Theme 4 - Managing coastal hazards Flashcards
Why is coastal managment needed? (5)
.homes and buisnesses need protection
.sea levels are rising increasing risk of coastal flooding
.litter pollution from sewage discharge or accidents such as oil spills need to be cleaned up
.the magnitude and frequency of storms is increasing
.natural habitats and heritage sites need preserving and protecting
State 3 hard engineering methods with description.
.sea walls - concrete sea walls reflect the energy of waves and prevent flooding
.groynes - wooden or rock barriers built down a beach to trap sand being trasported by longshore drift
.rip rap - large boulders of hard rock placed along base of a cliff to absorb the energy of the waves
What are advantages and disadvantages of sea walls?
adv:
.provide excellent defence where wave energy is high
.have a long life span
dis-adv:
.expensive
.affect access to beach
.recurved sea walls can increase erosion of beach materials
What are advantages and disadvantages of groynes?
adv:
.relatively cheap
.retain (continue to have) a wide sandy beach
dis-adv:
.beaches further along the coast are starved of beach material
What are advantages and disadvantages of rip raps?
adv:
.relatively cheap
.efficient
dis-adv:
.unattractive
.access to beach becomes difficult
.costs increase when rock is imported
Hard engineering?
building an artificial structure to reduce coastal erosion or the risk of coastal flooding. It is ussually expensive, has high impact on the environment and is unsustainable.
Soft engineering?
works with nature, using natural systems and processes. It is often less expensive, has low impact on the environment and is more sustainable.
State 3 soft engineering methods with description.
.beach nourishment - sand and shingle added to a beach to make it higher and wider
.sand dune stabilisation - planting vegetation or building wooden fences helps sand to build up and the dunes stabilise, which provides a barrier and absorbs wave energy
.managed retreat - allowing the sea to breach existing defences and flood the land behind it
What are the advantages and disadvantages of beach norishment?
adv:
.relatively cheap
.retains the natural look of the beach
dis-adv:
.offshore dredging (removing unwanted things) 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 sand dune stabilisation?
adv:
.dunes are left undisturbed
.boardwalks are constructed so the dunes become more accessible to tourists
dis-adv:
.management is time consuming
.cost is expensive
What are the advantages and disadvantages of managed retreat?
adv:
.retains the natural balance of the coastal system
.eroded material encourages the development of beaches and salt marshes
dis-adv:
.cost depends on the amount of compensaton that needs to be paid to landowners and homeowners
.people lose their livelihoods and homes
Intertidal zone?
area that is above water at low tide and under water at high tide.
Simply explain the two contrasting approaches to coastal management.
.hold the line - where existing coastal defences are maintained
.managed retreat - move people out of dangers zones and let nature take control
Cost-benefit?
an analytical tool for assessing the pros and cons of a decision.
Shoreline management plan (SMP)?
an assessment of the risks associated with coastal processes.