EQ4 Coasts

Question 1

definine mitigation

Answer 1

making efforts to reduce the size of a problem

Question 2

Define Adaptation

Answer 2

making changes to reduce the impacts of a problem.
e.g - building of sea walls, storm surge barriers, replanting mangroves or many other approaches

Question 3

two functions of costal protection

Answer 3

1) Stops the land being eroded
2) Prevents flooding behind the coast

Question 4

Define hard engineering

Answer 4

Structures that are built to alter or to defend the environment
e.g- revetments

Question 5

define soft engineering

Answer 5

solutions which adopt and encourage natural processes to take place
e.g- beach nourishment

Question 6

what are the 4 approaches to costal management ?
- what do they involve?

Answer 6

1) Hold the line- involves maintaining the current position of the coastline 9often using hard-engineering methods)
2) Advance the line- This involves extending the coastline out to sea.
3) Managed retreat/strategic realignment- Involves allowing the coastline to retreat, but in a managed way. It can involve the deliberate breaching of flood banks built to protect low-quality farmland from flooding (creating a salt marsh environment).
4) Do nothing/ no active intervention- Letting nature take its course and allowing the sea to erode cliffs and flood low-lying land (whilst letting the existing defences collapse).

Question 7

How do groins aim to prevent erosion or flooding?

Answer 7

Groynes are fences built at right angles to the coast. They can be made from wood, concrete or rock.
They trap beach material transported by longshore drift in front of cliffs. This creates wider beaches (keeps them in place), which slow the waves (reduce their energy) and gives greater protection from flooding and erosion.

Question 8

cost of groynes

Answer 8

£5k-10k each , at 200m intervals
- relatively cheap

Question 9

disadvantages of groynes

Answer 9

impact on physical processes- terminal gryone syndrome.
- gryones starve down-drift beaches of material, meaning they are more easily eroded.
2) some people find gryones unsightly
3) makes it difficult for people to walk along the beach

Question 10

Advantages of Groynes

Answer 10

• easy to construct
• have long-term durability and are low maintenance
• reduce the need for the beach to be maintained through beach nourishment (expensive)

Question 11

How do sea walls ai to prevent erosion or flooding?

Answer 11

A concerete wall reflects the waves back out to sea, preventing erosion of the coast and a barrier to prevent flooding
- they can have different designs, such as stepped or curved frontages.
- people cn use the top of the wall for access and as a promenade

Question 12

disadvantages of sea walls

Answer 12

• creates a strong backwash, which can erode under the wall or scour away beach material, -
• also unattractive

Question 13

cost of sea walls

Answer 13

£6k per metre
- expensive to built and maintain
can sometimes be made from sheet piling- however despite being cheaper, this is also uglier.

Question 14

how does rip rap/rock armour aim to prevent erosion or flooding?

Answer 14

Hard boulders piled up along the coast.
The irregular-shaped boulders have a large surface area, this absorbs more wave energy by increasing friction and so therefore reduces erosion.

Question 15

advantages/disadvantages of rip rap/rock armour

Answer 15

• boulders bought in by boat, can look out of place
• can shift in storms
• can be unattractive if not made from local rocks
• relatively cheap and easy to construct/maintain

Question 16

cost of rip rap/rock armour

Answer 16

£100k-300k for 100 metres

Question 17

How do revetments aim to reduce erosion./flooding?

Answer 17

Slanted structures, built at the foot of cliffs, can be made from concrete, wood or rock.
- They run parallel to the coast at an angle to the waves as they come in
- the waves break against the revetments, which absorb the waves energy and prevent cliff erosion (water flows between the slats).

