Coasts are Natural Systems

  • Inputs- sediment; energy from wind, waves, tides and currents.
  • Outputs- sediment can be transported at sea or deposited further down.
  • Flows/transfers- erosion, weathering, transportation and deposition occur.
  • Stores/components- landforms are stores of sediment.
  • They’re generally in dynamic equilibrium. A change in one input/output often causes negativefeedbacks that restore the balance of the system:
  • Negative feedback- a change in the system that neutralises the effects such as a beach is eroded, the cliffs behind it are exposed to wave attack. Sediment eroded from the cliffs is deposited on the beach, causing it to grow again.
  • They also experience positive feedbacksthat change the balance of the system, creating a new equilibrium:
  • Positive feedback- a change in the system that amplifies the effects such as a beach starts to form, it slows down waves.
  • This can cause more sediment to be deposited, increasing the size of the beach. The new equilibrium is reached when long-term growth of the beach stops.