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Geography A Level > Case Studies > Flashcards

Case Studies Flashcards

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1
Q

Amazon rainforest water cycle - precipitation

A

High average annual rainfall - >2000 mm

High intensity conventional rainfall

Interception by forest trees is high - 10% of precipitation account for 20-25% of all evaporation

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2
Q

Amazon rainforest - water cycle - evapotranspiration

A

High rates of evaporation and transpiration due to high temperatures, abundant moisture and dense vegetation

Around half of incoming rainfall is returned to the atmosphere by evaptranspiration

Most evaporation is from intercepted moisture from leaf surfaces

Moisture lost in transpiration is derived from the soil via tree roots

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3
Q

Amazon rainforest - water cycle - run-off

A

Rapid runoff due to high rainfall, intensive rainfall events and well-drained soils.

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4
Q

Amazon rainforest - water cycle - atmosphere

A

High temperatures allow the atmosphere to store large amounts of moisture

Absolute humidity and relative humidity is high

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5
Q

Amazon - water cycle - soil/groundwater

A

Abundant rainfall and deep tropical soils lead to significant water storage in soils leads to significant water storage in soils and aquifers.

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6
Q

Amazon - water - vegetation

A

Rainforest trees play a crucial role in the water cycle, absorbing and storing water from the soil and releasing it through transpiration.

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7
Q

Rainforest - carbon - climate

A

Humid equatorial climate creates ideal conditions for plant growth.

Net primary productivity is high, averaging 2500 grams/m squared/year.

Large forest trees typically store 180 tonnes c/ha above ground and a further 40 tonnes C/ha on their roots

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8
Q

Rainforest - carbon - exchanges

A

Exchanges between atmosphere, biosphere and soil is rapid

Warm humid conditions allow for decomposition of dead organic matter leading to the quick release of co2.

Rates of carbon fixation through photosynthesis are high

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9
Q

Rainforest - carbon - soil

A

Amazonia’s leached and acidic souls contain only limited carbon and nutrient stores.

The fact that such poor soils support a biome with the highest NPP and biomass of all terrestrial ecosystems, emphasising the speed with which organic matter is broken down, mineralised and recycled

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10
Q

Physical factors - amazon water cycle - geology

A

Impermeable catchments (eg large parts of the amazon basin are an ancient shield area comprising impermeable, crystalline rocks) have minimal water storage capacity resulting in rapid runoff.

Permeable rocks such as limestone and sandstone store rainwater and slow runoff

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11
Q

Physical factors - water - rainforest - relief

A

Most of the amazon basin comprises extensive lowlands

In areas of gentle relief water moves across the surface (overland flow) or horizontally through the soil (throughflow) to streams and rivers.

In the west the Andes create steep catchments with rapid runoff.

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12
Q

Physical factors - water - amazon - temperature

A

High temperature throughout the year generate high rates of evaporranspiration

Convection is strong leading to high atmospheric humidity, the development of thunderstorm clouds and intense precipitation.

Water is cycled continually between the land surface, forest trees and the atmosphere by evaporation, transpiration and precipitation

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13
Q

Physical factors - carbon - amazon - trees

A

100 billion tonnes of carbon is stored in the rainforest

60% of rainforest carbon is stored in above ground biomass of tree stems, branches and leaves.

Photosynthesis connects the rainforest to the atmosphere carbon stores

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14
Q

Physical factors - amazon - carbon - temperatures

A

Leaf litter and dead organic matter accumulates temporarily at the soil surface and within rainforest soils

High temperatures and humid conditions promote rapid decomposition or organic litter, releasing nutrients to the soil for immediate take up by tree root systems and emits co2 which is returned to the atmosphere

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15
Q

Physical factors - rainforest - carbon - geology

A

Dominated by ancient igneous and metamorphic rocks. Caribonates are largely absent from the mineral composition.

In west part of basin near Andes , outcrops of limestone occur

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16
Q

Human factors - amazon - water - floods

A

2014 - floods occurred in Madeira river due to deforestation

60 people died, 68,000 evacuated and outbreaks of cholera

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17
Q

Human factors - amazon - stores and flows of water cycle

A

Deforestation has reduced water storage in forest trees, permeable rocks (due to more rapid runoff)

Less evapotranspiration and therefore less precipitation.

Meanwhile total runoff and runoff speeds have increased, raising flood risks throughout basin

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18
Q

Floods of 2014

A

Between 2000 and 2012 30,000km of rainforest cleared for subsistence farming and cattle ranching. Much of this deforestation occurred on the steep slopes of the Andes.

Resulted in massive runoff and massive reduction in water storage

19
Q

Future deforestation - amazon

A

20% decline in regional rainfall as the rainforest dries out and forest trees are replaced by grasslands.

20
Q

Deforestation affect on carbon

A

Exhausts main store - grasslands only store 16.2 tonnes/ha

Reduces input of organic matter to the soil - reduces flow of carbon to the atmosphere

21
Q

Protection through legislation- amazon

A

1998 Brazilian government has established many forest conservation areas.

By2015 44% of the Brazilian amazon comprised national parks, wildlife reserves and indigenous reserves where farming is banned

22
Q

Projects to reforest areas - amazon

A

Parica project - aims to develop an1000km commercial timber plantation on government owned, deforested land.

