Theme 2 - Coasts Flashcards
wave formation
trough
the lowest part of the wave
wave formation
crest
the highest part of the wave
wave formation
wave length
the horizontal distance between the crests/troughs of two consecutive waves
wave formation
wave height
the distance between the crest and the trough of a wave
constructive wave
- beach builders
- long wavelength + low height
- low frequency (6-8 per minute)
- shallow wave gradient
- low energy
- stronger swash that carries material up onto beach and deposits
destructive wave
- erode the beach
- short wavelength + high height
- high frequency (10-12 per minute)
- steep wave gradient
- high energy
- strong backwash that drags materials out to sea
processes of erosion
hydraulic action
the sheer force of waves hitting the coast
processes of erosion
abrasion
waves pick up material and hurl it at the coast
processes of erosion
corrosion / solution
seawater is slightly acidic and can dissolve some coastal rock e.g. limestone
processes of erosion
attrition
material bump against each other, gradually becoming smaller and smoother
coastal weathering
biological weathering
the process by which rocks are broken down by living organisms
coastal weathering
physical weathering
when rocks are affected by physical environmental factors like wind, water, and temperature changes
coastal weathering
chemical weathering
a process that breaks down rocks by changing their chemical composition through the interaction of air, water, or acid
coastal transportation
swash
the movement of water up the beach
coastal transportation
which direction does swash go in?
the direction of prevailing wind
coastal transportation
backwash
the return movement of water back out to sea
coastal transportation
what direction does backwash go in?
in the direction of gravity
coastal transportation
longshore drift
main process of transportation along the coast
process of longshore drift explained
- Waves approach the beach at an angle due to
prevailing wind - swash carries material up the beach at the same angle
- As swash dies away, backwash carries the material down the beach at right angles (90°)
- The process repeats, transporting material along the beach in a zig-zag movement
how does coastal deposition work?
- heaviest particles deposit first
- material comes from erosion along coast
Cave, Arch, Stack, Stump explanation
- A crack in the cliff forms due to erosion
- As crack widens, erosion will act to form a cave
- The cave will become larger and eventually break through the headland to form an arch
- Due to weathering from above and erosion below, the arch’s foundation continues getting thinner and wider
- Eventually, the roof of the arch collapses, leaving behind an isolated column of rock called a stack
- The stack is undercut at the base by wave action and sub-aerial weathering above, until it collapses to form a stump
headlands and bays explanation
- Found in areas of alternating bands of resistant (hard) and less resistant (soft) rocks (discordant coastline)
2, Initially, less resistant rock (e.g. clay) is eroded back, forming a bay
3, The more resistant rock (e.g. limestone) is left protruding out to sea as a headland
Wave cut platform and cliff retreat explanation
- ‘wave-cut notch’ -> where the wave has undercut the rock
- Abrasion, corrosion and hydraulic action further undercut the rock
- the cliff above becomes unstable, eventually collapsing
- backwash carries away the eroded material, leaving behind a wave-cut platform
- The process repeats and the cliff continues to retreat, leading to a coastal retreat
when is the erosion rate highest?
at high tide
where does erosion occur?
high energy regions
why does erosion occur?
