coastal defences Flashcards
Rock Armour (HE)
Piles of large boulders made from hard rock dumped at the foot of the cliff. SPaces between the rocks force the waves to breakm and disperses its energy, protecting the coast.
Disadvantages: makes the access to the beach difficult, not aesthetically pleasing
Sea walls (HE)
concrete barriers placed at the foot of cliffs or top of beaches, They are curved and they reflect the wave back out to sea, reducing the erosive power of oncoming destructive waves. They don’t stop the movement of sediment downstream
Disadvantages: they can restrict acces to the beach, they are very expensive
Groynes (HE)
Rock structures built out to sea from the coast. They stop longshore drift and broaden the beach. The wider beach acts as a natural buffer to incoming destructive waves.
Disavdantages: restricts the supply of sand further along the coast, causing further erosion there.
Beach nourishment (SE)
When sediment lost due to LSD is replaced, resulting in a wider beach absorbs more of the wave’s energy and reduces erosion. The sediment is taken from the seabed or from downdrift.
Disadvantages - takes time to do restricting access to the beach, expensive
Beach reprofiling (SE)
The artificial re-shaping of a beach using existing material. Bulldozers move shingle up the bach against the direction of LSD.
Disadvantages - Restricts access to beach
Managed retreat (SE)
A method of coastal realignment whereby the sea is allowed, deliberately, to flood or erode an area of low-value land.
Disadvantages - relocation of people destroys communities, larga areas of land and habitats are destroyed.
