water Flashcards

1
Q

what are stores

A

reservoirs where water is held, such as the oceans

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2
Q

what are fluxes

A

they measure the rate of flow between the stores

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3
Q

what are processes

A

the physical mechanisms which drive the fluxes of water between the stores

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4
Q

why is the global hydrological cycle a closed system

A

fixed amount of water in Earth’s atmosphere system
no external inputs or outputs
total volume of water is constant and finite
-but water can be held in different states within the closed system, and the proportions can vary

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5
Q

what is the global hydrological cycle driven by

A

solar energy and gravitational potential energy

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6
Q

what are the 6 different types of water stores

A

oceans
cryosphere
biosphere
atmosphere
groundwater
surface water

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7
Q

how is the majority of water stored in the oceans

A

in liquid form
a small fraction as ice

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8
Q

what % of global water does the oceans contain

A

97%

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9
Q

how is the majority of water stored in the cryosphere

A

in a solid state
some in liquid form as melt-water or lakes

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10
Q

what % of global water does the cryosphere contain

A

1.9%

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11
Q

how is water stored in the biosphere

A

-rivers, streams, lakes and groundwater in liquid form
-vegetation after interception or beneath the surface in the soil

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12
Q

what % of global water does the biosphere contain

A

0.2%

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13
Q

how does water exist in the atmosphere

A

vapor
-clouds contain minute water droplets or ice crystals at high altitude which are both a precursor to rain

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14
Q

what is the carrying capacity of vapor in the atmosphere directly linked to

A

temperature

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15
Q

what does the global water budget limit

A

water available for human use

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16
Q

what is residence time

A

the average time a water molecule will spend in a store

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17
Q

what % of the Earth’s fresh water supply is stored in snowflakes, ice sheets and glaciers

A

69%

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18
Q

why is freshwater quite inaccessable

A

stored in snowflakes, ice sheets and glaciers is largely inaccesable for human use, altho some mountain streams are fed from meltwater
some groundwater is very deep and innaccessible- fossil water

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19
Q

what % of freshwater occurs as groundwater

A

30%

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20
Q

what is an example of an open system within the global hydrological cycle

A

the drainage basin

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21
Q

what is the hydrological cycle a system consisting of

A

linked processes: inputs, flows and outputs

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22
Q

what is a drainage basin

A

the area of land drained by a river and its tributaries, frequently referred to as a rivers catchment

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23
Q

what is the watershed

A

a ridge of high land which divides and separated water flowing to different rivers, creating the boundary of a drainage basin

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24
Q

why is a drainage basin an open system

A

has external inputs and outputs that cause the amount of water in the basin to vary

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25
Q

what is a drainage basin input

A

precipitation

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26
Q

what conditions need to be met for precipitation to occur

A

-air cooled to saturation point with a relative humidity of 100%
-condensation nuclei such as dust particles to facilitate the growth of droplets in clouds
-a temperature below dew point

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27
Q

what are the three main triggers for the development of rain

A

uplift, cooling and condensation

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28
Q

what are influencing factors which have impacts on the drainage basin

A

-amount of precipitation
-type of precipitation
-seasonality
-intensity of precipitation

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29
Q

how is amount of precipitation and influencing factor on a drainage basin

A

has a direct impact on drainage basin discharge, as a general rule the higher the amount the less variability in its pattern

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30
Q

how is seasonality an influencing factor impacting on drainage basins

A

in some climates strong seasonal patterns of rainfall or snowfall will have a major impact on physical processes in the drainage basin

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31
Q

what are the two fluxes involved in drainage basins

A

interception
infiltration

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32
Q

what is interception

A

process by which water is stored in vegetation

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33
Q

what are the three main components of interception

A

interception loss
throughfall
stem flow

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34
Q

when is interception loss from vegetation greatest

A

at the start of a storm
especially when following a dry period

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35
Q

how does the interception capacity or vegetation cover vary

A

-it varies considerably with the type of tree, needles if a coniferous forest allowing more accumulation of water
-contrast between deciduous forested in summer and winter due to leaves on the trees

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36
Q

what is infiltration

A

the process by which water soaks into the soil

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37
Q

what is infiltration capacity

A

the maximum rate at which rain can be absorbed by a soil in a ‘given condition’

