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la geografía 2 > Coastal Changes And Conflict > Flashcards

Coastal Changes And Conflict Flashcards

1
Q

When is a discordant coastline created?

A

When waves hit a coastline composed of hard and soft rock

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2
Q

When are concordant coastlines formed?

A

When the rock type is the same parallel to the coast

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3
Q

How do coves form?

A

Wave energy erodes joints and faults in resistant rock and expands them as this section of rock is weaker and easier to erode, the sea then reaches and erodes softer rock behind which can be eroded more quickly than the hard rock

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4
Q

How do headlands and bays form?

A

On a discordant coastline there are layers of resistant rock and less resistant rock which erode at different rates

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5
Q

How do stumps form?

A

Cracks are opened up by hydraulic action then grow into a cave by hydraulic action and abrasion which breaks through the headland to form a natural arch, the arch is eroded leaving a stack which is eroded to form a stump

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6
Q

How is a wave cut platform created?

A

Hydraulic action opens cracks in the rock and this area becomes more resistant to erosion which forms a wave cut notch, the wave cut notch becomes too deep and the cliff face falls but the process of hydraulic action continued which causes the cliff to recede

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7
Q

What happens to the process of erosion on a wave cut platform?

A

It decreases

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8
Q

What is longshore drift?

A

The movement of material along the coast by waves which approach it at an angle but recede directly away from it

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9
Q

What is a factor affecting the amount of material deposited by long shore drift?

A

Amount of wind

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10
Q

When are spits formed?

A

When longshore drift is fuelled by a strong prevailing wind blowing at an angle to the coastline

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11
Q

What is a spit?

A

An narrow extended stretch of beach material which projects out to sea and is joined to mainland at one end

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12
Q

When is a spit prevented growing any further?

A

When the river outlet removes material

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13
Q

Why do recurved laterals form?

A

Change in wind direction

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14
Q

Why do salt marshes form?

A

Due to deposition behind spit which is an area sheltered from wind and waves

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15
Q

Why do bars form?

A

When there is no river to prevent the spit’s movement continuing meaning it extends across a bay and leaves a lagoon behind it

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16
Q

How do storm beaches form?

A

Found behind normal beaches and are composed of pebbles because storm waves penetrate further and carry heavier sediment

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17
Q

Why don’t sand dunes get blown away?

A

The grasses planted on them stabilise them

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18
Q

Two examples of ecosystems

A

Lagoons, marshes

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19
Q

What are 4 negative affects of development on a coastline?

A

Housing and offices change the look of an area, weight of buildings increases cliff vulnerability, changes in drainage increase saturation, pollution due to increase of people

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20
Q

What are 2 positive affects of development on a coastline?

A

Money brought to area, raises interest in protecting coastal landscapes

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21
Q

What are 4 negative affects of agriculture on a coastline?

A

Vegetation changed as it is cleared and crops are grown in its place, soil erosion, increased sedimentation, fertilisers and pesticides seep into local water supplies

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22
Q

What is a positive affect of agriculture on a coastline?

A

Wildlife habitats created and preserved

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23
Q

What are 3 negative affects of industry on a coastline?

A

Sea industries locate on the coast which alters the look of an area, cause soil water and air pollution, destroy natural habitats for birds animals and sea life

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24
Q

What is are 2 positive affects of management on a coastline?

A

Coastal defences slow erosion, some sand dunes and salt marshes and sand bars and spits are preserved

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25
Q

What is a negative affect of management on a coastline?

A

Stops the supply of sediment through longshore drift to areas further along the coastline

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26
Q

What are two reasons sea levels are rising?

A

Glaciers melt and water enters seas and oceans, water in seas and oceans is warming which has a larger volume than cold water because the particles vibrate (thermal expansion)

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27
Q

When is coastal flooding worst?

A

When the spring tide and very low pressure coincide for example during a depression or cyclone

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28
Q

What happens to the surface of the sea in low pressure?

A

The surface domes and wind blows the dome of water towards the land as a storm surge

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29
Q

How often do high tides occur?

A

Twice a day

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30
Q

How often do spring tides occur?

A

Twice a month

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31
Q

What is hard engineering?

A

The use of solid structure to resist the forces of erosion

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32
Q

What is soft engineering?

A

The use of natural processes to cope with forces of erosion

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33
Q

How does rip rap/rock armour work?

A

Large rocks at the foot of cliffs absorb and dissipate wave energy, igneous rocks provide most resistance to erosion

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34
Q

How do recurved sea walls work?

A

Long concrete walls at the base of cliffs absorb wave energy and have a recurved face to reflect it back into the sea

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35
Q

How do groynes work?

