Coastal Management Flashcards
How does a sea wall work?
A wall made out of a hard material like concrete that reflects waves back to the sea
2 pros and 2 cons of a sea wall
Pro
- prevents erosion
- acts as a barrier to prevent flooding
Cons
- creates strong backwash
- expensive to build and maintain
How long does a sea wall last? Hard or soft engineering?
100 years
Hard
What is rock armour(rip-rap)?
Boulders that are piled up along the coast
2 pros and 1 con of rock armour
Pros
- absorbs heat energy
- reduces erosion and flooding
Con
-boulders can be moved around by strong waves need to be replaced
Is rock armour hard or soft engineering?
How long does it last?
120 years
Hard
How does a gabion work?
Rock filled cages built at the foot of cliffs with gaps to reduce energy
2 pros and 2 cons of gabions
Pros
- absorbs wave energy
- reduces erosion
Cons
- they look ugly
- short life span
How long does gabions last?
Hard or soft engineering?
5-10 years
Hard
How does revetments work?
Slanted structure made of concrete, wood or rocks built at the foot of cliffs
2 pros and 2 cons of revetments
Pros
- absorbs wave energy
- reduces erosion
Cons
- expensive to build
- creates strong backwash that erodes under the barrier
How long does wood and rock revetments last?
Hard or soft engineering?
Wooden- 10 years
Rock- 30 years
Hard
How does a groyne work?
Wooden or stone fences that are built at right angles to the coast they trap material transformed by longshore drift
2 pros and 2 cons of groynes
Pros
- creates wider beaches which slow waves down
- gives greater protection from flooding and erosion
Cons
- starves beaches further down the coast of sand making them narrow
- narrow beaches don’t protect coasts well
How long does groynes last?
Hard or soft engineering?
100 years
Hard
1 pro and 1 con of doing nothing
Pro
-no cost or labour
Con
-will flood and erode coast
How does a managed retreat work?
Removing an existing defence and allowing the land behind it to flood
2 pros and 1 con of managed retreat
Pros
- overtime, land will become marshland creating new habitats
- fairly cheap
Con
-people may disagree
Is managed retreat hard or soft engineering?
Soft
How does beach replenishment work?
Sand and shingle from elsewhere (e.g. The offshore seabed) that is added to beaches
2 pros and 3 cons of beach replenishment
Pros
- wider beaches slows waves
- greater protection
Cons
- has to be repeated
- expensive
- taking material from the seabed can kill organisms like sponges and coral
Is beach replenishment hard or soft engineering?
Soft
What is hard engineering?
Man made structure built to control the flow of the sea and reduce flooding and erosion
What is soft engineering?
Schemes set up using knowledge of the sea and its processes to reduce the effects of flooding and erosion
