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water EQ2 Flashcards

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1
Q

define drought

A

an extended period- a season, a year or several years- of deficient rainfall relative to the statistical multi-year average for a region

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2
Q

define positive feedback

A

something that amplifies an effect

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3
Q

give an example of positive feedback

A

storm damages vegetation on a sand dune. Causes more erosion on a sand dune

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4
Q

define negative feedback

A

a cyclical sequence of events that dampens an effect

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5
Q

give an example of negative feedback

A

a block fall occurs thus protecting an area from erosion

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6
Q

define tipping point

A

when a system changes from one to another

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7
Q

what is atmospheric circulation

A

the re-distribution of heat around the planet

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8
Q

what is the Coriolis effect

A

where the equator moves faster than the poles

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9
Q

what is the thermal equator

A

the region which receives the most heat

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10
Q

what form due to high levels of transpiration

A

clouds form, this leads to high levels of precipitation

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11
Q

whats a low pressure zone

A

-rising hot air, forms depressions, lots of rain

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12
Q

whats a high pressure zone

A
  • cool air sinks and causes dry conditions and drought- anticyclone ( hot with little to no rainfall)
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13
Q

What is a jet stream

A

fast-flowing current of air, exist at both high and low levels in the atmosphere

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14
Q

whats more dense, cold air or hot air

A

cold air is more dense

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15
Q

Whats the ITCZ

A

The Intertropical Convergence Zone, or ITCZ, is a band of low pressure around the Earth which generally lies near to the equator, it can move

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16
Q

describe the El Nino effect (ENSO)

A

-trade winds weaken thus warm water moves to the middle of the sea, this causes high amounts of rainfall in the sea and sinking air to the East of Australia which will then receive dry conditions and drought

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17
Q

describe the La Nina effect

A

-when normal conditions are strenthened. Here, trade winds are stronger which pushes warm water closer to Australia, here the increased heat causes air to rise which forms clouds and rainfall in Australia, sinking air occurs in South America causing drought/ dry conditions

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18
Q

what is overgrazing

A

intensive agriculture

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19
Q

how does human activity directly impact droughts

A

humans impact droughts through abstraction of rivers and groundwater, building of reservoirs and changing land use which has overall altered hydrological processes.
deforestation and overgrazing reduce vegetation cover, so reducing evapotranspiration rates, thereby reducing atmospheric moisture and precipitation.
-the removal of vegetation also removes soil conditions through compaction, this means less water can infiltrate and more surface runoff is present and there is less water storage= reduces evaporation as no water is in soil

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20
Q

what do desiccation cracks do

A

desiccation cracks reduce the ability of water to cause drought.

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21
Q

what is sensible heat related to

A

its related to chnages in temps of a gas or bjects with no change in phase

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22
Q

what are the 4 types of drought

A

-meteorological
-hydrological
-agricultural
-socio-economic

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23
Q

whats meteorological drought

A

when long term precipitation is lower than normal

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24
Q

whats hydrological drought

A

when the amount of surface and subsurface water ( rivers, lakes, reservoirs and groundwater) is deficient

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25
Q

whats agricultural drought

A

when there is not enough soil moisture to allow enough crops to grow

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26
Q

whats socio-economic drought

A

when water demand exceeds water availability, leading to food shortages, famine and starvation

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27
Q

how does forest die-off cause drought?***

A

deforestation=> less vegetation and thus less transpiration back into the atmosphere=> less humidity and recycling of water

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28
Q

El Nino case study- the Millennium drought in Australia:
What happened?

A

it was in 1997 and the drought was a result of many physical and human causes

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29
Q

what physical factors caused the Millennium drought

A

-El Nino events were partly responsible for the two-thirds of the rainfall deficit in East Australia
-Strengthening of the high pressure belt, known as the subtropical ridge, is estimated to account for 80% of the rainfall decline, this ridge of high pressure blocked storm tracks (depressions), forcing them towards higher latitudes thus reducing frontal rainfall

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30
Q

what human factors caused the Millennium drought

A

changes to the Hadley cell and the subtropical ridge are associated with anthropogenic climate change

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31
Q

Drought risk from human activity- The Sahel (Africa):
what happened?

A

the Sahel droughts of the late 20th century were caused by air pollution originating from Europe and North America, these pollutants ahve been thought to cause atmospheric cooling thus changing the global heat budget and atmospheric circulation so that tropical rains associated with the ITCZ did not arrive thus causing drought.

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32
Q

how can drought be caused by the removal of vegetation

A

the removal of vegetation causes changes to soil conditions through compaction, this means water cant infiltrate and more surface runoff is present and there is less water storage= reduces evapotranspiration as if no water is in soil

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33
Q

how does forest die off cause drought

A

deforestation-> less vegetation and thus less transpiration back into the atmosphere-> higher surface temp and higher albedo-> less humidity and recycling of water.

