Managing Coastlines Flashcards
What are the 2 core aims of coastal management?
Provide defence against and mitigate the impacts of coastal erosion.
Provide protection against, and mitigate the impacts of coastal erosion.
What are the three other aims of coastal management?
Stabilisé sand dune areas
Stabilise beaches by longshore drift
Protect fragile estuarine landscapes
What is hard engineering?
This is making a physical change to the coastal landscape using resistant materials like concrete, boulders and wood.
What is soft engineering?
Using natural systems for coastal defence such a as beaches, dunes and salt marshes which can absorb and adjust to wave and tide energy.
Hard or soft: Sea walls
Hard
Hard or soft: beach nourishment
Soft
Hard or soft: rip rap
Hard
Hard or soft: gabions
Hard
Hard or soft: dune regeneration
Soft
Hard or soft: revetments
Hard
Hard or soft: managed retreat
Soft
Hard or soft: groynes
Hard
Hard or soft: land-use management
Soft
Hard or soft: cliff fixing
Hard
Hard or soft: offshore reefs
Hard
Hard or soft: barrages
Hard
Hard or soft: do nothing
Soft
What do sea walls do?
They dissipate wave energy
What are sea walls?
These are recurred structures that will throw waves back onto other waves which reduces the following waves impact.
Give an advantage of sea walls.
They protect the coast
How much can a sea wall cost?
It can cost over £5,000/m
List 3 disadvantages of sea walls.
Expensive
Ugly
Must have continuous facing so the gaps can’t be exploited by hydraulic action.
What is rip rap?
These are large boulders.
Where is rip rap placed?
In front of a cliff or sea wall to dissipate wave energy.
Why are rip rap boulders angled?
This is to give a large surface area and to allow water to filter through.
Is rip rap secured in place?
No
What are two advantages of rip rap?
Protects the coast
Blend in to the environment.
What is a disadvantage of rip rap?
The boulders can be moved by the sea.
What are gabions?
These operate in a similar way to rip rap but are smaller rocks that are caged in mesh.
What is an advantage of gabions?
They are cheap.
What are two disadvantages of gabions?
They are not very effective
Ugly
What are revetments?
These are concrete or wooden structures that are placed across the beach or coastline to take the full force of the waves energy.
What are two advantages of revetments?
They prevent further erosion of the coast
Require less maintenance than a sea wall
What is a disadvantage of revetments?
They are expensive.
What are groynes?
These these are wooden/ stone/ steel breakwaters built nearly at eight angles to the waves. Thy control longshore drug by trapping sediment to create higher and wider beaches which will then also dissipate wave energy. Groynes also dissipate wave energy.
Why are groynes about 5-10 degrees to the perpendicular?
This is to prevent them being scoured by the waves.