Coastal management Flashcards
Examples of hard engineering
Sea Walls
Rock Armour
Gabions
Groynes
What is a sea wall?
Concrete walls placed at foot of cliff to prevent erosion. Curved to reflect energy back into sea.
Advantages of sea walls
Effective at protecting base of cliff
Sea walls usually have promenades so people can walk along them
Disadvantages of sea walls
Waves still powerful, break down and erode sea wall
Expensive- £2000 per metre
What is rock armour?
Large boulders placed at foot of a cliff. Break waves and absorb energy
Advantages of rock armour
Cheaper than a sea wall and easy to maintain
Can be used for fishing
Disadvantages of rock armour
Look different to local geology, rock been imported from other areas
Rocks expensive to transport
What are gabions?
Rocks held in mesh caves and placed in areas affected by erosion
Advantages of gabions
Cheap- £100 per metre
Absorbs wave energy
Disadvantages of gabions
Not very strong
Look unnatural
What are groynes?
Wooden or rock structures built out at right angles into the sea
Advantages of groynes
Builds a beach- tourism
Trap sediment being carried by longshore drift
Disadvantages of groynes
By trapping sediment, starved beaches further down coastline, increasing rate of erosion
Look unattractive
3 examples of soft engineering
Beach nourishment
Reprofiling
Dune nourishment
What is beach nourishment?
Sand pumped onto existing beach to build it up
Advantages of beach nourishment
Blends in with existing beach
Larger beaches appeal to tourists
Disadvantages of beach nourishment
Needs to be constantly replaced
Sand has to be brought in from elsewhere
What is reprofiling?
The sediment is redistributed from lower part of beach to upper part of beach
Advantages of reprofiling
Cheap and simple
Reduces energy of waves
Disadvantages of reprofiling
Only works when wave energy is low
Needs to be repeated constantly
What is dune nourishment?
Marram grass planted in sand dunes stabilises the dunes and helps to trap sand to build them up
Advantages of dune nourishment
Relatively cheap
Maintains natural look
Disadvantages of dune nourishment
damaged by storm waves
areas zoned off from public, unpopular
What is managed retreat?
Controlled flooding of low lying coastal areas. If area at high risk of erosion, managed retreat is option. Occurs where land is low value. Farm land
Advantages of managed retreat
Cheap option compared to paying for sea defences
Creates salt marsh can provide habitats for wildlife and natural defence against erosion and flooding
Salt marches are diverse ecosystems supporting many species
Disadvantages of managed retreat
Land is lost as reclaimed by sea
Landowners need to be compensated £5000-£10000
Holderness coastline
Located on east coast of England. Fastest eroding coastline in Europe
Reasons for management in Holder was
Rock type- cliff made from less-resistant boulder clay
Naturally narrow beaches- beaches give less protection to coast as it doesn’t reduce power of waves
Man-made structures- groynes have been installed to stop long shore drift. Narrows unprotected beaches elsewhere
Powerful waves/ waves at Holderness travel long distances over North sea ( long fetch) increase in energy
Management strategies in Holderness
Bridlington is protected by 4.7km long sea wall
Hornsea protected by sea wall, groynes and rock armour
Coastal management at Witherswa tries to make beach wider by using grounds, also uses seawall
Mappleton protected by rock groynes
Spurn head protected with groynes and rock armour
Conflicts in Holderness
Increase in erosion at Great Cowden because groynes used in Mappleton. Led to farms being destroyed by erosion and loss of 100 chalets at Golden Sands Holiday Park
Some people disagree with where sea defences are located, if it means land in their community unprotected
Some sea defences negatively impact tourism and reduce amount of money coming into area