Financial assistance is given to smallholders for land preparation, planting and the maintenance of plots.

Tree nurseries provide them with seedlings

Is sustainable and sequesters carbon in the trees, reducing the co2 emissions from deforestation and reduces runoff.

23
Q

Indigenous surui peope

A

2009 - first indigenous people to join the UNs reducing emissions from deforestation and degradation scheme

Provides payment to the tribe for protecting the rainforest and abandoning logging - granting them carbon credit.

2013 - natura (tnc) purchased 120,000 tonnes of carbon credit from the surui

24
Q

Improved agriculutural techniques

A

Diversification - soil fertility can be maintained by rotational cropping and integrating crops and livestock can help slow rates of deforestation

25
Q

Tundra - water cycle - precipitation

A

Low annual precipitation with most of it falling as snow

26
Q

Tundra - water cycle - atmosphere

A

Small stores of moisture in atmosphere lead to low temperatures which reduce absolute humidity

27
Q

Water cycle - tundra - evapotranspiration

A

Limited transpiration - due to spare ness of vegetation cover

Low rates of evaporation - much of suns energy used melting snow in summer

28
Q

Water cycle - tundra - river flows

A

Melting of active layer in spring results in sharp increase in river flows

29
Q

Water cycle - tundra - groundwater

A

Limited ground water and soil moisture stores-permafrost is a barrier to infiltration, percolation, recharge and groundwater flow

30
Q

Carbon cycle - tundra - storage

A

1600 GT of carbon - due to low temperatures which slow decomposition of dead plants

31
Q

Carbon cycle - tundra - temperatures

A

Flux of carbon concentrated in summer months when active layer thaws

Plants grow rapidly in summer due to long hours of daylight
During growing season tundra plants input carbon-rich litter into soil. The activity of microorganisms increases, releasing co2 to atmosphere through respiration

In winter pockets of unfrozen soil in permafrost act as a source of co2 and ch4. Snow cover may insulate microbial organisms and allow some decomposition

32
Q

Carbon cycle tundra - today

A

Now becoming a carbon source rather than a sink

More heat due to global warming leads to more plants - more decomposition

33
Q

Physical factors - water - tundra - temperature

A

Below freezing temps means for most of the year water is stored as ground ice in permafrost layer

Summer - active layer melts and liquid water flows on surface forming pools and shallow lakes

This meltwater forms pools but there is poor drainage as water cannot infiltrate soil

34
Q

Physical factors - water - tundra - evapotranspiration

A

Winter - no evapotranspiration due to sub zero temperatures

Summer - some evapotranspiration from standing water, soils and vegetation

35
Q

Physical factors - water - tundra - geology

A

Permeability is low owing to the permafrost and the crystalline rocks which dominate the geology of the tundra in the arctic

Minimal relief and glacial deposits impede drainage and contribute to water logging during summer months

36
Q

Physical factors - carbon - tundra - storage

A

Carbon is mainly stored as partly decomposed plant remains frozen in the permafrost

37
Q

Physical factors - carbon - tundra - plant growth

A

Low temps, unavailability of liquid water and limited nutrients limits plant growth

Low temperatures slow decomposition and respiration and the flow of co2 to the atmosphere

38
Q

Physical factors - carbon - tundra - geology

A

Owing to the impermeabilty of the permafrost, porosity and the mineral composition of rocks exert little influence over the carbon cycle

39
Q

Oil and gas production

A

North slope of Alaska

1990s - north slope accounted for nearly a quarter of usas domestic oil production

40
Q

Oil and gas production - melting

A

Construction and operation of oil and gas installations, settlements and infrastructure diffuses heat directly to the environment

Dust deposition along roadsides creates darkened snow surfaces, increasing absorption of sunlight

Removal of vegetation cover which stops the insulation of permafrost

41
Q

Oil and gas production - permafrost melting releases co2 and methane

A

North slope - losses of co2 from permafrost vary from 7-40 million tonnes per year

Gas flaring and oil spillages emit co2

Destruction of tundra vegetation reduces photosynthesis and uptake of co2 from atmosphere

Thawing of soil increases microbial activity, decomposition and emissions of co2

42
Q

Oil and gas production- affect on water

A

Increased runoff and river discharge - increased evaporation in summer

Strip mining of sand and gravel for construction creates artificial lakes which disrupt drainage and expose permafrost to further melting

Drainage networks disrupted by road construction

Water abstracted from creeks and rivers for industrial use and for building or ice roads in winter reduce runoff

43
Q

Oil and gas production - management strategies

A

Insulated ice and gravel pads - roads and other infrastructural features can be constructed on insulating pads - prevents permafrost from melting

Buildings and pipelines elevated in piles - allows cola air to circulate beneath these structures

Building laterally beyond drilling platforms - new techniques allow oil and gas to be accessed kms from drilling sites

Refrigerated supports - trans Alaska pipeline - stabilise the temperature of permafrost

Geography A Level (14 decks)

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