3.a. Human factors can disturb and enhance the natural processes and stores in the water and carbon cycles.

Question 1

State 2 human land use changes that disturb the water cycle.

(Urbanisation)
(Land-use changes)

Answer 1

Towns and cities often have drainage systems designed to remove surface water rapidly (e.g. gutters and pitched roofs). This means a high proportion of precipitation flows quickly into rivers.

Towns and cities also encroach onto floodplains. Urban areas will reduce a floodplains ability to store water, increasing river flow and flood risk.

Question 2

State a human land use change that disturbs the carbon cycle.

(Urbanisation)
(Land-use changes)

Answer 2

The removal and vegetation and its replacement with urban surfaces results in reduced amounts of organic carbon. Factories, homes, and vehicles increases carbon emissions to the atmosphere.

Question 3

State 3 human land use changes that disturb the water cycle.

(Farming)
(Land-use changes)

Answer 3

Conversion of land use from rural to towns and city spaces. Often it is farmland and woodland that is replaced by housing, offices, factories, and roads. Natural surfaces give way to impermeable artificial surfaces such as concrete, providing minimal water storage capacity.

Ploughing channels increase run-off and soil erosion. However, ploughing does increase infiltration and in turn, water transfer to rivers and streams increases.

Heavy machinery on farmland also compacts the soil. This will increase surface run-off and so peak flows in streams and rivers on farmland is generally higher than natural ecosystems.

Question 4

State 2 human land use changes that disturb the carbon cycle.

(Farming)
(Land-use changes)

Answer 4

The clearance of forest for farmland reduces carbon storage in both above and below ground biomass. Soil carbon is also reduced by ploughing and exposing organic soil matter to oxidation.

When harvesting crops, more carbon is lost when the material is removed and only a very small amount is returned to the soil. Lifting crops also leads to significant amounts of wind and water erosion of exposed soil.

Question 5

State 3 human land use changes that disturb the water cycle.

(Forestry)
(Land-use changes)

Answer 5

When plantations are created in natural forests there can often be higher rates of interception. In the UK the most popular planation tree species is the conifer. Their evergreen habit and high density contribute to consistently high rates of interception.

There is increased rates of evaporation as a large proportion of intercepted rainfall is stored on leaf surfaces. This is evaporated directly into the atmosphere.

Clear felling to harvest timber creates sudden but temporary changes to the local water cycle. Run-off is increased, evapotranspiration is reduced and there is higher stream discharge.

Question 6

State 3 human land use changes that disturb the carbon cycle.

(Forestry)
(Land-use changes)

Answer 6

Forest trees sequester CO2 from the atmosphere and store it for hundreds of years. Trees are only active carbon sinks for the first 100 years. After this, inputs of carbon captured is offset by leaf litter, the activity of decomposers and respiration.

Changing land use to forestry increases stores of carbon. Mature plantation forest trees in the UK contain around 170-200 C/ha. This is 10 times higher than grassland, and 20 times higher than heathland.

The soil in plantations represents an even bigger carbon store than the trees. In England, forest soil carbon holds around 500 tonnes C/ha.

Question 7

Why is water extracted (from both the surface and groundwater)?

(Water extraction)

Answer 7

To meet public, industrial, and agricultural demand.

Question 8

What does direct human intervention in the water cycle do?

(Water extraction)

Answer 8

Changes the dynamics of river flow and groundwater storage.

Question 9

Where is the River Kennet catchment?

(The River Kennet catchment)

Answer 9

Southern England.

Question 10

The River Kennet drains an area of how large?

(The River Kennet catchment)

Answer 10

Around 1200km2.

Question 11

The upper catchment of the River Kennet mainly compromises of what rock?

(The River Kennet catchment)

Answer 11

Chalk.

Question 12

The upper catchment of the River Kennet consists mainly of chalk. What lithology does chalk have, how does this mean for the River Kennet?

(The River Kennet catchment)

Answer 12

Chalk is highly permeable.

Thus groundwater flow contributes most of the Kennet’s flow.

Question 13

As the River Kennet t is a chalk stream, what does the river support?

(The River Kennet catchment)

Answer 13

A diverse range of habitats and wildlife.

Question 14

The River Kennet contains mainly chalk. What characteristics does this create in the water?

(The River Kennet catchment)

Answer 14

Exceptional clarity.

High oxygen levels.

Fast-flowing.

