Environmental Science > The Hydrosphere > Flashcards

The Hydrosphere Flashcards

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1
Q

What are the main human uses of water?

A

Agriculture = 70%
Industry = 22%
Domestic uses = 8%

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2
Q

Why is the global demand for water increasing due to an increase in population?

A

Birth rate is higher then death rate, immigration = more water needed for more people

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3
Q

Why is the global demand for water increasing due to an increase in per-capita use with increased affluence?

A

As piped water becomes more available and people become increasingly affluent, use more for washing etc

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4
Q

Why is the global demand for water increasing due to an increase in irrigation if farmland?

A

Subsistence agriculture relies on naturally available water, as commercial farming expands increased income allows money to be invested in irrigation schemes

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5
Q

Why is the global demand for water increasing due to industrialisation?

A

Different industries have different water requirements, heavy industry such as chemical and steel industries or paper making, use much more water than lighter industries

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6
Q

What are the main processes of the natural hydrological cycle?

A

Precipitation, interception, infiltration, percolation, groundwater flow, runoff, evaporation, transpiration, river channel discharge

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7
Q

What is residence time and how can it be calculated?

A

Residence times, transfer rates and water volume are connected and one value can be calculated if the other two are known
Residence time = volume of water in the reservoir/mean transfer rate

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8
Q

How does deforestation impact the hydrological cycle?

A
  • vegetation intercepts rainfall which may evaporate before it reaches the ground
  • trees also return a lot of water from the soil to the atmosphere by transpiration
  • loss of trees causes significant reduction in precipitation in downwind areas
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9
Q

How does agriculture impact the hydrological cycle?

A
  • soil compaction due to heavy machinery or by livestock means water does not infiltrate easily into the ground so runoff increases
  • crop irrigation increases evaporation rates
  • loss of soil biota such as worms reduces infiltration, increases runoff and reduces water retention
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10
Q

How does urban development impact the hydrological cycle?

A
  • urban areas often have impermeable surfaces
  • reducing infiltration, increasing runoff
  • flooding
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11
Q

How does global climate change impact the hydrological cycle?

A
  • higher global temperatures affects melting, evaporation and condensation as well as wind patterns = change the timing, amount, type and location of precipitation
  • more rapid snow melting may increase flooding after heavy rain and low river flow
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12
Q

How is habitat change an environmental effect of reservoirs?

A

Flooding the reservoir, destroys previous habitats, also creates new ones
- wetlands are uncommon habitats so it is valuable to create them

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13
Q

How are wildlife barriers an effect of reservoirs?

A

Dam and reservoir act as a barrier to wildlife that migrates along the river such as salmon and sturgeon

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14
Q

How is the downstream river regime affected by reservoirs/dams?

A
  • holding back water during times of surplus to ensure adequate river flow in times of shortage, reducing risk of flooding
  • it also reduces periods of lower flow which can be essential for turtles that lay their eggs in sandbanks
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15
Q

How is sedimentation an effect of reservoirs?

A
  • sediments in the river are carried down and settle there
  • sediment downstream may have been important for fertilising the floodplain
  • built up riverbanks and coastlines and counteracted erosion
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16
Q

How are microclimates an effect of reservoirs?

A
  • large bodies of water may change the local climate, high heat capacity of water helps to reduce temperature fluctuations
  • warmer in the winter, cooler in the summer
  • water provides less friction so wind speeds increase
  • greater evaporation may increase humidity, cloud cover and precipitation
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17
Q

How are rivers flowing into the Aral Sea exploited?

A

Syr Darya and Amu Darya flow through Central Asia to the Aral Sea = used to be fourth largest lake
- huge irrigation schemes reduced the lake size by 90%

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18
Q

How is the River Nile exploited?

A

Longest river in the world
- as populations grow and countries develop economically the demand for water will increase and the risk of conflict may grow

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19
Q

How are the Rivers of Tibet exploited?

A

1500 million people rely on the water
- growing populations and increased demand for agriculture and industry may lead to water shortages and conflict

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20
Q

What is porosity?

A

Measure of the proportion of a rock’s volume that is space and could therefore hold water
- chalk, limestone, and sandstone are porous rocks that can form aquifers

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21
Q

What is permeability?

A

Measure of the ease with which fluids may flow through a rock because of the interconnections between the spaces and their size

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22
Q

What are the associated geological structures of aquifer?

A

Rock below the water-bearing rock must be impermeable to prevent water escaping
- granite and clay are impermeable rocks
- some of the rock above the water rock must be permeable to allow the aquifer to be recharged

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23
Q

How are aquifers recharged?

A

Water in aquifers = dynamic equilibrium of natural inflow/recharge and water that flows out
Most aquifer recharge = precipitation infiltrating and percolating through soil and rock to the aquifer

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24
Q

what is an ancient aquifer?

