coats Pt2 Flashcards
Hard Engineering
Man-made structures built to control the flow of the sea and reduce flooding and erosion
Types of Hard Engineering
Sea wall
Rock Armour
Groynes
Gabions
Sea Wall
A wall made out of a hard material like concrete that reflects waves back to sea
Benefits of a sea wall
It prevents erosion of the coast. it also acts as a barrier to prevent flooding
costs of a sea wall
It creates a strong backwash that erodes under the wall. expensive to build and maintain
Gabions
A wall of wire cages filled with rocks, usually built at the foot of cliffs
benefits of Gabions
Gabions absorb wave energy and so reduce erosion. they are cheap and easy to build
Costs of Gabions
They’re ugly to look at and the wire cages can corrode over time
Rock armor
Boulders that are piled up along the coast.( it is also sometimes called rip-rap)
Benefits of Rock Armour
it absorbs wave energy, reducing erosion and flooding. it is a fairly cheap defense
Costs of Rock Armour
Boulders can be moved around by strong waves, so they need to be replaced
Groynes
Wooden or stone fences are built at right angles to the coast. They trap material transported by longshore drift
Benefits of Groynes
They create wider beaches that slow the waves. this gives greater protection from flooding and erosion. they are a fairly cheap defence
Costs of Groynes
They starve beaches further down the coast of sand, making them narrower. narrow beaches don’t protect the coast as well, leading to greater erosion
Types of soft engineering
beach nourishment and reprofiling
Dune regeneration
Beach Nourishment and reprofiling
Sand and shingle from elsewhere (e.g. from sea bed) or from lower the beach that’s added to the upper part of beaches
benefits of Beach Nourishment and reprofiling
it creates wider beaches which slow the waves. this gives greater protection from flooding and erosion
cost of Beach Nourishment and Reprofiling
Taking material from the sea bed can kill organisms like sponges and corals. it’s a very expensive defence. it has to be repeated
Dune Regenerations
creating or restoring sand dunes by nourishment, or by planting vegetation to stabilize the sand
Benefits of Dune Regeneration
Dunes Create a barrier between land and sea and absorb wave energy, preventing flooding and erosion. stabilization is cheap
Costs of Dune Regeneration
The protection is limited to a small area. Nourishment is very expensive
Describe how a wave-cut platform is formed?
The sea attacks the base of the cliff-forming a wave-cut notch.
The notch increases in size causing the cliff to collapse.
The backwash carries the rubble towards the sea forming a wave-cut platform.
The process repeats and the cliff continues to retreat.
How is a bar formed?
Longshore drift carries sediment along from a headland, depositing sediment further out from the headland. Over time, this line of sediment joins two headlands together; a bar is formed, cutting the bay off from the sea.
describe longshore drift
- Waves approach the beach at an angle
- As waves break the swash carries material up the beach at the same angle
- The backwash carries material straight back down the beach under gravity
- This causes the material to move along the beach in a zig-zag pattern