3.1.3.2 Coastal Landscapes in the UK - Coastal Management Strategies

Question 1

Hard engineering:

Answer 1

whereby the natural environment is protected when artificial structures are put in place to protect the coastline e.g. sea walls

Question 2

Coastal management hard engineering methods:

Answer 2

• sea walls
• groynes
• rock armour
• gabions

Question 3

Diagram of sea walls:

Answer 3

Question 4

How do sea walls work and protect the coastline?

Answer 4

• a sea wall provides is a concrete or rock barrier between waves and the land
• it is placed along the back of a beach or at the foot of cliffs
• recurved sea walls are more expensive than flat sea walls, but are more effective in reflecting waves and reducing overtopping
• steps are often added to give extra stability
• the recurved face rotates the wave backwards so some of the waves energy is reflected back out to sea
• this impedes the next wave and reduces its energy reducing erosive power

Question 5

Advantages of sea walls:

Answer 5

• Social: sea wall often gives people a sense of security, often has a promenade on top of it, which doubles up as a cycle route outside peak walking periods - steps at the base of walls act as seating areas for beach users
• Economic: if well maintained sea walls can last for many years - so don’t have to spend money replacing it
• Environmental: sea walls don’t impede the movement of sediment down drift, so they don’t disadvantage other areas

Question 6

Disadvantages of sea walls:

Answer 6

• Social:
  
  • they restrict people’s access to the beach and if waves break over the sea wall (overtopping)
  • coastal flooding may occur
• Economic: very expensive to build
  
  • £5,000 - £10,000 per metre
  • repairs are also expensive
  • reflected waves scour the beach in front of a sea wall and this undermines the foundations
  • if damaged is not repaired quickly, the result can. be devastating
  • in Dawlish, Devon (feb 2014), the sea wall carrying the main south coast railway collapsed causing £13mn repairs to the wall and track
  • to reduce scouring, rock armour and beach nourishment may be needed
• Environmental: from the beach, a wall of concrete can be obtrusive and unnatural to look at and sea walls can also destroy habitats

Question 7

Diagram of groynes:

Answer 7

Question 8

How do groynes work and protect the coastline?

Answer 8

• groynes are wooden or stone structures built in the foreshore, they look like fences or walls
• they are built at right angles to the beach and are spaced at regular intervals (50m apart)
• groynes trap sediment transported by longshore drift
• it builds up the beach on the updrift side of the groyne
• a larger beach provides a more effective buffer as it absorbs the waves’ energy, and reduces the impact of waves on the sea wall
• groynes are particularly effective when used in conjunction with beach nourishment

Question 9

Advantages of groynes:

Answer 9

• Social:
  
  • rock groynes at Sandbanks, Poole, have concrete crests for people to walk along to reach a viewing or fishing point
  • groynes also act as windbreaks
• Economic:
  
  • £5,000 each groynes are relatively cheap and, if well maintained, can last up to 40yrs
  • a larger beach, with more space for activities, attracts more tourists which boosts the local economy

Question 10

Disadvantages of groynes:

Answer 10

• Social:
  
  • groynes are barriers which impede walking along a beach
  • dangerous as they have deep water on one side and shallow water on the other
  • this is a particular hazard to children who find it hard to resist climbing on them
  • groynes may also be a danger to windsurfers who may collide with them
• Economic:
  
  • by trapping sediment, groynes restrict the supply of sediment down-drift
  • e.g. new groynes at Poole restrict sediment movement towards Bournemouth - the problem is merely passed on to incur more cost
  • Gorynes can be damaged in stormy conditions and need regular maintenance to keep them working for long time
• Environmental:
  
  • groynes may be considered unattractive - especially degraded ones

Question 11

Diagram of how rock armour protects the coastline:

Answer 11

Question 12

How does rock armour work and how does it protect the coastline?