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38
Q

what factors affect the rate of infiltration

A

duration of rainfall
saturation of soil
soil type
vegetation
slope angle

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39
Q

what are the different types of flows and transfers

A

overland flow
throughflow
percolation
saturated overland flow
groundwater flow
channel flow

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40
Q

what is overland flow also known as

A

surface run off

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41
Q

what is the main way in which water is returned to a river

A

overland flow

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42
Q

what must happen in order for overland flow to occur

A

precipitation intensity has to exceed the infiltration rate

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43
Q

what is throughflow

A

lateral transfer of water down slope through the soil via natural pipes
-slower than direct overland flow but can occur rapidly

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44
Q

what is percolation

A

the deep transfer of water into permeable rock

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45
Q

where is the throughflow percolation route more likely

A

more likely to be associated in humid climates or on vegetated slopes

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46
Q

what does saturated overland flow result from

A

then upwards movement of the water table into the evaporation zone

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47
Q

what causes saturated overland flow

A

after a succession of storms the water table rises to the surface in depressions and at the base of hill slides

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48
Q

what is groundwater flow

A

the slow transfer of percolated water through rocks

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49
Q

when does channel flow take place

A

takes place in the river once the water reaches it

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50
Q

what are the outputs of a drainage basin

A

evaporation
transpiration
evapotranspiration

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51
Q

what is evaporation

A

the physical process by which moisture is lost directly into the atmosphere from water surfaces and soil

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52
Q

what are climate factors influencing the rate of evaporation

A

temperature
hours of sunshine
humidity
wind speed

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53
Q

what is transpiration

A

the process by which water is lost from plants through pores into the atmosphere

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54
Q

what do transpiration rates depend on

A

the time of year
the type of vegetation

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55
Q

what is evapotranspiration

A

the combined effect of evaporation and transpiration

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56
Q

what physical factors within drainage basins determine the importance of inputs, flows and outputs

A

climate
soils
vegetation
geology
relief

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57
Q

what does climate influence in terms of drainage basins

A

role in influencing the type and amount of precipitation overall and the amount of evaporation
it also influences vegetation type

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58
Q

how do soils affect lag time

A

determine the amount of infiltration and through flow, so can increase or decrease lag time

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59
Q

how does geology affect the drainage basin

A

can influence the subsurface processes such as percolation and groundwater flow

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60
Q

how can relief impact the drainage basin

A

altitude can impact on precipitation levels, and slopes can affect the amount of run off

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61
Q

how can vegetation affect the drainage basin

A

presence or absence of vegetation has a major impact on the amount of interception, infiltration and occurrence of overland flow as well as transpiration rates

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62
Q

how do humans disrupt the drainage basin cycle

A

-accelerating processes such as deforestation, changing land use
-creating new water storage reservoirs
-abstracting water

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63
Q

how can human activity affect precipitation

A

cloud seeding

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64
Q

what is cloud seeding

A

the introduction of silver iodide pellets or ammonium nitrate to act as condensation nuclei to attract water droplets

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65
Q

what is the aim of cloud seeding

A

to increase rainfall in drought-stricken areas

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66
Q

what are some human impacts on evaporation and transpiration

A

-changes in global land use eg deforestation are a key influence
-increased evaporation from the artificial reservoirs behind mega dams
-the channelization of rivers in urban areas into the conduits cuts down surface storage and therefore evaporation

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67
Q

what are human impacts on interception

A

-interception largely determined by vegetation type and density
-deforestation and afforestation both have significant impacts
-deforestation leads to a reduction in evapotranspiration and an increase in surface run off
-this increases flooding potential, leads to a decline of surface storage and a decrease in the lag time between peak rainfall and peak discharge

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68
Q

what do human impacts on infiltration largely result from

A

a change in land use

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69
Q

how many times greater is infiltration under forests compared to grassland

A

5 times

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70
Q

what’s a human impact on infiltration and soil water

A

with conversion to farmland there is reduced interception, increased soil compaction and more overland flow

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71
Q

what is the human impact on groundwater

A

-use of irrigation for extensive farming has led to declining water table levels in aquifers
-reductions in water using manufacturing has led the o less groundwater being abstracted so levels have begun to rise leading to
flooding

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72
Q

what does climate type influence

A

water budgets which show the annual balance between inputs (precipitation) and outputs (evapotranspiration) and their impact on soil, water availability