when there is a stronger backwash than swash
coastal depositonal landforms
Spit formation explanation
SPIT = an expanse of sand or shingle that stretches from the shore out to sea
Spits occur when:
- a change in the shape of the coastline leads to a loss of energy, causing deposition of material
A spit may or may not have a ‘hooked’ end, depending on the winds and currents
coastal depositonal landforms
Beach formation explained
- Form in sheltered places like bays
- Constructive wave action causes deposition, with the swash being stronger than the backwash
coastal depositonal landforms
Bar formation explained
BAR = when a spit grows across a bay and joins two headlands together
- A bar of sand is formed (sandbar)
coastal depositonal landforms
tombolo
when a spit joins the mainland to an island
coastal deposition landforms
barrier island
- form parallel to the coast
- difference between a bar and barrier island = bar joins two headlands, whereas a barrier island is open at one or both ends
coastal depositonal landforms
marsh
a type of wetland, or low-lying area of land that is often covered with water
coastal depositonal landforms
sand dune formation explanation
1, Windblown sand is deposited against an obstruction, such as a pebble or driftwood
2. As more sand particles are caught, the dunes grow in size, forming rows at right angles to the prevailing wind
coastal depositonal landforms
embyro dune
- Deposition starts when debris or rubbish traps wind-blown dried sand
- Pioneer species such as Lyme Grass and Sea Couch Grass begin to colonise
- There is little soil content and high pH levels (alkaline)
- Embryo dunes are very fragile
- maximum is 1 metre
fore dune
- he embryo dunes give some protection against the prevailing wind
- other species of plant can therefore grow, such as Marram Grass
- Marram grass stabilises the dune with its root system
- These add organic matter to the dunes, making them more hospitable for plants
- A microclimate forms in the dune slack
- Maximum is 5 metres
coastal depositonal landforms
slack
hollow or shallow area between two stretches of rising ground
coastal depositonal landforms
yellow dune
- initially yellow, but darken
- Marram grass still dominates vegetation, but delicate flowering plants and insects are found in the dune slacks
- 20% of the dune is exposed, down from 80%
- do not exceed 8 metres
coastal depositonal landforms
grey dune
- more stable, less than 10% of exposed sand, good range of biodiversity
- Soil acidity + water content increase
- Shrubs and bushes begin to appear
- between 8 and 10 metres
coastal depositonal landforms
mature dune
- oldest and most stable of the dunes
- several hundred metres or more from the shoreline
- soil can support a variety of flora and fauna
where does deposition occur?
low energy regions
not enough energy to carry material
why does deposition occur?
when there is a stronger swash than backwash
erosional hazards
- loss of farmland
- loss of infrastructure
- loss of housing
coastal erosion management - HARD ENGINEERING
Recurved Sea Walls
reflect wave energy back out to sea
disadvantage -> damaging to visual landscape and restrict access to beach
coastal erosion management - HARD ENGINEERING
Groynes
wooden barrier built to prevent longshore drift
disadvantage -> can cause a lack of sediment elsewhere
coastal erosion management - HARD ENGINEERING
Breakwaters
artificial structures made of rock, built parallel to the shore.
- protect against waves, tides, currents, and storm surges
coastal erosion management - HARD ENGINEERING
Rip-rap
rocks uses to armor shorelines from erosion
coastal erosion management - HARD ENGINEERING
Gabions
coastal defences that consist of rocks and boulders encased in a wired mesh
coastal erosion management - HARD ENGINEERING
Revetments
sloping structures built on shorelines to absorb and dissipate the energy of waves in order to reduce coastal erosion.
coastal erosion management - SOFT ENGINEERING
dune stabilisation
coastal management practice that prevents the erosion of sand dunes and protects the coastline from flooding
coastal erosion management - SOFT ENGINEERING
clife regrading / vegetating
cliff regrading - reducing the slope of a cliff, making it less liable to collapse
cliff vegetating - planting vegetation on the cliff to stabilise the soil
coastal erosion management - SOFT ENGINEERING
beach nourishment
adding sediment to an eroding beach to maintain its width and protect it from erosion and storm damage
coastal erosion management - SOFT ENGINEERING
cliff drainage
reducing the risk of cliff collapse and landslips by removing water from the cliff face
coral reef types
fringing reef
a coral reef that lies close to the shore, separated by a shallow lagoon
coral reef types
barrier reef
a coral reef close and running parallel to the shore but separated from it by a channel of deep water.
