Sustainable Management Of Coasts Flashcards
Why are coastal defences needed?
People live near the coast:
3.2 billion people live within 200km of the coastline.
Coastal areas are important economically.
Coastal areas rely on ports for transport links. Hotels and caravan parks are built in coastal areas.
Coastal areas are under threat.
Rinsing sea levels due to global warming. 10 cm rise around the UK.
What physical reasons are there for coats to be managed?
Retain cliffs and beaches.
What are the three main types of hard engineering used on coasts?
Seawalls
Gabions
Gryones
What are sea walls?
What are the Pros and cons of building sea walls?
Tall concrete walls build at the back of beaches. They may have a curved shape to deflect waves.
Pros.
Effective at preventing coastal flooding
Can be economical acceptable if they are needed to protect many people or properties.
Cons.
Expensive to build and need constant maintenance (£10 million per kilometre)
They can erode.
What are Gabions?
What are the pros and cons of building gabions.
A metal cage filled with local rocks.
Pros:
Relatively cheap compared to other sea defences
Cons:
They can rust or be damaged during severe storms. Expected lifespan, 20-25 years.
What are Groynes?
What are the pros and cons of building Groynes.
Used when long shore drift is displacing sand from beaches. Hard wood fences stretching out along the beach at intervals of about 50m.
Pros:
They slow down long shore drift and promote the deposition of sand, building up the sand.
Cons:
The wood eventually weathers, expected lifespan of 20 years.
Leads to extra erosion down the beach as the material cannot move naturally by long shore drift.
£5 million per kilometre.
What are the 2 main types of soft engineering used on coastlines?
Beach nourishment
Managed retreat
What is beach nourishment?
What are the Pros and Cons?
Sand is dredged from the seabed and added to the beach.
Pros:
Can result in increased tourism in an area
Natural sea defence
Cons:
Very expensive, £1 million per mile.
Not a permanent fix, as nourished beaches erode faster as the sand is not as tightly packed.
What is managed retreat?
What are the Pros and Cons?
People move their land use further away from the coast.
Pros:
Farmers will be compensated
Cons:
People may be moved out and homes demolished.
Describe the coastal landforms in Newcastle, Co. Down (case study).
Newcastle contains spits, beach and sand dunes.
What hard engineering methods are used in Newcastle’s coastline.
Sea wall, Groynes, Gabions and rock armour
Where are the groynes in Newcastle located?
Near the Newcastle centre, between the mouth of the shimna river and sileve Donard hotel.
A new set of wooden groynes 20-30m long may be built, costing £1,250 per metre, replacing the degrading concrete groynes built in the 1980s.
Where are gabions found in Newcastle?
At the mouth of the shimna river.
The first set of Gabions had decayed, so they were replaced and a new footbridge was built
Probably the most sustainable hard engineering option
Why was a sea wall built in Newcastle?
Buildings were being built close to the shore, so the sea wall was built to support and protect them.
What happened to Newcastle’s sea wall?
In 2002 a severe storm partially eroded the wall, repairs costed 4 million as the height was increased by 1m and the shape was curved to help deflect waves.
Unfortunately the curved shape caused the refracted waves to erode the beach in front of them.
