traditional coastal management Flashcards
what are the traditional approaches to coastal management
hard and soft engeneering
what is hard engineering
physical change to landscape using resistant materials such as concrete/boulders/wood to reduce the impacts of coastal erosion
pros hard engeneering
last long
generally effective
cons hard engineering
expensive
eyesore
disrupt habitat
affect area down coast
(6) examples hard engineering + description
sea wall:
- concrete structure can be recurved
- dissipate wave energy + raise hight coastline
rock armour:
- large boulders at base of cliff
- absorb wave energy
gabions:
- smaller boulders in steel cage
- absorb wave energy
groynes:
- wood/rock/steel breakwaters built right angle to wave
- reduce effects LSD
revetment:
-slanted structure built along cliff
-absorb wave energy
hard engineering avg costs and an example
sea wall:
- up to £10,000/m
- lyme regis
rip rap:
- around £2000/m
- hengisbury head in dorset
groynes:
- £1.5 mill/ km when rock
- £0.6 mill / km when wood
- bournmouth beach
revetment:
- £2000/m
- holderness coast
what is soft engineering
use of natural system for coastal defence
pro soft engineering
normally blends with original environment
normally cheaper than hard strats
cons soft engineering
can be less effective
needs constant upkeep
soft engineering examples + description
beach nourishment:
-add sediment to eroding beach
-restore habitat and protects against waves
dune regeneration:
- restore sand dune
-wave energy absorbed
managed retreat:
- take hard engineering strats away
-allow land to be reclaimed by sea
marsh creation:
-encourage growth salt tolerant plants to stablise sediment
-to break waves up
- new habitat and slows waves
cliff drainage:
- drain of water reduce landslide
- reduce angle cliff so stable
soft engineering costs + example
beach nourishment:
- £3000/km
- lincolnshire beach
marsh creation:
-somerset WWT marshes
cliff drainage:
- £1mill/ 100m
-canford cliffs
dune stabilisation
- £1000/ 100m
pros and cons specific hard engineering
sea wall:
- protect base cliff erosion and area flood
-expensive/eyesore/erode under wall
groynes:
-reduce lsd, low maintanence
-starve beach further down coast, eyesore, cant swim near
riprap:
-reduce wave energy,fairly cheap
-move in storms, eyesore, expensive transport
pros cons specific soft engineering
beach nourishment:
-protect coast, natural
-need constant replace
cliff drainage:
-good for clay cliffs etc
-disruptive, too much then cliff collapse
dune stabalise:
-barrier sea-land
-small area protected, expensive
marsh create:
-new habitat, mudflats, slower wave
-fairly expensive, not work where erosion rates high
bahamas example
coastal land use is highly for recreational purposes due to the high number of tourists due to weather.
most successful types of coastal protection may be methods such as managed retreat, habitat restoration and breakwaters due to the low visual impact
These methods ranked in top 4 which suggests that they are very effective.
large number of tropical storms and the islands are very low and flat (no more than 20m above sea level)
more protective methods such as sea walls and rock armour may be more successful in protecting the coastlines
Whilst these methods overall ranked lower than some of the other methods, in terms of protecting the coastline from erosion and flooding they rank far higher than less invasive methods.
In conclusion, I think that in the Bahamas the installation of rock armour (4th) and gabions (3rd) would be greatly effective as they are relatively cheap (3000/m and 100/m) in comparison to other method
whilst somewhat visually unpleasant they are a better option than seawall
still adequate protection from coastal erosion and flooding.
