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Geography - Physical > Coastal Systems and Landscapes > Flashcards

Coastal Systems and Landscapes Flashcards

1
Q

Define an open system

A

Inputs and outputs of sediment through a system boundary.

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2
Q

Define a closed system

A

Inputs and outputs of energy but not matter through a system boundary.

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3
Q

Define an isolated system

A

No inputs or outputs of energy or matter.

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4
Q

What system is the coastal system?

A

Open System (energy and matter can enter and leave).

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5
Q

Give an example of a negative feedback cycle in the coastal system

A

1) Sediment eroded from a beach.
2) Sediment deposited forming an offshore bar.
3) Waves forced to break earlier, dissipating their energy.
4) After the storm, waves return offshore bar sediment back to the beach.

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6
Q

What is a small scale coastal system?

A

A beach.

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7
Q

What is a large scale coastal system?

A

A sediment cell. Often bounded by headlands.

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8
Q

What atmospheric condition operates in the UK? (The Ferrel Cell)

A

The Jetstream.

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9
Q

How are waves created?

A

Friction between wind and water transfers energy to water.

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10
Q

What factors determine the amount of energy transferred to waves?

A

Direction of wind
Duration of wind
Strength of wind
Fetch

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11
Q

Define fetch

A

The distance a wave travels interrupted by land masses.

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12
Q

What are some characteristics of waves?

A
  • Circular orbit
  • Wave crest and trough
  • Orbit becomes elliptical because of shore friction.
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13
Q

What are constructive waves?

A
  • Weak backwash, strong swash.
  • Low height.
  • Low frequency, 6-8/min.
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14
Q

What are destructive waves?

A
  • Weak swash, strong backwash.
  • High wave height.
  • High frequency, 10-14/min.
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15
Q

What is wave refraction?

A

Waves approach an irregular coastline, becoming more parallel to the coastline.

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16
Q

Where does wave refraction typically occur?

A

Headlands, high energy concentrated here.

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17
Q

Define currents.

A

The permanent or seasonal movement of surface water in seas and oceans.

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18
Q

How do longshore currents occur?

A

Waves approach in the coastline at an angle, swash in the direction of the prevailing wind, backwash perpendicular to the beach.

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19
Q

What are rip currents?

A

Strong currents moving away from the shoreline. The current flows parallel to the coast before flowing out.

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20
Q

Define upwelling

A

Movement of cold water from deep oceans to the surface. Colder water is more nutrient rich and is responsible for global ocean currents.

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21
Q

Define spring tides

A

Occurs twice a month when sun and moon are parallel to earth. Causes highest monthly tidal range.

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22
Q

Define neap tides

A

Occurs twice a month when sun and moon are perpendicular to earth. Causes lowest monthly tidal range.

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23
Q

Define the coastal sediment budget

A

Measures the inputs and outputs of sediment in a cell and can be used to estimate the net movement of sediment each year.

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24
Q

Define sub-aerial/aeolian processes.

A

Removal of rocks through mechanical, biological, or chemical means.

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25
Q

Define hydraulic action

A

Process by which air is forced into cracks in the rocks, mixture of acid and pressure erodes the cliff.

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26
Q

Define corrasion

A

Advancing waves picking up sediment and throwing it at the cliff face, transferring energy to the cliff.

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27
Q

Define solution/corrosion

A

Weak acids in seawater dissolve minerals such as calcium carbonate in cliffs.

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28
Q

Define attrition

A

Pieces of sediment hit against each other and become smaller, smoother, and rounder over time.

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29
Q

Define mechanical weathering

A

Processes that physically damage the cliff.

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30
Q

What are some examples of mechanical weathering?

A
  • Wetting and drying
  • Crystallisation.
  • Freeze-thaw
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31
Q

Define chemical weathering

A

Breakdown of rocks by changing the chemical composition, Carboniferous limestone dissolved by weak carbonic acids.

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32
Q

Examples of chemical weathering

A
  • Carbonation
  • Oxidation
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33
Q

Define biological weathering

A

Breakdown of rocks from living organisms.

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34
Q

Examples of biological weathering

A
  • Plant roots
  • Birds
  • Decaying material
  • Marine organisms.
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35
Q

What is mass movement?

A

Sudden or gradual movement of sediment downslope due to force of gravity.

