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2b.11
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- 1What are the three different approaches of managing the risks associated with coastal recession and flooding.Hard engineering
Soft engineering
Sustainable management - 2What are different hard engineering approaches?Groynes
Seawall
Rip Rap
Revetments
Offshore breakwater - 3What are groynes? Positives and negatives? CostsTimber 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.
Positives - increase tourist potential
- protects land behind
- work with natural processes to build up beach
- not too expensive
Negatives - starve beaches further down of sediment = increases erosion.
- unnatural, unattractive
Cost = £5,000 to £10,000 each (200m) - 4What are seawalls? Positives and negatives? Cost?Made of stone or concrete at the foot of a cliff, or at the top of the beach. They usually have a curved face to reflect waves back into the sea.
Positives - effective prevention of erosion
- often have a promenade for people to walk along
Negatives - reflect wave energy, not absorb it
- intrusive and unnatural looking.
- expensive to build and maintain
Cost = £6000 per metre - 5What are rip rap? Positives and negatives? Cost?AKA rock armour
large rocks placed at the foot of a cliff, or at the top of the beach.
It forms a permeable barrier to the sea - breaking up waves, but allowing some water to pass through.
Positives - relatively cheap and easy to construct and maintain
- often used for fishing from or sunbathing
negatives - from somewhere else = look out of place.
- intrusive
- dangerous for people clambering over them
Cost = £100,000 to £300,000 for 100m - 6What are revetments? Positive and negatives? Cost?Sloping wooden, concrete or rock structures - placed at foot of cliff or top of beach. They break up waves' energy
Positives - inexpensive to build
negatives - intrusive, unnatural looking
- high levels of maintenance
Cost = £4500 per m - 7What are offshore breakwater? Positives and negatives? Cost?A partly submerged rock barrier, designed to break up the waves before they reach the coast.
Positives - effective permeable barrier
Negatives - usually unappealing
- potential navigation hazard
Cost = similar to rip rap (£100,000- £300,000 for 100m). - 8What is the overall problem with hard engineering techniques?They are economically costly and directly alter physical processes and systems
- 9Complete the sentence: Actions by different players may have .......... ............unforeseen consequences
- 10What is soft engineering and what types are there?They work with natural processes to protect coasts.
They can be used to manage changes in sea level e.g. by allowing low-lying coastal areas to flood (creating marshes).
Beach nourishment
Cliff regrading and drainage
Dune stabilisation
Marsh creation - 11What is beach nourishment? Positives and negatives? Cost?The addition of sand or pebbles to an existing beach to an existing or wider. Sediment usually dredged from nearby seabed.
Positives - cheap
- easy to maintain
- looks natural and blends in with existing beach
- increases tourist potential as bigger beach
negatives - constant maintenance due to longshore drift and erosion.
Cost = £300,000 for 100m. - 12What is Cliff regrading and dredging? Positive and negatives?Reduces angle of cliff and removes water to prevent landslides and slumping.
Positives - work on clay or loose rock
-cost-effective
negatives - cliff retreats
- can dry out land and cause rock fall. - 13What is dune stabilisation? Positives and negatives? Cost?Marram grass stabilises dunes
Positives - maintaining natural environment
- provides important wildlife habitats
- relatively cheap and sustainable
Negatives - time consuming
- negative due to keeping off areas
Cost = £200 - £2000 for 100m - 14What is marsh creation? Positives and negatives? Cost?Low-lying coastal areas to be flooded = salt marsh (managed retreat). Allows natural flooding
Positives - relatively cheap
- natural defense for powerful waves
- important wildlife habitats
Negatives - agricultural land lost
- farmers or landowners need to be compensated
Cost = variable due to size of area - 15What do soft engineering approaches attempt to work with?with physical systems and processes to protect coasts and manage changes in sea level.
- 16What is sustainable management designed to cope with?Future threats (increased storm events, rising sea levels)
- 17However, its implementation can lead to what?local conflicts in many countries.
- 18What will both be needed for future stability?Mitigation and adaptation
- 19What is cost benefit analysis?It is carried out before a coastal-management project is given the go ahead. Costs are forecast (e.g. sea wall - its design, building costs, maintenance, etc) and then compared with the expected benefits (e.g. a value of land saved, housing protected, savings in relocating people, etc). A project where costs exceed benefits is unlikely to be given permission to go ahead
- 20What are the two different types of CBA?Tangible - where costs and benefits are known and can be given a monetary value (e.g. building costs)
Intangible - where costs may be difficult to assess but are important (e.g. the visual impact of revetment).
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- GCSE Geography Fichas sobre 2b.11, creado por Paige S el 20/11/2019.
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- Paige S
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