Summary AQA A Level Geography: Coastal Systems and Landscapes Detailed Notes
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Course
Coastal Systems and Landscapes
Institution
AQA
Full, detailed, A* level notes about the Coastal Systems and Landscapes topic in the Geography A Level. Case studies included. Clear and concise notes to help you build knowledge on the topic and achieve higher grades. Send me a message if you have any questions about what is in the document!
Coastal Systems and
Landscapes Revision
The Coastal System ● Coastal Processes ● Coastal Landforms ● Sea Level
Changes ● Coastal Management ● Coastal Environments ● Humans at
the Coast
Coasts are Natural Systems
They have:
● Inputs- such as sediments and energy from wind, waves, tides and
currents.
● Outputs- such as sediments deposited further along the coast or inland.
● Flows/transfers- erosion, weathering, transportation and deposition can
move sediment within the system.
● Stores/components- landforms such as beaches, dunes and spits.
Coasts are open systems and are generally in dynamic equilibrium because the
inputs and outputs are balanced. A change in one causes negative feedback
which restores the balance to the system.
Negative feedback- a beach is eroded → the cliffs behind it are exposed to wave
attack → sediment eroded from the cliffs is deposited on the beach → beach
grows in size again.
Positive feedback- as a beach starts to form, it slows down waves → more
sediment is deposited → the beach grows in size. This will cause long-term
growth.
,The Coastline
The coast officially extends 60 km inland and 320 km offshore. 40% of the world’s
population live within 100 km of the coast and 10% are less than 10m above sea
level.
● Backshore- An area of beach that extends from the limit of high water
foam lines to dunes, or the extreme inland limit of the beach. It is only
affected by waves in exceptionally high tides or severe storms.
● Foreshore- An area between the high water mark and low water mark,
Heavily influenced by marine activity. Tides will come in and out here.
● Inshore- An area between the low water mark and the point where the
waves cease to have any influence on the land around them
● Offshore- The zone extending seaward from the point of low tide to the
depth of wave-base level or outer edge of the continental shelf.
● Nearshore- where waves steepen and break and then reform in their
passage to the beach, where they then break for the last time and surge
up the foreshore. Much sediment is transported in this zone.
● Swash zone- The zone of water action on the beach which moves as water
levels vary.
● Breaker zone- the zone within which waves approaching the coastline
commence breaking (typically in depths of 5 and 10 metres). This moves
throughout the day.
Energy Sources
There are lots of sources of energy in a coastal system:
Wind ● Wind is caused by air moving from areas of high pressure to
areas of low pressure. During storm events, the pressure
gradient is high, so winds are strong.
● Strong winds can create powerful waves. Wind that blows
consistently from the same direction, a prevailing wind, will
cause higher-energy waves than those that change direction
frequently.
Waves ● Friction between wind blowing over the surface of the sea
gives the water circular motion which causes a wave.
● As a wave approaches a shore, it breaks. Because of friction
, with the sea bed, the bottom of the wave slows down, and
the top overtakes it which makes the motion more elliptical.
The crest of the wave rises up and then collapses.
● The effect of a wave on a shore depends on its height and
wave height can be determined by the wind speed, duration
and fetch (the maximum distance of sea the wind has blown
over to create the waves). A high wind speed, longer duration
and longer fetch create more powerful waves.
● Water washing up the beach is called the swash and
washing back towards the sea is called the backwash.
● Constructive waves have a low frequency (6-8 per minute)
and are long and low. They have a more elliptical profile and
a powerful swash which deposits material on the beach.
● Destructive waves have a higher frequency (10-14 per
minute) and are high and steep. They have a more circular
profile and a strong backwash which removes material from
the beach. They are most effective over steeply shelving
seabeds which cause a rapid increase in friction and a steep
wave front.
● In any area, waves usually predominate as either
constructive or destructive.
● Wave refraction is the bending of waves due to varying water
depths underneath. The part of the wave in shallower water
slows down compared to the part in deep water, causing the
wave to bend. For example, when a wave approaches a
straight shoreline at an angle, the part of the wave crest
closer to shore is in shallower water and moving slower than
the part away from the shore in deeper water, so it bends in
towards the beach.
● When a wave comes in, it has to go back out again, but if
there are many waves behind it, it can’t just go straight back
out. Instead, the waves find a divet in the seabed to go under
the waves behind causing a rip current.
Tides ● Tides are the periodic rise and fall of the ocean surface,
caused by the gravitational pull of the moon and sun.
● Tides affect the position waves break on the beach (high tide
means waves will go further up the beach). Most landforms
are created and destroyed in the area between maximum
high and low tide- the foreshore.
● Talbot Bay in Australia’s West Coast, can rise by 36 feet,
making it one of the largest tidal changes in the world
● A Spring tide is when the sun, moon and earth are aligned
and a gravitational pull creates a large tidal range. A low
spring tide occurs after a new moon and a high spring tide
occurs after a full moon, so this occurs twice a month.
● A Neap tide is when the sun and moon are at a right angle
to each other and there is a smaller gravitational pull on the
tide. This creates a low tidal range
● A tidal bore is a phenomenon where the leading edge of the
incoming tide forms a wave of water that travels up a river or
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