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Geography - Water Cycle > Unit 3 > Flashcards

Unit 3 Flashcards

1
Q

What is a water deficit?

A

experienced when an area lacks sufficient water to meet its needs, can be caused by both human and natural factors

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2
Q

What is a drought?

A

generally an extended period of low or absent rainfall relative to the expected average for a region (diff definitions of drought in diff areas)

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3
Q

What is the definition of a drought of the U.K?

A

a period of at least 15 consecutive days on none of which are there more than 0.2mm of rainfall

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4
Q

What are meteorological droughts caused by?

A

variations in the normal atmospheric pressure systems

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5
Q

What is the definition of high pressure?

A

where cold air descends through the atmosphere, it warms
- no condensation = no precipitation
- clear skies

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6
Q

What is the definition of low pressure?

A

When warm air rises, cools, reaches dew point, condenses forming precipitation

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7
Q

In which pressure system is drought most likely to occur in?

A

droughts are linked to extended periods of high pressure over a region

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8
Q

What process is important in determining what pressure system occurs in the UK?

A

The jet stream, and the Rossby waves it produces

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9
Q

Which side of the Jet Stream is there low/high pressure, in terms of the U.K?

A

Polar air = low pressure (north)
Tropical air = high pressure (south)

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10
Q

What is the case study for drought in the UK?

A

Summer of 1976 drought (extreme water deficit)

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11
Q

How did the position of the Jet stream cause the drought in 1976?

A

the Jet stream was positioned further north than normal, and a blocking high pressure system was located over the UK = extended periods of dry weather

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12
Q

What were the average temps and the peak temp during the 1976 drought in the UK?

A

high summer temps of 32 degrees (occurred for 2 consecutive weeks)
peak = 35.9 degrees in Cheltenham in July

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13
Q

What were some of the impacts of the 1976 UK drought?

A
  • businesses shut down (temporarily) - leaving them economically vulnerable
  • people’s lives disrupted, getting to school or work
  • dehydration and heat stress
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14
Q

What was the % decrease of rainfall between May 1975 to August 1976 in England?

A

rainfall levels where 55% decreased compared to average from 1967 to 1990

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15
Q

What was the number of days there was precipitation in 1976 compared to 2007?

A

1976 = 7 days of rain (>1mm)
2007 = 40 days of rain (>1mm)

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16
Q

Are meteorological droughts likely to be more frequent in the future?

A

Yes, due to increased temps, pushing jet stream further north, larger Rossby waves, last longer

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17
Q

What is the definition of a megadrought?

A

multiple drought events that contain periods of very high sensitivity, last longer than any events observed in the 19th and 20th century

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18
Q

What is the case study of a megadrought?

A

‘Megadrought’ in western USA

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19
Q

By how much have temps increased in western USA since 2000?

A

gone up by 1.2%

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20
Q

What other weather phenomena has made droughts worse? (led to megadroughts)

A

El Nino and La Nina

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21
Q

What are some of the impacts droughts in the future are likely to have, as they get worse, drier for longer?

A

severe water shortages
reservoir depletion
loss of earning income and jobs

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22
Q

What were some of the impacts of the Megadrought in the USA?

A

Lake Pavell and Meads shrunk dramatically,
severely depleted reservoirs provided water to 40 million people
California - important for crops, severely affected

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23
Q

What are the two human causes of water deficits?

A
  • growth in population
  • increased per capita consumption due to increased affluence
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24
Q

When did the global population reach 8bn?