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73
Q

what is a water budget

A

the balance between precipitation evaporation and run off

74
Q

at what levels can water budgets be useful

A

global
regional
local

75
Q

what’s the Uk’s water budget like

A

the annual precipitation exceeds evaporation on most heats and in most places, so there is a positive water balance

76
Q

what do river regimes indicate

A

the annual variation of discharge of a river

77
Q

what is a river regime

A

the annual variation in discharge or flow of a river at a particular point

78
Q

what is a lot of the river flow from in a river regime

A

not from immediate precipitation or run off but is supplied from groundwater between periods of rain

79
Q

what factors influence the charachter of a regime

A

size of the river
amount, pattern and intensity of rainfall
temperatures
geology and overlying soils
type of vegetation cover
human activities such as dam building

80
Q

what do river regimes result from the impacts of

A

climate
geology
soils

81
Q

what physical features of drainage basins affect the shape of storm hydrographs

A

size
shape
drainage density
rock type
soil
relief vegetation

82
Q

what human factors of drainage basins affect the shape of storm hydrographs

A

land use
urbanisation

83
Q

what do storm hydrography show

A

the variation of discharge within a short period of time usually an individual storm or a group of storms not more than a few days in length

84
Q

how does water supply to rivers change during a storm

A

-before storm- main water supply is through groundwater, as storm develops water comes by a number of routes
-water infilitrates into the soil and becomes throughflow
-water flows over surface as overland flow
-water reaches river in short time period

85
Q

main features of a storm hydrograph

A

rising limb
peal discharge
lag time
falling limb

86
Q

rising limb

A

once rainfall input begins the discharge starts to rise

87
Q

peak discharge

A

eventually reached, some time after peak rainfall because the water takes time to move through the system

88
Q

lag time

A

time interval between peak rainfall and peak discharge

89
Q

falling limb

A

once the storm input has been caesed the amount of water in the river starts to decrease

90
Q

what shape does a flashy hydrograph have

A

steep rising and falling limbs

91
Q

what shape does a delayed hydrograph have

A

gentle rising and falling limbs

92
Q

how can weather/climate affect a flashy river

A

-intense storm which exceeds the infiltration capacity of the soil
-rapid snow melt as temperatures rise
-low evaporation due to low temperature

93
Q

effect of weather/climate on flat river

A

-steady rainfall which is less than the infilitration capacity of the soil
-slow snow melt as temperatures gradually rise
-high evaporation rates

94
Q

effect off rock type on a flashy river

A

-impermeable rocks which restrict percolation and encourage rapid surface run off

95
Q

effect of rock type on a flat river

A

-permeable rocks which allow percolation and so limit rapid surface run off

96
Q

effect of soils on flashy river

A

-low infiltration rates in clay soils

97
Q

effect of soils on a flat river

A

-high infiltration rates in sandy soils

98
Q

effect of relief on a flashy river

A

high, steep slopes promote surface run off

99
Q

effect of relief on a flat river

A

low, gentle slopes allow infiltration and percolation

100
Q

effect of drainage density on a flat river

A

high drainage density means more stream and rivers in the area, so water will move quickly

101
Q

effect of drainage density on a flat river

A

low draiange density means few stream and rivers in an area so water is likely to enter the ground and move slowly through the basin

102
Q

effect of vegetation on a flashy river

A

low vegetation means low levels of interception and more rapid movement through the system

103
Q

effect of vegetation on a flat river

A

high vegetation means high levels of interception so slow movement through the system

104
Q

effect of human activities in a flashy river

A

-urbanisation produces imermeable concrete surfaces
-deforestation reduces interception
-downslope ploughing

105
Q

effect of human activities on flat river

A

-low population density so few impermeable surfaces

106
Q

impact of urbanisation on storm hydrographs

A

-building activity leads to clearance of vegetation which exposes soil and increases overland flow, piles of disturbed dumped soil increase erodibility, soil replaced by impermeable surfaces
-high building density means rainfalls on roofs then quickly goes into drains
- drains built reducing distance water must travel before reaching a channel, increase in velocity occurs because they generate less friction than natural pathways
-bridges restrqain free discharge of floodwater and act as local dams
-exreme weather events these urban areas are vunerable

