Flashcards in Coastal management Deck (18)
What is the definition of soft engineering?
Is the environmentally friendly approach which uses natural processes and materials.
What are the types of soft engineering?
1. Beach nourishment- Addition of sand to the beach (£300,000 each 100m)
- Relatively cheap and easy
- Looks natural and increases tourism
- Needs constant maintenance as moved away
2. Sand dune regeneration- Stabilising through planting vegetation maybe fenced off (£200-£2000 each 100m)
- Maintenance not required so cheap and sustainable
- Maintains environment and creates habitats
- People may respond negatively to being kept off land
3. Salt marsh creation- Low lying farmland is allowed to flood (Cost depends on compensation)
- Relatively cheap and only one single payment
- Creates natural barrier for waves while creating habitats
- Agricultural land is lost and may be hard to find suitable land.
4. Coastal land use management- Planning what can be built on land which is at risk of flooding
- Minimises future costs
- Looks at what is best for the environment
- People may not agree with managed retreat, protects money not land.
What is the definition of hard engineering?
Process of protecting the coast using man made structures which stop natural processes from occurring .
What are the types of hard engineering?
1. Sea walls- Concrete wall built on the edge of the coastline (£6000 per metre)
- Protects base of cliff and buildings and from flooding
- Expensive to build and unattractive
- Curved walls reflect energy back to they stay powerful
2. Groynes- Timber or rock structures built at right angles -to coast (£5000-£10,000 each)
- Work with natural process to build up beach this increases tourism
- Starves beaches further along the coast.
3. Revetments- Wood or concrete structures at bottom of the cliff or the top of the beach, break up wave energy (£4500 per metre)
- Relatively expensive to build
- Intrusive and unnatural looking
- High levels of maintenance needed
4. Rock armour- Large rocks at foot of the clidd which forms permeable barrier to break up waves (£100,000-£300,000 per 100m)
- Cheap and easy to construct and maintain
- Usually look out of place as not local to area
5. Off-shore break water- Partially submerge barrier which break up waves.
- Effective permeable barrier
- Potential navigation hazard
What is a revetment?
Wooden or rock structures placed at the bottom of the cliff or the top of the beach, to try to break up the wave energy.
Benefits of groynes?
- Work with natural processes to build up the beach.
- Not too expensive.
- Attracts tourists.
Advantages of the scheme at Abbotts hall farm?
1. New wildlife habitats
2. Acts as natural sea defence.
3. Income through tourists.
4. Marshes adapt to changes is sea level rise.
5. Cheap and sustainable.
Disadvantages of the scheme at Abbotts hall farm?
1. Agricultural land is lost so less produced.
2. Plan not accepted by local residents.
3. May set precedent for other areas as a 'defeat'.
4. Farmers fear they will lose income.
What happened at Abbotts hall farm?
Essex wildlife trust brought a farm in 1999.
Built counter walls which protected surrounding land and made breaches in existing sea wall. Land was allowed to flood in 2002, in order to create new salt marshes in the area.
What was the SMP in North Norfolk?
Only the most important settlements were protected and everywhere else is set to managed retreat.
How are cliffs eroded in North Norfolk?
1. Rotational slumping - When cliff becomes saturated and heavy due to rainfall which causes the clay to become unstable and it slumps away from the cliff.
2. Undercutting - Soft rock underneath erodes more quickly than hard rock on top, eventually overhang becomes too heavy and top also collapses.
What are the 4 strategies in a shoreline management plan?
1. Hold the line
2. No active intervention
3. Advance the line
4. Managed realignment
What are the long term factors to be considered in a SMP?
1. Promontory effect- Larger settlements protected by defences which stops them retreating while other areas are eroded, these then become more pronounced. Act as large groynes which inhibit LSD.
2. Climate change - how will climate change affect the processes that occur here.
3. Costs - will it become more expensive to protect than the land is worth
What is an integrated coastal zone management?
Considers the whole coastal zone as one, areas are interlinked so what happens in one area affects all others. Ensures the best sustainable futures for natural coast.
- Coastal zone thats part of the worlds largest delta over 1000km2 in Bangladesh and India. Formed by deposition of 3 rivers.
- Delta is a depositional landform that occurs when rivers transporting large amounts of sediment meet the sea and deposit it.
Threats to the area-
- Sea level rise + climate change
- Over exploitation of resources and destructive fishing
- Many goods can be produced using the material from the region.
E.G. Construction materials, fuels, textiles.
- Services can be provided here to help the people
E.G. Protection from floods and cyclones, Provision of fishing.
How does resilience, mitigation and adaptation help the people in the sundarbans:
- Mangrove swamps offer protection from storms and erosion. 30 Trees per 0.1 hectare offers 90% protection.
- Close knit communities and good levels of social capital based upon trust and co operation.
- High economic value as mangroves provide food and resources. 1 hectare has a value of over $12,000.
- Multi-purpose cyclone shelters built which also act as schools.
- Improvements to infrastructure mean support before and after extreme events is improved.
- Water storage tanks collect rainwater in areas at risk of salt water inundation.
- New ways to farm encouraged to use methods e.g. salt resistant rice.
- NGOs built new latrines on higher ground + educate communities.
- Water tight containers store important documents and belongings during floods.
Case study of Sheringham, shoreline management plan:
SMP at Sheringham is hold the line for next 10 years.
- Sea walls
- Wooden + rock groynes
- Rock armour
- Cliff drains and boreholes
Reasons for HTL SMP:
- Cost benefit analysis states value of Sheringham outweighs cost of protecting.
- Sediment is only taken from here to Cromer so other areas do not rely on LSD from here.
Is it sustainable:
- Coastline to each side currently unprotected and over time will become promontory, will become much harder and less cost effective to protect in the future.
- High tide therefore likely to rise so less beach and current defences such as groynes will become ineffective. Amplified by predicted sea level rise.
- SMP will need to be reconsidered in the future.