OCR A Level GL - 14 OCR A Level GL 2.4 ALASKA CASE STUDY_ Human Activity changes Periglacial landscape 2

Question 1

How much proven reserves of oil is in Prudhoe Bay?

Answer 1

3 billion barrels

Question 2

What is the average daily temperature in northern Alaska in February?

Answer 2

-29 °C

Question 3

What is the average daily temperature in northern Alaska in July?

Answer 3

8 °C

Question 4

When was oil discovered in Prudhoe Bay?

Answer 4

1968

Question 5

When was the Trans Alaskan Pipeline completed?

Answer 5

1977

Question 6

How long is the Trans Alaskan Pipeline?

Answer 6

1,300km

Question 7

How many barrels a day does the Trans Alaskan Pipeline transport?

Answer 7

1.4million barrels

Question 8

What is the name of the ice-free port where the Trans Alaskan Pipeline finishes

Answer 8

Valdez

Question 9

How many mountain ranges does the pipeline cross?

Answer 9

3

Question 10

Why was the Trans-Alaskan Pipeline built?

Answer 10

Energy Security

Question 11

How much did the USA rely on OPEC imports for its oil in 1977?

Answer 11

70%

Question 12

How successful has Alaskan oil been in providing energy security?

Answer 12

By 2018, the USA only imports about 29% from OPEC countries with Saudi Arabia accounting for only 9%

Question 13

How are energy flows affected by human activity in Alaska?

Answer 13

1. Flaring - raising temperatures 2. Heat Island Effect

Question 14

How are material flows affected by human activity in Alaska?

Answer 14

1. Gravel material - due to gravel extraction, transport and deposition in the river system is being disturbed.
2. Hydrological processes - due to gravel extraction, groundwater levels have fallen

Question 15

What are gravel pads?

Answer 15

a 1-2m thick layer of sand and gravel put underneath infrastructure such as roads, houses and oil rigs

Question 16

What is the purpose of gravel pads?

Answer 16

to provide an insulating effect to reduce transfer of heat from a man-made structure to the ground. This helps to maintain thermal balance of the ground therefore reducing permafrost thaw and subsidence.

Question 17

Give a named example of a material flow problem caused by extracting gravel?

Answer 17

On a glacial outwash aquifer near Palmer, ground water levels have dropped by over a metre in an area up to 2km from the gravel extraction site

Question 18

What have been some solutions to the problems caused by the Trans Alaskan Pipeline?

Answer 18

1. Built pipeline on stilts - to prevent melt of permafrost.​ 2. Designed Thermosyphons which conduct heat from the oil away from the ground - to prevent melt of permafrost.​ 3. Designed insulation with gravel pads and styrofoam - to prevent permafrost melting​ 4. Designed Sliders - to provide flexibility to the pipe in the event of an earthquake when it crosses the Denali fault zone

Question 19

What is a thermokarst landscape?

Answer 19

a landscape dominated by surface depressions (filled with water to form waterlogged hollows) due to thawing of ground ice.

Question 20

What creates a thermokarst landscape at a regional scale?

Answer 20

a warming climate in a periglacial environment

Question 21

What creates a thermokarst landscape at a local scale?

Answer 21

Human activity such as removing vegetation or construction which disturbs the thermal balance by removing the insulating layer that protects permafrost.

Question 22

What are the consequences of a more prevalent thermokarst landscape?

Answer 22

1. a thicker active layer 2. more extensive subsidence

Question 23

What designs are used to reduce the impact of buildings and infrastructure on the thermokarst?

Answer 23

buildings are elevated above the surface to allow air to circulate and remove heat, ​ ​ larger structures and many roads, railway tracks and airstrips are built on gravel pads.

Question 24

What energy flow problems are caused by flaring?

Answer 24

large amounts of CO2 and methane are released into the atmosphere contributing to the enhanced greenhouse effect - leading to warmer temperatures and further thawing of the permafrost.

Question 25

What negative local energy flow effect does human activity have on the town of Barrow, Alaska?

Answer 25

human activity has created an urban heat island effect with mean temperatures being on average 2.2oC higher than the surrounding rural areas. ​

Question 26

In what ways has human activity in Alaska affected key geomorphic processes in the periglacial environment of northern Alaska?

Answer 26

Heat energy released by human activities (mainly poorly insulated buildings) has resulted in 9% fewer days of temperature fluctuations around 0oc, key for freeze-thaw processes. 90cm thicker active layer (leading to more solifluction) Increased rates of subsidence (from average of 3-4cm/yr to 12cm/yr) which threatens the structural stability of roads, buildings, and pipelines.

Question 27

How has the population in Barrow, Alaska changed between 1900-2000?

Answer 27

grown from 300 in 1900 to more than 4600 by 2000.​

Question 28

Which landform is created when the active layer thickens on sloped ground?

Answer 28

solifluction lobes

Question 29

What are solifluction lobes?

Answer 29

​ When the active layer on sloped ground (as gentle as 1-2°) becomes saturated due to the impermeable permafrost below and moves slowly downslope (between 0.5 - 5cm/year).

Question 30

What large-scale landscape features are formed due to warming temperatures in periglacial environments?

Answer 30

​alases

Question 31

What are alases?

Answer 31

large scale, steep-sided depressions (5-50m in depth and 100m-15km in length).

Question 32

What is the average rate of subsidence in North Slope, Alaska?

Answer 32

3-4cm per year

Question 33

What is the maximum rate of subsidence in North Slope, Alaska?

Answer 33

12cm per year

Question 34

How thick is the permafrost in North Slope, Alaska?

Answer 34

300-600m

Question 35

How thick is the active layer in North Slope, Alaska?

Answer 35

30-80cm