Coasts 5 - Coastal managment Flashcards
What is the aim of coastal management?
To protect homes, business and the environment from erosion and flooding
Why is coastal management appropriate
As flooding and erosion have severe social, economic and environmental impacts
How are places that need to be protected chosen?
Cost-benefit analysis (CBA)
What are the 4 options for coastal erosion
- Hold the line
- Advance the line
- Do nothing
- Managed realignment
What is the money give to coastal settlements used for?
To protect large settlements and important industrial sites rather than the small isolated settlements
What is hold the line?
Maintain the existing coastal defences
What is advance the line?
Build new coastal defences further out to sea than the existing line of defence
What is doing nothing
Build no coastal defences at all and deal with the erosion and flooding as it happens
What is managed realignment
Allow the shoreline to move but manage retreat so it causes the least amount of damage
What Are 9 examples of hard engineering?
1) Sea wall
2) Revetment
3) Gabions
4) Riprap
5) Groynes
6) Breakwaters
7) Earth bank
8) Tidal barrier
9) Tidal Barrage
What does a sea wall do?
Reflects waves back out to sea, preventing erosion of the coast. It acts as a barrier to prevent flooding
What are 2 issues with sea walls
- Expensive to build and maintain
- Creates a strong backwash that erodes under the wall
What is revetment
Slanted structures built at the foot of cliffs. They’re made of concrete wood or rocks. Waves break against the revetments which absorb the wave energy and prevent cliff erosion
What are 2 issues with revetment
- Expensive to b build, but cheap to maintain
- Create a strong backwash
What are gabbion’s?
Rock filled cages. A wall of gaboon’s is built at the foot of the cliff. They absorb wave energy and reduce erosion
Whats an issue with gabion’s
Cheap but ugly
What are rip rap
Boulders piled along the coast, they absorb wave energy and reduce erosion
Give a - of rip rap
They’re cheap but can shift in storms
What are groynes?
Fences built at right angles to coast. They trap beach material that’s transferred by longshore drift. Creates wider beaches which slow the waves (reducing their energy) and gives greater protection from flooding and erosion
What are the issues with groynes
They’re cheap but they starve down-drift beaches of sand. Thinner beaches don’t protect the coast as well, leading to greater erosion and flooding
What are breakwaters?
Concrete blocks or boulders deposited at the coast. They force waves to break offshore, the waves energy and erosive power are reduced before they reach the shore
What are 2 negatives of breakwaters
- Expensive
- C an be damaged in storms
What are Earth Banks
Moulds of earth act as a barrier to prevent flooding
2 issues with earth banks
- Quite expensive
- Can be eroded
What are tidal barriers
Built across river estuaries. they con tain retractable flood gates that can be raised to prevent flooding from storm surges
- of tidal barriers
They’re very expensive
What are tidal barrages?
Dams were built across river estuaries, with the purpose to generate electricity. Waters trapped behind the dam at high tide. The controlled release of water through turbines in the dam at low tide generates electricity. They prevent flooding from storm surges
2 negatives of tidal barrages
- Very expensive
- They disrupt sediment flow which causes erosion elsewhere in the estuary
What does soft engineering involve
Natural processes
6 types of soft engineering
- Beach nourishment
- Beach stabilisation
- Dune regeneration
- Land use management
- Creating marshland
- Coastal realignment
What is beach nourishment?
Sand and shingle are added to beaches from elsewhere. This creates wide beaches, which reduces erosion of cliffs more than thin beaches
What is beach stabilisation
This is done by reducing the slope angle and planting vegetation or sticking stacks and old tree trunks in the beach to stabilise the sand creating wide beaches, reducing erosion
What is dune regeneration?
Where sand dunes are created or restored by nourishment or stabilisation of the sand
What is land u se management
Vegetation needed to stabilise the dune can easily be trampled and destroyed, leaving the dune vulnerable to erosion. Wooden walkways across dunes and fenced-off areas prevent walkers and cyclists from gaining access to the dunes and reduce vegetation loss
What is creating marshland
Doing this by utilizing mudflats can be encouraged by planting vegetation. This stabilises the sediment and stems and leaves help reduce the speed of the waves. This reduces their erosive power and how far the waves reach inland, leading to less fllooding of the area around the marsh
What is coastal realingment?
Breaching of an existing defence and allowing the sea to flood the land behind. Overtime, the vegetation will colonise the land and it’ll become marshland
What must coastal management be?
Sustainable
What does this mean?
That strategies shouldn’t cause too much damage to the environment or to peoples homes and livelihoods and shouldn’t cost too much
Whats an issue with hard engineering?
Expensive and disrupts natural processes
What type of engineering is more sustainable?
Soft engineering - Lower environmental impact and economic cost
WHy are soft engineering schemes better?
Cheaper and requires less time and money to maintain, they’re designed to integrate with the natural environment and it creates areas like marshland and sand dunes which are important habitats
What 2 ideas are included with managing a coast sustainabily
Shoreline management plans (SMP)
Integrates coastal zone management (ICZM)
How are coastlines split
Stretches by sediment cells
What happens to each sediment cell
A plan is devised to manage different areas with the aim of protecting important sites without causing problems elsewhere
What problems elsewhere can they cause
Starving an adjacent area of sediment could increase erosion
What can authorities do with each cell
Decide to hold, advance, retreat the line or do nothing
Who comes up with each SMP
All local authorities in 1 sediment cell to co-operate tp come up with a plan
What do ICZMs do?
Considers all elements of the coastal system (land, water, people, erosion) when coming up with a management strategy
What do ICZMs aim to do
Protect the coastal zone in a relatively natural side, whilst allowing people to use it and develop in a different way
What 3 ways is it integrated
- Environment as a whole-land and water are independent
- Different uses are considered eg - fishing, tourism, industry
- Local regional and national levels of authority all input into the plan
Why is it a dynamic strategy
Decisions are re-evaluated if the environment if demands on the area change
