COASTAL SYSTEMS AND LANDSCAPES CGP - The Coastal System Flashcards
What type of system are coasts?
Open systems - inputs and outputs of matter and energy.
Coast inputs
Sediment brought into system. Energy inputs come form wind, waves, tides and currents.
Coast outputs
Sediment can be washed out to sea, or deposited further along the coast.
Coast flows/transfers
Processes such as erosion, weathering, transportation and deposition can move sediment within system (e.g. from beach to dunes).
Coast stores/components
Landforms such as beaches, dunes and spits are stores of sediment.
What are coasts generally in?
Dynamic equilibrium - inputs and outputs are balanced.
Change in input or output often cause what that restores the balance of the system?
Negative feedbacks
Negative feedback in coastal systems and example
When a change in system causes other changes that have the opposite effect so effects of action are nullified. Restore balance of freedom. E.g. beach eroded, cliffs behind exposed to wave attack. Sediment eroded from cliffs deposited on beach, causing it to grow in size again.
Positive feedback in coastal system and example
When a change in the system causes other changes that have a similar effect so effect of change is amplified. Create new equilibrium. E.g. as beach stats to form it slows waves down, causes more sediment to be deposited, increasing beach size. New equilibrium reached when long-term growth of beach stops.
How is energy in coastal system transferred?
Air (as wind) and water (as waves, tides and currents).
How are winds created?
By air moving from areas of high pressure to areas of low pressure.
Why in events such as storms can winds be very strong?
The pressure gradient (difference between high and low pressure) is high.
What can strong winds generate?
Powerful waves
What is prevailing wind and what does this cause?
When wind consistently blows from the same direction. Causes higher-energy waves than winds that change direction frequently.
How are waves created? What gives it circular motion?
By wind blowing over surface of sea. friction between wind and surface of sea gives water circular motion.
What does the effect of a wave on the shore depend on?
Its height.
What is wave height affected by?
Wind speed and fetch of wave.
What is fetch?
Maximum distance of sea the wind has blown over in creating waves.
What creates higher and more powerful waves?
A heigh wind speed and a longer fetch.
What happens to waves as they approach the shore?
They break