Coastal Management 1194172427916177 5
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Coastal Management 1194172427916177 5

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Coastal Management 1194172427916177 5 Coastal Management 1194172427916177 5 Presentation Transcript

  • Problems and Solutions in Coastal Areas Coastal Erosion & Decline in Coastal Areas
  • Problems in Coastal Areas?
    • Coastal Erosion & flooding due to sea levels rising and an increase in storm events.
    • Decline in visitor numbers to coastal tourist resorts due to competition from overseas resorts (cheap airfares, package holidays and better weather).
  • Coastal Erosion & flooding due to sea levels rising and an increase in storm events.
    • Why is this a problem?
    • This problem needs to be managed in order to protect people’s homes and businesses (especially tourism and agriculture).
    • How is it managed?
    • Coastal defence techniques
  • There are 2 types of Coastal defence techniques. 1. HARD ENGINEERING - this is where man made coastal defence structures are used to reflect large amounts of wave energy and hence protect the coastline. 2. SOFT ENGINEERING - this is where beaches or naturally formed materials are used to control / re-direct erosion processes. You need to know examples of coastal management techniques and their advantages and disadvantages:
  • What do you know about coastal defences?
    • Sea Wall
    • Rock Armour/Rip-rap
    • Groynes
    • Gabions
    • Revetments
    Hard Engineering Techniques:
  • Sea Wall A concrete wall which is curved on the underside to deflect the power of the waves These can be very expensive (up to £1-2 million per km) and the deflected waves can scour material at the base of the wall causing them to become undermined These are however a very effective means of preventing erosion and they reflect rather than absorb wave energy.
  • Rock Armour/Rip-Rap 2. Rip Rap Large boulders on the beach absorb wave energy and break the power of the waves Although movement of the boulders is expensive this can be a much cheaper method than some other solutions The boulders can however be undermined easily by waves washing away sand and shingle beneath them. They also can be quite ugly, changing the appearance of a coastline.
    • These structures (usually either wooden or steel) are designed to top longshore drift and therefore act to build up and anchor beach material, protecting the base of cliffs.
    • They are effective at reducing erosion in the area they are constructed in by causing significant build up of beach material
    • Groynes may however starve areas further down the coast of material by stopping longshore drift, resulting in an increase in erosion in these areas .
    Groynes
  • How do groynes work? Groynes trap the sand which is carried along the coast by longshore drift . The sand acts as a natural protection against the force of the waves. The waves break onto the beach and not the cliffs.
  • Gabions These cages of boulders are built into cliff faces to protect the cliff from the force of the waves; they are cheaper than sea walls and can be very effective where severe erosion is a problem They are however visually intrusive
  • Revetments These wooden structures break the force of waves and beach material builds up behind them They are cheap and effective at breaking waves As well as being visually intrusive however they do need replacing more frequently than most other defence methods.
    • Beach Nourishment
    • Managed Retreat
    Soft Engineering Techniques:
  • Beach Nourishment Beach material is added to provide a "natural solution". Environmentally this is a preferred option as it maintains the beauty of the landscape and avoids visual intrusion, however it can be expensive to maintain as longshore drift continues to move beach material down the coast and therefore regular replenishment is required. Sand Dunes and salt marshes can also be encouraged to act as natural barriers to the waves.
  • Managed Retreat Managed retreat is also known as managed realignment. It involves breaching an existing coastal defence, such as a sea wall, and allowing the land behind to be flooded. This land is then left to be colonised by saltmarsh vegetation. When established, the vegetation disperses wave energy, reduces erosion rates and provides new habitats. The first attempt at managed retreat in the UK was on Northey Island, located in the Blackwater Estuary in Essex.
  • Study the photo and map extract. Is this Peveril or Ballard Point? pier Swanage Bay
  • What has been done to protect Swanage?
  • What is the best method of coastal protection? There are strong feelings about what should be done to protect Seaview!
