Coastal Management Flashcards
Why are coasts managed
1)The aim of coastal management is to protect homes, businesses and the environment from erosion and flooding
2)Flooding and erosion of the coastline can have several social, economic and environmental impacts
3)All coastal settlements want to be defended, but the amount of money available is limited, so not everywhere can be defended. Choosing which places are defended is based on a cost-benefit analysis. The money available is usually used to protect large settlements and important industrial sites.
Four options for coastal management
Hold the line-maintain the existing coastal defences
Advance the line-build new coastal defences further out to sea than the existing line of defence
Do nothing- build no coastal defences at all, and deal with erosion and flooding as it happens.
Managed realignment- allow the shoreline to move, but manage retreat so it causes least damage.
Hard engineering defences-Sea wall
The wall reflects waves back out to sea, preventing erosion of the coast. It also acts as a barrier to prevent flooding.
Expensive to build and maintain
Disadvantage: It creates a strong backwash, which erodes under the wall.
Hard engineering defences-Gabions
Gabions are rock filled cages. A wall of gabions is usually built at t he foot of cliffs. The gabions absorb wave energy and so reduce erosion
Cheap
Disadvantages:Ugly
Hard engineering defences-Riprap
Boulders piled up along the coast are called riprap. The boulders absorb wave energy and so reduce erosion.
Fairly cheap
Disadvantages: Can shift in storms
Hard engineering defences-Groynes
Groynes are fences built at right angles to the coast. They trap beach material transported by longshore drift. This creates wider beaches, which slow the waves (reducing their energy) and so gives greater protection from flooding and erosion.
Soft Engineering defences involve helping natural processes along-Beach stabilisation
Can be done by reducing the slope angle and planting vegetation or by sticking stakes and old tree trunks in the beach to stabilise the sand. It also creates wide beaches, which reduce erosion of cliffs
Soft Engineering-Beach nourishment
Is where sand and shingle are added to beaches from elsewhere. This creates wide beaches, which reduce erosion of cliffs more than thin beaches.
Soft Engineering- Dune regeneration
Is where sand dunes are created or restored by either nourishment or stabilisation of the sand and dunes provide a barrier between land and sea, absorbing wave energy and preventing flooding and erosion.
Soft Engineering- Coastal realignment
involves breaching an existing defence and allowing the sea to flood the land behind. Over time, vegetation will colonise the land and it’ll become marshland.
Management strategies-sustainable
Coastal management has to be sustainable- this means that strategies shouldn’t cause too much damage to the environment or to people’s homes and livelihoods, and shouldn’t cost too much
Difference between soft and hard engineering
Hard engineering is often expensive, and it disrupts natural processes
Soft engineering schemes are cheaper and require less time and money to maintain than hard engineering schemes. Soft engineering is designed to integrate with the natural environment and it creates areas like marshland and sand dunes, which are important habitats.
Shoreline management plans(SMP)
The coastline is split into stretches by sediment cells. For each cell, a plan is devised for how to manage different areas with the aim of protecting important site’s without causing problems elsewhere in the sediment cell.
For each area within a cell, authorities can decide to hold, advance or retreat the line or to do nothing.
The overall plan for each sediment cell is called a shoreline management plan(SMP). All the local authorities in one sediment cell co-operate in coming up with an SMP.