107
Q

different types of droughts causing deficits in the hydeological cycle
(physical causes)

A

meteoroligcal drought
agricultural drought
hydrological drought
famine drought

108
Q

meteoroligcal drought

A

shortfalls in precipitation as a result of short term variability or longer term trend, which increase the duration of the dry period.
precipitation deficiency usually combined with high temperatures, high winds, strong sun and low humidity

109
Q

agricultural drought

A

rain deficiency leads to a deficiency of soil moisture and soil water availability which has a knock on effect on plant growth and reduces biomass

110
Q

hydrological drought

A

associated with reduced stream flow and groundwater levels, which decrease because of reduced inputs of precipitation and continued high rates of evaporation
also results in reduced storage in lakes often with salinization and poor water quality

111
Q

famine drought

A

meteorological, agricultural and hydrological drought can all lead to famine drought
with widespread failure of crop, food shortages pccur resulting in malnutrition

112
Q

human impacts on drought

A

over abstraction of surface water resources and ground water aquifers

113
Q

human activity/influence contributing to the risk of drought

A

human factors dont cause drought, they act like positive feedback and enhance its impacts
over abstraction results in water being taken from rivers at high rates and used to irrigate land
ground water aquifers take a long time to replenish so when they are used up there is little water left- leads to desertification

114
Q

what ecosystem functioning can droughts impact

A

wetlands and forest stress

115
Q

what % of earth do wetlands cover

A

10%

116
Q

what key functions do wetlands perform

A

-temporary water stores within hydrological cycle so mitigating river floods downstream, protecting land from destructive erosion
-chemically act as filters by trapping and recycling nutrients and pollutants to maintain water quality
-high amount of biodiversity

117
Q

impact of drought on wetlands

A

less precipitation, there is less interception as vegetation will deteroiroaret and less infilitration and percolation to the groundwater stores causing water table levels to fall
the process of evaporation will continue and may increase due to shallower water

118
Q

meteorological causes of flooding

A

intense storms leading to flash flooding, unusually heavy or prolongued rainfall, extreme monsoon rainfall and snowmelt

119
Q

physical factors causing flooding in the uk

A

prolongued and heavy rainfall associated with the passage of low-pressure systems
traditional sequence is winter but can occur any time of year

120
Q

physical factors causing flooding in asia

A

monsoon rainfall causes flooding
due to intensity and volume of rainfall

121
Q

how are snow and ice physical factors that can affect flooding

A

usually in high latitude or mountainous areas
melting snow causes flooding due to meltwater running down the valleys
glacial outburst floods can also occur when an ice r moraine dam breaks, leading to the release of meltwater

122
Q

human actions that can exacerbate flood risk (changing land use within the river catchment, mismanagement of rivers using hard engineering systems)

A

-grazing animals trampling soil
-ploughing compacting soil
-streams chanelled into cultiverts to aid rapid drainage from farmland
-dams built
-irrigation
-impermeable surfaces
-deforestation
-urbansiation

123
Q

what impacts does damage from flooding have

A

environmental impacts (soil and ecosystems)
socio economic impacts (economic avtivity, infrastructure and settlement)

124
Q

socio economic impacts of flooding

A

-death of crops
-famine
-loss of communications and transport
-infrastructure losses

125
Q

environmental impacts of flooding

A

-maintain ecosystem functions
-recharge groundwater systems
-move sediment
-trigger breeding
-eutrophication
-loss of soil willdlife

126
Q

what are the two scales on which climate change can have significant impacts on the hydrological cycle

A

globally
locally

127
Q

what inputs and outputs within the hydrological cycle does climate change have an affect on

A

precipitation input
evaporation and transpiration

128
Q

effect of climate change on precipitation input to the hydrological cycle

A

mode of precpipitation more important than mean precipitation in determining hydrological impacts
increases in intense rainfall events have occured although overall amounts remain steady or decreased
areas if precipitation increase including the tropic and high latitudes
length, frequency and intensity of heat waves have increased widely- lead to an increase in drought occurences

129
Q

effect of climate change on evaporation and transpiration

A

research suggested in large areas of asia evaporation is increasing tho increased cloud cover from increased water vapour may work against this
transpiration is linked to vegetation changes linked to changes in soil moisture and precipitation and increasing transpiration which makes begetation more productive

