water Flashcards
1
Q
what are stores
A
reservoirs where water is held, such as the oceans
2
Q
what are fluxes
A
they measure the rate of flow between the stores
3
Q
what are processes
A
the physical mechanisms which drive the fluxes of water between the stores
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
5
Q
what is the global hydrological cycle driven by
A
solar energy and gravitational potential energy
6
Q
what are the 6 different types of water stores
A
oceans
cryosphere
biosphere
atmosphere
groundwater
surface water
7
Q
how is the majority of water stored in the oceans
A
in liquid form
a small fraction as ice
8
Q
what % of global water does the oceans contain
A
97%
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
10
Q
what % of global water does the cryosphere contain
A
1.9%
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
12
Q
what % of global water does the biosphere contain
A
0.2%
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
14
Q
what is the carrying capacity of vapor in the atmosphere directly linked to
A
temperature
15
Q
what does the global water budget limit
A
water available for human use
16
Q
what is residence time
A
the average time a water molecule will spend in a store
17
Q
what % of the Earth’s fresh water supply is stored in snowflakes, ice sheets and glaciers
A
69%
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
19
Q
what % of freshwater occurs as groundwater
A
30%
20
Q
what is an example of an open system within the global hydrological cycle
A
the drainage basin
21
Q
what is the hydrological cycle a system consisting of
A
linked processes: inputs, flows and outputs
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
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
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
25
what is a drainage basin input
precipitation
26
what conditions need to be met for precipitation to occur
-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
27
what are the three main triggers for the development of rain
uplift, cooling and condensation
28
what are influencing factors which have impacts on the drainage basin
-amount of precipitation
-type of precipitation
-seasonality
-intensity of precipitation
29
how is amount of precipitation and influencing factor on a drainage basin
has a direct impact on drainage basin discharge, as a general rule the higher the amount the less variability in its pattern
30
how is seasonality an influencing factor impacting on drainage basins
in some climates strong seasonal patterns of rainfall or snowfall will have a major impact on physical processes in the drainage basin
31
what are the two fluxes involved in drainage basins
interception
infiltration
32
what is interception
process by which water is stored in vegetation
33
what are the three main components of interception
interception loss
throughfall
stem flow
34
when is interception loss from vegetation greatest
at the start of a storm
especially when following a dry period
35
how does the interception capacity or vegetation cover vary
-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
36
what is infiltration
the process by which water soaks into the soil
37
what is infiltration capacity
the maximum rate at which rain can be absorbed by a soil in a ‘given condition’
38
what factors affect the rate of infiltration
duration of rainfall
saturation of soil
soil type
vegetation
slope angle
39
what are the different types of flows and transfers
overland flow
throughflow
percolation
saturated overland flow
groundwater flow
channel flow
40
what is overland flow also known as
surface run off
41
what is the main way in which water is returned to a river
overland flow
42
what must happen in order for overland flow to occur
precipitation intensity has to exceed the infiltration rate
43
what is throughflow
lateral transfer of water down slope through the soil via natural pipes
-slower than direct overland flow but can occur rapidly
44
what is percolation
the deep transfer of water into permeable rock
45
where is the throughflow percolation route more likely
more likely to be associated in humid climates or on vegetated slopes
46
what does saturated overland flow result from
then upwards movement of the water table into the evaporation zone
47
what causes saturated overland flow
after a succession of storms the water table rises to the surface in depressions and at the base of hill slides
48
what is groundwater flow
the slow transfer of percolated water through rocks
49
when does channel flow take place
takes place in the river once the water reaches it
50
what are the outputs of a drainage basin
evaporation
transpiration
evapotranspiration
51
what is evaporation
the physical process by which moisture is lost directly into the atmosphere from water surfaces and soil
52
what are climate factors influencing the rate of evaporation
temperature
hours of sunshine
humidity
wind speed
53
what is transpiration
the process by which water is lost from plants through pores into the atmosphere
54
what do transpiration rates depend on
the time of year
the type of vegetation
55
what is evapotranspiration
the combined effect of evaporation and transpiration
56
what physical factors within drainage basins determine the importance of inputs, flows and outputs
climate
soils
vegetation
geology
relief
57
what does climate influence in terms of drainage basins
role in influencing the type and amount of precipitation overall and the amount of evaporation
it also influences vegetation type
58
how do soils affect lag time
determine the amount of infiltration and through flow, so can increase or decrease lag time
59
how does geology affect the drainage basin
can influence the subsurface processes such as percolation and groundwater flow
60
how can relief impact the drainage basin
altitude can impact on precipitation levels, and slopes can affect the amount of run off
61
how can vegetation affect the drainage basin
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
62
how do humans disrupt the drainage basin cycle
-accelerating processes such as deforestation, changing land use
-creating new water storage reservoirs
-abstracting water
63
how can human activity affect precipitation
cloud seeding
64
what is cloud seeding
the introduction of silver iodide pellets or ammonium nitrate to act as condensation nuclei to attract water droplets
65
what is the aim of cloud seeding
to increase rainfall in drought-stricken areas
66
what are some human impacts on evaporation and transpiration
-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
