Coastal Management 4
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Coastal Management 4

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coastal management

coastal management

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    Coastal Management 4 Coastal Management 4 Presentation Transcript

    • Coastal Management
      • Large scale development of coastal areas will bring about problems if development is not properly planned and managed.
      • Proper coastal management and protection are needed to preserve quality of coastal environment.
    • Lost Villages Due to Coastal Erosion
    • Types of Approach
      • Hard engineering
      • Refers to the construction of physical structures to defend against the erosive power of waves.
      • - Also known as the structural approach .
    • Types of Approach
      • Soft Engineering
      • - Focuses on planning and management so that both coastal areas and properties will not be damaged by erosion.
      • - Also aims to change individual behaviour or attitude towards coastal protection by encouraging minimal human interference and allowing nature to take its course.
      • - Also known as the non-structural approach.
    • Hard Engineering Measures
      • Seawalls (+)
      • Seawalls absorb the energy of waves before they can erode away loose materials.
      • Seawalls can be made of concrete, rocks or wood.
      • They are effective in protecting cliffs from erosion.
    •  
    • Hard Engineering Measures
      • Seawalls (-)
      • - They can only absorb the energy of oncoming waves. They do not prevent the powerful backwash of refracted waves from washing away the beach materials beneath the walls.
    • Hard Engineering Measures
      • Seawalls (-)
      • - Base of seawalls will be undermined (weakened) and leads to their collapse.
      • - Seawalls are costly to build and maintain as constant repairs have to be made to prevent their collapse.
    •  
    • Hard Engineering Measures
      • Breakwaters
      • Protect coast and harbour by reducing force of high energy waves before they reach the shore.
      • They can either be built with one end attached to the coast or built away from coast.
    •  
    • Hard Engineering Measures
      • Breakwaters (+)
      • Breakwaters
      • Protect coast and harbour by reducing force of high energy waves before they reach the shore.
      • They can either be built with one end attached to the coast or built away from coast.
    •  
    • Hard Engineering Measures
      • Breakwaters (-)
      • Materials deposited in the zones behind the breakwater are protected while those in the zones located away from the breakwater are not.
      • Zones will not receive any new supply and thus be eroded away .
    • DEPOSITION EROSION
    • Hard Engineering Measures
      • Groynes
      • Built at right angles to the shore to prevent longshore drift .
      • These structures absorb or reduce the energy of the waves and cause materials to be deposited on the side of the groyne facing the longshore drift.
    •  
    • Hard Engineering Measures
      • Groynes (-)
      • Erosion can still take place on the part of the coast that is not protected by groynes.
    •  
    •  
    • Hard Engineering Measures
      • Gabions
      • - Gabions are wire cages usually filled with crushed rocks , and then piled up along the shore to prevent or reduce coastal erosion by weakening wave energy.
    •  
    • Hard Engineering Measures
      • Gabions (-)
      • This method offers only short-term protection (about five to ten years).
      • Wire cages need regular maintenance as they are easily corroded by sea water.
      • Affected by excessive trampling and vandalism.
    • Hard Engineering Measures
      • Gabions (-)
      • - Can be unsightly and become a danger along the beach.
    • Soft Engineering Measures
      • Beach nourishment
      • Refers to constant replenishment of large quantities of sand to the beach system.
      • Beach is therefore extended seawards, leading to improvement of both beach quality and storm protection.
    •  
    • Soft Engineering Measures
      • Beach nourishment (-)
      • Very expensive and impractical to constantly transport large quantities of sand to fill up beach.
      • Imported sand that can be continuously eroded and transported away could have serious consequences on wildlife living within coastal environment .
    • Soft Engineering Measures
      • Beach nourishment (-)
      • E.g. Coral reefs at Waikiki Beach of Hawaii are destroyed as imported sand gets washed out to sea and covers the corals.
      • Corals are deprived of sunlight they need to survive
    • Soft Engineering Measures
      • Beach nourishment (-)
      • E.g. Singapore – Large scale land reclamation along coast has led to muddy and polluted water and has destroyed coral reefs.
    • Soft Engineering Measures
      • Relocation of Property
      • Coastal planners protect man-made structures (e.g. buildings) by relocating them and letting nature reclaim the beach in its own time.
      • No building of new properties of structures would be allowed in coastal areas that are vulnerable to coastal erosion.
    • Soft Engineering Measures
      • Relocation of Property
      • - E.g. England – “Green Line” policy which discourages any building beyond a given line. Any properties built beyond the given line will not be defended or protected should they be threatened by coastal erosion.
    • Soft Engineering Measures
      • Relocation of Property (-)
      • Opposition by people with considerable investments in coastal areas .
      • This approach will be important in future coastal management due to rising sea level as a result of global warming.
    • Soft Engineering Measures
      • Planting of Mangroves
      • Mangroves have long and curved roots that prop up from soil. It traps sediments and reduce coastal erosion .
      • Mangoves can secure and trap enough sediments to form small islands – extend coastal land seawards.
    •  
    • Soft Engineering Measures
      • Planting of Mangroves
      • E.g. Aceh – More than 5,000 mangrove seedlings were planted to rehabilitate coast devastated by 2004 tsunami.
    • Soft Engineering Measures
      • Planting of Mangroves (-)
      • Not all coastal regions can support mangroves, especially in coastal regions with destructive waves.
      • As sediments build up along coast after planting mangroves, depth of coast may become shallower and thus affect port activities – (E.g. Pose a problem for countries like Singapore that depends heavily on maritime trade.)
    • Soft Engineering Measures
      • Stabilising dunes
      • Dunes are so fragile that delicate shrubs struggle to hold them in place.
      • Access points to the beach should be controlled and designated so as to prevent dunes from being disturbed by human traffic.
    •  
    • Soft Engineering Measures
      • Stabilising dunes
      • - Shrubs and trees can be planted to stabilise dunes because roots can reach downwards to tap groundwater and thereby anchoring the sand.
    • Soft Engineering Measures
      • Growth of coral reefs
      • Coral reefs weaken wave energy.
      • Artificial reefs can be created along coast by placing environmentally friendly and durable materials such as steel or concrete on sea floor.
    •  
    • Soft Engineering Measures
      • Growth of coral reefs
      • - These man-made reefs enhance fishing opportunities and serve as undersea barriers to reduce impact of wave energy.
    •  
    • Tyres used as man-made structure for coral reefs
    • Another example of man made structure as coral reef