Block 1 (The Operation Of The Coast As A System)

Question 1

Define system

Answer 1

• Set of interrelated components working towards a process

- Made up of: inputs, processes (stores + transfers), outputs

Question 2

Define coast

Answer 2

Point where land, sea and atmosphere meet

Question 3

What are the three types of systems?

Answer 3

• Open
• Closed
• Isolated

Question 4

Define open system

Answer 4

Energy and sediment can be input/output

E.g. coast

Question 5

Define closed system

Answer 5

Energy (not sediment) can be input/output

E.g. sediment cells (in theory)

Question 6

Define isolated system

Answer 6

Nothing can be input/output

E.g. the Universe

Question 7

What type of system is the coast?

Answer 7

Dynamic, open system

Question 8

What are the processes by which energy and sediment can be input/output?

Answer 8

• Sea (waves, tides, currents)
• Fluvial (rivers, estuaries) (BIGGEST FACTOR)
• Aeolian (wind)
• Anthropogenic (human - e.g. nourishment and dredging)

Question 9

How can sediment be stored?

Answer 9

Coastal landforms

Question 10

How can sediment be transferred?

Answer 10

• Transportation methods in water: solution, suspension, saltation, traction
• Transportation methods on land: suspension, saltation, creep
• LSD

Question 11

What are the supplies of sediment (where the sediment comes from)?

Answer 11

• Terrestrial (land) - coastal erosion
• Offshore (sea) - seabed, offshore landforms (bars, etc)
• Other (river + estuaries - 85% sediment from here) (humans)

Question 12

Define sediment budget

Answer 12

Balance between inputs, stores and outputs of sediment

Question 13

How do you calculate the sediment budget?

Answer 13

Sediment input - sediment output

If answer is negative - erosion increased

Question 14

Define sediment cell

Answer 14

A length of coastline and its associated nearshore area within which the movement of course sediment is largely self contained

Question 15

What type of system are sediment cells?

Answer 15

Closed - in theory only energy is transferred

BUT - finer sediment can sometimes move between cells

Question 16

How many sediment cells are there in England + Wales

Answer 16

11

Question 17

Give an example of a sediment cell

Answer 17

• Sediment cell 3
• NE Norfolk
• The Wash - The River Thames

Question 18

What separates sediment cells?

Answer 18

• Headlands
• Deep water
• Convergence of currents or LSD

Question 19

Define sub cells

Answer 19

Largely self-contained sediment within a cell - e.g. beaches

Question 20

Define equilibrium in a system

Answer 20

Equal inputs and outputs

Question 21

What are the 3 types of coastal equilibrium

Answer 21

• Steady state
• Meta-stable
• Dynamic

Question 22

What is steady state equilibrium

Answer 22

Variations in energy and the morphological (land) responses don’t deviate much from long-term average

• Flat graph
• E.g. beach profile maintains same average gradient

Question 23

What is meta-state equilibrium

Answer 23

Coastal system switches between two or more states of equilibrium, stimulated by a trigger

• Flat, increase, flat, decrease, flat graph
• E.g. summer and winter beach

Question 24

What is a dynamic equilibrium

Answer 24

State of equilibrium gradually changes over long period

• Gradually rising graph
• E.g. climate change causing coasts to slowly change due to rising sea levels

Question 25

What is negative feedback?

Answer 25

Feedback processes reduce the effect of the change - helping coast return to original state

• E.g. erosion of toe causes landslides, more material on beach, decreases erosion rates

Question 26

What is positive feedback?

Answer 26

Feedback processes amplify the initial change

• E.g. wave energy increases, erosion removes vegetation, erosion rates increase further as wind able to blow away more sand

Question 27

Outline a case study example of a sediment cell

Answer 27

North-East Norfolk 
Location:
- NE Norfolk 
- East coast of England
- Sediment cell 3
- The Wash-River Thames

Sediment mostly self contained

Sources include:

• Other-rivers
• Terrestrial-cliff erosion
• Offshore

Sinks include:
- Landforms, e.g. spit - Blakeney Point

Type of equilibrium:

• Naturally dynamic (sea levels rising, erosion increasing)
• Humans are trying to enforce steady state (hard defences, e.g. groynes) (disrupting sediment movement within cell)