COASTS management Flashcards
why do humans intervene in natural processes?
- manage the shape and profile of the coastline
- reduce rates of erosion
- limit the likelihood of flooding
what are the problems with human intervention?
unsustainable and uneconomic
what is the England and Wales enviro agencies criteria for coastal protection?
- households at risk
- agriculture and farming at risk
- ecosystems/ environment at risk
- infrastructure at risk
these factors are all looked at in a cost benefit analysis to decide which areas will be defended and which will be left.
what are the four options for coastal management
hold the line
advance the line
do nothing
managed realignment
hold the line
maintain existing coastal defences
advance the line
build new coastal defences further out to sea than existing ones
do nothing
allow nature to take its natural corse and deal with erosion and flooding as it comes.
managed realignment
allow the shoreline to move but manage retreat so it causes less damage. eg) change land use to flood farmland rather than town infrastructure.
what factors are responsible for a change in shoreline equilibrium? (5)
- supply of materials
- energy intensity
- consistency of shoreline geology
- changes in sea level
- key processes taking place
feedback loops
outputs modify the inputs/ processes = output cahnges
positive feedback (in terms of input and output)
outputs increase = inputs increase which causes a further increase in outputs
negative feedback (in terms of input and output)
output increases which slows the inputs and processes responsible for the increased output.
dynamic equilibrium
gradual shift in balance over a long period of time
metastable equilibrium
episodic shifts to a new equilibrium
steady state equilibrium
long term balance between inputs and outputs.
What is the SMP?
shoreline management plan
- used to address the risks of coastal evolution
- come up with flood defence strategies in the uk
what are hard engineering strategies used for?
to intercept and impede marine and coastal processes
what are 5 examples of hard engineering strategies?
Groynes, sea walls, revetments, rip rap and offshore breakwater.
what are groynes?
they are wooden fenses built at 90* to trap sediment (LSD)
ADV of groynes
- build up the beach = increased tourism
- works with natural processes
- protects the land behind from erosion
- quite cheap
DIS of groynes
-staved beaches further down the coast of sediment = more erosion and flooding
ADV of sea walls
- long lasting and effective at reducing erosion
- can act as a promenade for tourists
- act as a barrier to prevent flooding
sea wall
large concrete wall that reflects wave energy back to sea ad protects against large waves with a recurved shape.
DIS of sea wall
- expensive to build and maintain
- creates a strong backwash which erodes under the wall
rip rap / rock armour
boulders of resistant rock placed at the foot of a cliff to absorb wave energy and reduce erosion
ADV of rip rap
- easy to maintain
- cheap
- easy to construct
DIS of rip rap
- can shift in storms
- intrusive to environment
- not local rocks
- dangerous for tourists
Revetements
sloping wooden/ rock/ concrete structures to reduce wave energy while allowing sediment through.
ADV of revetements
- reduce erosion
- expensive to build but relatively cheap to maintain
- implemented quickly
DIS of revetements
intrusive
unnatural looking
create a strong backwash
offshore breakwater
partly submerged rock barrier that breaks up waved further out at sea. wave energy and erosive power is reduced before the waves reach the shore.
ADV of offshore breakwaters
effective permeable power
relocating a natural process
DIS of offshore breakwaters
materials may be eroded quickly
contamination of local areas with eroded material (concrete)
navigation hazard
expensive
what is soft engineering?
management techniques which work with natural processes to redirect them to the desired effect.
this requires long term intervention where the cost is shared over time.
what are 6 soft engineering strategies?
beach nourishment cliff regrading and drainage dune stabilisation marsh creation land use management coastal realignment
beach nourishment
addition of sand and pebbles to widen a beach
ADV of beach nourishment
blends in
increases tourism
DIS of beach nourishment
needs constant maintenance
dredging elsewhere effects habitats
expensive to maintain
cliff regrading and drainage
- reduces the angle of cliffs to stabilise it (less steep)
- remove water to reduce slumping and landslideds
ADV of cliff regrading & drainage
effective on clay and loose rock
drainage = cost effective
stabilised cliff
DIS of cliff regrading & drainage
cliff retreat
dries out and collapses
relatively low cost but ongoing maintenance
may be impractical if there are important land uses on the cliff top
dune stabilisation
use plants to prevent LSD
ADV of dune stabilisation
maintains the natural environment and is sustainable
relatively cheap
creates a wide beach, reducing erosion
DIS of dune stabilisation
time consuming to plant
cut off area for tourists
marsh creation
planting appropriate vegetation can stabilise sediment
= reducing the speed of waves = reduced erosive power and flooding.
ADV of Marsh creation
natural buffer
habitat creation
DIS of marsh creation
land loss
farm owners want compensation
coastal realignment
managed retreat - allowing sea to breach defences and reach land behind. overtime marshland will develop
land use management
wooden walk ways across dunes and fenced off areas protect regeneration of dunes and reducing vegetation loss.
causes of increased flood frequency and severity
- increased storm surges (warmer seas = low pressure systems)
- increased sea level (CC)
- estuarine flooding (river discharge)
flood barrage
hard engineering construction across estuaries = allow tidal waters through but prevent unusually high tides, storm surges and flood tides when forecasted.
is hard or soft engineering more sustainable?
soft engineering is usually cheaper
require less time and money to maintain
integrate with the natural environment
LOWER ECONOMIC cost and ENVIRONMENTAL impact/
ICZM
integrated coastal zone management
considers all elements of a coastal system to form a management scheme which protects the environment while allowing people to use it.
what are the 4 criteria for ICZM
- ENVIRONMENT viewed as a whole
- different LAND USE are considered - sustainably
- LOCAL, REGIONAL, and NATIONAL levels of authority have an input in the plan
- DYDNAMIC process where plans adapt to changing priorities and new information
IPCC
Intergovernmental panel for Climate Change
climate experts from 130+ countries
there are no political or company ties.
what are the aims of the IPCC
access the risks for human induced CC, its possible impacts and options for prevention.
