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Glaciated Landscapes > Unit 6 Notes > Flashcards

Unit 6 Notes Flashcards

1
Q

What type of lake develops behind a moraine?

A

A pro glacial lake

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2
Q

How many deaths were caused globally from GLOF’s?

A

12,445

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3
Q

What are the most affected regions by GLOF’s?

A

Central Asia, South America, European Alps, Iceland.

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4
Q

What are the causes of GLOF’s?

A

Triggers of wave generation, Dam failure.

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5
Q

What are the triggers of wave generation?

A

Contact glacier calving, icefall from hanging glaciers, rock, ice, snow avalanches, rapid input of meltwater, seismic activity.

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6
Q

What are the conditioning factors for dam failure?

A

Large lake volume, low point in dan wall, melting of buried ice, seismic activity.

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7
Q

What are the stages of a GLOF?

A

Formation of displacement waves in the lake, dam failure, resultant flood wave down valley.

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8
Q

What is contact glacier calving?

A

Large blocks of ice fall into a lake, displacing a large volume of water.

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9
Q

What is icefall from hanging glaciers?

A

The impact from rock hitting water generates a ripple effect, creating waves.

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10
Q

What is seismic activity?

A

When the ground shakes, sediment falls off, generating waves, moving water.

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11
Q

What are the dam failure causes of GLOF’s?

A

Rapid input of meltwater, large lake volume, melting of buried ice in the moraine structure, seismic activity.

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12
Q

What does rapid input of meltwater cause?

A

The lake will overflow, leading to dam failure, as more pressure is put on it.

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13
Q

What does large lake volume?

A

Easier for water to move over dam, weakening it.

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14
Q

What does melting of ice in the moraine structure cause?

A

If ice melts, as it’s holding sediment together, it will weaken, allowing water to push over the dam.

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15
Q

What happens as temperatures increase?

A

If ice which holds material together melts, dams are more likely to topple over. Flooding becomes more hazardous and severe, as there is more water, and they’re going to become more frequent. All trigger mechanisms except seismic activity increase due to climate change.

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16
Q

What is the case study for glof’s?

A

Bhutan - Lake thorthormi.

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17
Q

What is the profile of Lake Thorthormi?

A

Covers an area of 3.42km. If there was a glof, 53 million metres of water would be released, 117 buildings, 362 people, 16 monuments, 5.22km of road would be affected. Three major hydro power projects could be destroyed.

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18
Q

Why is Lake Thorthormi a potential threat to society?

A

It’s made up of supraglacial lakes, which have become interconnected.

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19
Q

What has glacial meltwater in the area done for locals?

A

Provided jobs for 350 workers, who drain water, improving local enterprise development.

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20
Q

What were the socio economic impacts of the 1994 Lugge Tsho GLOF?

A

91 households were affected, 12 houses were damaged, 816 acres of dry land were damaged, 24 people died.

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21
Q

Which strategy did the government use to manage the GLOF?

A

Lake lowering - the aim is to enhance adaptive capacity, to prevent climate change.

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22
Q

What are the benefits of lake lowering?

A

Provides drinking water, irrigation systems, hydroelectric power.

23
Q

What have the challenges been of lake lowering?

A

The air is thinner, meaning it’s harder to ignite, creating pressure.

24
Q

What have the effects of lake lowering been?

A

Water volume has reduced by 3.63 metres, which was below the target of 5 metres, but the lake avoided predictions of a GLOF in 2010.

25
Q

Where was there a GLOF in 2023?

A

India - Where lake lowering could have reduced the number of people who died in this situation.

26
Q

Where are many reservoirs located?

A

Upland glaciated areas by constructing dams across glaciated valleys.

27
Q

Why are glacial troughs ideal sites for constructing dams and reservoirs?

A

Steep slopes, narrow valleys, high precipitation, low population density, hard, impermeable rock, high levels of rainfall.

28
Q

What are the arguments for constructing reservoirs in glacial areas?

A

They have enabled people to collect and save water, they ensure water is still available without having to harm the environment, creates jobs in construction.

29
Q

What are the arguments against reservoir construction?

