Coastal Management 🪸 Flashcards
Why are coasts managed?
To protect homes, businesses and environment from erosion and flooding
Reduces social, economic and environment impacts
Money limited so not all coastal areas can be protected
Cost-benefit analysis used to determine which places are protected
Eg ones that have large populations or important transport links
Traditional approaches to coastal management
Hard and soft engineering
Sustainable approaches to coastal management
Shoreline management
Integrated coastal zone management
Soft vs hard engineering
Soft - more sustainable, less environmental damage and economic cost
Hard - unnatural and can impact environment and more expensive
Hard engineering strategies
Sea wall
Revetments
Gabions
Rock armour
Groynes
Breakwaters
Sea walls
Reflects waves back out to sea
Acts as barrier to flooding
+ creates promenade, tourism benefit
- expensive to build and maintain
- intrusive/ unnatural
Revetments
Slanted structures at foot of cliffs
Absorb wave energy when they break on it
Prevents cliff erosion
+ effective
- intrusive
- need maintenance
Gabions
Rock filled cages at foot of cliff
Absorb wave energy so reduce erosion
+ cheap
- unnatural and ugly
Rock armour
Boulders along coast or foot of cliff
Absorb wave energy
Reduce erosion
+ cheap
+ easy to build and maintain
- can shift in storms
- intrusive and unnatural
Groynes
Fences built at right angles to coast
Trap materials transported by long shore drift
Creates wider beaches so slow waves
Reduces their energy so less erosion
+ cheap
- increases erosion down coast, starved of material
Breakwaters
Boulders or concrete off coast
Force waves to break offshore
Waves energy reduced before reaching shore
+ expensive
- damaged by storms
- unnatural and intrusive to boats
Soft engineering strategies
Beach nourishment
Stabilisation
Dune regeneration
Land use management
Creating marshland
Managed retreat
Beach nourishment
Sand and shingle added from elsewhere (eg offshore)
Creates wide and high beaches
More wave energy absorbed
Reduced erosion
+ natural
+ tourism benefits
- need maintenance
- involves dredging seabed, bad for ecosystem
Beach stabilisation
Stabilises sand on beach - reducing angle, vegetation etc
Allows more deposition so wider
Absorb more wave energy
Reduces erosion
+ cheap and sustainable
+ creates habitats
- people walk on dunes and damage them
Dune regeneration
Dunes created or restored
By nourishment or stabilisation of sand
Provide barrier between land and sea to reduce flooding
Absorb wave energy to prevent erosion
Land use management
low value land in at risk areas
allowed to flood
Creating marshland
allowing land to flood
Planted vegetation on mudflats to stabilise sediment
become sat marsh
Creates barrier to reduce flooding
Absorbs wave energy and slows waves to reduce erosion
+ protects higher value land behind
- loss of and, agriculture loss
Managed retreat
deliberate flooding of certain areas to control the retreat
Breaching any flood defences in place
evaluation of traditional approach
+ many methods effective
- hard is expensive
- often have knock on impacts on other areas
eg groynes in Happisburgh - effectiveness against climate change unknown
Aims of a sustainable approach to coastal management
New approaches since 1990s
- more holistic, consider entire zone, seperate managment in each cell
- more sustainable - less damage to environment
involve:
- protect people
- maintain physical environment
- sustainable in long and short term
- monitor changes to update strategy
What are shoreline management plans?
Coastline split into zones by sediment cells
Different plans made for each cell, overall plan = SMP
treated as a closed system - managment largely contained within cells, have little knock on effects of other cells
- short term (up to 20yrs), medium (20-50yrs) and long (50-100yrs)
DEFRA advise whether to:
hold, advance or retreat line or do nothing
4 SMP management options
Hold the line
Advance the line
Do nothing
Managed realignment
hold the line
maintain current position of coastline
often uses hard engineering
when coasts are high value
rising sea levels make coastlines harder to maintain
advance the line
extend coastline out to sea
build defences out to sea - eg nourishment or groynes
very expensive
effected by rising sea levels - would need to be raised later
managed retreat
allowing coastline to erode and flood in managed way
eg creating salt marshes
do nothing
letting nature take its course
erosion and flooding occur, cliffs retreat
often used when costal land of low value, eg fields or few houses
when cost and speed of erosion to large to manage
how are the recommendations decided?
