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Geography > Physical: Coastal Systems > Flashcards

Physical: Coastal Systems Flashcards

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1
Q

What is systems theory?

A

Views the world as a complex system of interconnected parts. A collection of processes that transforms inputs into outputs.

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2
Q

What is within the boundary of a system?

A

Elements
Attributes
Relationships

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3
Q

What common characteristics do systems share?

A
  • Abstractions of reality.
  • Have behaviour, involving inputs, processing and outputs of material, information or energy.
  • Have functional as well as structural relationships between eachother.
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4
Q

What are the types of systems?

A

Open systems, closed systems and isolated systems.

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5
Q

What is an open system?

A

Both mass and energy can move across the system boundary.

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6
Q

What is a closed system?

A

May be a flow of energy but no flow of matter takes place.

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7
Q

What is an isolated system?

A

No interaction between the system and surroundings.
They no not exist and are only theoretical.

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8
Q

What are the characteristics of a coast?

A

It is a system, dynamic and a zone of interaction.

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9
Q

What are examples of inputs?

A

Energy, sediment, biogenetic inputs, changes in sea level, human activities.

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10
Q

What are examples of processes?

A

Erosion, longshore drift and depostition.

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11
Q

What are examples of outputs?

A

Erosional landforms, depositional landforms, accumulation of sediment above tidal limit and loss of wave energy.

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12
Q

What is positive feedback? Give an example

A

Positive feedback involves a change and then more change in that direction. E.g. Spit grows and reduces river speed. This causes more accumulation and further reduction.

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13
Q

What is negative feedback? Give an example.

A

Negative feedback involves a change and then change in the other direction. E.g. A slump reduces cliff retreat until the slump material is removed by wave action.

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14
Q

How is the coast dynamic?

A

The position of the coast is continually changing (temporal change) with land being lost by erosion and created by deposition. (Long term like sea level change and short term change like storms.)

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15
Q

What is steady state equilibrium?

A

A situation where variations in energy and the morphological response do not deviate too far from the long-term average.

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16
Q

What is meta-stable equilibrium?

A

Exists where an environment switches from 2 or more states of equilibrium then switch stimulates by some sort of trigger.

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17
Q

What is dynamic equilibrium?

A

The balanced state of a system when inputs and outputs are equal. If something is upset, the system adjusts gradually.

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18
Q

What four factors affect the dynamic equilibrium of a beach?

A
  • The supply of sand.
  • The energy of the waves.
  • Changes in sea-level.
  • The location of the shoreline.
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19
Q

What is the case study for short term change?

A

Beachy Head

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20
Q

What is the case study for long term change?

A

Holderness Coastline.

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21
Q

What terrestrial factors affect the coastline?

A
  • Tectonics
  • Geology
  • Weathering
  • Deposition
  • Biotic features
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22
Q

What marine features affect the coastline?

A
  • Waves and tsunamis
  • Tides
  • Salt spray
  • Biotic features
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23
Q

What human features affect the coastline?

A
  • Buildings
  • Pollution
  • Tourism and recreation
  • Sea defences
  • Conservation
  • Global warming
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24
Q

What atmospheric features affect the coastline?

A
  • Gravity
  • Solar energy
  • Climate (temp, precipitation, winds)
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25
Q

What is the breaker zone?

A

The area where waves break.

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26
Q

What is the offshore?

A

The area past the breaking waves.

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27
Q

What is the surf zone?

A

Seaward of the swash zone, extending out to where the waves break.

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27
Q

Where is the onshore zone?

A

Seaward of the foreshore, where the breaking waves form.

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28
Q

Where is the swash zone?

A

Part of the beach that is alternatively covered and uncovered with water each time a wave arrives.

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29
Q

What is the coast?

A

Part of the land affected by its proximity to the sea, and the part of the sea affected by its proximity to the land.

30
Q

Where is the near shore?

A

Sloping area seaward of the berm, making up most of the foreshore.

31
Q

Where is the coastal zone?

A

Narrow zone where the land and sea overlap and directly interact.

32
Q

Where is the backshore?

