First 290 words of the document:
Hard Engineering Coastal Management
Defence How it Works Cost Disadvantage
The wall reflects waves back out to sea,
Expensive to build It creates a strong backwash
Sea Wall preventing erosion of the coast. It also acts as
and maintain. which erodes under the seawa
a barrier to prevent flooding.
Revetments are slanted structures built at the
foot of cliffs. They can be made from concrete, Expensive to build,
They create a strong backwas
Revetment wood or rocks. Waves break against but relatively cheap
which erodes under the seawa
revetments, which absorb the wave energy to maintain.
and so prevent cliff erosion.
Gabions are rock filled cages. A wall of gabions
Gabions is usually built at the foot of cliffs to absorb Cheap. Not aesthetically pleasing.
wave energy and reduce erosion.
Boulders built up along the coast are called
Riprap riprap. The boulders absorb wave energy, Fairly Cheap. Can move in storms.
Built at a right angle to trap deposit from
Stops material, which is neede
longshore drift, creating a wider beach which
Groynes Quite cheap. down-drift, from getting to wher
causes the waves to break further away from
Tidal barriers are built across river estuaries.
Tidal Barrier They have retractable floodgates that can be Very expensive. Very expensive.
raised to prevent flooding during a storm surge.
Tidal barrages are dams built across river May disrupt sediment flow,
Tidal Barrage estuaries to generate electricity and protect Very expensive. causing erosion somewhere els
from flooding during storm surges. on the estuary.