Water Cycle Flashcards
Hydrological processes, influences, insecurity and management
1
Q
Why is the water cycle a closed system?
A
There is a fixed amount of water on Earth: no water is created or destroyed
2
Q
Examples of stores
A
- Oceans
- Lakes
- Aquifers
- The cryosphere
3
Q
What are aquifers?
A
A body of permeable rock which can contain or transmit groundwater
4
Q
What is the cryosphere?
A
Water stored as ice in the Antarctic or Arctic
5
Q
What percentage of water is stored in oceans?
A
97%
6
Q
What are flows?
A
How water moves from one store to another
7
Q
Examples of flows?
A
- Infiltration
- Throughflow
- Percolation
- Channel flow
- Surface run-off
8
Q
What are some examples of processes that drive water flows?
A
- Evaporation
- Transpiration
- Precipitation
9
Q
What percentage of water is fresh?
A
2.5%
10
Q
What percentage of freshwater is in the cryosphere?
A
68.8%
11
Q
What percentage of freshwater is stored as groundwater?
A
30%
12
Q
What is a drainage basin?
A
An area of land where precipitation collects and drains off into a common outlet
13
Q
Three types of precipitation
A
- Orographic
- Frontal
- Convectional
14
Q
What is orographic precipitation?
A
- Moist air rises over mountains
- It then cools and condenses at the top of the mountain, bringing precipitation
- Once passed over the mountain, it descends and warms, creating a rain shadow
15
Q
What is frontal precipitation?
A
- Occurs when a warm front meets a cold front
- Heavier cold air sinks and warmer air rises above it
- As warm air rises, it cools, forming clouds and precipitation
16
Q
What is convectional precipitation?
A
- Solar radiation warms air
- Warm air begins to rise
- Then then air cools and condenses into clouds
- These clouds can produce heavy rainfall and thunderstorms
17
Q
What processes are outputs in a drainage basin?
A
- Evaporation
- Transpiration
- Channel flow
18
Q
What is evaporation?
A
When water turns to water vapour (liquid to gas)
19
Q
What is transpiration?
A
Water leaving plants through holes in their leaves
20
Q
What is channel flow?
A
The volume of water that flows in a river channel
21
Q
What water flows are there in a drainage basin?
A
- Interception
- Infiltration
- Direct runoff
- Saturated overland flow
- Throughflow
- Percolation
- Groundwater flow
22
Q
What is interception?
A
When plants capture precipitation in their leaves
23
Q
What is infiltration?
A
When precipitation enters the soil
24
Q
What is direct runoff?
A
When water from precipitation or snowmelt flows across the ground’s surface (the surface is impermeable like tarmac)
25
What is saturated overland flow?
When the ground is full of water, resulting in runoff
26
What is throughflow?
The horizontal flow of water between soil/rock layers
27
What is percolation?
The vertical flow of water between soil and rock layers
28
What is groundwater flow?
The flow of water horizontally once it has reached the water table
29
How does vegetation cover affect a drainage basin?
When an area has a high coverage of vegetation, the interception and evapotranspiration increase but the surface runoff decreases
30
How does soil type affect a drainage basin?
Impermeable soils can stop infiltration and lead to surface saturation and increased surface runoff.
When there are permeable soils, infiltration and percolation can happen. This can cause groundwater to recharge.
31
How does land relief affect a drainage basin?
Steeper slopes mean faster surface runoff and shorter times for water storage
32
How does climate affect a drainage basin?
Where cold climates allow for precipitation to fall as snow, the water can be stored and held back until it is thawed (melted)
-> This may reduce channel flow during winter but lead to an increase during summer due to glacial melt water
33
How does rock type affect a drainage basin?
Some rocks are impermeable and can stop the infiltration of water into the ground.
34
How does deforestation affect a drainage basin?
- Reduced interception, rainfall strikes soil directly which causes soil compaction
- Soil compaction and removing tree roots increases infiltration
- Increased surface runoff and more soil erosion and flooding
35
How do reservoirs affect drainage basins?
- Increased water lost from evaporation
- Dams reduce flow downstream, vegetation dies
- Vegetation may grow on reservoir surface, causing evapotranspiration
36
What is abstraction?
The process by which humans remove water from underground water stores
37
Why is over-abstraction a problem?
Can lead to rivers drying up and periods of low rainfall
38
How does urbanisation affect a drainage basin?
- Leads to a large number of impermeable surfaces, like tarmac
- This reduces infiltration and increases surface runoff
39
What % of water on Earth is available for human use?
1%
40
What is residence time?
The amount of time water is held in a store
41
What is fossil water?
Non-renewable, untouched, ancient freshwater stores
42
Where can fossil water stores be found?
Beneath deserts and in polar areas
43
Why is fossil water becoming more available?