67
what are human impacts on interception
-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
68
what do human impacts on infiltration largely result from
a change in land use
69
how many times greater is infiltration under forests compared to grassland
5 times
70
what’s a human impact on infiltration and soil water
with conversion to farmland there is reduced interception, increased soil compaction and more overland flow
71
what is the human impact on groundwater
-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
72
what does climate type influence
water budgets which show the annual balance between inputs (precipitation) and outputs (evapotranspiration) and their impact on soil, water availability
73
what is a water budget
the balance between precipitation evaporation and run off
74
at what levels can water budgets be useful
global
regional
local
75
what’s the Uk’s water budget like
the annual precipitation exceeds evaporation on most heats and in most places, so there is a positive water balance
76
what do river regimes indicate
the annual variation of discharge of a river
77
what is a river regime
the annual variation in discharge or flow of a river at a particular point
78
what is a lot of the river flow from in a river regime
not from immediate precipitation or run off but is supplied from groundwater between periods of rain
79
what factors influence the charachter of a regime
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
what do river regimes result from the impacts of
climate
geology
soils
81
what physical features of drainage basins affect the shape of storm hydrographs
size
shape
drainage density
rock type
soil
relief vegetation
82
what human factors of drainage basins affect the shape of storm hydrographs
land use
urbanisation
83
what do storm hydrography show
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
how does water supply to rivers change during a storm
-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
main features of a storm hydrograph
rising limb
peal discharge
lag time
falling limb
86
rising limb
once rainfall input begins the discharge starts to rise
87
peak discharge
eventually reached, some time after peak rainfall because the water takes time to move through the system
88
lag time
time interval between peak rainfall and peak discharge
89
falling limb
once the storm input has been caesed the amount of water in the river starts to decrease
90
what shape does a flashy hydrograph have
steep rising and falling limbs
91
what shape does a delayed hydrograph have
gentle rising and falling limbs
92
how can weather/climate affect a flashy river
-intense storm which exceeds the infiltration capacity of the soil
-rapid snow melt as temperatures rise
-low evaporation due to low temperature
93
effect of weather/climate on flat river
-steady rainfall which is less than the infilitration capacity of the soil
-slow snow melt as temperatures gradually rise
-high evaporation rates
94
effect off rock type on a flashy river
-impermeable rocks which restrict percolation and encourage rapid surface run off
95
effect of rock type on a flat river
-permeable rocks which allow percolation and so limit rapid surface run off
96
effect of soils on flashy river
-low infiltration rates in clay soils
97
effect of soils on a flat river
-high infiltration rates in sandy soils
98
effect of relief on a flashy river
high, steep slopes promote surface run off
99
effect of relief on a flat river
low, gentle slopes allow infiltration and percolation
100
effect of drainage density on a flat river
high drainage density means more stream and rivers in the area, so water will move quickly
101
effect of drainage density on a flat river
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
effect of vegetation on a flashy river
low vegetation means low levels of interception and more rapid movement through the system
103
effect of vegetation on a flat river
high vegetation means high levels of interception so slow movement through the system
104
effect of human activities in a flashy river
-urbanisation produces imermeable concrete surfaces
-deforestation reduces interception
-downslope ploughing
105
effect of human activities on flat river
-low population density so few impermeable surfaces
106
impact of urbanisation on storm hydrographs
-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
different types of droughts causing deficits in the hydeological cycle
(physical causes)
meteoroligcal drought
agricultural drought
hydrological drought
famine drought
108
meteoroligcal drought
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
agricultural drought
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
hydrological drought
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
famine drought
meteorological, agricultural and hydrological drought can all lead to famine drought
with widespread failure of crop, food shortages pccur resulting in malnutrition
112
human impacts on drought
over abstraction of surface water resources and ground water aquifers
113
human activity/influence contributing to the risk of drought
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
what ecosystem functioning can droughts impact
wetlands and forest stress
115
what % of earth do wetlands cover
10%
116
what key functions do wetlands perform
-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
impact of drought on wetlands
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
meteorological causes of flooding
intense storms leading to flash flooding, unusually heavy or prolongued rainfall, extreme monsoon rainfall and snowmelt
119
physical factors causing flooding in the uk
prolongued and heavy rainfall associated with the passage of low-pressure systems
traditional sequence is winter but can occur any time of year
120
physical factors causing flooding in asia
monsoon rainfall causes flooding
due to intensity and volume of rainfall
121
how are snow and ice physical factors that can affect flooding
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
human actions that can exacerbate flood risk (changing land use within the river catchment, mismanagement of rivers using hard engineering systems)
-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
what impacts does damage from flooding have
environmental impacts (soil and ecosystems)
socio economic impacts (economic avtivity, infrastructure and settlement)
124
socio economic impacts of flooding
-death of crops
-famine
-loss of communications and transport
-infrastructure losses
125
environmental impacts of flooding