Question 18

Disadvantages of revetments

Answer 18

• expensive to build, but relatively cheap to maintain- impermeable revetments have a life expectancy of 30-50 years.
• creates a strong backwash, can cause further erosion
• makes some beaches inaccessible to locals and tourists
• can disrupt natural dune processes
• erosion at the base off the structure can cause structure failure

Question 19

cost of revetments

Answer 19

£4500 per metre
expensive to build

Question 20

Advantages of revetments

Answer 20

• less detrimental to beach levels than sea walls, for they reduce beach scour by dissipating wave energy rather than reflecting it. Often sediments – including sand, shingle and pebbles – are carried through or over the structure and, due to the less turbulent water behind, are deposited

Question 21

How do offshore breakwaters aim to reduce erosion/flooding

Answer 21

Breakwaters are usually concrete blocks/ boulders deposited off the coast in shallow waters.
- They force the waves to break OFFSHORE, reducing their energy and hence erosive power before they reach the shore.
- overtime, deposition may occur around the breakwater- increasing the effectiveness of the defence.
- The area between the breakwater and the beach can provide a sheltered area for swimming, water sports and harbour entrances

Question 22

cost of offshore breakwaters

Answer 22

£1k-3k per metre
expensive

Question 23

Disadvantages of offshore breakwaters

Answer 23

• Storms can damage breakwaters easily, hence they need constant maintenance (expensive and time costly)
• The deposition of sediment around the breakwater can starve another area of sediment along the coastline.

Question 24

Define soft engineering

Answer 24

Working with natural processes to reduce the effects of flooding and erosion, rather than trying to stop them.

Question 25

characteristics of soft engineering

Answer 25

- have a more 'natural' look that fits with coastline - more flexible- can be adapted to suit new and different conditions- e.g managing sea level change.

Question 26

What is beach nourishment ?

Answer 26

Soft engineering technique where sand/shingle is added to the beach- replacing the materials materials lost due to erosion and longshore drift.

Question 27

impacts of beach nourishment on physical processes

Answer 27

- nourishment needs to be regular and continuous as longshore drift will continue to remove material - orgasnims such as coral and sponges can be killed by this defence method.

Question 28

Advantages of beach nourishment

Answer 28

increases tourist potential by building upon the beach, also protects cliffs and costal settlements. cost effective and looks natural

Question 29

Disadvantages of beach nourishment

Answer 29

Needs constant maintenance Dredging may have consequences on local costal habitats.

Question 30

What is dune stabilisation?

Answer 30

- dues are stabilised by reducing the slope angle and planting vegetation. - marram grass planted- roots help bind to the dunes- protecting the land behind

Question 31

advantages of done stabilisation

Answer 31

cost effective and creates an important wildlife habitat old tree trunks can stabilise the sanding prevent wind erosion creates wide beaches- reduces erosion and flooding cheap

Question 32

disadvantages of dune stabilisation

Answer 32

needs regular maintenance as dunes will shift position naturally Planting time is consuming

Question 33

what is cliff regrading?

Answer 33

Changing the shape of the cliff so it has a gentler gradient and is less susceptible to erosion (steeper cliff would be more likely to collapse, undercutting, wave-cut notches etc).

Question 34

advantages of cliff regrading

Answer 34

vegetation can grow on the shallow cliff face and further stabilises the cliff slope and improves the local ecosystem

Question 35

Disadvantages of cliff regrading

Answer 35

expensive cost Can be hugely disruptive and may involve temporarily/permanently rehoming local people- disruption to livelihoods.

Question 36

What is cliff drainage?

Answer 36

The removal of water from a cliff face by building drainage channels into the rock structure- this reduces the pressure within the cliff face and hence the risk of collapse may look unnatural

Question 37

disadvantages of cliff drainage

Answer 37

effectiveness and ease of installation may depend on the geology of the cliff face cliff may collapse suddenly as the cliff dries- leading to rocks falls which pose a hazard

Question 38

Advantages of cliff drainage

Answer 38

cost effective, however expensive initially

Question 39

How much of the Holderness coast is protected by hard engineering?

Answer 39

Only 9km out of the 35km

Question 40

What is a cost benefit analysis?