Question 15

What town is the largest that relies on water from the River Kennet’s basin? What is the population?

(The River Kennet catchment)

Answer 15

Swindon, with a population of over 220,000.

Question 16

Other than domestic urban use, what else does Kennet water supply for?

(The River Kennet catchment)

Answer 16

Local industries.

Agriculture.

Public use.

Question 16

Give 3 example of fauna native to the River Kennet.

(The River Kennet catchment)

Answer 16

Atlantic salmon.

Brown trout.

Water voles.

Otters.

White-clawed crayfish.

Question 17

Who extracts water from the River Kennet?

(The River Kennet catchment)

Answer 17

Thames Water.

Question 18

Thames Water abstracts groundwater from the upper catchment through what?

(The River Kennet catchment)

Answer 18

Boreholes.

Question 19

Is any water returned to the River Kennet (as waste water) after abstraction?

(The River Kennet catchment)

Answer 19

None of this water is returned to the river as waste water.

Question 20

Rates of groundwater extraction have exceeded rates of what? The falling water table has reduced flows in the River Kennet by what percentage?

(Impact of water extraction on the regional water cycle)
(The River Kennet catchment)

Answer 20

Rates of groundwater extraction have exceeded rates of recharge.

The falling water table has reduced flows in the River Kennet by 10-14%.

Question 21

During the 2003 drought, flows fell by how much? How much did they fall by in the dry conditions of the early 1990s?

(Impact of water extraction on the regional water cycle)
(The River Kennet catchment)

Answer 21

During the 2003 drought, flows fell by 20%.

In the dry conditions of the early 1990s by up to 40%.

Question 22

How have lower flows in the Kennet impacted the water cycle?

(Impact of water extraction on the regional water cycle)
(The River Kennet catchment)

Answer 22

Reduced flooding and temporary areas of standing water and wetlands on the Kennet’s floodplain between Marlborough and Hungerford.

Question 23

How have lower groundwater levels in the Kennet impacted the water cycle?

(Impact of water extraction on the regional water cycle)
(The River Kennet catchment)

Answer 23

Caused springs and seepages to dry up and reduced the incidence of saturated overland flow on the chalk hills of the Marlborough Downs.

Question 24

Aquifers rely on what types of rock? Give an example.

(Aquifers)

Answer 24

Permeable rock, or porous, water-bearing rock.

E.g. chalk.

Question 25

How is water extracted from aquifers?

(Aquifers)

Answer 25

Using wells or boreholes.

Question 26

Where does water escape from an aquifer? How?

(Aquifers)

Answer 26

Can emerge naturally from springs and seapages; this is due to pressure forces.

Question 27

Why are springs and seapages very important for streams and rivers?

(Aquifers)

Answer 27

They contribute a significant amount to the base flow of a stream or river.

Question 28

What is the upper part of the aquifer called?

(Aquifers)

Answer 28

Upper part of the aquifer (area of saturation) is called the water table.

Question 29

When may the water table fall?

(Aquifers)

Answer 29

Over abstraction or in the summer when there is limited rainfall.

Question 30

What is abstraction?

(Aquifers)

Answer 30

Abstraction involves taking too much water out of a ground source.

Question 31

When are water tables recharged?

(Aquifers)

Answer 31

In winter.

Question 32

What is base flow?

(Aquifers)

Answer 32

The normal expected amount of water flowing in a river at any point.

Question 33

Why does rainfall not reach aquifers in the Summer?

(Aquifers)

Answer 33

Any rain is taken up by wetting the soil, growing vegetation, or evaporating back to the atmosphere.

(This is why it recharges in the winter).

Question 34

How does water enter the basin?

(Case Study: London Artesian Basin)

Answer 34

When precipitation falls onto the chalk outcrops in the Chilterns and North Downs.

Question 35

How does precipitation (water) get to the basin once falling onto the Chiltern and North Downs chalk outcrops?

(Case Study: London Artesian Basin)

Answer 35

Through rock infiltration, and via gravity make its way to the centre of the basin.

Question 36

How does pressure exist in the basin?

(Case Study: London Artesian Basin)

Answer 36

Due to the LAB’s syncline geological feature.

Question 37

When tapping into the basin via aquifers, how is water extracted? What is this called?

(Case Study: London Artesian Basin)

Answer 37

The water rises to the surface under its own pressure.

This pressure is called artesian pressure.