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34
Q

how many times does the El Nino event occur

A

1 time per 7 years

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35
Q

what are the two reasons why drought occurred in the Sahel

A

-the ITCZ did not arrive causing drought
-overgrazing occurred= reduce vegetation cover, so reducing evapotranspiration rates, thereby reducing atmospheric moisture and precipitation.

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36
Q

what prevents the ITCZ moving north bringing the usual rain to the Sahel region in some years resulting in drought

A

subtropical high pressure zones associated with the descending part of the convection cell.

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37
Q

did human factors or physical factors cause drought in the Aral sea

A

human factors

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38
Q

what caused the Aral sea to almost disappear 3 reasons)

A

-due to the arid and seasonally hot climate, there is extensive evaporation and limited surface waters in general
-the two rivers supplying the Aral sea were re-diverted in the early 1960s by the soviet union for irrigation
-it has progressively shrunk due to evaporation and lack of recharge by rivers

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39
Q

by the early 1980s, how much freshwater did the Aral sea receive

A

no fresh water

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40
Q

what are the environmental impacts of the shrinkage of the Aral sea

A
  • ecosystems have disappeared due to dryness
    -its salinity started to increase and now its around 3 times more saline than sea water
    -a once thriving fishing industry is now dead, 24 species of fish lived there
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41
Q

what are the social impacts of the drying of the Aral sea

A

-when dust storms occur, salt, pesticides and herbicides are blown into nearby towns causing respiratory illness

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42
Q

some examples of causes of flooding

A

Intense storms
Unusually heavy or prolonged rainfall Extreme monsoonal rainfall
Rapid snowmelt during a particularly warm spring, as on the plains of Siberia

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43
Q

what changes the direction of trade winds

A

the Coriolis effect

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44
Q

whats latent heat

A

Related to changes in phase between liquids, gases and solids.

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45
Q

whats sensible heat

A

Related to changes in temperature of a gas or object with no change in phase.

46
Q

what are the 3 physical causes of drought

A
  1. The Intertropical Convergence Zone
  2. Mid Latitude Anticyclone Blocking
  3. El Niño Southern Oscillation Cycles (ENSO)
47
Q

how does mid latitude anticyclone blocking cause drought

A

this is a high pressure system so doesn’t bring about rain, prevents the ICTZ from moving

48
Q

How does the ITCZ move around the Equator?

A

Seasonally, e.g it’s further north during the northern hemisphere summer.

49
Q

The ITCZ moves north in the Northern hemisphere in which season?

A

Summer

50
Q

Explains what happens in the ITCZ.

A

The trade winds of the northern and southern hemispheres come together here, which leads to the development of frequent thunderstorms and heavy rain.

51
Q

The UK experienced a prolonged period of below average rainfall in the South East due to what?

A

Blocking anticyclones. The stability of anticyclones, with their sinking air and calm conditions, means that they can persist and block weather systems.

52
Q

Sometimes, what can the subtropical high-pressure zone (associated with the descending part of the Hadley convection cell) do?

A

Block the high humidity, rain-bearing air masses associated with the ITCZ.

53
Q

In the mid-latitudes, what system is frontal precipitation created in?

A

Low-pressure systems that form along the polar front

54
Q

What direction do depressions move in the mid-latitudes?

A

From west to east, as a result of the Coriolis force (caused by the rotation of the Earth)

55
Q

What is the polar front jet stream?

A

A very fast-moving, meandering belt of air in the upper troposphere.

56
Q

What allows high-pressure areas (anti-cyclones) from the subtropics to move northwards?

A

The loops of the polar front jet stream occasionally stabilising, or breaking up

57
Q

How can anticyclones cause drought?

A

They can persist and block weather systems from the West for up to two weeks. If this situation is repeated over the months, normal precipitation levels are greatly reduced.

58
Q

what is pervious rock

A

rock with faults- water can pass through

59
Q

what are imperious surfaces

A

doesn’t allow water to pass through

60
Q

what are the 6 physical causes of flooding

A

-amount and type of rain
-snowmelt
-temperature
-relief
-rock type
-previous weather conditions

61
Q

describe how amount and type of rain causes flooding

A

-prolonged rainfall and intense rainfall leads to an increase in surface runoff (short lag time).
saturated ground becomes impermeable meaning little or now water can infiltrate/ percolate into the soil rock below

summer monsoon rains in India and South East Asia are often heavy, as the ICTZ moves northwards and warm moist air follows behind. Brings humid climate and torrential rain

62
Q

describe how snowmelt causes flooding

A

flooding can arise after winter snowfall, when a sudden rise in air temperature in spring causes rapid snowmelt, especially in mountain environments. resulting in increasing surface runoff and flash floods.
snowmelt in Red River in North Dakota, USA and Norfolk 2013 caused flooding.

