Feedback loops

Question 1

Give a negative feedback loop for coastal systems

Answer 1

1. sediment eroded from beach in a storm
2. sediment deposited offshore, forming a bar.
3. waves break, loose energy before reaching beach, minimising erosion.
4. After the storm normal wave conditions rework the sediment from the offshore bar back to the beach.
5. Sediment is deposited back to the beach.

Question 2

Give a positive feedback loop for coastal systems

Answer 2

At Portlock, Somerset, the shingle ridge at the back of the beach was breached, flooding the land behind.

Regular flooding has widened breached and land behind the beach is now a saltmarsh.