Coastal Management Flashcards
what is hard engineering in terms of coasts?
manmade structures built to control the flow of the sea and reduce flooding and erosion
what is soft engineering in terms of coast?
schemes set up using knowledge of the sea and its processes to reduce the effects of flooding and erosion
what are the forms of coastal hard engineering?
-sea wall
-gabions
-rock armour
-groynes
what is a sea wall?
a wall made out of hard material like concrete that reflects waves back to sea
what are the advantages of using a sea wall?
-it prevents erosion of the coast
-it acts as a barrier to prevent flooding protecting houses by the coast
what are the disadvantages/costs of using a sea wall?
-sea walls are very expensive to to build and maintain as they create strong backwashes which can erode under the wall weakening it. This could lead to the diversion of finance from other things to help maintain it
-some people think they are unsightly which can reduce tourism
what are gabions?
a wall of wire cages filled with rocks usually built at the foot of cliffs
what are the advantages of gabions?
-the boulders absorb wave energy reducing the erosive force of waves meaning there is less erosion and sediment displacement reducing coastal erosion and the destruction of coastal habitats
-it is a fairly cheap defence
what are the disadvantages/costs of gabions?
-they are not pleasent to look at
-the wire cages can corrode over time reducing its effectiveness and stability which can pose a risk to communties and infrastrcuture
what is rock armour?
boulders that are piled up along the coast (its also sometimes called a rip-rap)
What are the advantages of rock armour?
-reduces wave energy
-fairly cheap defence
what are the disadvantages of rock armour?
-they can be moved around by strong waves so they need to be replaced
what are groynes?
-wooden or stone fences that are built at right angles to the coast
-they trap material transported by long shore drift
what are the advantages of groynes?
- they create wider beaches which slow the waves , this gives protection from flooding and erosion and also attracts toursts
-they are a fairly cheap defence
what are the disadvantages/costs of groynes?
-they starve beaches further down the coast of sand making them narrower
-narrow beaches do not protect the coast as well leading to greater erosion and flood
what are the forms of coastal soft engineering?
-beach nourishment and reprofiling
-soft engineering
what is beach nourishment and reprofiling?
sand and shingle from elsewhere (e.g. from the sea bed) or lower down the beach that is added to the upper part of beaches
what are the advantages of beach nourishment and reprofiling?
-it creates wider beaches which slow down waves
-this gives greater protection from flooding and erosion
what are the disadvantages/costs of beach nourishment and reprofiling?
-taking material from the sea bed can kill organisms like sponges and coral
-it is a very expensive defence and has to be repeated
what is dune regeneration?
creating or restoring sand dunes either by nourishment or planting vegetation to stabalise the sand (make sure the sand won’t drift or move)
what are the advantages of dune regeneration?
-sand dunes provide a barrier between land and sea
-wave energy is absorbed which prevents flooding and erosion
-stabalisation is cheap
what are the disadvantages/costs of dune regeneration?
-the protection is limited to a small area
-nourishment is very expensive
What is meant by managed retreat?
1)Managed retreat involves removing current defences and allowing the sea to flood the land behind.
2)Over time the land will become marshland, which then protects the land behind it from flooding and erosion.
What are the advantages of managed retreat?
-It is a cheap and easy strategy, and it doesn’t need maintaining. -The marshland can create new habitats for plants and animals.
What are the disadvantages of managed retreat?
it can cause conflicts, e.g. flooding farmland affects the livelihood of farmers and saltwater can have a negative effect on existing ecosystems.
