✅coasts protection Flashcards
what are the hard engineering defences?
sea wall
gabions
groynes
rock amour
what is a sea wall?
wall made out of hard material like concrete that reflects wave energy back to sea
adv of sea wall
prevents erosion
acts as barrier to prevent flooding
dis of sea wall
strong backwash that erodes under the wall
expensive to build and maintain
what are gabions
wall of wire cages filled with rocks usually built at foot of cliffs
adv of gabions
absorb wave energy —> reduce erosion
cheap and easy to build
dis of gabions
ugly and wire cages corrode over time (rust)
what is rock amour
rocks that are piled along the coast (sometimes called rip-rap)
adv of rock armour
absorbs wave energy —> reduce erosion and flooding
fairly cheap
if made out of resistant rock like granite then erodes slowly
dis of rock amour
boulders can be moved around by strong winds so need to be replaced
what are groynes
wooden or stone fences built at right angles to the coast
trap material transported by longshore drift
adv of groynes
create wider beached which slows the waves —> greater protection from flooding and erosion
fairly cheap
dis of groynes
no deposition further down coast —> greater erosion
what are the soft engineering defences?
beach nourishment and reprofiling
dune regeneration
what is beach nourishment and reprofiling
sand and shingle from elsewhere from lower down the beach that’s added to upper part of beach
adv of beach nourishment
creates wider beach —> slows waves —> greater protection from erosion and floods
beach for tourists —> generate money
dis of beach nourishment
taking material from places like seabed can kill organisms like sponges and corals
very expensive defence (has to be repeated)
what is dune regeneration?
creating or restoring sand dunes by nourishment or by planting vegetation to stabilises sand
adv of dune regeneration
dunes can create barrier between land and sea and absorb wave energy —> prevent flood and erosion
stabilisation is cheap
dis of dune regeneration
protection is limited to a small area
nourishment is expensive
what is managed retreat?
removing current defences and allowing sea to flood the land which creates a marshland
this then becomes a protective strategy as the land behind marshland is protected from flooding and erosion
adv of managed retreat
cheap and easy
doesn’t need maintaining
marshland can create new habitats for plants and animals
dis of managed retreat
cause conflict e.g. flooding farmland affects livelihood of farmers and saltwater can have a negative effect on existing ecosystems
where is the holderness coast located
east coast of yorkshire
how much does holderness coast erode each year
fastest eroding coast in europe at 1.8m on average each year
what does the holderness coast have to protect from erosion
groynes —> trap sand —> wider beach —> reduce erosion
sea walls —> reflect waves back to sea and prevent flooding
rock amour/riprap —> placed in front of sea wall —> reduce energy of the destructive waves
adv of soft engineering
cheaper than hard engineering
usually more long term and sustainable
less impact on the environment