  • Case Study – Holderness Coast
    • Problems
    • Soft boulder clay cliffs were easily eroded – 1m a year.
    • 29 villages already lost to sea.
    • Farmland, hotels & houses lost – economic impact.
    • Sea walls and existing defences were over 100 years old and not effective.
    • Storm events have become more current in recent years – long fetch.
    • Sea level rise is 4mm a year
    • Attempts to protect the coast has led to increased erosion further along (Groyne to the south of Mappleton).
    • Major roads eg B1242 run along the coastline.
  •  
  • What are the disadvantages of groynes? Mappleton is located on the Holderness Coastline.
    • In 1991 a rock revetment and two rock groynes were built. Sand accumulated and halted erosion.
    • South of Mappleton, the rate of erosion has increased significantly.
    • Material that usually moves south via longshore drift is becoming trapped within the groynes.
    • Now there is no beach to protect the cliffs - the sea reaches the base of the soft cliffs and erosion occurs.
  • Solutions
    • Scarborough - 2002
    • Cost £50 million
    • New Sea Wall Built
    • Granite rock armour placed at bottom of sea wall (each 6-10 tonnes)
    • 4000 interlocking concrete blocks placed on top of these.
    • Aim: to absorb sea energy & reduce erosion.
  • Solutions
    • Mappleton
    • Cost £2 million.
    • Norweigan granite rock armour placed at bottom of cliff.
    • 2 rock groynes put in place to trap beach material.
  • Practice makes perfect!
    • (c) Study Figure 16 , on the insert, a photograph of coastal defences at Mappleton, east Yorkshire.
    • Explain how the coast is being protected from erosion by the sea.
    • .......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
    • (4 marks)
    • Study Figure 13, on the insert, a photograph of some coastal defences in an area of sand dunes.
    • Describe one method of coastal protection shown.
    • ................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
    • (2 marks)
    • (c) Explain how some coastal defences work.
    • ....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
    • (4 marks)
  • Decline in visitor numbers to coastal tourist resorts due to competition from overseas resorts (cheap airfares, package holidays and better weather).
    • Why is it a problem?
    • Several coastal resorts in the UK rely on tourism for an income. If visitor numbers are declining this means businesses shut down, unemployment increases and a downwards economic and social spiral can occur.
  • Case Study: Blackpool
    • Visitor numbers dropped by 6 million between 1990-1997.
    • 1000 hotels ceased trading.
    • 300 holiday flats closed
    • Blackpool was not exciting to visitors.
    • Blackpool developed an image as hen/stag night capital – not for families.
    • Beach erosion was occurring during winter storms.
    • Beach & water pollution
    • Downward spiral occurred with run down areas and lack of investment.
    • High unemployment out of season.
    • Since 2001 old run down buildings have been pulled down.
    • Car parks have been landscaped.
    • Beaches have been cleaned up and by 2006 3 had the EU ‘Blue Flag’ for cleanliness.
    • Sand is no longer removed from further down coast.
    • Blackpool illuminations have been extended into autumn to extend the tourist season and have had £10 million invested.
    • Off-season events such as conferences are being promoted.
    • Pleasure beach has been improved with new rides such as the Water World in 2006.
    • Covered walkways have been built to protect visitors during bad weather.
    Problems Solutions
    • (i) Weymouth, shown on Figure 2 , is a coastal holiday resort.
    • Suggest two problems caused by the large numbers of visitors to Weymouth.
    • 1 ................................................................................................................................
    • ...................................................................................................................................
    • 2 ................................................................................................................................
    • ...................................................................................................................................
    • (2 marks)
    • (ii) For a holiday resort you have studied, describe some of the solutions to problems
    • caused by tourism.
    • ...................................................................................................................................
    • ...................................................................................................................................
    • ...................................................................................................................................
    • ...................................................................................................................................
    • ...................................................................................................................................
    • ...................................................................................................................................
    • ...................................................................................................................................
    • ...................................................................................................................................
    • (4 marks)