systems and processes Flashcards
What are the four sources of energy in coastal systems?
wind
Waves
tides
currents
What happens to the wind during storms?
pressure gradient (difference between high and low pressure) is high and winds very strong
what do strong winds lead to?
powerful waves
prevailing wind
wind consistently blowing in the save direction
causes higher energy waves compared to winds that change direction frequently
how are waves created?
wind blowing over the surface of the sea
friction between wind and surface of sea gives water a circular motion
what is the fetch?
maximum distance of sea the wind has blown over uninterrupted
what creates more powerful higher waves?
high wind speed
long fetch
What happens when waves approach the shore?
friction with sea bed slows the bottom of the waves and makes motion more elliptical, crest of wave rises and then collapses
swash
water running up the beach
backwash
water washing back towards the sea
characteristics of constructive waves
low frequency
low and long
strong swash
characteristics of a destructive wave
high and steep
high frequency
strong backwash
tides
periodic rise and fall of the ocean surface caused by gravitational; pull of moon and sun
why are tides important?
affect the position at which the wave breaks
high tide break higher up the shore
where are most landforms created?
between maximum high tide and minimum low tide
currents
general flow of water in one direction
what are currents caused by?
wind
water temperature
salinity
why are currents important?
move material along the coast
high energy coastline
large powerful waves
strong winds long fetches and steeply shelving offshore zone
rate of erosion higher
low energy coastline
low inputs of energy small gentle waves gentle winds short fetches deposition
what features are found at low energy coastlines
salt marshes and tidal mudflats
why might a coastline be low energy?
might be a reef or island offshore which protects coast from full power of waves
how are rivers sources of sediment?
rivers carry eroded sediment into coastal system
especially in high rainfall environments where significant river erosion occurs
how are river valleys a source of sediment?
sea level rise floods river valleys creating estuaries
sediment in the estuary becomes part of coastal system
