Coasts: How can we manage coastal areas in a sustainable manner? Flashcards
What laws and regulations can we implement to manage coasts sustainably? Give an example for each.
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Limit damaging activities (eg. blasting of coral reefs for channel creation, dumping waste into seas).
Eg. Port Phillip, Melbourne: fence off dunes and built access paths to beach to prevent trampling of vegetation that stabilises the dunes)–> +: allows coastal environment to recover, -: unattractive -
Protect coastal resources (ie. prevent resources from exploitation or depletion).
Eg. Goat Island Marine Reserve, NZ: Zones marked off to prevent commercial fishing–> +: tourist attraction; spread message abt importance of protecting coastal resources, allows fish to breed and thrive, -: Local fishermen strongly oppose -
Restrict development in areas prone to natural hazards–> natural hazards destroy natural environments and disrupt human activities.
Eg. Tohoku Earthquake, Japan 2011–> tsunami killed many, nuclear meltdown–> planned retreat policy–> houses must be beyond 20m of the coast minimum
What are the soft engineering methods for coastal protection?
- Beach nourishment
- Planting vegetation
- Stabilising dunes
- Encouraging coral reef growth
What is beach nourishment and what are the pros and cons? Give examples
- Using sand from external sources to replenish sand on a depleted beach
+:
- Wider sandy beach–> protect immediate inland coastal area (eg. Siloso Beach, Singapore)
- Slows down erosion of beaches
-:
- Expensive to pipe or truck sand fromm ext. source
- Time consuming (5 years to nourish Florida Beach)
- Renourished beaches can be eroded again
- Sand washed out to sea can suffocate corals (eg. Waikiki beach, Hawaii)
What is planting vegetation as a coastal protection measure and what are the pros and cons?
- Planting mangroves along the coastal area to stabilise coastlines
+:
- Roots trap sediments and reduce coastal erosion
- Absorb wave energy through dense root system
-:
- Vulnerable to natural elements like storms
- Vulnerable to human elements like trampling and vandalism
What is stabilising dunes as a coastal protection measure and what are its pros and cons? Give examples.
- Planting grasses to stablilise sand dunes
- Access points to beach are designated and controlled
+:
- Roots anchor the sand and prevent erosion by wind and water
- Matting put over the dunes keep sand down while grass matures
- Added nutrients in time while matting rots away
-:
- Need to build fences and paths to prevent disturbance from human traffic (eg. Goat Island Marine Reserve, NZ)
- High costs incurred from maintaining fences and paths
- Taller fences needed as sand accumulates
What is encouraging coral reef growth as a coastal protection measure and what are the pros and cons?
- Artifical reefs created with durable materials like steel, concrete placed on sea floor (steel rods charged with low voltage solar panels to speed up coral growth; 5 times faster; large variety of organisms
+:
- Weaken wave energy up to 97%
- Breeding ground for marine species
-:
- Need to be surveryed for suitability
- Coral growth rate is naturally slow (20-30 years), impact not easily observed
What are the different hard engineering methods?
- Seawalls
- Breakwater
- Groynes
- Gabions
- Tetrapods
What are seawalls as coastal protection methods and what are its pros and cons?
- Built parallel to the coast
- Made up of either concrete of stone
+:
- Absorbs wave energy to reduce coastal erosion and protect coastal developments
- Curved seawalls enable waves to break seawards and not over seawalls–> more long lasting
-:
- Costly to build and maintain as constant repairs have to be made to prevent collapse
- Absorb some energy and reflect incoming waves so backwash erodes beach materials at the foot of the seawall undermining the base which renders it vulnerable in time
What are breakwaters as coastal protection measurea and what are its pros and cons?
- Built parallel to the coast or with one end attached to the coast
- Act as artifical headlands
+:
- Reduce the force on oncoming waves
- When built offshore, there is a zone of calm water created behind it
- Sand is deposited behind the breakwaters, building up beaches for recreation eg. East Coast Park, Singapore
-:
- Aesthetically unappealing
- Costly to build
- Protects the coast unevenly
What are groynes as coastal protection measures and what are its pros and cons?
- Low walls built at right angles to the shore to retain sediment that are otherwise removed by longshore drift
+:
- Absorb or reduce the energy of waves and cause materials to be deposited on the updrift side of the groyne facing the longshore drift
- Sustain and extend beach areas
-:
- Expensive to build and maintain
- Unsightly
- No materials replenish the downdrift side of the longshore drift, gradual erosion on this side
What are gabions as coastal protection measures and what are its pros and cons?
- Wire cages filled with crushed rocks built along the shore or behind a beach
+:
- Prevent or reduce coastal erosion by absorbing wave energy
- Absorb waves better than seawalls–> gaps between crushed rocks allow seawater to filter through thus reducing wave energy
-:
- Unsightly
- Costly as they need regular maintainance
- East corroded by seawater and damaged by excessive trampling or vandalism
What are tetrapods as coastal protection measures and what are its pros and cons?
- 4 pronged concrete structures help dissipate wave energy
- Stacked offshore in an interlocking position
+:
- Precasted so can be quickly set up
- Allow water to pass through to break wave energy, reduce backwash–> minimal damage to structures and slow down coastal erosion
-:
- Aestically unappealing
- Expensive to build
- Dangerous to beach users