Answer 12

• rock armour (rip rap) is made up of thousands of tonnes of huge boulders of hard rock like granite, to act as a barrier between the sea and the land
• rocks are usually brought by a barge to the coast
• boulders are generally big enough not to be moved by storm waves
• the rocks force waves to break, absorbing their energy and protecting the cliffs
• as water enters gaps between boulders, pressure is released and this reduces the waves’ energy, so there is little scouring of the base - highly effective form of hard engineering

Question 13

Advantages of rock armour:

Answer 13

• Economic:
  
  • relatively cheap £1,000 - 3,000 per metre, compared to £5,000 - £10,000 for a sea wall
  • structure is quick to build and easy to maintain, can be built in weeks rather than months it takes to make a sea well - if well-maintained, rock armour lasts a long time
  • it is versatile, as it can be placed in front of a sea wall to lengthen its lifespan or use to stabilise slopes on sand dunes
  • often used for fishing
• Social:
  
  • can provide interest to coast

Question 14

Disadvantages of rock armour:

Answer 14

• Social:
  
  • makes access to beach difficult as people have to clamber over it or make long detours
  • people may have accidents when clambering over as rocks may be unstable
  • if rocks are regularly covered by the tide they may collect slippery seaweed, which adds to the hazard
• Economic:
  
  • highly resistant rocks from Norway and Sweden are often used in preference to rocks from local quarries
  • may cause resentment - inflates cost considerably
  • heavy storm waves will move rocks and so armour needs regular maintaining
  • expensive to transport
• Environmental:
  
  • rock armour not visually appealing and often covers vast areas of beach
  • driftwood and litter may become trapped in structure
  • imported rocks don’t blend in with geology
  • obtrusive

Question 15

Diagram of how gabions protect the coastline:

Answer 15

Question 16

How do gabions work and protect the coastline?

Answer 16

• gabions are steel-wire mesh cages filled with pebbles or rocks
• they are placed at the back of a sandy beach to create a low, wall-like structure
• water enters the cages and this absorbs and dissipates some of the waves’ energy, thus reducing the rate of erosion
• gabions may also be placed in front of a cliff, where they ay be covered with vegetation
• this gives stability to a cliff and reduces the risk of landslides

Question 17

Advantages of gabions:

Answer 17

• Economic:
  
  • £110 per metre - relatively cheap and easy to construct
  • gabions often constructed on site using local pebbles
  • makes them much cheaper than sea walls, rock armour or groynes
  • makes them ideal as a quick-fix solution
  • for the cost, they are good value for money, as they last 20-25 years
  • flexible in design
  • can improve drainage of cliffs
• Environmental:
  
  • blend in better than other hard engineering methods, esp. when sand is blown onto them or when they are covered with vegetation - merge into the landscape

Question 18

Disadvantages of gabions:

Answer 18

• Economic:
  
  • use of gabions is restricted to sandy beaches as shingle hurled at them would quickly degrade them
  • gabions are easily destroyed, so regular maintenance is needed
  • repair of embedded, vegetation-covered gabions can be expensive
  • the gabions built at Thorpeness, Suffolk in 1976 had their covering of topsoil and vegetation washed away by storms in 2010 - cost £30,000 to repair them
  • cages only last 5-10 yrs before they begin to rust
• Social:
  
  • in damaged state, gabions are dangerous as people may trip over them or cut themselves on the broken wire mesh
• Environmental:
  
  • damaged gabions are not visually pleasing
  • sea birds may damage feet in gabions

Question 19

Soft engineering:

Answer 19

works with the natural environment, it is less expensive than hard engineering and often more sustainable as it is less intrusive and more environmentally friendly (to protect coastline)

Question 20

Coastal management soft engineering strategies:

Answer 20

• beach nourishment
• beach re-profiling
• sand dune regeneration

Question 21

Diagram of how beach nourishment protects the coastline:

Answer 21

Question 22

How does beach nourishment work and protect the environment?

Answer 22

• beach nourishment is the replacement of lost sediment - addition of sand/shingle to an existing beach to make it higher or wider
• a nourished beach means fewer waves reach the back of the beach, as more wave energy is absorbed and dissipated by the beach, the rate of erosion is reduced

Question 23

What techniques are used to nourish beaches?