A

Wooden rock or concrete defences stretch from the coastline to the sea and prevent longshore drift so sand builds up on the side of it , widening the beach and creating a buffer between waves and cliffs

36
Q

How do gabions work?

A

Wire cages filled with rocks absorb wave energy to reduce erosion as it doesn’t reach the cliff behind

37
Q

How does beach replenishment work?

A

The placing of sand and pebbles on a beaver to make is wider

38
Q

How does slope stabilisation work?

A

Drains at the top of cliffs remove groundwater, preventing rocks becoming saturated and reduces slumping . Wire mesh placed over cliffs and piles and long nails hold them in place

39
Q

Give two advantages of rip rap/ rock armour

A

Can be very cheap (£300 per metre), effective for many years

40
Q

Give three disadvantages of rip rap/ rock armour

A

Unattractive, make beach inaccessible, ineffective in storm conditions

41
Q

Give 3 advantages of recurved sea walls

A

Effective for many years, make residents feel safe, protects cliffs and buildings

42
Q

Give three disadvantages of recurved sea walls

A

Expensive to build and maintain (£3000 per metre), can deflect waves if positioned incorrectly and cause scouring of the sea bed which reduces water clarity, make beach unattractive

43
Q

Give two advantages of groynes

A

Effective for many years, keeps beach in place

44
Q

Give three disadvantages of groynes

A

Expensive at £5000, look unnatural, disrupts longshore drift therefore exposes other areas of the coastline to erosion

45
Q

Give an advantage of gabions

A

Cheaper style of wall at £100 per metre

46
Q

Give two disadvantages of gabions

A

Not very strong, if cages break material used in abrasion is added to sea

47
Q

Give 4 advantages of beach replenishment

A

Beaches for tourists, quite cheap, look natural, sand reduces wave energy

48
Q

Give 3 disadvantages of beach replenishment

A

Sea continues to erode it, needs to be replaced every few years, expensive

49
Q

Give three advantages of slope stabilisation

A

Mass movement is less likely, safer on beach, keeps cliffs in place

50
Q

Give 3 disadvantages of slope stabilisation

A

Expensive, difficult to install, foot of cliff still needs protection from waves

51
Q

What are 7 factors to consider when choosing a coastal defence?

A

Geology, effectiveness, cost, appearance, durability, land use, installation

52
Q

What is integrated coastal zone management?

A

A holistic approach that takes into account the needs of different groups of people, economic costs and benefits of current and future strategies, the environment on land and in sea. Involves holding the line, doing nothing, advancing the line or strategic realignment

53
Q

What does hold the line mean?

A

Use sea defences to stop erosion so that the coast stays where it is

54
Q

What does advance the line mean?

A

Use sea defences to move the coast further into the sea and make more land

55
Q

What is strategic realignment?

A

Gradually letting the coast erode and moving people at risk away

56
Q

Give 2 benefits of strategic realignment

A

Less maintenance, people and activities move inland

57
Q

Give four costs of strategic realignment

A

Evacuation, expensive, lack of tourism, erosion therefore is unpopular with local residents

58
Q

Define discordant coastline

A

Rock strata is at right angles to the coast

59
Q

What is the difference between joints and faults?

A

Joints are small cracks in rock, faults are large cracks

60
Q

Identify 5 factors which determine rate of coastal erosion

A

Geology most important (soft rock eroded faster than hard), geological structure (whether soft and hard rockjs occur together), ‘wave climate’, local currents and tidal range (difference between low and high tide heights), groundwater levels (saturated cliffs with high groundwater are more vulnerable)

61
Q

What 4 things does wave climate take into account and how does this increase rate of erosion?

A

Power of waves, fetch (how far winds travel over open water), wave height, wave direction (destructive waves with a long fetch are more erosive, storms and strong winds increase eroding power of waves)

62
Q

2 characteristics of a destructive wave

A

Weak swash and strong backwash so material is dragged back down the beach into the sea

63
Q

Identify 4 ways waves erode the coast

A

Solution, attrition, abrasion, hydraulic action

64
Q

Define abrasion

A

Breaking waves throw sand and pebbles or boulders at the coast during storms

65
Q

Define attrition

A

Rocks and pebbles carried by the waves rub together and break into smaller pieces

66
Q

Define hydraulic action

A

Sheer weight and impact of water erodes the coastline, waves compress air in cracks in the rock causing them to expand and weakening the rock

67
Q

How does the UK climate increase coastal erosion? 3 ways

A

Four seasons have different impacts on coastal erosion (cold temperatures in winter lead to freeze thaw), prevailing winds are from the south West bringing warm moist air from the Atlantic and frequent rainfall which leads to weathering and mass movement, storm frequency is high in many parts of the UK so coasts are often subject to strong winds leading to an increase in eroding power of waves and also leading to heavy rainfall contributing to mass movement

68
Q

Define sub aerial processes

A

Processes that impact on the land (weathering and mass movement)

69
Q

What kind of weathering is freeze thaw and when is it most effective?

