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Embed code for: 8. The coast as a system
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The coast as a system
Coasts as natural systems
Sum up the coastal system in three words.
A Coastal system
Open or closed? Why?
Main System Elements
Introduction of sediment (from land and offshore) and energy (from wind, waves, tides and currents).
erosional and depositional landforms
Some components such as beaches are also stores.
Transfers of energy and sediment from one location to another
Marine (sea), terrestrial (land), atmospheric (e.g. freeze thaw weathering) and biological mechanisms
Sediment and energy losses to the system
Coastal landscapes as open systems
A simple beach system
Landward material outputs
Landward material inputs
Sand dune development
When sediment is lost to the system by transfer to a location beyond further access.
This is different to a sediment store where additions and removal of sediment is possible.
Example: Sediment may be lost to deeper offshore areas during unusual very high energy conditions which cause stronger waves and currents than normal.
Or when a transfer of sediment to stores beyond the active coastal zone such as upper beaches, coastal dunes and mudflats.
Recap – negative feedback cycle
Definition: Where a flow or transfer leads to a decrease or decline.
Alternative: where changes within the system slow down or reduce the causes of further disruption, dampening down the impetus for change.
Negative feedback cycle
Why is this an example of a negative feedback cycle?
Recap – positive feedback cycle
Definition: Where a flow or transfer leads to an increase or growth.
Alternative: where the effect of change is to amplify the original causes so that additional further changes occurs.
Positive feedback cycle
Why is this an example of a positive feedback cycle?
Definition: The degree of change taking place within a system in terms of scale and/or rate.
Remember systems are always trying to achieve a state of equilibrium.