Coasts - KQ2 (protecting coastlines) Flashcards
1
Q
Why is Norfolk vulnerable?
A
- Continued eustatic sea level rise/isostatic sinking in the south east
- Global warming on a lowland coast
- Cliffs made from low-resistant boulder clay and outwash sands = very susceptible to marine erosion
- Local taxes cannot fund £100M+ needed for coastal defences for next 10 years (67km of man made defence)
2
Q
What are the names and locations of the case studies?
A
Sea Palling
- East Norfolk
- 19.6 miles north-east of Norwich and 140 miles north-east of London
Overstrand
- North coast of Norfolk
- Two miles east of Cromer
Abbotts Hall Farm
- Essex
- Great Wigborough in the Blackwater estuary
3
Q
Why does Sea Palling need protection?
A
- 1953 storm surge in North Sea led to extreme flooding and water broke through dunes
- Cliffs made from weak clays and sands which will absorb rainwater which percolates the cliff
- Fens inland of Sea Palling is home of significant human activity
- Previous flooding means protection is needed
4
Q
Why does Overstrand need protection?
A
- Village of 1100 people on a 35 metre high cliff (with a history of collapse)
- 1994 and 1995 20m lost each of the cliff (only 5m away from the road)
- Cliffs underlain by Upper Chalk which is easily eroded
- Landslide in 1994 means people cannot sell homes easily/have insurance
5
Q
Why does Abbotts Hall Farm need protection?
A
- Large areas of salt marsh and mudflats lost to coastal erosion and development = significant impact on flora and fauna
- Heavy engineering could damage environmental and economic opportunities
- Many fish spawning and vegetation habitats in the salt marshes which needed protection
6
Q
What are the main coastal defence strategies in Sea Palling?
A
- 100,000 tonnes of boulders in front of the sea wall to prevent it collapsing
- Beach replenished with 1 million cubic metres of sand
- New set of offshore bars to break the waves before they reach the beach and absorb wave energy during storm events
SMP
- Maintain existing sea walls and reef structures
- Replace groynes and replenish beaches
7
Q
What are the main coastal defence strategies in Overstrand?
A
- Concrete sea wall built which protects majority of area
- Revetments and groynes
- Recurved sea wall with drainage holes
8
Q
What are the main coastal defence strategies in Abbotts Hall Farm?
A
Realignment of the coast = managed retreat
- Construction of counter walls at both ends of the existing sea wall (protect neighbouring farms)
- Construction of earth bunds to protect freshwater areas from saltwater intrusion
- An Environmental Impact Assessment was carried and area was monitored for 3 years prior to realignment
9
Q
What are the two types of coastal defence methods?
A
Hard engineering = controlled disruption of natural processes by using man-made structures
Soft engineering = more long-term and sustainable, with less impact on the environment
- Less expensive than hard engineering
10
Q
Sea wall
A
HARD
- Expensive (£5000 a metre to build)
- Can slowly erode (hydraulic action in the gaps between concrete sections)
- Curved wall to reflect wave energy
- Vertical to protect base of slop from marine erosion
11
Q
Wooden revetments
A
HARD
- 45* angle = large surface area for wave to break on so energy is dispersed and power reduced
12
Q
Gabions
A
HARD
- bundles of rocks in a metal mesh
- Placed at the base of a cliff in an attempt to reduce the impact of waves on the cliff and prevent the cliff from being undercut
- Not particularly effective and they’re quite unsightly but very cheap
13
Q
Groynes
A
HARD
- Low lying wooden walls that extend out to sea
- Capture sand that moves down the beach via longshore drift and helps build up a larger section of beach in front of an area that’s experiencing coastal erosion
- New beach will increase the distance that waves have to travel to reach the coast and, in the process, they’ll lose most of their energy, reducing their impact
- Effective but will remove a lot of the sand that’s present down-drift of the beach which will result in a thinner beach at this area = sections of the coast will be more exposed to erosion down drift of the groynes which can create new problems
14
Q
Rip Rap
A
HARD
- Rocks and stones that have been put against the base of a cliff
- Similar to gabions in their purpose but they aren’t bound together in a mesh = look slightly more appealing as they blend into the environment better however the rocks are susceptible to being moved by the sea
15
Q
Beach nourishment
A
SOFT
- Sand and shingle are added to a beach in order to make it wider
- Increases the distance a wave has to travel to reach the cliffs and so the wave will lose more energy and have less erosive power when it reaches the cliffs
- Sand and shingle has to be obtained from elsewhere and is normally obtained from dredging
16
Q
Land management
A
SOFT
- Used to help protect and rebuild dunes
- Act as a good barrier against coastal flooding and erosion and can be exploited as a natural defence against the sea
- Dunes must be left relatively undisturbed so boardwalks are constructed and sections of sand dune systems are marked as out of bounds to the general public in order to reduce the erosion of the dunes by humans
17
Q
Marshland creation
A
SOFT
- Used to break up the waves and reduce their speed, reducing the waves erosive power
- Limit the area which waves can reach preventing flooding
- Created by encouraging the growth of marshland vegetation such as glassworts
18
Q
Beach Stabilisation
A
SOFT
- Widens the beach and dissipate as much wave energy as possible before it reaches the cliffs
- Dead trees planted in the sand stabilise it and lower the profile of the beach while widening the beach too
19
Q
When are groynes used?
A
- To reduce long shore drift
- Build up beach, dissipate wave energy
20
Q
When are riprap used?
A
- Subaerial weathering/mass movements
- Strengthen base of cliff
- Reduce rate of cliff erosion
21
Q
When is cliff drainage used?
A
- Subaerial weathering/mass movements
- Reinforce cliff and strengthen
- To drain and remove surface water which could lead to cliff instability
22
Q
When are concrete sea walls used?
A
- Marine erosion
- Reduce wave energy
23
Q
When are wooden revetments used?
A
- Marine erosion
- Reduce wave energy
24
Q
When are gabions used?
A
- Sub aerial weathering/mass movements
- Reinforce base of cliff
- Reduce abrasion by beach materials
25
What factors affect the type of sea defence used?
- Budget available
- Type and strength of coastal processes
- Environmental/aesthetic value of coastline
26
What is a Shoreline Management Plan? (SMP)
- Examines the risks associated with coastal processes and presents a policy to manage the risks
- Considers risks to people and the environment
27
What is an Integrated Coastal Zone Management? (ICZM)
- Method of managing the whole coastal zone
- Set up in 1996 by European Union
- Sees management being 'environmentally sustainable, economically fair, socially responsible and culturally sensitive' and that 'uncoordinated coastal policies can lead to conflict or further deterioration of the coast'
