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Coastal erosion - Coggle Diagram
Coastal erosion
Hard engineering techniques
Rock armour
Large boulders
Placed along the base of a cliff
Absorb energy from waves
Protects the cliff
Expensive
Obtain
Transport the boulders
Revetments
Wooden or concrete slatted barriers
At the top of beaches
Protect the base cliffs
When waves break against them
Cheaper than others
Less visual impact
Not suitable when wave energy is high
Groynes
Barriers
From wood
Built at right angles to the beach
Trap sediment
Stop it being moved
Longshore drift
Not attractive
Expensive
Built
Maintain
Gabions
Metal cages
Enclose rocks and boulders
Absorb the energy from waves
Less expensive than a sea wall
Short lifespan
Unattractive
Sea walls
Built along the base of cliffs
Prevent
Erosion
Flooding
Often curved
Waves are reflected
Can cause
Erosion of beach
At base of sea wall
Expensive
Visually intrusive
High cost of maintenance
Offshore breakwaters
Large concrete blocks and boulders
Located offshore
Reduce the power of the waves
Change their direction to reduce longshore drift
Beaches and cliffs retain their natural appearance
Breakwaters
Unaattractive
Expensive
Why defend it?
Presence of fragile ecosystems
would recover in a long time
Valuable economic areas
People live and work
in coastlines
Ways of managing the coast
Hard engineering
May have a negative impact
Landscape
Natural environment
Unsustainable
Expensive
Soft engineering
Less impact
Natural environment
Long term
Sustainable
Less expensive
Works alongside natural processes
Soft engineering techniques
Beach nourishment
Replace beach material
Removed by erosion and longshore drift
Creates higher and wider beaches
Transporting sand and shingle
Sometimes from off-shore
Preserve natural appearance of beach
Cheap
Dredging of sand and shingle
Increases erosion in other areas
May affect the natural environment
Managed retreat
Areas of coast
Allowed to erode and flood
Areas where the land is of low value
Eroded material encourage
Development of beaches and saltmarshes
Natural environment is not destroyed
People
Farmers lose their land