Systems and Processes Flashcards
What are the three sources of coastal energy?
Wind
Waves
Tides
How is wind formed?
Air moves from areas of high pressure to areas of low pressure
In what 3 ways does wind affect coastal energy? How?
Wind strength-Determines how much energy is transferred per second
Fetch-Determines what area of water is exposed to wind
Wind duration-Determines how long the wave can gain energy for
Define tides
The periodic rise and fall in sea level caused by the gravitational pull of the Sun and Moon
What is the difference between a Spring Tide and a Neap Tide? What does this mean?
Spring tide-Sun and Moon pull are parallel
Neap tide-Sun and Moon pull are perpendicular
This means that Spring tides are very high, while Neap tides are very low
Define tidal range
The difference in height between the low and high tide marks
Why does a small tidal range cause greater erosion?
Because the wave processes are more focused on the area they affect, meaning more erosion can occur in less time
Why can bays contain beaches on a high energy coastline?
Waves are refracted by submarine rock outcrops, focusing the waves on the headlands and dissipating the wave energy that reaches the bay, allowing deposition to occur
How do waves carry energy to the coast?
As wind blows over the water and frictional drag occurs, the water begins to move in a circular motion caused by the successive rise and fall of particles
How do tides influence the energy of the coastal system?
At a higher tide, more water is available through which energy can be transferred and a greater area of the coast is exposed to this energy, both of which are decreased at low tides
What is a low energy coast and why do they occur?
It is a coastline where the water has less energy, and so any material transported in the water is deposited. These may occur where there is a short fetch, where the area is sheltered from wind or where waves are diffracted such that energy is dissipated along the shore.
What is a high energy coast and why do they occur?
It is a coastline where the water has more energy, and so fine sediment is eroded and transported. These may occur where there is a long fetch, where the area is exposed to strong wind or where waves are diffracted such that energy is concentrated onto the shore.
What is a sediment cell?
A stretch of coastline to which the transfers of sediment in that area are roughly confined. Changes to the volume of sediment in a cell should not affect its neighbour
What is a sediment source? Give three examples
A supply of sediment into the coastal system. Fluvial (river) sediment, Eroded sediment and Aeolian sediment
Explain why sediment is (more or less) confined to sediment cells
Sediment cells are bordered by landforms through which sediment cannot pass, such as large headlands or river estuaries with strong currents