Answer 40

carried out before a costal-management project is permitted. Cost and benefits are of two types: 1) Tangible- Where costs and benefits are known and can be given a monetary value (ew.g building costs) 2)Intangible- where costs may be difficult to assess, but are important (e.g the visible impact of a revetment) A project where costs exceed benefits is UNLIKELY to be given permission to go ahead.

Question 41

What are the defences at Hornsea and what are the impacts of this?

Answer 41

Defences- Concrete sea wall, groynes and rock armour Impact- The gryones trap sediment and maintain the beach of Hornsea, but Appleton (downdrift) has been starved of sediment as a result (terminal groyne syndrome). There, rapid wave attack has eroded the cliffs - by the 1990s, nearly 4m of cliff was being eroded each year! - wooden groynes are located at Hornsea, trap the sediment carried by longshore drift. - Keep the beach in place and in turn protects the cliff and the town

Question 42

What happened in Appleton in 1991, why?

Answer 42

After a campaign by residents in Appleton, Homberside council built 2 rock groynes in 1991, which cost £2 million - The cliff facing the groynes help to protect was also regraded to make it less steep- therefore more stable.

Question 43

What happened at Cowden - how much did erosion occurred per year between 1991 and 2007?

Answer 43

- 3km south of mappletons rock groynes, sediment starvation has caused increased erosion of the cliffs- terminal groyne syndrome This occurs whenever groynes trap beach material and starve other areas From 2.3-3.8 metres per year between 1991 and 2007

Question 44

What re the defences at Withernsea

Answer 44

A straight sea wall was built I 1875, however, overtime, wave energy eroded the base of the wall, causing it to collapse In the 1990s (following a CBA), the straight walll was replaced by a curved wall- at a cost of £6.3 million (5k per metre)

Question 45

Impact of the 1991 sea wall in Withernsea

Answer 45

The waves are now noisier when they break against the wall, and the promenade is smaller. Restricted views from sea from seafront hotels. - some countries find the riprap at the base of the sea wall unattratcive recurred walls dissipate out some of the wave energy-reduces the erosion at the BASE of the wall and hence extends its lifespan. However, expensive to build, as of shape

Question 46

what strategy is used at withernsea

Answer 46

'hold the line'- has prevented further decline in the value of the local property and has saved employment in tourism.

Question 47

cost of sea wall at withernsea

Answer 47

£5k per square metre Now £6.3 million for the entire wall

Question 48

What defences are there at hornsea

Answer 48

Riprap- protects the sea wall at Hornsea, forms a permeable barrier to the sea The waves lose energy in the riprap because of the friction with the rock faces Can be made of any rock that is resistant to erosion; granite, carboniferous limestone or even concrete. sea wall and 15 wooden groynes

Question 49

Cost effectiveness of the costal defences (HARD) at Hornsea

Answer 49

BAD! Has a score of 1.25, so the cost benefit score is poor. There are 50 homes and 1 caravan park but they only add up to £9.1 million and the defences cost £11.46 million

Question 50

Negatives of the riprap at Hornsea

Answer 50

- Does nit look 'natural' at the back of a sand shingle beach- engineers do not blend it with the colours of the beach/cliffs- ruins visual aesthetics and deters tourists - strong waves can move boulders so it needs regular maintenance

Question 51

Costal defences at Easington (important power plant situated here)

Answer 51

Revetments- Has been built to protect Washington's gas terminal; - these sloping structures, placed at the foot of a cliff/top of beach break up the wave energy Absorbs (not reflects, leading to destructive waves) wave energy using large air spaces between the boulders and a broad surface area up a slope.

Question 52

Cost effectiveness of the rock groynes and a revetment at Mappleton

Answer 52

They were built in 1991 and cost £2 million. They protect 12 homes and one business and the cost effectiveness is 0.76 A cost-effectiveness ratio of 0.76 is generally considered good. In cost-effectiveness analysis, a lower ratio typically indicates a more cost-effective intervention.