Coasts as Natural Systems

a system

a set of things working together or interacting as parts of a mechanism or an interacting network

What is a coastal example of a system?

a sediment cell

input

material or energy moving into the system from outside

What are some coastal examples of inputs?

• precipitation 

• wind

output

material or energy moving from the system to the outside

What are some coastal examples of outputs?

• ocean currents

• rip tides

• sediment transfer

• evaporation 

energy

power or driving force

What are some coastal examples of energy?

• flowing water

• gravity

• moving air (wind energy)

• wave energy

stores/components

the individual elements or parts of a system

What are some coastal examples of stores/components?

• beaches

• sand dunes

• sediment

controls

attributes of an area that are controlled by stores/components

What are some coastal examples of controls?

• geology

• climate

• rock structure

• sea level

flows/transfers 

the links or relationships between stores/components

What are some coastal examples of flows/transfers?

• mass movement processes 

• longshore drift

• wind-blown sand

positive feedback

where a flow/transfer leads to increase or growth

What is a coastal example of positive feedback?

coastal management sometimes inadvertently leading to an increase in erosion elsewhere along the coast

negative feedback

where a flow/transfer leads to decrease or decline

What is a coastal example of negative feedback?

1. the rate of weathering and mass movement exceeding the rate of cliff-foot erosion

2. a scree slope is formed

3. the apron of material extends up the cliff face

4. the cliff face is protected from subaerial processes

5. a reduction in the effectiveness of weathering and mass movement

dynamic equilibrium

a state of balance within a constantly changing system

What is a coastal example of dynamic equilibrium?

when erosion from the system and deposition on beaches are equal, balancing the sediment budget