A

Landward side of the foreshore. Submerged only during the highest of tides.
Changes only occur during storm activity.

33
Q

Where is the foreshore?

A

Area between the average high tide and low tide lines. The most important zone for marine processes.

34
Q

What is the beach face?

A

The area of land that is next to the sea but not directly affected by it.

35
Q

What are sediment cells?

A
  • Length of coastlines where movement of sediment is largely self-contained.
  • 11 cells in England and Wales.
  • They are (theoretically) closed systems.
36
Q

What is an example of a sediment cell and its inputs, outputs, sources and sinks?

A

South Downs sediment cell 4d: Selsey Bill to Beachy Head.
Input: Wave cut platform may contribute 400m³ of sediment.
Output: Dredging Shoreham Harbour removes 32000m³.
Transfers: Onshore shingle movement or shingle creep in water of 15m or less and kelp rafted sediment (10,000m³)
Sinks: Major store of gravel at Birling Gap is being depleted.

37
Q

What is tidal range?

A

The vertical difference in height of the sea level between high and low tide.

38
Q

What is a storm surge?

A

The pushing of water against a coastline to abnormally high levels, usually a combination of extremely low pressure and high tides.

39
Q

What is a spring tide?

A

Tides that occur twice a month when the sun and moon align on the same side of the Earth. The sun enhances the moon’s gravitational pull. Causes extreme high and low tides.

40
Q

What is a neap tide?

A

Tides that occur twice a month when the moon is at right angles to the Earth. The sun diminishes the moon’s gravitational pull. Causes the higher low tides and lower high tides.

41
Q

What affects the amount of energy on a coastine?

A
  • Air movement- wind speed. Actual speed depends on pressure gradient (High –> Low) (Based on large difference –> Strong winds).
  • Water: in the form on tides, waves and currents. Affected by fetch.
42
Q

What are tides?

A

The periodic rise and fall of the sea level due to the gravitational pull of the sun and the moon.
High and low tides are approx 6 hours, 13 mins apart.

43
Q

What are the characteristics of high energy coastlines?

A
  • Typical landforms include headlands, bays, cliffs and wave-cut platforms.
  • Rate of erosion is higher than deposition.
  • Coastlines where strong, steady prevailing winds create high energy waves.
  • E.g. The Atlantic coasts of northern Europe and north America. (Including SW England on the Cornish Coast).
44
Q

What are characteristics of low energy coastlines?

A
  • Rate of deposition exceeds rate of erosion.
  • Typical landforms include beaches and spits.
  • Examples include many estuaries, inlets and sheltered bays.
  • E.g. The Baltic Sea has a low tidal range and very sheltered waters.
45
Q

What are the names for different tidal ranges?

A

Average= 1 meter
Microtidal= Less than 2 meters
Mesotidal= 2-4 meters
Macrotidal= Greater than 4 meters

46
Q

What are the examples of extreme tidal ranges?

A

Macrotidal is Bay of Fundi, Canada.
Tidal range is 16.3 meters.
Water is funneled into a constricted channel.
Microtidal is the Gibralter Straits.
Tidal range is 0.2 meters.
Very little water passes through.

47
Q

Why is the Severn Bore significant?

A

A tidal bore that can be seen on the tidal reaches of the River Severn in south western England. The sudden influx of water sends a 1 meter high tidal wall up the river which can move upstream at up to 30km an hour.

48
Q

Why are tides significant?

A
  • The larger the tidal wave is, the more extensive the intertidal zone is subject to erosional and depositional processes.
  • Smaller tidal range- more consistently a part of the coastline and will be subject to waves.
  • Significant flow of water into and out of a coastal section can generate strong currents and influence sediment.
49
Q

What are ocean currents caused by?

A
  • Tides, wind and the thermohaline.
50
Q

How do tides influence ocean currents?

A

Flood currents –> up the beach.
Ebb currents –> down the beach.

51
Q

How does the wind influence ocean currents?

A

The gulf stream (North Atlantic Drift)- warm ocean current (affects GB west coast).
Kuroshio current- largest current (east coast of Japan)

52
Q

How does the thermohaline affect ocean currents?

