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Sec 3 Coastal Management
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Sec 3 Coastal Management

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Sec 3 Coastal Management Sec 3 Coastal Management Presentation Transcript

  • Coastal Protection Management
    • Differentiate between hard engineering methods and soft engineering methods of coastal management.
    • Evaluate the success of coastal protection measures.
  • Coastal Protection Management
    • Types of Approaches
      • 1. Hard engineering approach (structural approach):
        • the construction of physical structures to defend against erosive power of waves.
      • 2. Soft engineering approach (non-structural approach):
        • focuses on planning and management so that both coastal areas and properties will not be damaged by erosion.
        • aims at changing individual behaviour or attitudes towards coastal protection by encouraging minimal human interference.
  • Coastal Protection Management
    • Hard Engineering Measures
      • Seawalls
        • They are built along the coast to absorb the energy of waves before they can cause erosion.
        • They can be made of concrete, rocks or wood.
        • They are especially effective in protecting cliffs from erosion.
  • Coastal Protection Management
    • Hard Engineering Measures
      • Seawalls
        • However they cannot prevent the backwash of the refracted waves from washing away beach materials beneath the walls.
        • This undermines the base of the seawalls and they collapse.
        • Seawalls are costly to build and maintain.
  • Coastal Protection Management
    • Hard Engineering Measures
      • Breakwaters
        • It can be built with one end attached to the coast or away from the coast.
        • They break the force of high energy waves before they reach the shore.
        • When constructed offshore, it can create a zone of calm water behind them and allow deposition to occur, forming beaches.
  • Coastal Protection Management
    • Hard Engineering Measures
      • Breakwaters
        • Materials deposited behind the breakwater are protected but the zone located away from the breakwater is not.
        • It will not receive new supplies of materials and it will get eroded away.
  • Coastal Protection Management
    • Hard Engineering Measures
      • Groynes
        • They are built at right angles to the shore to prevent longshore drift.
        • They absorb or reduce the energy of waves and cause materials to be deposited on the side of the groyne facing the longshore drift.
        • However erosion can occur at places not protected by it.
  • Coastal Protection Management
    • Hard Engineering Measures
      • Gabions
        • They are wired cages filled with crush rocks.
        • They are piled up along the shore to prevent or reduce coastal erosion by weakening wave energy.
        • It offers short-term protection (5 to 10 years).
        • The cages require regular maintenance and are easily corroded by sea water, trampling and vandalism.
  • Coastal Protection Management
    • Hard Engineering Measures
      • Gabions
        • If not properly maintained, the wire baskets can be unsightly and dangerous along the beach.
  • Coastal Protection Management
    • Soft Engineering Measures
      • Beach nourishment
        • The constant replenishment of large quantities of sand to the beach system.
        • The beach is extended seawards, which leads to the improvement of beach quality and storm protection.
        • It is costly to transport large quantities of sand to fill up the beach and sufficient sand is needed.
        • Sand being eroded and transported away by waves and wind and can affect wildlife e.g. coral reefs at Waikiki Beach in Hawaii.
  • Coastal Protection Management
    • Soft Engineering Measures
      • Relocation of properties
        • No building of properties are allowed in coastal areas vulnerable to costal erosion.
        • The east coast of England has a “green line” policy that discourage building located beyond it.
        • With the danger of increasing sea levels due to global warming, relocation is important to future coastal management.
    • Soft Engineering Measures
      • Planting of mangroves
        • Mangroves with their prop roots help trap sediments and reduce coastal erosion.
        • As mangrove communities grow seawards, they extend the coastal land seawards.
    Coastal Protection Management
    • Soft Engineering Measures
      • Stabilising dunes
        • Access points to the beach should be controlled and designated so as not to be disturbed by human traffic.
        • Shrubs and trees can be planted to stabilize them. Roots of trees reach downwards to tap groundwater and anchor the sand in the process.
    Coastal Protection Management
  • Coastal Protection Management
    • Soft Engineering Measures
      • Growth of coral reefs
        • Artificial reefs can be created by placing environmentally friendly and long-lived materials like steel or concrete on the sea floor.
        • Once the material is put in place, living organisms start to grow on it.
        • Man-made reefs are as productive as natural reefs in enhancing fishing opportunities and serve as undersea barriers to reduce impact of wave energy.
  • Coastal Protection Management Comparison of the Effectiveness of Coastal Management Protection Measures – Hard Engineering
    • Need regular maintenance
    • Weaken wave energy
    • Reduce coastal erosion
    Gabions
    • Erosion on parts of coast not protected by groynes
    • Protect coast from high energy waves
    • Encourage build-up of beach
    Groynes
    • Erosion on parts of coast not protected by breakwaters
    • Protect coast from high energy waves
    • Encourage build-up of beach
    Breakwaters
    • Erosion may lead to collapse of seawall
    • Costly
    • Absorb shock of waves
    • Reduce erosion of shore
    Seawalls Disadvantages Advantages
  • Coastal Protection Management Comparison of the Effectiveness of Coastal Management Protection Measures – Soft Engineering
    • Can affect the depth of coasts – implications for port activities/coastal transportation
    • Helps trap sediments to form islands
    • Prevents coastal erosion
    Planting of mangroves
    • Affects investment opportunities in coastal areas
    • Allows nature to take its course
    • Avoids loss of lives and properties
    Relocation properties
    • Expensive
    • Affects marine ecosystem
    • Requires constant supply of new sand
    • Improves beach quality
    • Improves storm protection
    Beach nourishment Disadvantages Advantages
  • Coastal Protection Management Comparison of the Effectiveness of Coastal Management Protection Measures – Soft Engineering -
    • Reduces wave energy
    • Encourages the growth of living organisms
    • Improves fishing opportunities
    Growth of coral reefs
    • Dunes are easily eroded if vegetation is not present
    • Vegetation growing on dunes anchor sand
    • Protects coast from sea
    Stabilizing dunes Disadvantages Advantages
  • Homework
    • Briefly describe the difference between “hard engineering approaches” and “soft engineering approaches”.
    • Describe three hard engineering measures of coastal protection.
    • Describe three soft engineering measures of coastal protection.
    • With reference to examples, explain why soft engineering approaches of coastal protection may be more effective than hard engineering approaches of protection.