Hard Engineering

Question 1

What are advantages of hard engineering?

Answer 1

Obvious to at-risk people that something is being done to protect them.
A one-off solution that could protect a stretch of coast for decades.

Question 2

What are disadvantages of hard engineering?

Answer 2

Costs are usually very high, and there are on going maintenance costs.
Prone to failure
Coastlines made visually unattractive and needs of coastal ecosystems are overlooked.
Defences built in one place frequently have adverse effects further along the coast.

Question 3

How much do groynes cost per metre?

Answer 3

£150 - £250

Question 4

How much do sea walls cost?

Answer 4

£3000 - £10,000

Question 5

How much does rip rap cost?

Answer 5

£1300 - £6000

Question 6

What are construction and materials for Rip-Rap?

Answer 6

Large ingeous or metamorphic rock boulders, weighing several tonnes.

Question 7

What is the purpose of Rip-rap?

Answer 7

Break up and dissipate wave energy.

Often used at the base of sea walls to protect them from undercutting.

Question 8

What is the impact on physical processes of Rip-rap?

Answer 8

Reduces wave energy.
Sediment deposition between rocks.
May become vegetated over time.

Question 9

What is construction and materials for Offshore rock breakwater?

Answer 9

Large ingeous or metamorphic rock boulders, weighing several tonnes.

Question 10

What is the purpose of offshore rock breakwater?

Answer 10

Forces waves to break offshore, rather than at the coast, reducing wave energy and erosive force.

Question 11

What is the impact on physical processes of offshore breakwaters?

Answer 11

Deposition encouraged between breakwater and the beach.

Can interfere with longshore drift.

Question 12

What is the construction and materials of sea walls?

Answer 12

Concrete with steel reinforcement and deep piled foundations; can be stepped or vertical.

Question 13

What is the purpose of a sea wall?

Answer 13

A physical barrier against erosion.
They often also act as flood barriers.
Modern sea walls are designed to dissipate, not reflect, wave energy.

Question 14

What is the impact on physical processes of sea walls?

Answer 14

Destruction of the natural cliff face and foreshore environment.
If reflective, can reduce beach volume.

Question 15

What are the construction and materials of revetments?

Answer 15

Stone, timber or interlocking concrete sloping structures, which are permeable.

Question 16

What is the purpose of revetments?

Answer 16

To absorb wave energy and reduce swash distance by encouraging infiltration.
Reduce erosion on dune faces and mud banks.

Question 17

What is the impact on physical processes of revetments?

Answer 17

Reduced wave power.

Can encourage deposition and may become vegetated.

Question 18

What is the construction and material of groynes?

Answer 18

Vertical stone or timber fences built at 90 degrees to the coast, spaced along the beach.

Question 19

What is the purpose of groynes?

Answer 19

To prevent longshore movement of sediment, and encourage deposition building a wider, higher beach.

Question 20

What is the impact on physical processes of groynes?

Answer 20

Deposition and beach accretion.

Prevention of longshore drift, sediment starvation and increased erosion downdrift.