130
Q

how does climate change effect run-off and stream flow

A

evidence to suggest with more climate extremes, there will be an increase in hydrological extremes, with more droughts and floods
an accelerated cycle with more intense rainfall will increase run-off rates and reduce infiltration

131
Q

effects of climate change on resevoir, lake and wetland storage

A

regional variations in lakes and reservoirs have been linked to regional changes in climate.
changes in wetland storage are occuring, but cant conclusively be linked to climate change

132
Q

effects of climate change on permafrost

A

changes in physical climate at high latitudes leading to permafrost degradation
with deepening of active layer, this impacts groundwater supplies and releases methane leading to positive feedback by accelerating change

133
Q

effect of climate change on snow

A

length of the snow cover season has decreased especially in the northern hemisphere and spring melt has occured earlier

134
Q

how can climate change resulting from ENSO cycles and global warming cause concerns over the security of water supplies

A

climate change expected to influence precipitation, temperature and evapotranspiration and through combined effects tje occurence and severity of droughts
the occurence of droughts determined by changes in sea surface temperatures
-ENSO associated with both extreme flooding and droughts

135
Q

what has led to a global pattern of water stress and water security

A

growing mismatch between water supply and demand

136
Q

renewable water resources

A

long term annual average total of internal and external renewable water resources

137
Q

water stress

A

countries experience water stress if renewable water resources are low
between 500 and 1000m3 per capita
it involves unsatisfied demand, tension and conflict, over-abstraction and insufficient flows to the environment

138
Q

water security

A

low renewable water resources
between 500-1000m3 per capita
involves unsatisfied demand, tension and conflict, over abstraction and insufficient flows to environment

139
Q

absolute water scarcity

A

renewable water resources very low
less than 500m per capita
situation leads to widespread restriction on water use and rationing

140
Q

physical causes of water insecurity

A

climate variability
salt water encroachment at coast

141
Q

human causes of water insecurity

A

over abstraction from rivers, lakes and groundwater aquifers
water contamination from agriculture
industrial water pollution

142
Q

why is there a global variation in the distribution and availability of freshwater resources

A

natural climate variability
between arid and humid climates and over wet and dry seasons
climate change increases these variations and risk associated with scarce supplies

143
Q

what are the direct and indirect effects on the hydrological cycle of increased variability in precipitation patterns

A

changes in run off and aquifer recharge and water quality
warmer climate at some locations increases rate of evaporation and transpiration leading to less effective precipitation
higher water temps of a warmer climate and localised industrial discharges of warm waste water increase many forms os pollution
warmer waters encourage growth of bacteria
water quality affected by sedimentation, nutrient enrichment, pestcicides and thermal pollution

144
Q

salt water encorachment at the coast

A

seaward movement of freshwater reduces saltwater encroachment in coastal zones and soil moisture and groundwater remain fresh
however global sea level rise and localised abstraction of groundwater are increasing the risk of saltwater intrusion into many coastal areas
extensive groundwater pumping from freshwater wells lowers the water table and allows saltwater to move into soils and aquifers

145
Q

human causes of water insecurity

A

population growth, urbansiation and increase in consumption have created increased demands
increase in the middle class also increased water use
agriculture has the largest use of water and excessive water withdrawals have increased water use
agriculture has largest use of water and excessive water withdrawals have created problems
water for energy production required
problems from contamination and pollution by eutrophication or indisustrial run off

146
Q

how do finite water resources face pressure from rising demand

A

increasing population
improving living standrads
industrialisation and agriculture
increasingly serious in some locations and is leading to increasing risk of water insecurity

147
Q

The United Nations World Development Report of 2015

A

projected an increase in global water demand by 55% by 2050
this is mainly due to growing demand from secondary industries, thermal energy and domestic use, all are linked to increasing urbanisation in developing countries
UN projects a 40% global water deficit by 2030

148
Q

what factors is water scarccity related to

A

availability
access
usage

149
Q

availability

A

having enough water to meet the demand

150
Q

access

A

freedom to use or income to buy water in a particular location

151
Q

usage

A

entitlement to and understanding of water use and health issues

152
Q

physical scarcity

A

determined by climate and the balance between inputs and outputs
continentality and topography are regional factors
local factors- geologyy
physical scarcity can also be caused by climate change