Answer 23

• Beach recharge
  
  • when sediment is taken away from a bay and placed on a beach that is losing sand
  • happens every summer at Pevensey (East Sussex), where longshore drift removes 20,000 cubic metres of beach sediment a year
  • a dredger collects shingle from the seabed and, on the high tide, comes in twice daily to pump out the sand
  • at Sandbanks in Poole (Dorset), beach recharge takes place every 10 yrs - bulldozers often used to spread out the sand
• Beach recycling
  
  • removal of sand from a down-drift area, which is building up sand and returning it up-drift
  • at some beaches e.g. Seaford, East Suffolk, trucks mover approx. 100,000 cubic metres of shingle twice every year

Question 24

Advantages of beach nourishment:

Answer 24

• Social:
  
  • wider beach means ore room for beach users
  • people living along seafront are more protected from coastal flooding
• Economic:
  
  • at Sandbanks, the wider, nourished beach protects very expensive properties
  • the buffer of a widened beach reduces sea wall maintenance costs
  • a broader beach may also attract more tourists
• Environmental:
  
  • nourished beach is natural and blends in with environment

Question 25

Disadvantages of beach nourishment:

Answer 25

• Social:
  
  • during re-nourishment, access to beach is restricted for several weeks
  • beach recycling may cause resentment from residents living close to the donor area
• Economic:
  
  • although cheaper than hard engineering options, has high overhead costs - approx. £300,000 to hire a dredger
  • the 137,000m3 of nourishment at Sandbanks in 2014 cost £1.95mn
  • needs constant maintenance unless structures are built to retain the beach

Question 26

Diagram showing how beach re-profiling protects the beach:

Answer 26

Question 27

How does beach re-profiling work and how does it protect the coastline?

Answer 27

• beach re-profiling is the artificial re-shaping of a beach using existing beach material
• in winter, a beach is lowered by destructive waves
• after winter storms, bulldozers move shingle back up the beach
• like beach nourishment, re-profiling ensures that the beach is large enough to be an effective buffer between land and sea to absorb the energy from the wave and reduce erosion

Question 28

Advantages of beach re-profiling:

Answer 28

• Social:
  
  • at Pevensey, the residential area behind the beach is now protected so the residents feel safe
• Economic:
  
  • if the shingle ridge at Pevensey is breached, the estimated repair cost would be about £125mb whereas the combined cost for nourishment and reprofiling would be £30mn iver 25yrs
• Environmental:
  
  • in preventing a beach, the Pevensey Levels has been protected and the beach still looks reasonable natural

Question 29

Disadvantages of beach re-profiling:

Answer 29

• Social:
  
  • bulldozers restrict access to Pevensey’s beach esp. in Winter
• Economic:
  
  • major re-profiling costs can be expensive
  • further westa long the coast at Selsey (West Sussex) £200,000 a yr was paid to realign the beach prior to the Medmerry scheme
• Environmental:
  
  • a steep, high crested beach may look unnatural and uninviting to tourists

Question 30

Diagram showing sand dune regeneration protects the coastline:

Answer 30

Question 31

How does sand dune regeneration work and protect the coastline?

Answer 31

• artificial creation of new sand dunes/restoration of old ones
• are effective as buffers to sea as absorbed energy from waves and act as physic barrier against Sea reducing erosion
• however, can be easily damaged and destroyed by trampling
• marram grass can be planted to stabilise dunes and help them to develop
• fences can be used to keep people off newly planted areas

Question 32

Advantages of sand dune regeneration:

Answer 32

• Social:
  
  • sand dunes protect land behind them and provides opportunities for recreation
• Economic:
  
  • small planting projects used volunteer labour so costs are minimal
  • relatively cheap
• Environmental:
  
  • regeneration helps to develop and maintain habitats for wildlife

Question 33

Disadvantages of sand dune regeneration:

Answer 33

• Social:
  
  • people don’t always respond well to being prohibited from accessed planting areas
  • area when fenced off when being regenerated - deter tourists
• Economic:
  
  • time-consuming to plant marram grass and fence areas off
  • can be damaged by storms - costs money to fix
  • maintenance required - checked twice/yr and have fertilisers applied