coral reef types
atoll
a ring-shaped coral island that encircles a lagoon
coral reef development
coral
small, soft-bodied polyps that secrete calcium carbonate to form a hard skeleton
found 30 degrees north + south of equator
coral reef development
polyp
tiny, soft-bodied animal that secretes calcium carbonate, which forms the skeletal structure of coral
have algae zooxanthellae inside -> gives coral colour
coral reef development
biodiversity
the range and variety of different species of organisms on Earth, or within an ecosystem
coral reef development
conditions needed for coral growth
- 23-25 degree temp
- clear, shallow saltwater (no deeper than 50m)
- lots of sunlight to aid photosynthesis
- no plants that can take up oxygen
coral reef development
global reef locations
30 degrees north and south of equator
coral reef development
environmental threats to coral reefs
climate change -> warmer temps -> gets rid of zooxanthellae algae -> corals lose colour (CORAL BLEACHING)
rising sea levels -> coral needs shallow water to thrive
trash such as plastic bags destroying sea life, altering food webs
overfishing alters food webs
coral reef development
socioeconomic threats to coral reefs
- tourism
- human activities causing water pollution
- destructive fishing practices like dynamite harm coral
coral reef management
conservation
Planting nursery-grown corals back onto reefs
coral reef management
benefits of maintaining reefs
supports clearer waters and healthier marine environments
coral reef management
hazards of removal
- home to over a million species of marine life, without coral they would die
- Dredging can also degrade coral habitats through noise, remobilization of contaminants, and sedimentation
mangroves development
mangroves
a tree or shrub which grows in tropical coastal swamps
mangroves development
lenticels
tiny pores in the bark and roots of mangrove trees that allow oxygen to enter the plant
mangroves development
conditions needed for mangrove growth
- temps above 19 degrees
- fine grained alluvium soil
- sheltered shorelines, such as bays
mangroves development
global locations
tropical areas, mostly near the equator in Asia
mangroves development
environmental threats to mangroves
- extinctions due to climate change
- roots of mangroves can be clogged by sediment and soil
mangroves development
socioeconomic threats to mangroves
- urbanisation
- conversion of mangrove swamps for agriculture
mangrove management
benefits of maintaining mangroves
provide natural infrastructure to help protect nearby populated areas by reducing erosion and absorbing storm surge impacts during extreme weather events such as hurricanes
mangrove management
hazards of removal
- Coastal areas without mangroves are more susceptible to erosion -> land loss + displacement of communities.
- their absence exposes coastal settlements to greater risks from rising sea levels and extreme weather events
tropical storm hazards
causes of tropical storms
- ocean surface waters reaches at least 27°C due to solar heating -> warm air above water rises quickly, creating an area of very low pressure.
- As air rises quickly more warm moist air is drawn upwards from above the ocean creating strong winds.
tropical storm hazards
hazards of tropical storms
storm surge flooding
inland flooding from heavy rains
destructive winds
tornadoes
high surf and rip currents
tropical storm hazards
responses to tropical storms
evacuation
rescue
providing temporary accommodation
opportunities of living at the coast
- tourism and leisure
- fishing
- aesthetic setting for residential
- oil and gas
- industrial trade + ports
CASE STUDY: coastal opportunities & hazards at HOLDERNESS
Introduction
- East coast of Yorkshire
- runs for 61km
- from flamborough head to spurn head
- made of soft boulder clay and chalk
- fastest eroding coastline in europe (2m per year)
CASE STUDY: coastal opportunities & hazards at HOLDERNESS
opportunities
- tourism opportunities (20 million annually) -> tourist resort at hornsea
- chalk rocks are home to many bird species -> perfect for birdwatchers
- holderness fishery represents largest lobster fishery in Europe
- 1,900 tonnes of crab annually
- boulder clay makes for fertile farmland
CASE STUDY: coastal opportunities & hazards at HOLDERNESS
hazards
- Great Cowden Farm has a lack of sediment due to groynes at Mappleton
- Storm surges increasing in size due to rising sea levels and increasing wind strength
- golden sands caravan park lost 100 caravans since 2010 due to cliff retreat -> economic loss
- 23 villages and towns lost since roman times
- incomes are low
CASE STUDY: coastal management at HOLDERNESS
Introduction
- East coast of Yorkshire
- runs for 61km
- from flamborough head to spurn head
- made of soft boulder clay and chalk
- fastest eroding coastline in europe (2m per year)
CASE STUDY: coastal management at HOLDERNESS
causes
- discordant coast line
- destructive waves
- fastest eroding coastline in Europe (2m per year)
CASE STUDY: coastal management at HOLDERNESS
Hard Engineering
WITHERNSEA:
- sea wall
- rip rap
SKIPSEA:
- gabions
MAPPLETON:
- rock groynes
HORNSEA:
- concrete revetments
CASE STUDY: coastal management at HOLDERNESS
Soft Engineering
MAPPLETON:
- cliff regrading
SPURN HEAD:
- managed retreat
HORNSEA:
- beach nourishment