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36
Q

What is rockfall?

A

Rapid free fall of rock from a steep, bare cliff face.

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37
Q

What are three features that allow a mudflow to occur?

A
  • Slopes of 10’ or more.
  • Layer of top soil that can be saturated.
  • Impermeable rock below to allow soil to slide as it gets heavier.
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38
Q

What are key features that allow rotational slumping to occur?

A
  • Permeable rock above impermeable rock.
  • Step effect.
  • Undercutting.
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39
Q

What is soil creep?

A

Soil expands at right angles and increases in size and weight. When it dries out, it moves downslope. Very slow and occurs on gentle slopes.

40
Q

What are the four transportation processes?

A

Traction
Saltation
Suspension
Solution

41
Q

Define traction

A

Boulders and other large materials are dragged along seabed.

42
Q

Define saltation

A

Large pebbles and gravel bounce along seabed.

43
Q

Define solution (transport)

A

Dissolved substances are carried in the water.

44
Q

Define suspension

A

Fine material like silt carried by the water.

45
Q

What is a concordant coastline and what landform often occurs here?

A

Rocks are organised in bands of harder and softer rocks parallel to coastline.

Coves occur here e.g. Lulworth Cove

46
Q

What is a discordant coastline and what landform often occurs here?

A

Rocks are organised in band of hard and soft rocks perpendicular to the coastline.

Headlands and bays occur here e.g. Isle of Purbeck.

47
Q

Outline the formation of caves

A
  • Hydraulic action and abrasion
  • Wave energy concentrated on cracks that expand.
  • May form an arch in the future.
48
Q

Outline the formation of headlands and bays

A
  • Harder rocks eroded more slowly, forming headlands.
  • Softer rocks eroded more quickly, forming bays and beaches.
49
Q

Outline the formation of Geos

A
  • Concentrated wave energy and weathering erodes a long vertical crack.
  • Geo is widened by waves over time.
50
Q

Outline the formation of spits

A
  • Caused by change in direction in coastline, prevailing wind blows sediment across a river or body of water.
  • Decrease in wave energy behind spit, forming salt marshes.
51
Q

Outline the formation of barrier beaches/bars

A
  • Spit cuts off an entire body of water.
  • Bar may be infilled over time and start a new cycle of headlands and bays.
52
Q

Outline the formation of a tombolo

A
  • Occurs when a spit connects an island to the mainland.
  • May be eroded by marine processes or be tidal.
53
Q

Outline the formation of sand dunes

A
  • Lots of deposited sand needs to build up.
  • New dunes may form in front of older ones.
54
Q

What are three different types of sea level rise?

A
  • Eustatic
  • Isostatic
  • Tectonic
55
Q

How high has the sea level risen in the Holocene period?

A

120m on average.

56
Q

Are we currently in a glacial or interglacial period?

A

Interglacial

57
Q

What is the name of the current period we are in?

A

Holocene period - started 10,000-12,000 years ago.

58
Q

What is eustatic sea level change?

A
  • Sea level itself rising and falling.
  • Global changes.
  • Affected by human induced climate change (1-2m rise by 2100).
59
Q

What is isostatic sea level change?

A
  • Land rising and falling relative to the sea.
  • Local change.
60
Q

Define tectonic sea level change

A
  • Tectonic activity.
  • Local change.
  • Juan de Fuca plate causing tectonic uplift (1mm/yr).
  • Most changes reverted by large earthquake or volcanic eruption.
61
Q

Define marine regression

A

Where the sea level drops and produces emergent coasts.

62
Q

What are some examples of marine regression?

A
  • Eustatic fall in sea level.
  • Isostatic rebound of earth’s crust.
63
Q

Define marine transgression

A

Where sea level rises and produces submergent coasts.

64
Q

What has led to consistent transgression in the Holocene Period?

A
  • Thermal expansion
  • Melting ice
65
Q

Define emergent coastlines

A

Results of local tectonic uplift or fall in sea level. Often leaves rocky coastlines.

66
Q

Define submergent coastlines

A

Coastlines flooded due to relative sea level rise. Often river valleys flooded by ocean water.

67
Q

What are raised beaches?

A

Isostatic rebound - Glacial ablation allows land to rise.

Can also occur because of tectonic uplift but is restricted to areas of volcanic and earthquake activity.

