coastal management Flashcards
(17 cards)
What are the main aims of coastal management strategies?
-Provide defence against the impacts of flooding
-To provide defence against coastal erosion
-Stabilising beaches affected by longshore rift
-Stabilising sand dune areas
What is hard engineering?
Hard engineering is when you make a physical change to the coastal landscape using resistant materials like concrete boulders wood and metal.
What is soft engineering?
Soft engineering is when you use natural systems for coastal defence such as beaches, dunes and salt marshes which can absorb and adjust to wave and tide energy
What are sea walls?
-They aim to dissipate wave energy and the recurved structures throws waves back out at sea into the next wave to reduce impact.
-They provide a physical barrier to flooding by raising the height of the coastline
-They must have a continuous smooth facing as any small gap will be exploited by waves
What is rock armour (rip-rap)
These consist of large boulders placed in front of a cliff or sea wall to take the full force of waves.
-Have gaps between to let the water filter through
-Not secured in place so energy is taken out of the wave by rocking/moving the largest rocks
What are gabions?
-These are small boulders that are contained within steel wire mesh cages, each of which can be joined together to form a large structures or walls
What are revetments?
Revetments are concrete or wooden structures placed across a beach or coastline to take the full force of the wave energy and prevent further erosion of the coast
What are groynes?
These are wooden, stone or steel breakwaters built nearly at right angles to waves ( usually 5 to 10 degrees from the perpendicular)
-Built to control longshore drift by trapping sediment to create higher and wider beaches which will then also dissipate wave energy
-They break up waves as they hit the coast
-A disadvantage is it may have serious effects down the coast where it breaks off sand supply and leaves the area vulnerable to erosion
What is cliff fixing?
Cliff fixing is often done by driving metal bar into the cliff face to stabilise it and to absorb some wave power
What are offshore reefs?
These force waves to break offshore which reduces impacts at the base of the cliff
What are barrages?
These are large structures built to prevent flooding on major estuaries and other large sea inlets
-Act as a dam across an estuary and prevent incursion of sea water
What are the disadvantages of hard engineering strategies?
-Structures can be expensive to build and maintain
-A defence put up in one place can have serious consequences for another area of the coast
-Structures can be an eyesore and disrupt natural habitats
What are the 4 defence options?
-Hold the line
-Do nothing but monitor
-Retreat the line
-Advance the line
What is beach nourishment?
-This strategy aims to replace material that has been lost through longshore drift
-Local councils material may be moved from one end of the beach to another before the start of the tourist season
What is dune regeneration?
-Dune regeneration is when vulnerable areas of the dunes are:
-Replanted with plants such as marram grass
-Stabilised by the use of wired mesh or sacking
-Restricting access by fencing off areas
-Selective grazing
-Afforestation with quick growing conifers
What is managed retreat?
-This is when the current line of sea defences are abandoned and instead you develop the exposed land in some way like using salt marshes.
What are the key features of Shoreline management plans?
–They provide an assessment of risks associated with the evolution of the coast.
-adresses risks in a sustainable way
-Provide long term management policies for the 22nd century
-Aim to be technically sustainable, environmentally acceptable and economically viable.
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