Geography: Coasts

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Destructive Wave
large wave height, short wave length, strong backwash, weak swash
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Constructive wave
short wave height, large wave length, weak backwash, strong swash
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Weathering
the breaking down of rock in situ
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Types of weathering
biological=plant roots, chemical=acid rain, physical=freeze thaw
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Erosion
the movement and wearing away of weathered material
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Factors for erosion
wind, water, ice, gravity
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Attrition
rocks knocked against each other in the sea to produce smooth rounded rocks/sand
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Corrosion/Solution
acids in the sea dissolve certain rocks (soft=chalk)
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Hydraulic Action
air gets trapped and compressed in cracks in the cliff face which weakens the rock and causes pieces of rock to break off
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Corrasion/Abrasion
rocks carried by the sea are thrown against the cliff
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Soil Creep
slowest downhill movement. gravity pulls water down bringing soil particles too causing ripples to appear in the slope= terracettes
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Slumping
large area of land which is pulled down by gravity as the soil becomes saturated=slip plane for rock
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Formation - Weakness
HYDRAULIC ACTION erodes a crack in the cliff face. This is when air gets trapped in the cliff and is compressed when the water returns causing pressure and weakens it
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Formation - Cave
As the cliff get weaker, the cracks get larger
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Formation - Arch
If it forms at a headland= CORRASION undercuts the sea as pieces of rocks are thrown against the cliff, breaking off pieces of rock at a low tide.
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Formation - Stack
More corrasion, weaker, unbalanced = arch collapses due to gravity
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Formation - Stump
High tide= sea erodes bottom of the stack= collapses
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LSD
the movement of sediment along the shore in the direction of the prevailing wind(swash) and gravity(backwash) =spit/bar
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Spit
narrow stretch of sediment joined to land at one end due to LSD
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Bar
material that goes across a spit
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Formation of a Cliff
CORRASION=weakens rock at low tide=WAVE CUT NOTCH, more corrasion= unsupported top= falls, BACKWASH takes rubble back to sea= WAVE CUT PLATFORM
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Fetch
distance wind travels over open water
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Fetch?
longer=stronger wave
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Geology
type of rock and structure of an area
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Geology?
hard=less erosion
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Coastal Erosion
where the coastline is eroded backt o
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Coastal Erosion?
hard engineering defence=slower erosion
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Flood - Forecasting
Environment Agency=monitor sea conditions 24/7/365= update website. Met Office=forecast likelihood on TV,Radio,Web
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Flood - Planning
Bangladesh= Coastal Embankment Project= 12 sea facing flood walls+500 shelters
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Flood - Design
Bangladesh= 1/2 storey buildings= external staircase
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Flood - Education
Bangladesh=flood warning systems
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Hard Engineering
Revetments/RipRap/Recurved Seawall/Groynes/Gabions/Offshore Reefs
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Revetments
slatted wooden structures. +absorb wave energy, effective for years, cheap -not effective in storms, maintenance, beach inaccessible
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Rip-rap
rocks in front of cliff. +dissipate wave energy, effective for years, cheapest. -not effective in storms, unattractive, beach inaccessible
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Recurved Seawall
concrete shape.+absorb wave energy, effective for years, visible=safe. -scouring if wrong, expensive, visible=ugly
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Gryones
wood stretched into sea. +prevents LSD, effective for years, keeps beach intact. -unattractive, disruptive process
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Gabions
wire cage. +absorb wave energy, cheap. -can break, not efficient
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Offshore Reefs
concrete blocks. +reduce wave energy -not effective in storms, hard to install
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Soft Engineering
Beach Replenishment/Cliff Regrading/Managed Retreat
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Beach Replenishment
additional sand/pebbles. =dissipates wave energy, natural, tourists, cheap. -affect wildlife, maintenance, disruptive
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Cliff Regrading
gentle slope created. +increase vegetation, increase wildlife. -not effective alone, demolish homes
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Managed Retreat
allow sea to flood land. +new habitat, cheap. -lose land, difficult to estimate loss
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Effects of Coastal Recession
Cliff erodes 1.5m/year= bye bye Tower. 2020=18 buildings gone. Houses on Beach Road £80k--->£1
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Happisburgh, Walton On The Naze
1997, Groynes(stop LSD south to north/Regrading/Seawall(protect London Clay)
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Other cards in this set

Card 2

Front

Constructive wave

Back

short wave height, large wave length, weak backwash, strong swash

Card 3

Front

Weathering

Back

Preview of the front of card 3

Card 4

Front

Types of weathering

Back

Preview of the front of card 4

Card 5

Front

Erosion

Back

Preview of the front of card 5
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