The Coastal System Flashcards
True or false? Coasts are a natural system
True
What are sediment stores on coasts?
Depositional landforms are stores of sediment.
What are the flows/transfers of sediments on coasts?
Processes such as erosion, weathering, transportation and deposition move sediment within a system
What are the energy inputs on coasts?
- wind
- waves
- tides
- currents
Coastal system aren’t normally in dynamic equilibrium. True or false?
False. They are normally in dynamic equilibrium.
What restores the balance in a system if a change in an output or input occurs?
Negative feedbacks
Give an example a negative feedback in a coastal system.
As a beach is eroded cliffs are exposed to wave attack. Sediment eroded from cliffs is then deposited and builds the beach up again.
Give an example of a positive feedback in a coastal system.
As a beach starts to form it slows waves down, causing more deposition, increasing beach size
What are positive feedbacks?
When a change in the system causes amplification of effects.
How is wind created?
By air moving from areas of high pressure to areas of low pressure.
Describe the pressure gradient and therefore wind strength in storms.
Very high making winds very strong
What is prevailing wind?
Wind that blows from the same direction
Prevailing wind generates higher energy waves than winds that change direction. True or false?
True.
How are waves formed?
Wind blowing over the sea’s surface causes friction between the wind and surface, creating a circular motion in the water
What are the higher and lower levels of a wave called ?
Wave crest and trough respectively.
How do you work out a wave’s wavelength?
The distance between two wave crests.
How does a wave break?
As the beach gets shallower friction occurs and causes the circular motion to topple, causing it to crash.
What is a wave’s fetch?
The maximum distance of sea the wind has blown over in creating the waves.
What effects a wave’s height?
Wind speed and fetch.
What are the two wave types?
Constructive and destructive.
What are the characteristics of a constructive waves?
- low frequency (6-8 per minute)
- low and long wave
- strong swash
- weak backwash
What are the characteristics of a destructive wave?
- higher frequency (10-14 per minute)
- high and steep
- weak swash
- strong backwash
What are tides?
The periodic rise and fall of the ocean surface
What are tides caused by?
The gravitational pull of the moon and sun
Describe how tides affect waves.
The position at which waves break on the beach
Where are most landforms created and destroyed on a beach?
The area of land between maximum high tide and minimum low tide
Define current
Current is the general flow of water in one direction
What causes currents
Caused by wind OR variations in water temp. and salinity
True or false. Currents do not move material along the coast
False, they do
High energy coasts receive high inputs of energy in the form of large, powerful waves. What 3 things are they caused by?
- strong winds
- long fetch
- steep offshore zones
Characterise the landforms on a high energy coast.
Sandy coves
And rocky landforms (eg caves, stacks and arches)
On a high energy coast what is the relationship between erosion and deposition?
Erosion rate > deposition rate
On a low energy coast what is the relationship between erosion and deposition?
Deposition rate > erosion rate
What landforms night you commonly find on a low energy coast?
Salt marshes and tidal mudflats
What are the 4 potential causes of low energy inputs on a low energy coast?
- gentle winds
- short fetch
- gently sloping offshore zones
- offshore obstacles like islands or reefs, slowing waves down
What are low energy coast waves like?
Small and gentle
How can sea level rise create a source of sediment on a coast?
It can flood river valleys, forming estuaries, their sediment becomes part of the coastal system
Name the 3 sediment sources (inputs) to a coast (vary your answer)
- rivers bringing sediment from Inland
- sea level rise ( explained in other card)
- sediment eroded from cliffs
- crushed shells of marine life
- waves, tides & currents transporting sediment from offshore deposits
Define sediment budget
Difference between amount of sediment inputs and amount of sediment outputs
Describe what happens if a coast has a positive sediment budget
The coast builds outwards ( and vice versa for negative)
Define sediment cells.
Lengths of coastline that are self-contained for the movement of sediment.
Why are sediment cells closed systems?
Because processes In one cell don’t affect movement of sediment in another cell
