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The Coastal System

The coast can be seen as a system in order to help to understand the processes and interactions involved. In theory, the inputs, processes and outputs work together to create coastal equilibrium. However, as we will see in this unit human actions affect the state of equilibrium within the coastal system. Coastal landscapes are open systems. This means energy and matter can enter and leave the system.

Coastal Inputs

Marine – waves, tides and currents
Energy – kinetic energy from waves and wind, thermal energy from the sun and potential energy from material on cliffs/slopes and material from processes of weathering, mass movement, erosion and deposition
Geological – rock type, structure and tectonics. material from marine deposition, weathering and mass movement
Atmospheric – climate, weather and climate change
People – urban planning, housing, industry, coastal management/defences, leisure

Coastal Transfers

Stores such as sediment on a beach, and flows (transfers), such as longshore drift moving sediment along the coast.

Coastal Processes

Deposition
Erosion – attrition, corrasion/abrasion, hydraulic action
Weathering – freeze-thaw, solution, salt crystallisation
Mass Movement e.g. slumps, soil creep and slides

Coastal Outputs

Marine and wind erosion as well as evaporation.
Landforms of erosion – cracks, caves, stacks, stumps, wave-cut platforms, blowholes
Landforms of deposition – beaches, spits, tombolos, sand dunes, salt marshes

System feedback

If inputs and outputs within a coastal system are the same then a state of equilibrium exists. An example of this would be when the rate of sediment being added to a beach is the same as the amount leaving the beach resulting in the beach remaining the same size. If something happens the break this equilibrium the system will change to restore the equilibrium. This is known as dynamic equilibrium, as the system responds to the disturbance.

When an initial change within a system brings about further change in the same direction this is known as positive feedback.When a system returns to equilibrium following a change in the system this is known as negative feedback.

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Waves

Find out about types of waves and how they are formed

Sub-aerial

Find out about sub-aerial processes including weathering

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