cost-benefit analysis
costs - money and physical impacts
vs
benefit to population and environment
benefits must outweigh the costs
factors considered in a CBA
social - how it will affect the people, safety
economic - impact of tourism, cost of defences, value of land protected
environmental - impact on ecosystems
What is integrated costal zone management?
whole sections of the coast managed together
manages wider coastal zone (eg land, water, people and economy)
- recognise cells interact, reduced impacts on next cell
- aims to be sustainable in long and short term
Aims:
- manage flood and erosion risk
- coordinate activities to be more sustainable
- manages natural resources
It is integrated - brings together all involved in development and use of coast, many stakeholders involved
evaluation of ICZMs
+ more sustainable in protecting coast
+ have less impact of other parts
relocation may be need where defences too expensive or ineffective
- can’t protect all
create conflicts
- people disagree about choices
eg farm owners attached to land left to erode
future sea level rise creates uncertainty on effectiveness of plan
location of Norfolk Coast
east Norfolk
includes
- Bacton (+ gas terminal)
- Happisburgh - 1400 people
- Sea Palling - 650 people
- Winterton
geology of Norfolk coast
glacial till and layers of silt, clay and sands
deposited by advancing ice in glacial period
unconsolidated and soft rock
= low, unstable and vulnerable cliffs
Happisburgh cliffs - 6-10m
coastal process in east Norfolk
high rates of erosion - 2m per year
- high energy waves (due to fetch)
frequent mass movement - landslides and slumping
- especially in winter when runoff makes cliff less stable
drift aligned = longshore drift
- sediment moves south
- creates narrow beaches, vulnerable
history of flooding in Happisburgh
- due to low pressure storms over North Sea = high waves and storms
- worsened by rising sea levels
why is Norfolk vulnerable to erosion? + in future
geology
- soft, unconsolidated rock cliffs
- glacial till
= erosion
vulnerable slumping after heavy rain
long fetch from north sea
- destructive waves
drift aligned = longshore drift
- creates narrow beaches, less protected
erosion and flooding increased by climate change
- rising sea levels
- increased storm events
- heavier rainfall = more slumping
traditional approach in Norfolk
developed 1950s after floods
groynes
- trap LSD sediment to widen beach, protect
- moved issue to Sea Palling, south of Happisburgh, starved of sediment
wooden revetments and rock armour
- absorb wave energy to protect from erosion
change in government policy stopped funding
- road to sea eroded
- storm destroyed 300m revetments
why was the traditional approach unsustainable?
cost of maintaining defence to high due to:
- geology
- storms and fetch of North Sea
- frequent surges
- rising sea levels
sustainable approach in Norfolk
1996 SMP6 to manage coast as a unit
stakeholders - environmental agency and north Norfolk district council, local residents
why was SMP6 more sustainable?
environmentally sustainable
economically justifiable
holistic and integrated - not piecemeal
long term - next 100 years
approach in Bacton
hold the line
using hard engineering strategies
- maintain sea walls
- new rock armour
- gryones to maintain beach and absorb wave energy
reason:
protect gas terminal - national importance and creates jobs
but expensive
trapping sediment starves coast to the south
approach in Happisburgh
managed retreat
reason:
higher relief then Bacton, less flood risk
small population - 1400
surrounded by low value agricultural land
- cost benefit analysis, new defences not justifiable
unpopular with locals
- financial losses as house prices fallen
- land and agriculture lost
approach in Sea Palling
hold the line
reason:
protect low lying Norfolk Broads behind - environmental benefits
and economic benefits
- 7 million visitors a year making £400 million for local economy
orignal plan - advance the line
offshore reefs made to break waves before coast - reduced energy
- starved areas south - Winterton
approach in Winterton
do nothing
despite:
Area of Outstanding Natural Beauty snd nature reserve - environmental impacts
reefs at Sea Palling reduced sediment supply to area
reason:
village 1km from sea
no direct threat
evaluation of SMP6
+ more sustainable management
+ involves local people and groups more
+ more holistic and long term
- removal of old defences to allow coast to retreat
people feel they are bing left to fend for themselves = conflicts - increasing costs due to climate change, increased erosion so more defences needed