A

Changes in heat and salt content change the density of the water, causing a circulation.
Cold, salty water sinks —> Mixing and upwelling cause rising.
It takes 1000 years to complete a loop.

53
Q

What is the crest of a wave?

A

The top of the wave.

54
Q

What is backwash?

A

The movement of water and load back down the beach due to gravity.

55
Q

What is wave velocity?

A

The speed the wave is travelling at. Influenced by the wind, fetch and depth of water.

56
Q

What is wavelength?

A

The distance between two crests/troughs.

57
Q

What is a trough?

A

The low area between 2 waves.

58
Q

What is wave height?

A

Distance between height of wave crest and trough.

59
Q

What is swash?

A

The movement of water and load up the beach.

60
Q

What is wave frequency?

A

The number of waves per minute.

61
Q

What is a wave period?

A

Time required for wave crest at point A to reach point B.

62
Q

What are the characteristics of constructive waves?

A
  • Gentle wave slope.
  • Locally generated waves.
  • Low and flat.
  • Lower frequency.
  • Swash > backwash.
  • Spilling breaker.
  • Short fetch.
  • Long wavelength.
  • Low energy.
  • Lose a little energy.
  • Long wave period.
  • Gentle wide beach.
  • Deposition.
63
Q

What are the characteristics of destructive waves?

A
  • Plunging breaker.
  • Short wavelength.
  • Long fetch.
  • Lose a lot of energy.
  • Backwash > swash.
  • High and short.
  • Distant storm.
  • High frequency.
  • High energy.
  • Short wave period.
  • Steep wave slope.
  • Steep, narrow beach.
  • Erosion.
64
Q

Why does a wave break?

A

As water depth decreases, wave length becomes shorter and wave height increases to compensate.
Circular motion becomes elliptical as the wave base drags on the seabed and the velocity decreases.
Once ratio of height to length is 1:7, the wave breaks and goes up the beach.

65
Q

What causes the size and energy of a wave?

A
  • How long the wind has been blowing for.
  • The strength of the wind.
  • The fetch.
66
Q

What are the 3 types of current?

A
  • Longshore drift- movement of water and sediment up the beach.
  • Rip currents- currents moving away from the shoreline due to a build up of seawater and energy along the coastline.
  • Upwelling- global patterns circulating within the ocean.
67
Q

Why does erosion occur on a headland?

A

Wave motion is circular until water depth changes. As the wave approaches land, water depth becomes shallower faster at a headland than at a bay. This causes the motion of the waves approaching the headland to become elliptical, but not those approaching the bay. This causes waves approaching a headland to slow down, making the waves bend/be refracted. This wave refraction causes wave energy to be concentrated on the headland, causing high rates of erosion.

68
Q

Why does deposition occur in a bay?

A

However, at a bay, the wave depth stays deeper for longer causing the waves to bend towards the headland. This leads to them being less concentrated on the bay, causing less erosion. Similarly, as the water depth decreases, there is more friction between the water and the seabed, causing the wave to slow down, lose energy and become constructive. This means the wave has a greater swash than backwash and deposition occurs.

69
Q

What are the characteristics of high energy coastlines?

A
  • Landforms include headlands, bays, cliffs and wave-cut platforms.
  • Erosion > deposition.
  • Strong, steady prevailing winds create high energy waves.
  • Examples are the exposed Atlantic coasts of northern Europe and North America.
70
Q

What are the characteristics of low energy coatlines?

A
  • Deposition > erosion.
  • Example is the Baltic Sea due to sheltered waters and low tidal range.
  • Landforms include beaches and bays.
  • Also includes estuaries, inlets and sheltered bays.
71
Q

What is a sediment cell?

A

Theoretically closed systems which are separated by well-defined boundaries, like headlands. Movement of sediment occurs within them. They vary in size and there are 11 around England and Wales.

72
Q

What are the 6 types of erosion?

A
  • Hydraulic action
  • Attrition
  • Abrasion
  • Solution
  • Corrosion
  • Quarrying
73
Q
A

Geography (2 decks)

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