Coastal management Flashcards
What is beach nourishment?
soft engineering strategy
- sediment is taken from offshore sources to build up the existing beach
- widens beach which works as a buffer for oncoming waves so less erosion
- can replace sediment lost eg. through storm surges
What are the advantages and disadvantages of beach nourishment?
advantages
- leads to lower rates of erosion - protects cliffs behind
- increases tourist potential
- cost effective and natural looking
disadvantages
- needs constant maintenance
- dredging (removal of sediment from elsewhere) has consequences on habitats and can lead to erosion elsewhere
What is managed retreat?
soft engineering strategy
- controlled flooding of low-lying coastal areas
- usually in areas at high risk of erosion
What are the advantages and disadvantages of managed retreat?
advantages
- cheap compared to paying for sea defences
- creates a saltmarsh which provides habitats and a diverse ecosystem
- saltmarsh can act as a natural defence against flooding and erosion
disadvantages
- land lost as it is reclaimed by the sea
- landowners need to be compensated which is expensive
What are the advantages and disadvantages of doing nothing?
- leaves the coastline as it is without putting in place any coastal management strategies, leaving the area to be flooded and eroded (usually because it is not of economic value)
- no money spent on defences
- landowners need to be compensated
What is dune regeneration/mangrove planting?
soft engineering strategy
- planting specific plants such as mangroves or marram grass which has a large frictional area, causing sand to be deposited
- marram grass has long roots which stabilises dunes
- dissipate wave energy to prevent flooding and erosion
What are the advantages and disadvantages of dune regeneration?
advantages
- maintains natural environment
- provides wildlife habitats
- relatively cheap and sustainable
- stabilises fragile dunes
disadvantages
- time consuming
- easily damaged by people
- people must be kept off certain areas, may reduce tourism
What is rock armour?
hard engineering strategy
- large boulders placed at the foot of cliffs
- dissipate wave energy by absorbing impact of waves and permeable which allows water and sediment to pass through
- protect cliffs from undercutting
- approx £3000/metre
What are the advantages and disadvantages of rock armour?
advantages
- cheap to install and maintain
- natural looking
- prevents erosion of cliffs
disadvantages
- dangerous access to beach
- increased costs when rock is transported or imported great distances
What is a sea wall?
hard engineering strategy
- concrete/rock barriers built along the front of cliffs
- they are often recurved at the top so wave energy is reflected back on itself
- modern sea walls designed to dissipate not reflect wave energy
- approx £4000/metre
What are the advantages and disadvantages of sea walls?
advantages
- good defence where energy is high
- long life span
- storm drains so water can flow back out to sea
disadvantages
- expensive to build/maintain
- can effect beach access
- recurved top can increase beach erosion by scouring the base
What are groynes?
hard engineering strategy
- timber or rock ‘fences’ built out to sea at right angles to the coast
- trap sediment being moved along the shoreline by LSD which widens beach
- wide beach acts as a buffer to oncoming waves to absorb energy
- approx £5000/metre
What are the advantages and disadvantages of groynes?
advantages
- cheap
- retain wide and sandy beaches so wave energy is absorbed - prevents erosion
- do not effect beach access
disadvantages
- visually unappealing
- deprives areas down the coastline of sediment which shifts the problem rather than solving it
What are revetments?
Hard engineering strategy
- timber/rock fences with open slats placed parallel to the coastline
- absorb wave energy allowing water and sediment to pass through, trapping sediment to build up the beach
- approx £2000/m
What are the advantages and disadvantages of revetments?
advantages
- less beach material eroded
- wave scour prevented
- cheaper and less intrusive than other strategies
disadvantages
- short life span
- unsuitable when wave energy is high
- access problems
What are gabions?
Hard engineering strategy
- rocks and boulders encased in wired mesh
- absorb energy from waves and allow water and sediment to pass through
- approx £100/m
What are the advantages and disadvantages of gabions?
advantages
- cheap and efficient
- uses local materials
disadvantages
- short life span
- wires can break and cause injury
- visually unappealing
What is an estuary barrage?
Hard engineering strategy
- acts as a dam across an estuary to prevent flooding and creating freshwater lakes behind them
- can be controlled to open or close depending on sea conditions
- £30 billion each
- eg. Thames barrier
What are the advantages and disadvantages of estuary barrages?
advantages
- protect large areas
- very effective
- long life spans
disadvantages
- very expensive to build and maintain
- huge environmental impacts on mudflat areas
- negative impacts on tourism industry
What are SMP’s?
Shoreline management plans
- uses a combination of approaches that aim to be cost-effective and long lasting including soft and hard engineering strategies
- the overall plan aims to be sustainable economically, socially and environmentally
- 20 SMP’s in the UK
What 3 strategies do SMP’s use?
hold the line - strengthen/maintain existing defences
no active intervention - natural processes operate without human intervention
managed realignment - deliberate flooding of previously protected areas. Saltmarshes and mudflats can then trap sediment and create natural and diverse defences and ecosystems
What is an ICZM?
Integrated coastal zone management plan
- contributes to the sustainable development of coastal zones by the application of an approach that respects the limits of natural resources and ecosystems ‘ecosystem based approach’
- designed to integrate views and interests of all stakeholders and coordinate policies affecting coastal zones eg. fishing/industry
What are the sustainable features of SMP’s and ICZMs
- holistic view
- conserve biodiversity
- work with the environment using nature-based solutions
- long term
- good for locals
- resource efficient - locally sourced
- planned well to protect against sea level rise
