Coasts End Of Topic Test Rev Flashcards
What are salt marshes?
Salt marshes are areas of periodically flooded low-lying coastal wetlands
-They are often rich in plants, birds and animals
How do salt marshes develop
Development of a salt marsh?
-Starts as accumulated mud and silt in a sheltered part of the coastline
-Deposition occurs and mud breaks the surface to form mudflats
-Salt-tolerant plants colonise the mudflats (early colonisers = pioneer plants)
-Level of mud rises and so it is less frequently covered by water
-Conditions become less harsh as rainwater begins to wash out some of the salt, and decomposing plant matter improves the fertility of the newly forming soil
-New plants (eg sea asters) start to colonise area and gradually vegetation sucession develops
Concordant coasts
Concordant coasts:
-Forms where rocks run parallel to the coast
-Some have long, narrow islands running parallel to the coastline
-Also known as dalmatian coasts
Discordant coasts
Discordant coasts:
-Where rocks run perpendicular to the coastline
-Have a pattern of projecting headlands and bays
-Known as Atlantic Coasts
Hard engineering
Hard Engineering:
-Economically costly and deliberately alter physical processes and system through the use of hard, resistant materials
Advantages of hard engineering techniques
Advantages of hard engineering techniques:
-Effective and often reassuring to people as it is a visible form of defence
-Long-lasting
Disadvantages of hard engineering techniques
Disadvantages of hard engineering techniques:
-High costs along with high maintenance costs
-Visually unattractive
-Coastal ecosystem needs overlooked
-Defences built in one place frequently have adverse consequences futher along the coasts
Hard engineering examples
Hard engineering examples:
-Groynes
-Sea walls
-Rock armour/rip rap
-Revetments
-Offshore breakwaters
Revetments
Revements:
-Made up of rock, concrete and other durable materials constructed on top of the beach or along the shorelines
-Dissipates the energy of the waves and slow coastal erosion
-Used to protects vulnerable areas from erosion eg cliffs
Offshore breakwaters
Offshore breakwaters:
-Rocks, concrete or other materials placed out to sea to create offshore protecting, by breaking the waves before they reach the beach
Soft engineering
Soft engineering approaches attempt to work with physical systems and processes to protect coasts and manage changes in sea level
Beach nourishment
Beach nourishment:
-Artificial replenishment of beach sediment to replace sediment lost by erosion, enlarge the beach to dissipate wave energy and reduce erosion
-Ongoing costs are high
-Sediment must not be sources from elsewhere in the sediment cell
Cliff regrading and drainage
Cliff regrading and drainage:
-Cliff slope angles reduced to increase stability
-Re-vegetated to reduce surface erosion
-In-cliff drainage reduces pore-water pressure and mass movement risk
-Costs of Β£1 million per 100m
-Can be disruptive during construction
Dune stabilisation
Dune stabilisation:
-Fences used to reduce wind speeds across dunes - dunes then replanted with marram and lyme grass to stabilise the surface
-Reduces erosion by wind and water
-Cost effective in the long term
Soft engineering technique examples
Soft engineering technique examples:
-Beach replenishment
-Cliff regrading and drainage
-Dune stabilisation