Coastal Management Flashcards
All 14 cards in this deck
Give one benefit and one cost of a sea wall.
Benefit: reflects waves back out to sea, preventing erosion and flooding, and can include a promenade. Cost: very expensive to build and maintain, and looks unnatural.
Give one benefit and one cost of rock armour (rip rap).
Benefit: large boulders absorb and break up wave energy, and it is cheaper and quicker than a sea wall. Cost: boulders are usually imported from elsewhere, look out of place and can be dangerous to climb on.
What are gabions, and what is their main disadvantage?
Wire cages filled with rocks built at the foot of a cliff to absorb wave energy; they are cheap, but look ugly and the cages rust and break within about 5–10 years.
How do groynes protect the coast, and what problem do they cause?
Wooden or rock barriers built at right angles to the beach trap sediment moved by longshore drift, creating a wider beach that absorbs wave energy; but they starve beaches further along the coast, increasing erosion there.
What is beach nourishment, and give one disadvantage of it.
Adding sand or shingle (often dredged offshore) onto an existing beach so it absorbs more wave energy; it is expensive and has to be repeated regularly.
What is beach reprofiling?
Reshaping the beach by moving sediment from the lower beach back up to the upper beach, usually after a storm; cheap and simple, but only works in low-energy conditions and must be repeated.
What does dune regeneration involve, and give one benefit.
Planting marram grass and fencing off dunes or adding boardwalks to stop trampling; it is cheap and creates a natural barrier to flooding as well as a wildlife habitat.
What does managed retreat (coastal realignment) mean?
Allowing the sea to flood or erode an area of low-value land, which then usually becomes salt marsh or mudflat.
True or false? Managed retreat is normally used where the land is of low value, such as farmland.
True. It would not be used to protect high-value land such as a town centre, where hard engineering is more likely.
Give two benefits of managed retreat compared with hard engineering.
It is much cheaper with low maintenance costs, and the salt marsh created stores water, buffers wave energy and provides a wildlife habitat.
Give two reasons why the coastline at Lyme Regis, Dorset, needed managing.
Unstable cliffs with frequent landslips threatened homes and roads, and erosion of the beaches and old sea walls threatened the town and its tourist economy.
Which management strategies were used in the Lyme Regis coastal scheme, Dorset?
New sea walls and promenades, rock armour, beach nourishment to create a wider sand and shingle beach, plus cliff drainage and nailing to stabilise the land.
Give one conflict or negative effect resulting from the Lyme Regis coastal management scheme.
It cost around £43 million of public money; more visitors bring traffic and litter, and some residents object that the defences spoil the natural look of the coast.
True or false? Rock armour is an example of soft engineering.
False. Rock armour is hard engineering – an artificial structure built to resist the sea.