A

Mechanical. When temperature rises above and falls below 0

70
Q

When does chemical weathering occur? + 2 examples

A

When rock’s mineral composition is changed. Granite contains feldspar which converts to soft clay minerals when it reacts with water, limestone dissolved by carbonation (carbon dioxide combines with rainwater to form carbonic acid which changes calcium carbonate into calcium bicarbonate which is carried away by water in solution)

71
Q

Define mass movement

A

Downhill movement of material under the influence of gravity. Different typed of mass movement depend on: material involved, amount of water in material, nature of the movement (falls, slips, slides)

72
Q

Define coastal retreat

A

When the coast moves further inland

73
Q

5 steps of longshore drift

A

Waves approach coast at angle, swash pushes sand and gravel up beach at same angle, backwash carries sand and gravel back down beach at 90 degrees to coastline under force of gravity, sand and gravel move along beach in zig zag fashion, sand is lighter than gravel so is carried further up the beach

74
Q

4 characteristics of constructive waves

A

Load carried by waves id deposited by these waves which have a strong swash (break gently and carry material up beach), weak backwash (does not erode material already on the beach), are long in relation to their height and their crest breaks forward

75
Q

Identify 3 factors which influence deposition by reducing the wave’s energy

A

Calm conditions, sheltered spots like bays, gentle gradient offshore causes friction

76
Q

What is a beach?

A

Accumulation of sand and shingle formed by deposition and shaped by erosion, transportation and deposition

77
Q

Identify 4 ways waves transport material

A

Traction, solution, suspension, saltation

78
Q

What is a positive impact of industry on the coast?

A

Brings wealth and jobs to an area

79
Q

What are 2 negative affects of tourism on the coast?

A

Increased development for hotels impacts on natural processes, increased litter and noise and air pollution

80
Q

What are 2 positive affects of tourism on the coast?

A

Increased revenue benefits people living there, increased desire to protect and preserve landscape so tourism continues

81
Q

How does geology influence erosion on the Dorset coastline? 3 points

A

At Lulworth Cove waves have cut through the resistant Portland stone and eroded into softer sands and costs behind to form a perfect horseshoe shaped cove, Durdle Door is a natural coastal arch carved out of Portland limestone at Lulworth Cove, at Studland Bay the chalk cliffs have been dramatically eroded into a series of stacks and stumps called Old Harry Rocks

82
Q

How does weathering influence erosion on Dorset’s coastline?

A

Weather is warm so salt crystal growth is a predominant type of physical weathering (salty water is thrown up by the sea lands in the cliffs, the water evaporates and leaves behind salt which forms crystals which grow and weaken the rocks)

83
Q

How does industry influence erosion on the Dorset coastline? 7 points

A

Dredging the seabed for sand and gravel leads to increased erosion along the coastline, many specific tourist resorts such as Bournemouth and Swanage, investment banks such as JP Morgan -this one bank employs 4000 people, Britain’s sixth largest oil field is located at Poole Harbour, high quality limestone is quarried on the isle of Portland, sheltered harbours like Portland provide direct access to the English Channel therefore are major shopping routes for imports/exports to/from Europe, Bournemouth Conference Centre is a service industry that helps to provide year-round jobs

84
Q

How does climate change increase flood risk in the UK? 3 points

A

As atmospheric temperature rises it is likely storm frequency and strength will rise which can increase height and strength of waves reaching the coast, increase in heavy rainfall would increase weathering and mass movement, as sea temperatures rise thermal expansion occurs so sea levels rise

85
Q

Identify 4 future effects on coastlines of climate change

A

Erosion may increase causing some beaches to disappear, depositional features like spits may be submerged or destroyed, natural ecosystems and habitats may be destroyed, increased risk of coastal retreat and cliff collapse

86
Q

Identify 6 effects of increased flood risk on people

A

Storm surges put people at risk of injury or death, psychological impacts of losing homes/livelihoods, settlement need to be moved or defended which will be expensive, coastal tourism may diminish, flooding of rods and damage to railways makes transport more difficult, loss of agricultural land affects food production and economy

87
Q

How does coastal management affect erosion on the Dorset coastline?

A

Much of the Dorset coastline is valuable for tourism so has been protected, Swanage Bay and Bournemouth beach both have groynes and a sea wall and use beach replenishment to add sand to the beach

la geografía 2 (5 decks)

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