153
Q

economic scarcity

A

different global distribution
associated with developing countries that lack capital and technology and good governance to fully exploit their supplies of water

154
Q

what factors determine the price of water

A

-physical costs of obtaining the supply, many cities water has to be piped from mountain reservoirs through pipelines
-demand for the water- scarce water price increases to manage demand
-developing mega cities there is insufficient infrastructure, poor people living in slums have to rely on water tankers and bottled water- costs high

155
Q

why is water supply important for ecconomic development

A

industry
energy supply
agroculture

156
Q

why is water supply important for human wellbeing

A

sanitation
health
food preperation

157
Q

why is water supply important in agriculture

A

-rain fed agriculture fields and land entirely dependent on rainwater
farers focus on storing water (rainwater harvesting) to conserve supplies

158
Q

importance of water supply for insudtry and energy production

A

over 20% of all fresh water is used for energy production and industry
major concern is global shift in industrial production towards emerging nations such as china
rapid industrialisation has contaminated rivers and groundwater affecting the quality
water used for HEP and growth of biofuels

159
Q

importance of water supply for human well being

A

some of population still rely on unimproved water and no sanitation
unsafe drinking water can spread disease but water used for domestic use such as cleaning can prevent disease transmission
fundamental source of disease is lack of sanitation combined with low perdonal hygeine

160
Q

how is there potential for conflicts to occur between users within a country and internationally over local and trans boundary water sources

A

competition for freshwater increases risk of localised or international conflict over inequalities in water access or allocation
-during conflicts need to maintain water and ecosystem sustainability for life and economic development is overlooked
-natural environment are biggest losers in the compeition for water

161
Q

what is a trans bpundary water source

A

where a water source crosses one or more political borders

162
Q

how many transboundary water sources are there

A

263

163
Q

what do techno-fix hard engineering schemes include

A

water transfers
mega dams
deslination plants

164
Q

water transfer schemes

A

involve diversion of water from one drainage basin to another by either diverting the river itself or constructing a large canal to carry water from an area of surplus to area of deficit

165
Q

examples of water being transferred by pipelines

A

welsh reservoirs to liverpool and birmingham or chinas north south transfer
schemes have been successfull but there are environmental and social disadvantages

166
Q

mega dams

A

allow for water to be collected and stored for when it is required

167
Q

disadvantage of mega dams

A

high rates of evaporation

168
Q

desalination

A

draws supplies from the ocean

169
Q

postitive and negative impacts of desalination

A

technological advance has been made more cost effective
is sustainable
very costly
has negative impacts on marine life

170
Q

more sustainable schemes of restoration of water supplies and water conservation

A

smart irrigation
recycling of water

171
Q

problems with water in signapore

A

recieves abundant rainfall
limited land for collection and storage of rainwater, high evaporation rates due to tropical climate abd lack of groundwater resources- considered to have water scarcity

172
Q

what did Signapores national water agency to solve their water problems

A

invested in research and tech to creaye a diversified water supply
-comprising local catchment water
-imported water
-recycled water
-desalinated water

173
Q

what does local catchment water involve

A

collecting rainwater through a network of drains, canals, rivers, collection ponds and reservoirs before it is treated to supply dribking water

174
Q

signapore has an agreemnt with malaysia to import water until what year

A

2061

175
Q

smart irrigation in china and australia

A

smart irrigation provides crops with a suboptimal water supply causing mild stress during crop growth stages less sensitive to moisture deficiency
technique been found to conserve water without a significant reduction in yield

176
Q

smart irrigation study in china

A

6 year study of winter wheat production in china showed water savings of 25%
controlled irrigation such as drip feeds, ensures that water goes directly into the soil next to the roots of crops which evaporation losses

177
Q

wateraid

A

wateraid is an international non governmental organisation that raises funds to improve access to safe water, sanitation and hygeine for poorer people

178
Q

an example of waiter aids work

A

Uganda
3000 people lack access to safe water
local builders trained in construction of rainwater harvesting jars made from locally available materials
-usually designed to collect rainwater from roofs and store water for drier periods

179
Q

integrated drainage basin management

A

aims to establish a frameowkr for coordination whereby all administrators and stakeholders in river basin planning and management come together to develop an agree set of policies and strategies
aim to achieve a balanced and mutually acceptable approach to land, water and natural resources

180
Q
A