Coasts As Natural Systems

Question 1

What are the inputs in coastal systems?

Answer 1

Energy from:
Waves
Wind
Tides
Sea Currents
Sediment
Geology of coastline
Sea level change

Question 2

What are the stores in coastal systems

Answer 2

Erosional landforms and landscapes
Depositional landforms and landscapes

Question 3

What are the outputs in coastal systems

Answer 3

Dissipation of wave energy
Accumulation of sediment above tidal limit
Sediment removed beyond local sediment cells.

Question 4

Give an example of negative feedback in a coastal system

Answer 4

A beach is eroded
Cliffs behind it exposed to waves
Sediment eroded from cliffs is deposited on the beach
Causes beach to grow in size again

Question 5

Give an example of positive feedback in a coastal system

Answer 5

As a beach starts to form it slows down waves
This causes more sediment to be deposited, increasing size of beach

Question 6

What are the UK sediment cells?

Answer 6

11 sediment cells that stretch around the coastline of England and Wales.

Within each cell, sediment is
recycled, maintaining a state of balance - closed sediment systems

Each cell can be seen as a system in which there are clear inputs, transfers and stores.

Within each cell changes may occur
leading to feedback, either positive or negative

Question 7

Although sediment cells are generally seen as closed systems where would there be loss of sediment?

Answer 7

To outputs beyond the system
Eg) if wave energy is very high or currents very strong, then sediment may be transferred to neighbouring cells, lost to deeper sea areas off-shore or be transferred to stores beyond the active coastal zone. Eg) mudflats

When sediment is permanently lost to the system, destinations are known as sediment sinks.

Question 8

What are the different zones of a beach?

Answer 8

Backshore - area between high water mark (HWM) and limit of marine activity, changes only take place here during storms.

Foreshore - area between HWM and the Low water mark (LWM). Most important zone for marine processes.

Nearshore - area between LWM and point where waves no longer have effect on land beneath them.

Offshore - area beyond the point where waves cease to impact upon the seabed.
Activity is limited to deposition of sediments.

Question 9

What are the sediment budgets?

Answer 9

Coastal systems can be seen operating at various scales.
An individual beach can be seen as
a sediment store that has inputs and outputs. If inputs of sediment exceed outputs then the beach will extend in height, length or width.
would result in a positive sediment budget.

If outputs exceed inputs the beach will become smaller over time (a negative sediment budget).

By tracking the changes in and movement of sediment within a cell we can better understand the connections within
the system.