68
Q

What is a fjord?

A

Carved from mountainous glaciers, usually several km thick. Abrasion of material dragged down mountain.

69
Q

What key characteristics does a fjord have?

A
  • Longer than it is wide.
  • Mountains often range up to 1km above sea level around fjord.
70
Q

What are rias?

A

Flat, low lying areas. Commonly nicknamed a ‘drowned valley’. Common in SE England where sea levels rose following deglaciation period.

71
Q

What are dalmation coasts?

A

Forms where ridges and valleys are parallel to coastline and have been flooded. The ridges stay exposed.

72
Q

Why do people manage coastal areas?

A
  • 1 billion people live near the coastline.
  • 50% of the population live within 60km of the coast.
  • 75% of large cities are coastal.
  • Coastlines are very economically active for shipping and trade.
73
Q

Define hard engineering

A

Man-made structures that physically protect the coastlines.

74
Q

What are two different types of management plans?

A

SMP - Shoreline Management Plan

ICZM - Integrated Coastal Zone Management

75
Q

In the SMP in the UK, what are DEFRA’s four terms that are used for each plan?

A
  • Hold the line
  • Advance the line
  • Managed retreat/realignment
  • No active intervention
76
Q

Describe a sea wall

A

Hard engineering

A solid barrier that reflects waves back out to sea. Reduces erosion against flooding.

77
Q

What are the advantages and disadvantages of sea walls?

A

+ Reduces erosion and lowers flooding risks.
- Expensive to build and maintain.
- Stronger backwash can undercut the sea wall and erode underneath.

78
Q

Describe gabions

A

Hard engineering

Rock filed cages usually placed at the foot of cliffs to absorb wave energy.

79
Q

What are the advantages and disadvantages of gabions?

A

+ Relatively cheap
+ Very good temporary solution
- Can be unappealing
- Cliffs can still be eroded.

80
Q

Describe groynes

A

Hard engineering

Fences or boulders built perpendicularly to coastline. Trap material moving by longshore drift.

81
Q

What are the advantages and disadvantages of groynes?

A

+ Usually cheap
+ Widens beaches and reduces erosion in that area.
- Increases erosion further along coastline, beach starved of sediment.

82
Q

Describe breakwaters

A

Hard engineering

Concrete blocks or boulders dropped off coastline, forcing waves to break earlier.

83
Q

What are the advantages and disadvantages of breakwaters?

A

+ They can physically reduce the wave energy before it reaches coastline.
- Quite expensive
- Can be damaged by large storms.

84
Q

Define soft engineering

A

Use of natural looking structures that improve sustainability and are less visually pollutive.

85
Q

Describe beach nourishment

A

Soft engineering

Sand and shingle added to beaches from other areas.

86
Q

What are the advantages and disadvantages of beach nourishment?

A

+ Cheap if done once
+ Creates wider beaches
- Often has to be repeated which can become expensive

87
Q

Describe dune regeneration

A

Soft engineering

Sand dunes are created or repaired by readding or stabilising sand.

88
Q

What are advantages and disadvantages of dune regeneration?

A

+ Cheap to start
+ Allows wave energy to be absorbed
- Can be difficult to encourage growth of dunes
- Expensive to maintain

89
Q

Describe land use management

A

Soft engineering

Use of physical structure to limit the levels of activity on certain areas of coastline.

90
Q

What are the advantages and disadvantages of land use management?

A

+ Reduces vegetation loss from specific areas.
- Can be expensive
- Requires coordination from the public.

91
Q

Describe managed retreat

A

Soft engineering

Planting of vegetation or reducing wave power by breaching existing flood defences and flooding the area behind.

92
Q

What are the advantages and disadvantages of managed retreat?

A

+ Created salt marsh ecosystems which are dying out.
- Requires coordination from all stakeholders, agriculture hit badly.
- Expensive to remove existing defences.

93
Q

Define coastal accretion

A

Movement of sediment from the sea back to the foreshore/backshore. Usually occurs after submersion in stormy periods.

94
Q

Define brackish water

A

Water with a grater salt content than fresh water but lower than sea water. Common in tidal zones and spits. Ideal for mangroves.

95
Q

Define halophyte

A

An organism that can tolerate salt water.

96
Q
A

Geography - Physical (18 decks)

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