Section 4- Coastal Hazards and Their Management Flashcards
What is a coastline?
is the boundary where land meets the sea
What is vulnerability ?
the potential to be harmed by a natural hazard.
What are the 4 physical factors that increases the vulnerability ?
Magnitude - the stronger the hazard, the more severe the impacts
Duration - the longer the hazard lasts, the more severe the impacts are
Predictability - hazards that hit without warning will have more serious results
Regularity - if hazards often and in quick succession, so the communities dont have the capacity to recover before the next storm hitd
What is Magnitude?
a quantitative measure of the size of a natural event
What is Capacity?
the ability if a country or region to react to recover from a natural hazard
What are the social and economic factors that increase vulnerability ?
Wealth : poor people are less able to afford housing that can withstand extreme events and are less likely to have the money or insurance that can help recover
Education : when population are literate, messages can be used to spread information either before the event or to issue warning and give advice during
What is a storm surge?
a rapid rise in sea level caused by storms forcing water into narrow sea area
What is isostatic change?
change in the height of land relative to the sea, often because of the melting ice from the last ice age
How are coastlines managed (HARD) ?
- sea walls
- groynes
- rip rap
- gabions
- revetments
How are coastlines managed (SOFT) ?
- beach nourishment
- managed retreat
What are the advantages and disadvantages of sea walls ?
\+ provide excellent defence where wave energy is high \+ have a long life span - expensive - affect access to the beach - can increase erosion of beach material
What are the advantages and disadvantages of groynes ?
+ relatively cheap
+ retain a wide sandy beach
- beaches further along the beach dont get as much beach material
What are the advantages and disadvantages of rip rap?
\+ relatively cheap \+ effective - unattractive - access to beach becomes difficult - costs increase when rocks is imported
What are the advantages and disadvantages of gabions ?
+ cheap
+ effective
- visually unattractive
- shorter life span than sea wall
What are the advantages and disadvantages of revetments ?
\+ cheaper \+ less intrusive than sea walls \+ cause less erosion of beach material - short life span - unsuitable where wave energy is high
What are the advantages and disadvantages of beach nourishment ?
+ relatively cheap
+ it retains the natural look of the beach
- offshore dredging of sand and shingle increases erosion in other areas and affects ecosystems
- beach replenishment is necessary on a regular basis, increasing costs
What are the advantages and disadvantages of managed retreat ?
+ it retains the natural balance of the coastal system
+ eroded material encourages the development of beaches and salt marshes
- the costs depends on the amount of compensation that needs to be paid to landowners and homeowners
- people lose their livelihoods and homes
What is soft engineering ?
works with natural systems, using natural materials and processes. Less expensive and low impact on the environment and is more sustainable
What is hard engineering?
building artificial structures to control coastal processes. Usually expensive and has high impacts on the environment and is unsustainable
What is managed retreat?
allowing the sea to breach sea defences and flood the land behind it
What is beach nourishment ?
sand and shingle are added to the beach to make it higher and wider
What is hold the line ?
where existing coastal defences are maintained but no new ones built. Hard and soft engineering is used to keep the coastline in the same place
What happens in managed retreat ?
people move out of danger zones and let the coastline move inland.
What is cliff regrading ?
reducing the angle of a cliff to reduce mass movement
For the Holderness Coastline why does it have high erosion rates?
- rocks are weak boulder clay
- tides and winds from north-east
- beaches are narrow and offer little protection
What are the risks for the Holderness Coastline ?
- fertile farmland will be lost to the sea
- more villages will disappear
- major roads will disappear into the sea
What are the management strategies for the Holderness Coastline?
- Hornsea has been protected by groynes, a sea wall and rip rap
- Mappleton has been protected by groynes, rip rap and cliff regrading
How can the community be protected by a hazard?
monitoring - being able to predict extreme weather
hazard mapping - being able to know which areas will be affected by the hazard
emergency services - having the resources and training to react to the hazard
What are hazard maps?
a map that highlights are that are affected by, or vulnerable to a particular hazard.
Why are some coastlines at greater risk than others?
- some coasts are sinking or subsiding
- rocks which make the coast soft or hard
- coastal storms affect some coastlines more than others
What are the effects on the Maldives and the sea rising
- threaten the existence of the Maldives
- flooding od beach resorts, damaging tourism that the economy depend on
- more intense tropical storms
- damage to coral reefs due to warmer sea temperatures.
- agricultural land is lost and fishing industry is disrupted
How can the Maldives manage the risk of the sea level rising?
- a 3m high wall has been built in Male the capital, cost $63 million funded by Japan
- the smaller islands could be evacuated.
- dyke could be built to hold back the sea.
- the height of the islands could be increased, requires a lot of sand
- the population could be relocated in Australia