Question 38

What is a potentiometric surface?

(Case Study: London Artesian Basin)

Answer 38

The layer that the escaped water will reach.

(A hypothetical surface representing the level to which groundwater would rise if not trapped in a confined aquifer).

Question 39

What influences the potentiometric surface?

(Case Study: London Artesian Basin)

Answer 39

Rates of abstraction and recharge (e.g. if recharge fails over a winter).

Question 40

What happens to potentiometric surfaces if aquifers over abstract? How does this affect future abstraction?

(Case Study: London Artesian Basin)

Answer 40

They may fall, resulting in limited water, thus drilling must occur deeper to access water.

Question 41

What happened to the LAB during the industrial revolution/ during the early 20th century?

(Case Study: London Artesian Basin)

Answer 41

The artesian basin was over abstracted, and levels fell by over 90m.

Question 42

Over the last 50 years, what have recharge rates been?

(Case Study: London Artesian Basin)

Answer 42

A rate of 3m per year.

Question 43

What has happened to the LAB in the past decade? What happened as a result of this?

(Case Study: London Artesian Basin)

Answer 43

The water table rise to flood basements and tunnels.

Because of this, Thames Water has been granted additional abstraction licenses.

Question 44

Fossil fuels have driven what two processes?

(Fossil fuels and the carbon cycle)

Answer 44

Global industrialisation and urbanisation.

Question 45

Despite the development of what, the global economy remains overwhelmingly dependent on fossil fuels?

(Fossil fuels and the carbon cycle)

Answer 45

Nuclear power and renewable energy.

Question 46

In 2019, fossil fuels accounted for what percentage of global energy consumption?

(Fossil fuels and the carbon cycle)

Answer 46

84%.

Question 47

Fossil fuel consumption releases how much CO2 to the atmosphere annually? What does this increase?

(Fossil fuels and the carbon cycle)

Answer 47

10 billion tonnes of CO2 to the atmosphere annually.

This increases atmospheric CO2 concentration by over 1 ppm (parts per million).

Question 48

It is estimated that since 1750, cumulative anthropogenic CO2 emissions total how much? What percentage of these emissions are from burning fossil fuels?

(Fossil fuels and the carbon cycle)

Answer 48

Nearly 2000 GT.

75% of these emissions are from the burning of fossil fuels.

Question 49

Since 1750, how many giga tonnes of human CO2 emissions have remained in the atmosphere? What has this raised, and to what?

(Fossil fuels and the carbon cycle)

Answer 49

Since 1750, 879 GT of human CO2 emissions have remained in the atmosphere.

This has raised CO2 concentrations from 280 ppm to 400 ppm.

Question 50

What are CO2 levels in the atmosphere like today? (ppm). Is this the highest they have been?

(Fossil fuels and the carbon cycle)

Answer 50

Over 415 ppm.

This is the highest for at least 800,000 years.

Question 51

Human carbon emissions comprise what percentage of the natural influx from the biosphere and oceans to the atmosphere? Even though this is low, what do they significantly impact?

(Fossil fuels and the carbon cycle)

Answer 51

Less than 10%.

They impact significantly on the size of the atmosphere, ocean and biosphere carbon stores.

Question 52

Despite international efforts to limit human carbon emissions, what period saw the fastest growth than in any previous decade? What happened by 2019?

(Fossil fuels and the carbon cycle)

Answer 52

In the period 2000-09 they grew faster than in any previous decade.

By 2019 they had stopped rising.

Question 53

Without increased absorption of human carbon by the oceans and biosphere, today’s atmospheric CO2 concentrations would exceed how much? (ppm)

(Fossil fuels and the carbon cycle)

Answer 53

500 ppm.

Question 54

What is the main driver of present-day global warming?

(Sequestration of waste carbon)

Answer 54

The combustion of fossil fuels and the transfer of carbon from geological store to the atmosphere and oceans.

Question 55

The combustion of fossil fuels and the transfer of carbon from geological store to the atmosphere and oceans, is the main driver of present-day global warming. What is one solution to this? What is this called?

(Sequestration of waste carbon)

Answer 55

To capture and store CO2 released by power plants and industry.

This new technology of carbon sequestration is known as carbon capture and storage (CCS).

Question 56

Have many fossil fuel burning sites used CCS?

(Sequestration of waste carbon)

Answer 56

So far the technology has been piloted at just a handful of coal-fired power stations.

