3.1.3.1 Coasts as natural systems Flashcards
What type of system is a coast?
Open system
Give one example of a Negative feedback within a coast?
Sediment is eroded from the beach during a storm. When the destructive waves from the storm loose their energy excess sediment will be deposited as an offshore bar. The bar dissipates the waves energy which protects the beach from further erosion. Over time the bar gets eroded instead of the beach. Sediment is then deposited onto the beach with constructive waves. Overtime the bar will completely erode away leaving the beach now unprotected from future storms
Give another example of a negative feedback within the coast?
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 in size again
Give an example of a positive feedback within the coast?
Coastal management leading to increased erosion elsewhere along the coast. Eg: groynes trap sediment so cause narrow beaches further down the coast.
Give another example of a positive feedback within the coast?
People walking over sand dunes destroys vegetation growing there and causes erosion. As the roots from the vegetation have been holding the sand dunes together, damaging the vegetation makes the sand dunes more susceptible to erosion. This increases the rate of erosion of the dunes
Give an example of dynamic equilibrium within the coast?
When the rate of weathering exceeds the rate of erosion of fallen material at the foot of the cliff (scree) creating a natural defensive barrier to wave erosion at the foot of a cliff.
give an example of another dynamic equilibrium within the coast?
Constructive waves build up a beach, making it steeper. This encourages the formation of destructive waves that plunge rather than surge. Redistribution of sediment offshore by destructive waves reduces the beach gradient which, in turn, encourages the waves to become more constructive.
