Hard engineering strategies Flashcards
what is a sea wall?
a concrete rock wall which is placed at the foot of the cliffs or top of the beach
it aims to dissipate wave energy by providing a physical barrier to flooding by raising the height of the coastline
what are the advantages of a sea wall?
- often has a promenade for people to walk along
- effective at stopping the sea
what are the disadvantages of a sea wall?
- can be intrusive and unnatural to look at
- very expensive to build and requires alot of maintenence
what are groynes?
Timber or rock structures
built at right angles to the waves
they trap sediment being moved along beach by LSD
what are advantages of groynes?
- the built up beach increases tourist potential
- not too expensive
- work with natural processes to build up beach
what are the disadvantages of groynes?
- unattractive
- short life span
- starve beaches along the shore of sediment
what are gabions?
wire cages filled with small rocks built up to create walls, often built to support weak cliffs
what are the advantages of the gabions?
- inexpensive and flexible
- encourages upper beach stability
- may eventually blend in with landscape as vegetation grows
what are the disadvantages of gabions?
- look very unsightly to begin with
- the metal cage can rust and become broken and dangerous
what is rock armour/rip rap
consists of large boulders being dumped in front of the cliffs or sea wall to take the full force of the waves
what are the advantages of rip rap?
- cheap and easy to place and maintain
- often used for subathing by tourists
what are the disadvantages of rip rap?
- rocks are usually from abroad or other parts of the coast so don’t fit with geology
- can be intrusive
- can be dangerous
what are revetments?
wooden or rock barriers placed at foot of cliff or top of the beach
they take full force of waves
what are the advantages of revetments?
- absorb wave energy through the slats
- effective for many years
- can be cheap compared to other techniques
what are the disadvantages of revetments?
- not effective in storm conditions
- can make the beach inasccesible
- need regular maintenence
what is cliff fixing?
iron bars are driven into the cliff both to stabalise it and absorb some wave power
what are the advantages of cliff fixing?
- hidden structures
- prevents landslides / mass movement
what are the disadvantages of cliff fixing?
- cliff still open to erosion
- ongoing maintanence costs
- eyesore
- expensive as uses metal bars
what are offshore reefs?
force the waves to break offshore which reduces their impact on the base of the cliffs
what are advantages of offshore reefs?
- allow the build up of sand dune to reduce the wave energy
- waves break further offshore and therefore reduce the erosive power
what are the disadvantages of offshore reefs?
- may be removed by heavy storms
- difficult to install
what are barrages?
large scale engineering involving the construction of a partly submerged wall in a bay or estuary
sluice gates control the flow of water in and out of a bay
what are the advantages of barrages?
- can be used to generate hydro-electric power
- renewable
- reliable
- no fuel costs
what are the disadvantages of barrages?
- very expensive to construct and maintain
- environmental impacts are considerable
- environmental impacts on habitats as water levels change
what are the arguments for hard engineering strategies?
- Sloping walls absorb rather than reflect energy
- easy to repair
- cost less than the damage coastal erosion could cause to coastal communities and industry
- prevent loss of property
what are the arguments against hard engineering strategies?
- expensive
- eyesore
- can cause increased rates of coastal erosion further down the coast
- hard engineering strategies have to be maintained which can cost a lot
- loss or of damage to the natural environment
- people are not compensated for any land they lose
- can trap sediment reducing sediment transfer by LSD
