Managing Coastal Erosion And Flooding Flashcards
What are the methods against erosion?
Hard engineering
Soft engineering
What is hard engineering?
This involves building structures along the coast
What are the methods of hard engineering?
Groynes Sea walls Rip rap (rock armour) Revetments Offshore breakwater
What are groynes?
Timber or rock structures built at right angles to the coast.
What do groynes do?
Trap sediment being moved along the coast by LSD - building up the beach.
What are the advantages of groynes?
The built-up beach increases tourist potential and protects the land behind.
Groynes work with natural processes to build up the beach
Not too expensive.
What are the disadvantages of groynes?
Starve beaches further along the coast of fresh sediment, because they interrupt LSD, so there may be increased erosion
Unnatural looking and rocks groynes can be very unattractive
What are sea walls?
Made of stone or concrete at the foot of a cliff, or at the top of a beach
What do sea walls do?
Usually have a curved face to reflect waves back into the sea - reduce energy
What are the advantages of sea walls?
Effective prevention of erosion
They often have a promenade for people to walk along
What are the disadvantages of sea walls?
They reflect wave energy, rather than absorbing it
They can be intrusive and unnatural looking
They are very expensive to build and maintain
What is rip rap?
Large rocks placed at the foot of a cliff, or near the top of a beach?
What does rip rap do?
Forms a permeable barrier to the sea - breaking up the waves, but allowing some water to pass through
What are the advantages of rip rap?
It’s relatively cheap and easy to construct and maintain
It’s often fishing from, or for sunbathing by tourists.
What are the disadvantages of rip rap?
The rocks used are usually from somewhere else (e.g. granite), so they don’t fit in with the local geology and can look out of place.
It can be intrusive.
The rocks can be dangerous for people clambering over them.
What are revetments?
Sloping wooden, concrete or rock structures placed at the foot of a cliff or at the top of a beach
What do revetments do?
They break up the waves energy
What are the advantages of revetments?
They are relatively inexpensive to build
Less beach material is eroded compared to a sea wall
What are the disadvantages of revetments?
They are intrusive and very unnatural looking
They can need high levels of maintenance
What are offshore breakwaters?
A partly submerged rock barrier, designed to break up the waves before they reach the coast.
What are the advantages of offshore breakwaters?
An effective permeable barrier
What are the disadvantages of offshore breakwaters?
It’s visually unappealing
It’s potential navigation hazard
What is soft engineering?
Designed to work with natural processes in the coastal system, in order to manage
What are examples of soft engineering?
Beach nourishment
Dune stabilisation
Managed retreat
Natural beach/do nothing
What is beach nourishment?
The addition of sand or pebbles to an existing beach to make it higher or wider.
The sediment is usually dredged from the nearby seabed
What are the advantages of beach nourishment?
Relatively cheap and easy to maintain
It looks natural and blends in with the existing beach
It increases tourist potential by creating a bigger beach
What are the disadvantages of beach nourishment?
It needs constant maintenance, because of the natural processes of erosion and LSD.
Offshore dredging can increase erosion
Large storms can be expensive
What is due stabilisation?
Marram grass can be planted to stabilise dunes.
Areas can be fenced in to keep people off newly planted dunes
What are the advantages of due stabilisation?
It maintains a natural coastal environment.
It provides important wildlife habitats.
It’s relatively cheap and sustainable.
What are the disadvantages of dune stabilisation?
It’s time consuming to plant marram grass
People may respond negatively to being kept off certain areas
What is managed retreat?
Redrawing the defensive line on the landward side of existing defences and allowing the coast to migrate.
What are the advantages of managed retreat?
Re-creates costal environments
Delays expensive defence strategies
What are the disadvantages of managed retreat?
Not popular choice - landowners and locals see it as defeatist and abandonment.
What is natural beach/do nothing?
Natural processes are left to shape the coastline
What are the advantages of do nothing?
No direct costs
Unprotected areas provide beach materials
No unsightly coastal defences
What are the disadvantages of do nothing?
Compensation and social perception make it a contentious strategy
