Coastal System

Question 1

What is a coast?

Answer 1

• narrow zone where land a sea overlap
• dynamic environment - influences from atmospheric, terrestrial and marine processes and from humans

Question 2

How can the coast change over different time scales?

Answer 2

• hours - tides
• days - weather - waves
• weeks/months - erosion/transport
• years - development of landforms
• millennia - sea level change

Question 3

Coastal system inputs

Answer 3

• wave energy
• wind energy
• tidal energy
• sea currents
• sea level change
• longshore drift
• geology of coastline

Question 4

Coastal system stores

Answer 4

• erosion landforms (e.g. cliffs)
• deposition at landforms (e.g. spits, beaches)

Question 5

Coastal system outputs

Answer 5

• dissipation of wave energy
• accumulation of sediment ABOVE the tidal limit
• sediment removed beyond local sediment cells

Question 6

Coastal Systems Key Flows/Transfers

Answer 6

• erosion
• mass movement
• weathering
• transportation
• deposition

Question 7

Negative Feedback in Coastal system example

Answer 7

• diminishing effect, returns beach to equilibrium

1. Beach in dynamic equilibrium
2. Sediment eroded from beach during storm by destructive waves
3. Sediment deposited offshore (forming an offshore bar)
4. Waves forced to break out at sea. Energy dissipated and reduces erosion of beach
5. After storm, constructive waves return and redistribute sediment from offshore bar back onto the beach
6. Dynamic equilibrium

Question 8

Positive feedback in coastal system example

Answer 8

• amplifying effect

1. Vegetation on sand dune trampled on by tourists
2. Sand becomes exposed
3. Sand eroded by the wind
4. Vegetation struggles to re-grow and hold the dunes together
5. Back to step 2 and repeat