Coastal Management 4

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coastal management

coastal management

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  • 1. Coastal Management
  • 2.
    • 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.
  • 3. Lost Villages Due to Coastal Erosion
  • 4. 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 .
  • 5. 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.
  • 6. 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.
  • 7.  
  • 8. 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.
  • 9. 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.
  • 10.  
  • 11. 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.
  • 12.  
  • 13. 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.
  • 14.  
  • 15. 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 .
  • 16. DEPOSITION EROSION
  • 17. 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.
  • 18.  
  • 19. Hard Engineering Measures
    • Groynes (-)
    • Erosion can still take place on the part of the coast that is not protected by groynes.
  • 20.  
  • 21.  
  • 22. 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.
  • 23.  
  • 24. 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.
  • 25. Hard Engineering Measures
    • Gabions (-)
    • - Can be unsightly and become a danger along the beach.
  • 26. 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.
  • 27.  
  • 28. 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 .
  • 29. 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
  • 30. 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.
  • 31. 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.
  • 32. 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.
  • 33. 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.
  • 34. 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.
  • 35.  
  • 36. Soft Engineering Measures
    • Planting of Mangroves
    • E.g. Aceh – More than 5,000 mangrove seedlings were planted to rehabilitate coast devastated by 2004 tsunami.
  • 37. 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.)
  • 38. 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.
  • 39.  
  • 40. 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.
  • 41. 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.
  • 42.  
  • 43. 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.
  • 44.  
  • 45. Tyres used as man-made structure for coral reefs
  • 46. Another example of man made structure as coral reef