18 terms

Coastal Systems

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Flows/transfer
A form or linkage between one store/ component and another that involves movement of energy or mass.
Inputs
energy from waves, wind, tides and sea currents; sediment; geology from coastline and sea level change.
Coastal components
Erosional landforms and landscapes
Coastal outputs
Dissipation of wave energy, accumulation of sediment above the tidal limit, sediment removed beyond local sediment cells.
Coastal energy
provided by wind, waves, tides and currents
Dynamic Equilibrium
Where there is a balance between inputs and outputs.
How is equilibrium upset?
If the elements of the system changes, then the beach may change.
Positive Feedback
Where the effects of an action are multiplied by subsequent knock,on effects.
Negative Feedback
where the effects of an action is dampened by its subsequent knock,on effects.
Example of negative feedback
A beach is in dynamic equilibrium. Sediment is eroded from the beach during a storm and is deposited offshore forming an offshore bar; waves now forced to break before reaching the beach dissipating their energy thus reducing further erosion when they reach the beach; normal wave conditions return when storm calms and rework sediment from the offshore bar back to the beach. The beach returns to dynamic equilibrium.
Backshore
Area between the high water mark and the landward limit of marine activity. Change takes place during storm activity.
Foreshore
The area lying between the high water mark and the low water mark.
Inshore
Area beyond the point where waves cease to impact upon the seabed and in which activity is limited to deposition of sediment.
Offshore
area beyond the point where waves cease to impact upon the seabed and in which activity is limited to deposition of sediments.
Nearshore
Area extending seaward from the high water mark to where waves begin to break.
Swash Zone
Area where a turbulent layer of water washes up the beach following the breaking of a wave.
Surf Zone
Area between the point where waves break and where the waves begin to move up the beach
Breaker Zone
Area where waves approaching the coastline begin to break, usually where the water depth is 5,10m.