-maintain ecosystem functions
-recharge groundwater systems
-move sediment
-trigger breeding
-eutrophication
-loss of soil willdlife
126
what are the two scales on which climate change can have significant impacts on the hydrological cycle
globally
locally
127
what inputs and outputs within the hydrological cycle does climate change have an affect on
precipitation input
evaporation and transpiration
128
effect of climate change on precipitation input to the hydrological cycle
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
effect of climate change on evaporation and transpiration
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
how does climate change effect run-off and stream flow
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
effects of climate change on resevoir, lake and wetland storage
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
effects of climate change on permafrost
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
effect of climate change on snow
length of the snow cover season has decreased especially in the northern hemisphere and spring melt has occured earlier
134
how can climate change resulting from ENSO cycles and global warming cause concerns over the security of water supplies
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
what has led to a global pattern of water stress and water security
growing mismatch between water supply and demand
136
renewable water resources
long term annual average total of internal and external renewable water resources
137
water stress
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
water security
low renewable water resources
between 500-1000m3 per capita
involves unsatisfied demand, tension and conflict, over abstraction and insufficient flows to environment
139
absolute water scarcity
renewable water resources very low
less than 500m per capita
situation leads to widespread restriction on water use and rationing
140
physical causes of water insecurity
climate variability
salt water encroachment at coast
141
human causes of water insecurity
over abstraction from rivers, lakes and groundwater aquifers
water contamination from agriculture
industrial water pollution
142
why is there a global variation in the distribution and availability of freshwater resources
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
what are the direct and indirect effects on the hydrological cycle of increased variability in precipitation patterns
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
salt water encorachment at the coast
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
human causes of water insecurity
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
how do finite water resources face pressure from rising demand
increasing population
improving living standrads
industrialisation and agriculture
increasingly serious in some locations and is leading to increasing risk of water insecurity
147
The United Nations World Development Report of 2015
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
what factors is water scarccity related to
availability
access
usage
149
availability
having enough water to meet the demand
150
access
freedom to use or income to buy water in a particular location
151
usage
entitlement to and understanding of water use and health issues
152
physical scarcity
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
economic scarcity
different global distribution
associated with developing countries that lack capital and technology and good governance to fully exploit their supplies of water
154
what factors determine the price of water
-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
why is water supply important for ecconomic development
industry
energy supply
agroculture
156
why is water supply important for human wellbeing
sanitation
health
food preperation
157
why is water supply important in agriculture
-rain fed agriculture fields and land entirely dependent on rainwater
farers focus on storing water (rainwater harvesting) to conserve supplies
158
importance of water supply for insudtry and energy production
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
importance of water supply for human well being
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
how is there potential for conflicts to occur between users within a country and internationally over local and trans boundary water sources
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
what is a trans bpundary water source
where a water source crosses one or more political borders
162
how many transboundary water sources are there
263
163
what do techno-fix hard engineering schemes include
water transfers
mega dams
deslination plants
164
water transfer schemes
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
examples of water being transferred by pipelines
welsh reservoirs to liverpool and birmingham or chinas north south transfer
schemes have been successfull but there are environmental and social disadvantages
166
mega dams
allow for water to be collected and stored for when it is required
167
disadvantage of mega dams
high rates of evaporation
168
desalination
draws supplies from the ocean
169
postitive and negative impacts of desalination
technological advance has been made more cost effective
is sustainable
very costly
has negative impacts on marine life
170
more sustainable schemes of restoration of water supplies and water conservation
smart irrigation
recycling of water
171
problems with water in signapore
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
what did Signapores national water agency to solve their water problems
invested in research and tech to creaye a diversified water supply
-comprising local catchment water
-imported water
-recycled water
-desalinated water
173
what does local catchment water involve
collecting rainwater through a network of drains, canals, rivers, collection ponds and reservoirs before it is treated to supply dribking water
174
signapore has an agreemnt with malaysia to import water until what year
2061
175
smart irrigation in china and australia
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
smart irrigation study in china
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
wateraid
wateraid is an international non governmental organisation that raises funds to improve access to safe water, sanitation and hygeine for poorer people
178
an example of waiter aids work
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
integrated drainage basin management
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