A

Land could be used as agricultural land, could cause displacement of people, changes flow patterns of people, requires significant initial funding.

30
Q

When were the Elan valley reservoirs built?

A

Between 1893 and 1904, by Birmingham city council, providing a safe, clean source of water.

31
Q

Which locations were chosen for the reservoirs, and why?

A

Elan and Alarewen rivers were dammed to create reservoirs, because they had high levels of rainfall.

32
Q

How were narrow valleys used?

A

They were easy to dam, and impermeable bedrock allows large amounts of water to collect in to refill reservoirs.

33
Q

What were the disadvantages of dam construction?

A

Over 100 people were relocated, some didn’t receive compensation. Two churches and a school were flooded, and 18 farms. Dams provide hydroelectric energy to people in the area.

34
Q

Which areas near Birmingham contain deposits of sand?

A

Parts of the midlands, and the south.

35
Q

What are the uses of sand and gravel?

A

Road construction - mix with asphalt. Production of construction materials - concrete blocks, bricks, pipes. Icy roads in winter, water filtration, glass making.

36
Q

Where is the case study of sand and gravel quarrying?

A

Ellesmere, 15km north of shrewsbury.

37
Q

What are the negatives of sand and gravel extraction?

A

Natural outlook of land is ruined, dust would be generated, increased traffic, more congestion, hole in the ground could become a landfill site.

38
Q

What are the positives of sand and gravel extraction?

A

More than 180 species of bird have been recorded at the nature reserve, local sand and gravel extraction reduces overall co2 emissions, suffering of local people is offset by overall national impact.

39
Q

Which fish have been seen at the reserve?

A

Sand martin, kingfisher, heron.

40
Q

How is climate change affecting the active layer?

A

It’s increasing the rates of thawing.

41
Q

What are the causes of melting permafrost globally?

A

Buildings and infrastructure, Trans-Alaskan pipeline.

42
Q

How do buildings and infrastructure cause melting permafrost globally?

A

The heat from buildings can be transferred to the ground, which melts permafrost.

43
Q

How do some buildings reduce effects on the outside?

A

Some buildings are built on stilts, reducing effects, as buildings start to sink. Outside of buildings are metal, stopping heat from escaping.

44
Q

How much does thaw related damage in Alaska?

A

$35 million a year, as roads increase melting of permafrost.

45
Q

What is the history of the trans-Alaskan pipeline?

A

Pipeline was completed in 1977, pumping oil, causing permafrost to thaw, as oil is pumped through pipeline at 80 degrees.

46
Q

How does the pipeline stop permafrost melting, and how much does this cost?

A

Built on elevated thermosyphon piles, to help keep the ground frozen. Cost - $800 million extra, and the pipeline in total cost $8 billion.

47
Q

What will melting permafrost cause in the future?

A

Melting permafrost causing breaks in the pipeline will cost $2 billion per mile.

48
Q

What is thawing of permafrost causing in Siberia?

A

Leaving mounds, hollows, ponds and lakes, and less pasture land.

49
Q

What are the impacts of permafrost melting in Siberia?

A

Ground has fallen away, and become less even. Organic matter releases methane which goes into the atmosphere.

50
Q

What management strategies are being used in Siberia?

A

Local farmers and residents are putting scrap onto permafrost lakes, building on stilts.

51
Q

What is burning of fossil fuels doing to tundra regions?

A

They have caused global warming, and overall temperatures have increased by 1.2 degrees since 1880. In tundra regions, temperature has increased by up to 4 degrees, causing permafrost to melt.

52
Q

What are the effects of increased temperature in tundra regions?

A

Plants decomposing, C02 releasing, methane releasing, which is 23x more potent than C02. Methane emissions from the arctic increased by 31% from 2003-2007. By 2090, it’s predicted there will be warming by up to 10 degrees celsius?

53
Q

What is the positive feedback loop for glacial environments?

A

Temperatures increase by 4 degrees, permafrost melts, methane is released, albedo changes, so surfaces are lighter. More warming takes place, as rays aren’t reflected.

Glaciated Landscapes (13 decks)

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