Managing Coastal Hazards Flashcards
Why is coastal management needed for habitats and sites?
Natural habitats + heritage sites need preserving + protecting.
Why is coastal management needed for homes and businesses?
Protect them from coastal erosion, landslides + flooding.
Why have storms increased the need for coastal management?
Magnitude + frequency of storms increasing - cause storm surges, flooding + wind damage.
Why have sea levels increased the need for coastal management?
Sea levels rising, increasing risk of flooding.
Why has litter increased the need for coastal management?
Litter, pollution from sewage discharge or accidents (oil spills) need to be cleaned up.
What are the two coastal defence methods?
Hard + soft engineering
Define hard engineering
Building an artificial structure to control coastal processes - expensive, high impact on environment + unsustainable.
Define soft engineering
Works with natural systems, using natural materials and processes - less expensive, low impact on environment + more sustainable.
What are some hard engineering techniques?
Sea walls Groynes Rip rap Gabions Revetments
What are sea walls?
Concrete sea walls that reflect energy of waves + prevent flooding.
Often recurved so waves reflected back on themselves.
Why are sea walls used?
Protect settlements
What are the advantages of sea wall?
Provide excellent defence where wave energy is high.
Has long life span
What are the disadvantages of sea wall?
Expensive
Affect access to beach
Can increase erosion of beach material
What are groynes?
Wooden barriers built down a beach, traps sand being transported by longshore drift.
Resultant wider beach absorbs wave energy, reducing rate of cliff erosion.
What are the advantages of groynes?
Relatively cheap
Prevents beach material being carried away, allowing sand to build up - so provides natural barrier.
What are the disadvantages of groynes?
Unattractive
Difficult to walk along beach
Disrupts natural processes
Beaches further along coast are starved of beach material.
What is rip rap?
Large boulders of hard rock placed along base of cliff + absorb energy of waves.
What are the advantages of rip rap?
Relatively cheap
Efficient
Ensure waves break before the cliff
Retains natural appearance of the beach
What are the disadvantages of rip rap?
Unattractive
Access to beach is difficult
Costs increase when rock is imported
What are gabions?
Steel cages, containing boulders, absorb energy of waves.
What are the advantages of gabions?
Cheap
Efficient
What are the disadvantages of gabions?
Visually unattractive
Shorter life span than sea wall
What are revetments?
Wooden slatted barriers constructed towards the rear of beaches - energy from waves is absorbed by breaking against the slats.
What are the advantages of revetments?
Cheaper + less intrusive than sea wall
Effective where wave energy is low
Cause less erosion of beach material
What are the disadvantages of revetments?
Short life span since made of wood
Unsuitable where wave energy is high
Define intertidal zone
Part of the shoreline between the high and low tide.
What is beach nourishment?
Beach made higher + wider by importing sand.
So provides a wider beach for energy to be absorbed.
What are the advantages of beach nourishment?
Relatively cheap (approx £20 per metre cubed)
Retains natural look of beach
Provides a beach for tourists
What are the disadvantages of beach nourishment?
Offshore dredging increases erosion in other areas + affects ecosystems.
Can disappear so requires constant maintenance, increasing costs.
What is sand dune stabilisation?
Act as natural defence against coastal flooding + erosion.
What are the advantages of sand dune stabilisation?
Dunes left undisturbed - so maintains natural ecosystem.
Boardwalks are constructed, sections of sand dunes are marked out of bounds, so dunes more accessible to tourists.
What are the disadvantages of sand dune stabilisation?
Time consuming management
Cost is expensive (approx £2000 per 100m)
What is managed retreat/realignment?
Areas of low value are allowed to flood naturally, creates new intertidal zone - acts as natural buffer against storms + rising sea levels.
What are the advantages of managed retreat/realignment?
Retains natural balance of coastal system
Eroded material encourages development of beaches + salt marshes.
New habitat created for plants and birds.
Cheap
What are the disadvantages of managed retreat/realignment?
Cost depends on amount of compensation to be paid to landowners + homeowners.
People lose their livelihoods + homes.
Can be unpopular
What is hold the line?
Existing coastal defences are repaired but no new defences are set up.
Define cost-benefit
An analytical tool for assessing the pros and cons of a decision.
Define shoreline management plan (SMP)
It is a plan councils create to state what they are going to do with the coastline.
Define cliff regrading
Reducing the angle of a cliff to reduce mass movement.
What three things do councils have to consider when creating a SMP?
Impacts coastal defences would have on other locations
Impacts of coastal defences on animal habitats and the environment
Costs and Benefits of the scheme.
What is the integrated coastal zone management (ICZM)?
Concept that aims to develop sustainable solutions.
What are the sustainable solutions of ICZM based on?
Which areas need protecting + which are not cost effective to protect?
What type of defence should be used?
What is best for wildlife + natural environment?
What is best solution for those living at coastline - take balanced view + not favour one group over another?
What is a hazard map?
A map that highlights areas that are affected by, or vulnerable to, a particular hazard.
What do communities depend on that make them prepared for hazards?
Monitoring - able to predict extreme weather
Hazard mapping - know which areas affected by hazard
Emergency services - have resources + training to react
Define environment agency
A non-departmental public body with responsibility for the protection and enhancement of the environment in England (also Wales since 2013).
Define tropical storm
An intense low pressure weather system that can last for days to weeks within the tropical regions of Earth.
North America - hurricanes
India - cyclones
Japan + East Asia - typhoons
Why is there an increased vulnerability of coastal communities in the future?
Climate change is putting increasing pressure on coastal regions which are already affected by intensive human activity.
Coastal ecosystems + habitats are also under threat.
Define river estuary
The wide mouth of a river where it meets the sea.
Define small island developing states (SIDs)
Low-lying coastal countries that tend to share similar development challenges: small but growing populations limited resources remoteness susceptibility to natural disasters vulnerability to external shocks excessive dependence on international trade fragile environments
Why are coastlines that are sinking or subsiding more at risk than other coastlines?
River estuaries + deltas sink under their own weight as more sediment deposited.
Why are coastlines with different types of rock more at risk than other coastlines?
Rocks that make the coast can be hard or soft - more soft rock causes higher erosion rates.
How do storms make some coastlines more vulnerable than others?
Coastal storms affect some coastlines more than others.
Tropical storms only affect coastlines in some parts of world.
What coastal communities might be at a greater risk?
Those living on the world’s river deltas - Bangladesh, Egypt, Nigeria, Vietnam + Cambodia
Define environmental refugees
People who are forced to leave their home region due to changes in their local environment - droughts, desertification + sea level rise.
Define dyke
An artificial earthen wall built to prevent flooding by the sea.
Is there a higher or lower amount of intertidal zones today than what there were in the past?
Lower
Are salt marshes found in intertidal zones?
Yes
Give 2 reasons why salt marshes are disappearing?
Farmland
Sea erosion
Why are the salt marshes along the Essex and the Thames gateway being eroded?
Land is subsiding (sinking) due to Isostatic recovery.
What does managed realignment aim to do?
It aims to create a wider intertidal zone to act as natural stores of flood water during high tide.
What managed realignment scheme did you study and when was it completed?
Medmerry in Sussex, 2014
What happened to the coastline (Medmerry) you studied due to this managed realignment?
The coastline is now a further 2m inland than what it was.
What are the 4 different types of shoreline management?
Hold the line
Advance the line
Managed retreat (retreat the line)
Do nothing
What SMP does Sea Palling have?
Hold the line
What SMP does Happisburgh have?
Managed retreat (Retreat the line.)
Why is coastal mapping good?
Gives warnings
People know what places will be affected
Allows emergency services to plan
Plan building
