Coasts KQ3 Flashcards
What is management?
Controlling development and change based on rules and regulations
What is sustainability?
Managing change in a way that does not does not compromise the environment for present and future generations
Laws and regulations in managing coasts
1) Limiting damaging activities
2) Protect coastal resources
3) Restrict development in areas prone to natural hazards
L&R: Limiting damaging activities
- Damaging activities: Activities that disturb the functioning of the natural system
- Banning activities is costly, ineffective and unsustainable in long run
- Govts restrict activities by meeting demands of people while ensuring maintenance of coastal environment
L&R: Limiting damaging activities example
Port Phillips, Australia
- Sand dunes destabilised by visitors
- Authorities fence off dunes and construct access pathways into the beach
L: Fencing unattractive and restrict visitors from certain parts of the beach
L&R: Protect coastal resources
- Prevents resources from being depleted/overused
i.e. Fish near coastlines overfished
- 90% of marine animals caught close to shore
- Blasting and cyanide fishing used, destroying coastal habitat
- Needs to be prevented to protect and preserve coast
L&R: Protecting coastal resources example
1) Wakatobi National Park, Indonesia
2) Goat Island Marine Reserve, New Zealand
- Zones blocked off to prevent commercial fishing
- Enable marine species to breed and thrive
L: Fishermen see access to resources and income as being denied
L&R: Restricting development in areas prone to natural hazards
- Protects people and coastal resources
- People attracted to coasts despite unpredictability of natural hazards
A:
- Coasts provide natural resources and food
- Coasts have substantial range of built services such as docks, ports, housing and recreational facilities
L:
- More expensive to construct and maintain coastal buildings
- Mental preparation needed in case of emergencies
- Management policies needed to deal with threats and natural hazards in coastal areas (Govt/Authorities)
L&R: Restricting development in areas prone to natural hazards examples
1) Retreat/Relocate from areas prone to natural hazards
- Federal Emergency Management Agency (FEMA) diverts development away from areas vulnerable to floods/coastal erosion
2) Avoidance/Regulating development
- Govts restrict development of farms, buildings and infra. in vulnerable, low-lying coasts.
3) Defence via coastal protection measures
- Soft/Hard Engineering measures
Coastal Protection measures
> Soft Engineering methods
- Protecting coasts using natural processes
- Does not involve construction of physical structures
1) Beach nourishment
2) Planting vegetation
3) Stabilizing dunes
4) Encouraging coral reef growth
> Hard Engineering methods
- Building physical structures to shield coasts from erosion
1) Sea Walls
2) Gabions
3) Groynes
4) Breakwaters
5) Tetrapods
SE: Beach nourishment
- Replenishing sand lost through erosion by adding fresh sand brought in from other beaches or dredged from seafloor
A: Transforms eroded coast into wide sandy beach that provides protection to nearest inland areas
L: Trucking, dredging and piping is costly and time consuming
- Sediments swept into sea may choke corals and dredging destroys seafloor habitats
- Not sustainable in long run, re-erosion occurs if no other measures are in place
SE: Beach nourishment examples
- Palawan, Siloso, Tanjong beach, Sentosa
- Beaches made more attractive after beach nourishment
SE: Planting vegetation (Mangroves)
- Planting of trees and shrubs to stabilize shoreline
A: Wave energy absorbed and dissipated by dense networks of roots
- Buffer zones formed between seas and inland coastal areas
- Roots able to trap sediment and promote deposition, extending coasts/form small islands
L: Takes long time to stabilize sediments on beach
- Not effective enough to withstand natural hazards
- Threatened by human activities
SE: Stabilizing dunes
- Planting grasses (Maran grasses) so roots can anchor to sand and prevent erosion
- Matting placed over dunes and plants are planted over matting
A: Vegetation becomes rooted and stabilizes dunes
- Matting rots away, adding nutrients to the sand
L: Fences used need regular maintenance and need to be made taller when sand accumulates
- May restrict access to coasts
e.g. Port Philip
SE: Encouraging coral reef growth
- Artificial reefs grown in open waters to weaken wave energy
- Low voltage currents passed through cages, speeding up coral reef growth
- Serves as breeding grounds and nursery for fish
A: Corals grow 3-5x faster
L: Sites must be suitable for coral reef growth
- Effects not immediate, corals still take long time to grow
- Research and equipment costly
SE: Encouraging coral reef growth example
- Island of Ihuru, Maldives
- Colonising efforts since 1996
- Wide variety of corals and marine creatures
- Received international recognition
HE: Sea walls
- Concrete or stone walls built parallel to coastline to absorb wave energy
A: Absorb wave energy and reflect approaching wave energy
L: Expensive to construct and maintain in order to prevent collapse
- Scouring common when wave energy reflected to base of sea walls, causing undercutting and collapse
HE: Sea walls example
- East-Coast park, 4800m
- Drake islands, England
- Collapsed due to scouring
HE: Gabions
- Wire cages filled with rocks and piled up against shore
A: Waves weaken when passed through rocks
L: Unsightly, expensive to maintain
- Easily eroded and damaged (vandalised)
- Water causes corrosion to cages (Hazardous to humans)
HE: Gabions examples
- East-Coast park
- Gabions removed due to vandalism
- Northfolk, UK
HE: Breakwaters
- Built parallel to coast off-shore and creates zone of sheltered water behind it
- Converging waves towards BW, diverging waves behind BW
A: Encourages deposition behind it, forming beaches
- Sheltered areas used as harbour/marina
L: Unattractive and costly to construct
- Only protects coast behind it
HE: Breakwater examples
- East-Coast park
- Portland Harbour, England
- Resulted in erosion and flooding problems, affecting properties, beaches and communication infra.
HE: Groynes
- Low walls constructed perpendicularly to shore to retain sediments transported by LSD
A: Absorb and decrease wave effects on coast
- Allow materials to be deposited on updrift side of groynes facing LSD
L: Material erodes on downdrift side before being deposited on updrift side.
- Makes coast uneven and unattractive
- Areas not protected by groynes still eroded
HE: Groyne examples
- East-Coast park along abrupt turns of coast
- Sandy Hook, New Jersey, USA
- Groyne demolished due to continued erosion on downdrift side of groyne
HE: Tetrapods
- 4-pronged concrete structures stacked off shore/along shore in interlocking position to disseminate wave energy
A: Allow waves to pass through and around them instead of hitting and reflecting off them
- No backwash generated, decreasing chances of damage
- Precasted and easily deployed at vulnerable coasts
L: Unsightly and dangerous to people
- Casting and transportation is costly
HE: Tetrapods examples
- Hokkaido, Japan
- Crescent city, North California
- Prevent coastal erosion and decrease impact of tsunamis
