Geography - Coasts EQ3 Flashcards
What is coastal management?
controlling the development and change in the coastal zone
according to agreed principles and criteria
What is limiting damaging activities in laws and regulations?
Damaging activities include blasting coral reefs to create channels, clearing mangroves for shrimp farms and constructing facilities. Since these activities contribute to economy, the government instead limits them.
Example of limiting damaging activities
Management of sand dunes on Port Phillip, Melbourne. They were often trampled on, causing dune vegetation to be destroyed and the sand dunes were left exposed to wind erosion. Houses nearby were in danger of being partly buried. 1.8km of dune fencing was installed.
Pros: Grasses were not trampled on and could recover fully.
Cons: Unattractive, not all parts of beach can be accessed by residents.
What is protecting coastal resources in laws and regulations?
Aims to prevent resources from being exploited
or depleted (e.g. blasting and poison fishing).
Goat Island Marine Reserve in NZ. Zones were marked off to prevent commercial fishing. The marine reserves protect ecosystems and allow endangered species to breed and thrive.
Pros: It is now a tourist attraction for its endangered species
Cons: Marine reserves are strongly opposed by local fishermen, as they see their source of food being denied.
What is land zoning in laws and regulations?
Development areas prone to natural disasters are restricted or limited. This includes relocation. The Danish Lighthouse (Rubjerg Knude) was preserved by relocating it 70m from the coastline. It can be kept for at least 1 more generation.
Pros: It can protect lives and properties from falling off cliffs.
Cons: Often involves the resettlement of people. Costly –> compensate. People may be reluctant (sentimental) to move.
What are sea walls in hard engineering?
Protects coastlines against wave attacks by absorbing wave energy. Made of concrete or stone and are built parallel to the coasts.
Pros: Good defense, deflects waves, immobilises sand, prevents flooding. Easy to construct, lifespan of 30-40 years.
Cons: Costly, frequent maintenance, seawalls along the Island Bay New Zealand costed $1.3mil in repairs. Erosion can occur at the base of the wall.
Powerful backwash. Seawalls in Drakes Island, England collapsed due to erosion at the base.
What are gabions in hard engineering?
Wire cages filled with crushed rocks. Reduces coastal erosion by weakening wave energy (more than seawalls).
Pros: Easier to construct, less damage control
Cons: Shorter life span, costly maintenance, rust easily (danger to fishermen), unsightly, easily vandalised
Removed in East Coast Park, SG after being vandalised.
What are breakwaters in hard engineering?
Built parallel to the coast. Breaks the force of oncoming waves before they reach the coast.
Pros: Creates a zone of calm water offshore. Material deposited to create beaches. 30 year lifespan.
Cons: Costly. Protects only the coast behind it (uneven). Unattractive. Breakwaters in Portland Harbour, England, led to flooding and erosion, affecting properties, beaches, communication infrastructure.
What are groynes in hard engineering?
Low walls constructed perpendicularly –> retain sediments that could be removed by LSD –> prevent erosion
Pros: Absorbs wave energy. 30 year lifespan.
Cons: Downdrift side is unprotected. Costly to build and maintain and unsightly. Groynes in Sandy Hook, USA were removed —> downdrift side eroded.
What are tetrapods in hard engineering?
Four-pronged concrete structures that help dissipate wave energy. Crescent City in California uses tetrapods for many years to protect its coasts against coastal erosion. It protected it from more than 31 tsunami impacts.
Pros: Allows water to pass through –> no powerful backwash. Pre-casted, can be quickly placed
Cons: Expensive, unsightly, dangerous to swimmers and boaters.
What is beach nourishment in soft engineering?
Using sand from an external source to replenish the sand on a depleted beach. 10 year lifespan. Miami coast was revived. New sand poured on beach yearly.
Pros: Natural, attractive beaches. Supports tourism. No species introduced that could threaten the natural biodiversity.
Cons: Expensive and time-consuming. Sand washed out to sea and suffocates corals –> coral bleaching. Short-term method.
What is planting vegetation and stabilising dunes in soft engineering?
Can help stabilise coastlines. E.g. mangroves absorb wave energy. 6000-8000 mangrove saplings planted in Pulau Tekong, Singapore (span 1.9km) –> prevent erosion + promote biodiversity
Pros: Relatively cheap.
Cons: Takes a long time to grow and has to be able to withstand natural elements + human interference (vandalism). Require specific climactic conditions to grow (not conditions with natural disasters).
What is encouraging coral reef growth in soft engineering?
Weakens wave energy. Breeding ground and nursery for fish.
Pros: Enhances natural beauty of the beach. Rich biodiversity, boosts fishing industries, supports tourism. Coral-growing programme in the Maldives gained global recognition (refer to google doc).
Cons: Sensitive to temperature and water quality changes. Slow coral growth (20-30 years). Growth may not be significant. Not suitable for all environments. Human activities such as farming and mining has to be restricted to avoid coral bleaching. Affects livelihoods of communities nearby.