New technology such as oil drilling techniques and satellite imagery
44
What is the global water budget?
The balance between water being evaporated from the oceans and precipitated onto the land
45
Hydrology of a polar area
- Cryosphere, made up of ice sheets and glaciers
- Little vegetation due to low temperature and limited light
46
What is permafrost?
Soil that is permanently frozen
47
What % of solar radiation is reflected off snow and ice in winter in polar climates?
85%
48
What are biogenic gases?
Gases produced or used by organisms such as methane
49
Difference in polar hydrology between winter and summer?
WINTER:
- Ground, lakes and rivers frozen in the cryosphere
- Solar radiation reflected
SUMMER:
- Frozen water thaws, rapid surface runoff, increased evaporation
- Biogenic gases released by ice and soil thawing
50
What % of precipitation is returned via evapotranspiration in tropical climates?
Around 50%
51
Hydrology of a tropical area
- Vegetation collects precipitation
- Consistent temperature and sunlight
- High rainfall
- Generate their own water cycle due to convectional rainfall
52
Consequences of deforestation on a tropical area's water cycle
- Reduced evapotranspiration and precipitation
- Water instead travels through rivers and streams (slower)
- Vegetation is crucial for the area's convectional rainfall
- Rainfall is essential for maintaining ecosystems
53
Where is the Yukon river?
Alaska
54
How does the Yukon's flow vary between winter and summer?
In winter it is frozen so flow is lower
In summer there is snowmelt and the flow dramatically increases
55
Is there much human interference with the Yukon river?
No - the area is largely natural
56
What is the climate of the Amazon?
- Tropical
- Consistent high temperature
- Wet and dry seasons
57
How does the flow of the Amazon river vary?
While there is little variation as the temperature and precipitation levels stay mostly consistent, it does increase more in the wet season
58
How do dams in Brazil affect the Amazon river's flow?
- More discharge above the dam
- Reduced flow below the dam
59
Where is the Murray-Darling river?
Australia
60
What is a rain shadow?
The basin is surrounded by mountains that collect most of the region's rain, which causes periods of prolonged drought
61
Issue with the Murray-Darling river?
Its basin is mostly in a rain shadow
62
What is the climate like in the Murray-Darling river basin?
North: Monsoon
South: Temperate
Wet and dry season causes different river flows.
63
What do humans use the Murray-Darling river for?
- Water for cities
- Irrigating farms
64
Why is it bad that the natural flow path of the Murray-Darling has been altered?
- Loss of habitat for local animals
- Decline in quality of water
65
Definition of drought
When an area suffers from a water deficit
66
4 types of drought
- Meteorological
- Agricultural
- Hydrological
- Socio-economic
67
What is a meteorological drought?
When an area is much dryer than the normal level of precipitation for that time of year
68
What is an agricultural drought?
When there is insufficient water for crops, leading to the loss of crops without irrigation
69
What is a hydrological drought?
When the drainage basin suffers shortfalls, such as reduced streamflow
70
What is a socio-economic drought?
When there is a demand for water to be used in social and economic purposes
71
What does ENSO stand for?
El Nino Southern Oscillation
72
How often does El Nino happen?
Every 3-5 years
73
What happens during El Nino?
- South America experiences increased rainfall due to lower air pressure
- Australia experiences less rainfall and is more likely to have a drought
74
How is Australia affected by El Nino?
During an El Nino year they get less rainfall so are more likely to experience droughts
75
What happens during La Nina?
- Low air pressure descends on South East Asia and Australia, increasing their rainfall
- South America has higher air pressure and less rainfall, which may lead to a drought
76
What may cause a short-term precipitation deficit?
A sudden change in air pressure
77
What does a storm hydrograph show?
How river discharge changes over time at a particular point in the river
78
What is river discharge?
The volume of water each second flowing into a river
79
5 features of storm hydrographs
- Peak discharge
- Peak rainfall
- Lag time
- Rising limb
- Falling limb
80
What is lag time on a storm hydrograph?
The interval between peak rainfall and discharge
81
What is the rising limb on a storm hydrograph?
When the discharge is increasing
82
What is the falling limb on a storm hydrograph?
When the discharge is decreasing
83
What physical factors affect storm hydrographs?
- Rock type
- Soil type
- Size and shape of the drainage basin
- Relief
- Vegetation
84
How does the size and shape of a drainage basin affect a storm hydrograph?
The larger the catchment of the basin, the higher the peak discharge, but the lag time is longer
85
Example of a permeable rock
Limestone
86
What human factors affect storm hydrographs?
- Water management (dams and reservoirs)
- Abstraction of aquifers
- Urbanisation
- Land use (deforestation)
87
What is a drought?
