Coasts

• Coastal landscapes are open systems that are in a state of dynamic equilibrium. 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. 
• 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.

  It is negative feedback that allows systems to adjust to short-term changes. For example, storms can remove huge quantities of beach material in a short time. After reverting to normal conditions, sediment is slowly shifted back to the beach by waves, so that equilibrium is restored, and the beach looks much the same as before the storm.