A

November 2022

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25
How is the demand for water increasing with affluence, include examples?
increased affluence = more water usage per person e.g. dishwashers, washing machines, showers, baths, electricity and oil generation
26
How much water a day does the average person in the USA use?
310 liters daily
27
What is meant by water scarcity?
the lack of available freshwater resources to meet demand
28
How many people (approx.) live in areas experiencing high water stress?
over 2 billion people
29
What are the three factors that are increasing levels of water stress globally?
- Climate change - Population growth/increased affluence - increase water withdrawals
30
How much water does the average person in an economically developed country typically use in their home per day?
- 300 litres
31
What are some examples of water withdrawals, that humans use water for?
- washing - flushing toilets - laundry -cleaning - food prep
32
How much water does the average person actually use per day? why is it higher?
5000 litres because of agriculture - their water footprint = high
33
What % of the global freshwater is used in agriculture?
70%
34
What is meant by 'blue water'?
water in rivers, lakes and greenwater
35
What is meant by green water?
precipitation that infiltrates into the soil
36
What is the second largest user of water after agriculture?
industry = 19% electricity generation
37
What is meant by 'virtual' or indirect water?
water used in the production of food and goods that we consume
38
What is meant by your water footprint?
a measurement of the water consumed by an individual both directly and indirectly
39
What % of indirect/virtual water that is used in food and other goods consumed?
95%
40
What is another name for virtual water?
' external water'
41
What % of the water you consume is virtual external water?
22%
42
What % of the water you consume is used in agriculture?
92%
43
What can the human caused water deficits be expressed as?
as a ratio of withdrawals to supply
44
What is an aquifer?
a body of permeable rock which can contain and transmit fresh groundwater
45
What are the two types of aquifer?
an unconfined aquifer a confined aquifer
46
What is meant by a confined aquifer?
lies directly below the water table
47
What is meant by an unconfined aquifer?
lies below a layer of impermeable rock or sediment such as clay, therefore confined under high pressure
48
What is an artesian well?
if the well is drilled into a confined aquifer, the water will naturally rise up to the well due to the high pressure it is under q
49
If the rate of extraction of an aquifer is greater than the rate of recharge, what happens to the water table?
the groundwater source will disappear
50
What is the case study for agricultural water consumption for export?
Growing potato's in Egyptian desert
51
What are the climatic conditions of Egypt?
high temperatures (45 degrees in the shade) little precipitation high levels of evaporation
52
Why are the conditions in Egypt bad for agricultural practises?
little precipitation = low surface storage, these will deplete through time, making irrigation ineffective - sprinklers are ineffective due to high levels of evaporation - sandy environment, has no nutrients
53
What is the case study for depletion and management of aquifers?
California's Central Valley Aquifer (megadrought)
54
How much of the USA's fresh food is produced in the Central Valley?
1/3
55
What % of California's water used in the Central Valley?
80%, due to droughts it has seen increasing pressure on the Central Valley Aquifer
56
What % of California's water supply does groundwater account for?
70%
57
What were the number of wells in Central Valley in 2011 compared to 2013?
2011 = 1250 2013 = 2440
58
How much groundwater has been lost since since 1962 in the Central Valley?
62 millions of acre feet
59
Why is California's great San Josquin Valley subsiding (sinking)?
1. farmers drill wells through the Corcoran clay layer into the deep aquifer 2. the pumping reduces the water pressure and causes the layers particles to compact (before they were filled with water), stacking them like pancakes 3. causes the heavy ground to collapse
60
What is the difference between health and unhealthy clay, how does this impact the Central Valley?
healthy = granular structure of healthy clay is fille with water Damaged = once the clay compacts, it can never be repaired, permanently limiting further water storage
61
How many years would it take for the aquifer in the Central Valley to naturally fill?
50 years - if everyone stopped using the groundwater supplies
62
What are the socio-economic issues of allowing the aquifer to naturally refill, without anyone using it?
no farming - agricultural economy would collapse - global impact on food sources
63
What is an artificial recharge?
involves recapturing excess runoff during periods of heavy precipitation diverting this water into recharge basins/canals - these bases have porous bases that allow the captured (allows percolation of water into the aquifer)
64
What is the name of a form of irrigation, that would reduce the pressure on dwindling groundwater supplies?
Drip irrigation
65
What is meant by drip irrigation?
running small tubes through crops and having water slowly drip straight onto the soil, uses less water - soil moisture levels are kept constant = increased productivity
66
How does natural ground water recharge work?
aquifers can be recharged (replenished) naturally overtime through precipitation, river bed seepage, flooding and other natural processes including seasonal snow melt
67
What conditions are needed for a water table to rise?
rate of percolation is greater than the rate of groundwater flow the water table will rise
68
What is the case study of rising groundwater, Natural Groundwater Recharge?
London Basin
69
How big is the London Basin and what is the geology of it?
Chalk, located 60m below the central surface of London (precipitation of the north/south of London results in percolation into the chalk)
70
What is the historical water use in London?
- in the 19th century, industrial demand for water increased, resulting in steady groundwater decline = abstraction
71
What was the state of the London Basin aquifer between the 1950's and 60's?
a dynamic equilibrium existed (long term balance despite short - term fluctuations)
72
After deindustrialisation, what happened to the London Basin?
- due to deindustrialisation, resulting in reduction in water demand in the 1970's the aquifer started recharging at a rate of 3m per year
73
What were some of the issues of the rising groundwater beneath London? What happens if the water level is allowed to return to its natural state?
threatened the underground structures - foundations and infrastructure for Modern London where built int he 1940's 50's when water levels were low and clay was dry - if the water table is allowed to return to its natural level, the clay will saturate, forcing pressure to rise affecting modern day infrastructure
74
What are some of the management strategies to cope with the rising water level in the London Basin?
the Environmental agency is involved in developing a large scale operational strategy: - agency recommends that 50 million litres of water a day are pumped out to avoid damage to the warren communication cables, sewers and underground tube
75
What is the case study for (human cause of water deficit) surface water extraction?
Aral Sea located between Kazakhstan and Uzbekistan
76
When was the Aral sea the 4th largest body of inland water? What was the % cover of the Aral sea in 2014?
1960 = 4th largest 2014 = 10% of its original size
77
Why did the Aral sea begin to disappear?
- inadequate irrigation policies - cotton industry -> rapid expansion and the development of agriculture and irrigation
78
What were the environmental impacts of the severe reduction of the Aral Sea?
- extremophiles dominate the environment - Dust and storms (over 75 tonnes of dust and salt - Dust storms on avg. 90 days per annum - desertification 5.5 million acres
79
What are some of the socio-economic impacts of the severe reduction of the Aral sea?
Thousands of lost jobs, ill health among locals - 50.8% of the pop have access to piped drinking water - population decreased from 510,000 in 1960's to 17,911 in 2005
80
What is the management solution for the reduction in the Aral Sea?
New Dam = Northern Aral Sea project (World Bank helped build) 8 mile KOK-Aral Dam (completed in August 2005)
81
Evaluation of the Aral Sea dam as a management solution?
dam will allow the accumulation of over 29 cubic km of water, helping to restore delta and wetland ecosystem aim = to sustain and increase agriculture and fish production

Geography - Water Cycle (4 decks)

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