Question 57

Outline the three stages of CCS.

(Sequestration of waste carbon)

Answer 57

First the CO2 is separated from power station emissions.

The CO2 is then compressed and transported by pipeline to storage areas.

Finally it is injected into porous rocks deep underground where it is stored permanently.

Question 58

In the USA, what percentage of all CO2 emissions are from coal and gas-fired power stations? CCS has the potential to reduce these emissions by what percentage?

(CCS could eventually play an important part in reducing CO2 and other greenhouse gas emissions)
(Sequestration of waste carbon)

Answer 58

40%.

CCS has the potential to reduce these emissions by 80-90%.

Question 59

Where in the UK is a CCS pilot project underway?

(Sequestration of waste carbon)

Answer 59

Peterhead in north-east Scotland.

Question 60

Where is the Drax project located?

(The Drax project)
(Sequestration of waste carbon)

Answer 60

North Yorkshire.

Question 61

What is the Drax project? When did it commence?

(The Drax project)
(Sequestration of waste carbon)

Answer 61

A project designed to capture 2 million tonnes of CO2 per year.

It commenced operation in 2019.

Question 62

Where is carbon from the Drax project transported? Where is it stored?

(The Drax project)
(Sequestration of waste carbon)

Answer 62

Carbon to be transported by pipeline to the North Sea.

It will be stored in depleted gas reservoirs.

Question 63

How can CO2 gas be used with ‘mature’ oilfields?

(The Drax project)
(Sequestration of waste carbon)

Answer 63

CO2 gas can be pumped into ‘mature’ oilfields to extract oil that would otherwise be uneconomic to recover.

This is called gas injection.

Question 64

What is gas injection?

(The Drax project)
(Sequestration of waste carbon)

Answer 64

A process that uses CO2 gas to expand within a reservoir, in order to push additional oil to a production wellbore.

Question 65

What is a wellbore?

(The Drax project)
(Sequestration of waste carbon)

Answer 65

A man-made hole that is drilled to aid recovery of natural resources, including oil, gas, or water.

Question 66

CCS is limited by economic and geological factors. Outline two.

(Sequestration of waste carbon)

Answer 66

High costs: Drax and Peterhead projects will cost over £1 billion.

High energy output required.

Specific geological conditions are needed, these being porous rock overlain by impermeable layers.

Question 67

Outline the positive and negative feedback loop in the water and carbon cycle.

(Positive and Negative feedback loops in the water and carbon cycle)

Answer 67

Equilibrium exists in a system when inputs and outputs are equal.

Positive feedback throws a systems equilibrium out of balance. E.g. change in climates increase rates of evaporation.

Positive feedback can trigger greater positive feedback within the system (a snowball effect), creating widespread change in the natural system.

Natural systems are incredibly adaptable, undergoing negative feedback as a response.

Negative feedback is the changes a system undergoes in order to restore balance.

This creates a dynamic equilibrium, as the system has changed in order to compensate - not equilibrium, as the balance has been changed.

Question 68

State 2 examples of positive feedback-negative feedback in the water cycle.

Answer 68

Rising temperatures, increases evaporation, creates greater cloud coverage and more precipitation. Water vapour is a greenhouse gas so more vapour increases Earth’s long-wave radiation absorption - further increasing temperatures. To regain balance, the system is able to use the greater cloud coverage and reflect more solar radiation back into space. As smaller amounts of solar radiation are absorbed by the atmosphere, ocean temperatures fall.

Increases in precipitation in drainage basins. The system regains balance by increasing river flow and evaporation. Excess water can also be used to recharge aquifers - increasing water storage in permeable rocks.

Question 69

State an example of a positive feedback-negative feedback in the carbon cycle.

Answer 69

Human activity e.g. burning fossil fuels increases the concentration of CO2 in the atmosphere. To regain balance the system neutralises rising sea level of atmospheric CO2 by stimulating photosynthesis - referred to as ‘carbon fertilisation’. Excess CO2 is extracted from the atmosphere and stored in the biosphere - CO2 is then stored long-term in ocean sediments.

Question 70

Give an example of positive feedback in the carbon cycle for the Arctic tundra.

Answer 70

In the Arctic tundra global warming is occurring faster than in any other region. Arctic sea ice and snow cover shrinks, large expanses of sea and land are exposed.

This increases sunlight absorption, warming the tundra and melting permafrost.