63
Q

describe how temperature causes flooding

A

due to high temps, more evapotranspiration occurs, this causes the soil to become drier and has less of an infiltration capacity so when precipitation occurs, there is high surface runoff leading to flood risk. Higher temps lead to an increase in storms, so more precipitation and more flooding.

64
Q

describe how relief causes flooding

A

orographic rainfall- warmer moist Atlantic air from the south-west is forced to rise as it reaches the western uplands. As it rises, it cools over the high ground producing heavy rain over western and northern parts of the UK

Cumbria case study- the Cumbrian fells created orographic rainfall (occurs in areas where land increases height).
In Cumbria - the moist air mass stayed over Cumbria for up to 48hrs - delivering record amounts of rain.

65
Q

describe how rock type causes flooding

A

permeable= more infiltration
impermeable e.g. metamorphic- more surface runoff

66
Q

describe how previous weather conditions causes flooding

A

if the ground is already saturated, water will be more likely to runoff along the surface, which quickly moves water to river channels and increases their discharge. Increases the likelihood of flash flooding.

Drought- makes ground crack, so cant hold water, results in flooding

67
Q

what is a monsoon

A

a seasonal change in the direction of prevailing winds of a world region. In India and south East Asia, the summer monsoon is associated with very heavy rainfall

68
Q

what factors increase lag time

A

-rural environments
-large basin
-elongated basin
-permeable rock
-elongated basin
- gentle slopes
-slow snowmelt
-higher drainage density.

69
Q

what factors decrease lag time

A

-urban environment
-small basin
-impermeable rock
-circular basin
-steep slopes
-fast snowmelt
-lower drainage density

70
Q

how does intensive crop growing affect a hydrograph

A

-due to crop growing, there area bare and drier soils this means faster surface runoff, reduced stream lag time and higher discharge peaks, rainwater now reaches floodplains more quickly. (flashy hydrographs)

70
Q

how do urban drainage systems contribute to flooding

A

reduces the natural storage capacity of the floodplain. The land may shrink as it dries out, getting lower and thus an even greater susceptibility to flooding

71
Q

what does the IPCC predict about climate change and the hydrological cycle

A

predicts considerable changes to the global hydrological cycle as a result of increasing greenhouse gas concs.

72
Q

draw a flow diagram showing changes to flooding as a result of climate change

A

increasing anthropogenic greenhouse gas emissions
↓
Increasing heat trapped in the atmosphere (enhanced global warming)
↓
increasing average air temps and sea surface temps
↓
increasing convection and evaporation
↓
increased condensation and cloud cover
↓
increased precipitation in low-pressure regions in the tropics and mid latitudes
↓
increasing flood risk in these locations

73
Q

recall a flow diagram showing changes to flooding as a result of climate change (snowmelt)

A

increasing anthropogenic greenhouse gas emissions
↓
Increasing heat trapped in the atmosphere (enhanced global warming)
↓
increasing average air temps and sea surface temps
↓
decreased snow, permafrost and ice cover. Initial increase in meltwater will increase river flows during next decades but decrease there after

74
Q

recall a flow diagram showing changes to drought as a result of climate change

A

increasing anthropogenic greenhouse gas emissions
↓
Increasing heat trapped in the atmosphere (enhanced global warming)
↓
increasing average air temps and sea surface temps
↓
increasing intense high pressure systems in certain seasons or high-pressure regions e.g. subtropics and drier soils
↓
decreased humidity and precipitation in these locations
↓
increased incidence and severity of drought

75
Q

list some potential impacts of climate change on the UK water cycle by 2050

A

-rainfall events will be much more intense (heavy downpour)

-more flooding expected

-Coldwater species will decline, this increases invasive species

-Estuaries at increasing risks from floods

-sea level will rise between 0.4m and 1m by 2100

-urban areas will see more flash flooding

-higher demand for water

76
Q

what does climate change do do naturally occurring physical causes of drought and flooding such as ENSO

A

Enhances and amplifies them

77
Q

give an overview on how climate change will affect the global hydrological cycle

A

warmer temperatures will increase the atmospheres ability to hold water vapour, thus rain will be more intense

change in storm patterns

as temperature rises, more likely precipitation will fall as rain rather than snow e.g in Western USA

warmer temperatures will cause earlier snow melt, this means less water available for human use

more flooding

increased incidence of drought

78
Q

how will climate change impact places around the world

A

different impacts will be experienced in different climatic zones (diff latitudes)

79
Q

what does climate change mean countries will have to cope with

A

countries will have to cope with changes in water budgets, which in turn will impact how climate change is managed to secure water in the future

80
Q

what is the troposphere

A

the lower atmosphere, moisture can circulate here

81
Q

when there is earlier snowmelt due to warming of the earth how does this affect water supply

