Coastal systems and landscapes Flashcards
Define what is meant by a coast.
A coast is an open system with both inputs and outputs which cross the boundary of the system to the surrounding environment.
Give me examples of inputs.
Inputs:
1) energy in the form of wind, waves, tides and currents
2) stores/components
3) transfers/flows
4) sediment
5) geology of the coastline
6) sea level change
Give me examples of outputs.
Outputs:
1) energy
2) matter
Describe how coasts adjust to imbalances in the system.
Coasts are dynamic places (always changing) therefore the system is in a state of dynamic equilibrium with a balance between inputs and outputs. Change occurs due to an upset in the system e.g. storms/human activity, and a way to adjust is through the process of feedback.
Describe what feedback is.
The way in which a coast adjusts to an imbalance in the system.
What does positive feedback achieve?
Positive feedback ensures progressively greater change from the original condition of the system.
What does negative feedback achieve?
Negative feedback ensures the system returns to its original condition.
Define what is meant by waves.
Waves are undulations on the surface of the sea driven by the wind.
What are the key features of waves?
1) Height- the difference between the trough and crest
2) Length- the distance between crests
3) Frequency- the time lapse between crests
What are the functions of a wave?
A wave enters shallow water Friction with the seabed increases The wave slows Increases in height And plunges or breaks onto the shoreline The wash of water up the beach is a swash and the drag down the beach
What are the different types of waves?
1) Constructive: low, long length, low frequency, strong swash, weak backwash –> form berms
2) Destructive: high, steep, high frequency, weak swash, strong backwash –> form storm beaches
What is meant by wave refraction?
When waves break onto an irregularly shaped coastline e.g a headland separated by two bays.
Explain the process of wave refraction.
Waves drag in shallow water approaching a headland
The wave becomes high, steep and short
The part of the wave in the deeper water moves forward faster
The wave bends
The low energy waves spill into the bays as most of the wave energy is concentrated on the headland
What are currents?
The permanent or seasonal movement of water in seas and oceans
What are the different types of currents?
1) Longshore current- most waves approach the shoreline at an angle. This creates a current of water running parallel to the coastline.
2) Rip currents- these are strong currents moving away from the shoreline due to a build up of seawater and energy along the coastline.
3) Upwelling- the global pattern of currents circulating in the oceans can cause deep, cold water to move towards the surface, displacing the warmer surface water.
