Coasts (Management) Flashcards
Outline the 4 types of coastal management
- Hold the line - maintain existing coastal defences
- Advance the line - build new coastal defences further out to sea
- Do nothing - build no defences deal as it happens
- Retreat the line - move ppl away from coast
Outline the limitation of coastal management
Can’t protect every area as $ limited
Use cost benefit analysis - usually protect large settlements/industrial sites
Define Hard Engineering
Sea protection is built out of concrete or rocks for permanent defence - specific
Outline sea walls (H.E)
(Pros, cons and costs)
Pros:
Absorb wave energy
Recurved to throw waves back, preventing erosion of the coast & prevent flooding
Cons:
Gaps eroded by hydraulic action
Create strong backwash = more erosion
Cost:
£800-5000/m
Outline Rock Armor/rip rap (H.E)
(Pros, cons and costs)
Pros:
Large boulders piled on coasts
Absorb wave energy to reduce erosion
Can look natural
Cons:
Can shift in storms
Can look unattractive
Outline Gabions (H.E)
(Pros, cons and costs)
Pros:
Rock filled cages - absorb wave energy to reduce erosion & increase wave percolation
Cons:
Fail quickly - spill contents if stacked
May move in strong waves
Ugly
Costs:
£11/m^2
Outline Revetments (H.E)
(Pros, cons and costs)
Pros:
Slanted structures built at foot of cliffs (wood, rocks or concrete)
Absorb wave energy - prevent cliff erosion
Cons:
Create a strong backwash - erode
May damage foreshore ecosystem
Costs:
£1000/m but cheap to maintain
Outline Groynes (H.E)
(Pros, cons and costs)
Pros:
Fences built at right angles to coast - trap sediment from lsd
Creates wider beaches - slow waves - greater protection from flooding & erosion
Cons:
Starve down-drift beaches
Thinner beaches don’t protect - more erosion & flooding
Costs:
£200,000/groyne
Outline Offshore reefs (H.E)
(Pros, cons and costs)
Pros:
Run parallel to the shore forcing waves to break offshore & protects the area
Cons:
Can be damaged by storms
Costs:
£2000/m
Outline Barrages (H.E)
(Pros, cons)
Built on river estuaries - generate e- by controlling the release of H2O through turbines at low tide.
Pros:
Prevent storm surge flooding
Create freshwater source & can reclaim land
Cons:
$
Disrupt sediment flow - cause increased erosion elsewhere
Disrupt natural habitat e.g mudflats
Outline 4 cons of Hard Engineering
- Expensive to build & maintain
- Defence can cause problems down drift
- May not keep up with sea level rises
- Eyesores
Define Soft Engineering
Uses natural materials & processes to help coastlines
Outline Beach Nourishment (S.E)
Replace sediment lost through lsd
Councils move sand from 1 side -> other at the start of tourist season = wide beaches -> reduce erosion
Imported sand = environmental & visual cons
Outline Beach Stabilisation (S.E)
Reducing slope angle, planting veg or sticking stakes/old tree trunks in the ground
Wide beaches which reduce cliff erosion
Outline Dune Regeneration (S.E)
Sand dunes created/restored by nourishment/stabilisation
Sand dunes absorb wave energy to reduce erosion/flooding
Management strategies include:
Replanting vulnerable areas (e.g marram grass)
Conifer afforestation
Selective grazing
Restrict access
Tourist boardwalks or information abt damage
Outline Creating Marshland (S.E)
Made from mudflats by planting appropriate veg - stabilises sediment and leaf stems reduce wave speed
Less erosion & distance inland (less flooding)
Outline how soft engineering is more sustainable than hard engineering
Hard engineering:
$ & disrupts natural processes
Soft Engineering:
Cheaper - less $/time to maintain
Integrates with natural environments (e.g coasts & mudflats)
Lowers cost & environmental impact
