes.
Areas can be fenced to keep people off newly planted dunes
Advantages and disadvantages of dune regeneration
ADVANTAGES- -maintains natural coastal environment -provides important wildlife habitats -relatively cheap and sustainable DISADVANTAGES- -time consuming to plant marram grass -people may respond negatively to being kept off certain areas
What is managed retreat?
Allowing the coastline to retreat in a managed way eg. creating salt marsh environments by deliberately breaching flood banks that protect low lying farmland
Advantages of managed retreat
- sand dunes act as a good barrier against coastal flooding and erosion
- can be exploited as a natural defence against the sea
- creating salt marshes increases biodiversity
Advantages and disadvantages of doing nothing to prevent further erosion
ADVANTAGES-
-saves money if the land is worth less than the defence would cost
DISADVANTAGES-
-eventually the cliffs may be eroded so far that high value land becomes at risk- so sea defences will have to be constructed eventually
What are sea walls?
Stone or concrete walls at the foot of a cliff or top of a beach
Usually have a curved face to reflect waves back into the sea
Advantages and disadvantages of sea walls
ADVANTAGES-
-effective prevention of erosion
-often have promenade for people to walk along
DISADVANTAGES-
-reflect wave energy rather than absorbing it
-can be intrusive and unnatural looking
-very expensive to build and maintain
What are groynes?
Timber/rock structures built at right angles to the coast
Trap sediment being moved along the coast by longshore drift-building up the beach
Advantages and disadvantages of groynes
ADVANTAGES-
-work with natural processes to build up beach- increases tourist potential
-relatively inexpensive
DISADVANTAGES-
-starve beaches further along the coast of sediment
-unnatural and can be unattractive
