Human activity in periglacial landscapes

Question 1

Describe the Alyeska pipeline:

Answer 1

• 1300km long
• From Prudhoe Bay to Valdez
• Transports up to 1.4million barrels per day

Question 2

How much oil did the US consume in 2014?

Answer 2

6.95 billion barrels

Question 3

How much oil is imported to US + why is this a concern?

Answer 3

40% is imported

Concern as grave political implications of not having energy security

Question 4

Exploration of Alaska’s oil fields has been permitted, describe the area of interest:

Answer 4

Area 1002 in the Arctic National Wildlife Refuge contains an estimated 16 billion barrels

Question 5

Benefits of extracting oil from Area 1002:

Answer 5

Increased employment opportunities

Can use the existing Alyeska pipeline

Question 6

How are material flows affected by extraction and transportation? x2

Answer 6

• Gravel extracted from river beds and used as insulating base layer for road construction
  Loss of gravel = alert rate at which gravel is transported and deposited downstream and affects equilibrium between erosional and depositional processes
• Hydrological processes affected as glacial outwash aquifer near Palmer found that ground water levels fell by more than a metre over 2km from extraction site

Question 7

How are energy flows affected?

Answer 7

1. Release/burning of gas during drilling releases CO2 and methane into atmosphere = significantly contribute to enhanced greenhouse effect with higher levels of terrestrial radiation being trapped in lower atmosphere, raising temperatures
2. Production of heat from extraction and transportation processes and poorly insulated buildings has led to urban heat island effect in Barrow where mean temp on avg 2.2 degrees higher than in rural areas surrounding (maximum of 6 measured) Affects geomorphic processes with 9% fewer days of fluctuation around 0 degrees since drilling began

Question 8

What is permafrost?

Answer 8

Perennially frozen ground ie. remains frozen from one year to the next despite temp rising above 0 in summer

Question 9

What is the active layer?

Answer 9

A shallow layer of surface material that overlays the permafrost and thaws in summer, but freezes in winter

Question 10

Why does permafrost experience less variation in temp than active layer?

Answer 10

It is not directly exposed to seasonal difference in the air temperature, like active layer

Question 11

What happens if a building is built directly onto active layer:

Answer 11

If a building is built directly onto ground surface, heat produced is transferred to active layer, melting the permafrost and leading to subsidence + solifluction

Question 12

What is solifluction?

Answer 12

The slow flow of fine, water-saturated regolith (unconsolidated rock) from higher to lower ground

Question 13

What are solifluction lobes?

Answer 13

Tongues of debris at the base of slopes that form when the moving material loses energy on a lower gradient - caused by the downslope movement of the thawed active layer

Question 14

What is a thermokarst?

Answer 14

A landscape dominated by surface depressions due to thawing of ground ice - includes extensive areas of hummocky ground interspersed with water-logged hollows

Question 15

What are alases?

Answer 15

Flat-floored, steep-sided depressions ranging from 5-50m in depth and 100m-15km length that develop from large-scale subsidence

Question 16

What forms when alases combine?

Answer 16

Alas valleys which can be tens of km in length

Question 17

How does removal of vegetation cause ground ice to thaw?

Answer 17

Decreases insulation of ground ice = thawing to larger depths which creates a thicker active layer and more extensive subsidence

Question 18

Describe subsidence rates in Alaska:

Answer 18

On the North Slope of Alaska, subsidence rates average 3-4cm per year with a maximum rate of 12cm per year