Hard engineering processes Flashcards
(32 cards)
What is hard engineering?
Using man-made structures as a barrier between the land and sea. These change or disrupt natural processes
Where are sea walls built?
In front of cliffs to prevent cliffs from eroding and then collapsing
Why are sea walls curved?
To deflect the energy of the waves back onto themselves
Advantages of sea wall
Very strong coastal defence with a long life-span. Can be used where wave energy is high
Disadvantages of sea wall
Very expensive. They prevent tourists from accessing the beach
What are groynes?
Barriers of wood or concrete at right angles to the beach
How do groynes provide coastal defence?
They trap sediment transported by longshore drift and help create wider beaches. These absorb more wave energy and reduce cliff erosion
Advantages of groyne
Cheaper than sea walls, don’t prevent access to beach and retain a wid, sandy beach for tourists
Life-span of groyne
Don’t last as long as other hard engineering strategies
How do groynes affect beaches further along the coast?
They deprive beaches further along the coast of sediment by trapping it
What is a revetment?
Wooden slated barriers built at the back of beaches to protect the base of a cliff
How do revetments work?
The energy of the waves is reduced when they break against the revetment
Life-span of revetment
Short
Cost of revetment
Cheaper than sea wall
How do revetments cause less damage to the beach?
Erode less beach material than a sea wall
Where aren’t revetments suitable?
Places with high wave energy
What is rock armour?
Large boulders of resistant rock placed at the back of beaches or at the bottom of cliffs to absorb wave energy
What is rock armour used along with?
A sea wall of revetment
Cost of rock armour
Cheaper than sea walls
Life-span and efficiency of revetment
Last a long time and are efficient at absorbing wave energy
Disadvantage of rock armour to beach access
Are unattractive. Make access to the beach dangerous and difficult
When can rock armour become expensive?
When the boulders are imported or are transported a long distance
What are gabions
Cages of wire mesh filled with rocks or stones. Are placed at the back of beaches or the base of cliffs
How do gabions provide defence?
They absorb wave energy, reducing erosion