A
  • saline and can cause salinisation as irrigation water evaporates, leaving the salt behind
  • can cause osmotic dehydration and the death of crops
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25
How do over exploited aquifers cause changes in surface hydrology?
Many rivers, lakes and marshes are fed by groundwater flowing out of aquifers - over-exploitation of aquifers lowers the water table, reducing or stopping the outflow if water into the wetland, causing it to dry up
26
What are the ecological impacts of over-exploited aquifers?
Lower water table, plants with higher water requirement will die or become less abundant as they fail to compete for water - semi-aquatic animals will die if wetlands dry out and species dependent on theses species too
27
How is salt-water incursion caused by over-exploited aquifers?
As rain percolates down to the aquifer, water flows a sideways and out into the sea Seawards flow of freshwater prevents seawater from flowing into the aquifer - if aquifer is over exploited then seawater flows into aquifers replacing the freshwater
28
How do over-exploited aquifers result in subsidence?
Water that is no longer present in the interstitial spaces in the rock cannot provide support for the rock particles so they ill be compacted by the weight of the material above, causing subsidence which causes damage to buildings and pipelines
29
How do over-exploited aquifers result in reduced supplies?
Unsuitable use of aquifer water results in a reduction in the water available that nearly half of the worlds population relies on
30
How can aquifer depletion be monitored?
Checking the level of the water table in wells or boreholes = very slow and very difficult on a large scale GRACE satellites = Gravity Recovery And Climate Experiment Their orbit is affected by the force or gravity which is influence by the mass of water in aquifers below their flight path
31
How are High Plains Aquifers over exploited?
- USA - food production relies on irrigation with aquifer water - water in the aquifer is largely paleo water = recharged in the last ice age
32
How does Malta over exploit aquifers?
- annual precipitate = 550mm - evapotranspiration = 400mm - only 150mm available for use - many of their aquifers are contaminated by industrial or agricultural wastes or saltwater incursion - now have to use desalination = expensive
33
What is rainwater collection?
- collecting water from rain is often cleaner and can reduce flooding
34
How can rivers be a source of water?
- accessible - low natural contaminants - possible pollutants from humans - flow fluctuations and annual water flow can affect its usefulness
35
How can reservoirs be a new sources of water? And what features go into site selection?
Allows storage of water at times of surplus so it can be used in times of storage - topography, geology, catchment area, water supply, pollution risk, sedimentation, infrastructure, land use conflicts
36
How can estuary barrages be a new sources of water?
- freshwater reservoir created by building dams across an estuary where the water enters the sea
37
How can seawater be a new source of water?
Desalination of seawater is very energy intensive and expensive so is only used in countries where seawater os the only source of water
38
What is artificial recharge of aquifers?
Using surplus water during periods of high rainfall to recharge the aquifers by pumping it underground or by diverting it into lagoons where it can infiltrate into the ground gradually
39
What is river-regulation reservoirs?
During periods of low rainfall the reservoir is used to maintain river levels by opening the dam to maintain river levels by opening the dam to allow more water into the river Following periods of heavy rainfall the reservoir is used to store surplus water to reduce flooding downstream
40
What are inter-basin transfers?
Canal and pipe systems may be used to transfer water from areas with a water surplus to areas with water shortages E.g. China, England, Russia
41
How can afforestation and unexploited reservoirs be used to sustainably managed water?
Newly discovered aquifers cab be used as a source of water - trees reduce soil erosion and reduce flow rate of rainwater into rivers, reducing flooding after heavy rain as well as maintaining river levels during periods of low rainfall
42
What is low volume uses in terms of water conservation?
- low water appliances = washing machines, dishwashers, dual flush toilets, tap timers, low flow shower heads - xeriscaping = planting areas with species adapted to dry conditions so less water is needed - low voles irrigation = drip irrigation delivers water directly to plants
43
How can used water be recycled?
Grey water used to flush toilets or garden uses
44
What is pollution control in terms if water conservation?
- oil pollution control - sewage treatment - acid mine drainage - control of heavy metal waste - landfill leachate treatment - buffer strips next to rivers to reduce fertiliser runoff
45
How can water wastage be reduced?
Water meters match the charges that consumers pay to the volume of water used = encouraging people to use less water for a lower water bill - repairs and good maintenance to pipes
46
What is the quality requirements of potable water?
- no pathogenic microorganisms - toxins at acceptable levels - smells, looks and tastes good
47
What are the quality requirements of spray irrigation?
- low turbidity - low levels of toxins that may be absorbed
48
What are the quality requirements of textile washing with soap?
Soft water with low calcium ion concentration
49
What are the quality requirements of power station condenser cooling water?
No gross solids = pipe blockage
50
What are the quality requirements of industrial boiler water?
No dissolved minerals = build ups and blockages
51
What is sedimentation?
Water remains static to let suspended solids such as silt to settle
52
What is screening?
Metal girls or meshes remove vegetation and litter
53
What is aeration?
Bubbles of air or water sprays are used to aerate the water and ensure a high dissolved oxygen content - reduces decay of dead matter - dissolved metals remained as they become insoluble
54
What is flocculation?
Adding flocculants e.g. aluminium sulfate allows particles to settle in a clarifier tank
55
What is filtration?
To remove any suspended solids and bacteria - often involve slow flow through layers of sand and gravel
56
What are activated carbon filters?
Used to remove organic chemicals such as pesticides which absorb onto the carbon particles
57
What is sterilisation?
Adding chlorine, ozone of UV light to sterilise and kill pathogens
58
What is pH control?
Sterilisation with chlorine can make the water too acidic, pH adjusted by adding crushed lime
59
What is fluoridation?
Fluorides are added to water too improve dental health
60
What is ion exchange?
Toxic ions such as those of ;end, mercury and arsenic can be removed using ion exchange regions Toxic ions also absorb onto polymer beads or particles of zeolite = soft water
61
What is reverse osmosis?
Seawater is the most abundant source of water Desalination = expensive - saline water is filtered at very high pressure through the partially permeable membrane of very small polyamide tubes
62
What is distillation?
Water is boiled by heating or reducing the pressure, the steam that is produced is condensed and collected
63
How is salt-water incursion caused by over-exploitation of aquifer?
Seawards flow of freshwater prevents seawater from flowing into aquifer under the land surface - if the aquifer is overexploited then seawater from the land,
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