Hard Engineering Flashcards
What are groynes
Timber or rock structures built at right angles to the coast. They trap sediment being moved along the coast by longshore drift - building up the beach
Advantages of groynes
Work with natural processes to build up the beach, increasing tourist potential and protects the land behind it
Not too expensive
Disadvantages of groynes
Starve beaches further along the coast of fresh sediment (as they interrupt longshore drift) = increased erosion elsewhere
Unnatural and can be unattractive
Cost of groynes
£5000 to £10000 each
What are sea walls
Stone or concrete walls at the foot of a cliff or at the top of a beach. They usually have a curved face to reflect waves back into the sea
Advantages of sea walls
Effective prevention of erosion
Often have a promenade for people to walk along
Disadvantages of sea walls
Reflect wave energy, rather than absorbing it
Can be intrusive and unnatural
Very expensive
Cost of sea walls
£6000/m
What is rip rap (rock armour)
Large rocks placed at the foot of a cliff, or at the top of a beach. It forms a permeable barrier to the sea- breaking up the waves but allowing some water to pass through
Advantages of rock armour
Relatively cheap and easy to construct and maintain
Often used for recreation-fishing, sunbathing
Disadvantage of rock armour
Can be intrusive
Rocks used are usually not local and can look out of place with local geology
Costs of rock armour
£100000 to £300000 /100m
What are revetments
Sloping wooden, concrete or rock structures placed at the foot of a cliff or at the top of a beach. They break up the waves’ energy
Advantages of revetments
Relatively inexpensive to build
Disadvantages of revetments
Intrusive and very unnatural looking
Need high levels of maintenance