A

the seasons with high demand for water such as spring and summer are seeing a reduced availability of freshwater

82
Q

what percentage of the worlds land area is severely affected by drought

A

30%
this has doubles over the last 30 years

83
Q

what areas are particularly affected by drought

A

-southern Europe
-parts of the USA
-parts of Asia
-eastern Australia

84
Q

what is the IPCC

A

The Intergovernmental Panel on Climate Change (IPCC) is the international body for assessing the science related to climate change

85
Q

what does the IPCC consistently predict about climate change and the water cycle

A

-precipitation will become more variable
-increased risk of droughts and flooding
-IPCC represent serious concerns over the security of water supplies in the future

86
Q

what are 3 reasons why predicting the impact of climate change is difficult

A

-climate dynamics- the way the atmosphere, ocean, terrestrial, cryosphere and biospheres interact is only partially understood

-Its difficult to distinguish between the impacts of oscillation such as ENSO (El Nino Southern Oscillation) and climate warming

-Global records are very incomplete- there is no reliable evidence on trends on climate change in many parts of the world making firm predictions hard

-variables and uncertainty

87
Q

what is permafrost

A

frozen soil

88
Q

what are ecosystems

A

ecosystems are interconnected communities of living organisms within a defined physical environment

89
Q

why are ecosystems vital for human wellbeing

A

provide us with innumerable and invaluable services, from tangible amenities such as clean air and water, food and fuel to intangible amenities such as aesthetic and psychological benefits

90
Q

what does the term ‘ecosystem functioning’ refer to

A

the biological, chemical and physical processes that take place within the ecosystem

91
Q

why are ecosystems vulnerable to drought

A

all ecosystem components are dependent on supplies of water

92
Q

levels of ecosystem resilience to drought can vary, what ecosystems are most resilient?

A

desert and semi-arid ecosystems

93
Q

what are forest ecosystems highly valued for

A

forests are highly valued for their ecological functions and services, which include water storage and regulation of hydrological processes, timber production, wildlife habitat, carbon sequestration and recreational opportunities.

94
Q

following a period of drought, how long does it take a tree to recover and resume to normal growth rates

A

an average of between 2 to four years

95
Q

what are the long term impacts of drought on trees and forests

A

Foliage loss, impairing growth, increased accumulation of pests and diseases, reduced carbon sequestration, lasting damage to vascular tissues which impairs water transport.

96
Q

give an example of a forest ecosystem affected by severe drought

A

Pinion pines in the four corners region of the south west USA

97
Q

What did drought do to the Pinion pines

A

in some areas more than 90% of the pinions died resulting in major ecosystem changes

98
Q

what did the Global Footprint Network measure how much forests sequester per year

A

the GFN calculated that forests store an average of 0.73 tonnes of carbon per hectare per year, which is important for climate change

99
Q

whats a wetland

A

a land area saturated with water, either permanently or seasonally, including marshes, swamps and fens

100
Q

give a real life example of a large wetland

A

the Everglades in Florida

101
Q

what did the environment agency find about drought on wetland ecosystems

A

As the supply of water is reduced, areas of open water shrink or dry up altogether, resulting in progressive loss of habitat.
Soil moisture is reduced, and extended drying can lead to soil erosion and a reduced ability to store water in times of flood (potentially increasing downstream flood risk) or to release water in times of drought.
Organic soils may oxidise, releasing carbon in the atmosphere; as water availability diminishes, concentrations of dissolved nutrients of dissolved nutrients or pollutants may increase.

102
Q

Why do birds, terrestrial vegetation and invertebrates show varying responses to drought?

A

Because it will depend on species’ resistance and resilience, competitive and predatory interactions, availability of food, and time and characteristic of drought.

103
Q

How can drought alter communities?

A

By eliminating some species and creating gaps in food webs in which other species can establish themselves.

104
Q

Two types of wetlands which can experience drought?

A

River-fed wetlands
Groundwater-fed wetlands

105
Q

How do river-fed wetlands cope with drought?

A

Because river-fed wetlands experience a wider range of water levels naturally, they support communities that may be more adapted to such fluctuations.

106
Q

How do groundwater-fed wetlands cope with drought?

A

Because they experience a smaller range of water levels, supporting communities that may thrive in this environment are therefore more vulnerable to prolonged drought over several seasons.

107
Q

what tree species have a low resilience to drought

A

pine- tends to keep using water at a high rate, even during a drought

108
Q

what are the short term impacts of

A

.

109
Q

2007 flooding in England:
what was the cause of flooding

A

-there was a rare abnormality in large scale air currents

110
Q

2007 flooding in England:
what were the impacts

A

-the national death toll reached 7
-in hull, 30,000 people had to leave their homes
-in hull, one in 5 homes were damaged
-in Sheffield there was damage worth of £30 million

geography physical a2 (8 decks)

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