COASTS Flashcards
what is a closed system?
transfers energy both into and beyond the system. NOT A TRANSFER OF MATTER
what is an open system?
matter and energy can be transferred from the system across the boundary into the surrounding environment.
what is positive feedback?
when an effect of an action are amplified or multiplied by its knock on effects
what is negative feedback?
where the effects of an action are nullified by its knock on effects.
inputs into coastal system
- tidal energy
- wind energy
- sediment
- changing of sea levels
- current energy
- humans
- tsunamis
- storm surge
outputs into coastal system
- kinetic energy
- sand
- depositional landforms
- erosional lanforms
what are depositional landforms?
- beaches
- mudflats
- sand dunes
- coral reefs
Erosional landforms?
- cliffs
- shore platforms
processes of the coastal system
- erosion
- transport
- deposition
crest definition
highest point of a wave
trough definition
lowest point of a wave
backwash
any water returning down to the sea
wave height
distance between the crest and the trough, rarely exceeds 6 metres unless storm conditions.
swell
waves of low height, gentle steepness, long wavelength and period.
wave velocity
speed of movement of a crest in a given period
wave steepness
is the ratio of wave height to wavelength
swash
the body of foaming water rushing up the beach
wave length
the distance between two successive crests
what does the energy obtained by the waves depend on?
- wind velocity
- length of fetch
- period of time during which the wind has blown
- depth of water
what are waves?
the main input into the coastal system
what does the size of a wave depend on?
it’s fetch
what are constructive waves?
depositional waves as they lead to sediment build up
destructive waves
destroy beaches
features of constructive waves…
- low waves
- strong swash
- weak backwash
- break on the shore and deposit material
- associated with calm weather
- less powerful waves
features of destructive waves…
- waves are high and frequent
- backwash has less time to soak into sand
- destructive waves create steep narrow beaches
- associated with storm weather
what are longshore currents?
occur as most waves hit the coast at an angle. they transport material along the coast
what are rip currents?
strong currents moving away from the coast, they develop when seawater is piled up along the coastline.
what is upwelling?
the movement of cold water from the deep ocean towards the surface.
what are tides the result of?
gravitational pull of the moon and the sun
what has the greatest influence over tides
the moon
what is tidal range?
the difference between high tide and succeeding low tide
what does the gravitational pull of the moon do?
the moon pulls water towards it creating a high tide and there is a compensatory bulge on the opposite side
what is spring tide?
the moon and sun are aligned which means you get the highest high tide and the lowest low tide - greatest tidal range
what is neap tide?
the moon and sun are proportional at 90 degrees lowest high tide and the highest low tide- smallest tidal range
where are tidal ranges high and where are they low?
mediterranean sea- low
british isles - high
what influence does the tidal range have?
a wide zone of wave attack which results in wave cut platforms being formed
what are the sources of coastal sediment?
seabed beaches river channels/estuaries erosion from cliffs material from biological origin
what are the inputs of sediment cells?
from the river, coastal erosion and offshore sources such as banks and bars
what are the transfers of sediment cells?
longshore drift and rip currents
what are the outputs of sediment cells?
beach
sand dunes
offshore deposits