When an area suffers a water deficit
88
4 types of drought
1. Meteorological
2. Agricultural
3. Hydrological
4. Socio-economic
89
What is a meterological drought?
When there is less rainfall than the normal precipitation levels for that area
90
What is an agricultural drought?
When there is insufficient water for crops
91
What is a hydrological drought?
When the drainage basin suffers shortfalls such as reduced streamflow in rivers
92
What is a socio-economic drought?
When there demand for water in everyday life exceeds the availability
93
What physical factor can cause a short-term precipitation deficit?
In areas that are used to low-pressure systems they may have a change in weather and experience a high pressure system.
Cool air sinking in a high pressure system does not have the ability to form clouds.
94
What year did Brazil have droughts?
2014-15
95
Why did Brazil have droughts?
Over-abstraction of groundwater
96
What caused the over-abstraction of groundwater in Brazil?
The Brazilian government had not properly monitored and an estimated 70% of wells were illegal
97
Why are illegal wells dangerous?
They are not filtered so water may contain pollutants and bacteria
98
What is ecosystem resilience?
How capable an ecosystem is of responding to an event (e.g. drought)
99
How are rainforests impacted by drought?
- Younger trees die which reduces canopy cover
- Reduced canopy cover means less interception and EVT
- Rainfall decrease
100
How can droughts affect forests?
With dead vegetation and lots of sunlight, wildfires are common as dry organic material easily sets alight
101
Example of wildfires
Croatia experienced 2.5 months of no rainfall in 2017
102
How are wetlands impacted by drought?
- Vegetation dies
- This reduces habitats for wild animals
- This can create a knock on effect as food chains are disrupted
103
Example of a wetland affected by drought?
In Minsmere, Suffolk, birds such as snipe and thrush are less able to penetrate the dry soil to reach the inverbrates they feed off
104
Human causes of flooding
- Agricultural activity
- River management (e.g. building dams)
- Urbanisation
- Deforestation
- Floodplain drainage
105
How can agricultural activity lead to increased flooding?
Having more soil exposed causes increased soil erosion, so less infiltration can take place
106
What is channelisation?
When the river is widened or deepened
107
How can urbanisation lead to increased flooding?
- The removal of vegetation causes increased surface run-off
- Impermeable surfaces like concrete reduce infiltration
108
How can artificial drainage lead to increased flooding?
The lag time to reach the river is significantly reduced, so the chance of reaching peak discharge is much higher
109
How can deforestation caused increased flooding?
- Less interception from trees
- Removal of plants decreases infiltration
110
Why are floodplains drained?
The land is often extremely fertile and perfect for agricultural activity
111
What is a consequence of draining floodplains?
- Habitats destroyed
- The area dries out and becomes lower, increasing flood risk
112
What do low pressure systems cause?
Intense storms which can produce heavy rainfall
112
What do low pressure systems cause?
Intense storms which can produce heavy rainfall
113
What is a depression?
Low air pressure systems that cause a lot of rain
114
How are depressions caused?
- Two air masses, one hot and one cold
- Cold air pushes hot air up
- Hot air cools
- Condensation occurs and then precipitation
115
Why does heavy rain lead to flooding?
The soil becomes saturated, stopping infiltration and increasing surface run off
116
What is a monsoon?
A seasonal change in the direction of prevailing wind which leads to an annual period of heavy rain in an area
117
Example of a monsoon causing human loss
Myanmar 2015
103 deaths
118
Why can mountainous areas be prone to flooding?
Snowmelt at spring time can increase water levels and cause flash floods
119
How can flooding negatively affect the environment?
- Plants can be uprooted
- Farmer's crops completely destroyed
- Ecosystems affected (lack of food, shelter, etc)
120
How many homes were without power in the 2015 Cumbria floods?
42,000 - caused by flooded power station being shut off
121
How many homes were flooded in the 2015 Cumbria floods?
5,000
122
Cost of damage to homes from the 2015 Cumbria floods?
£150m
123
How many bridges were damaged in the 2015 Cumbria floods?
100
124
How much did the 2015 Cumbria floods set back the local economy?
£200m
125
How will climate change impact precipitation?
- Increased in some regions
- Likelihood of tropical storms increases
- Sea levels rise
- Many areas that are used to precipitation face a reduction
126
How will climate change impact evaporation?
- Increased temperatures causes more evaporation
- If temperature decreases below freezing water stored as ice so reduced evaporation
127
How will climate change affect lakes?
- Not being recharged due to reduced rainfall
128
How has Lake Chad been affected by climate change?
- Once 3rd largest freshwater lake in Africa
- Now 1/20 size it originally was
- Many African countries like Cameroon and Nigeria rely on it as a water source
129
How will climate change affect snow and glaciers?
- Reduction in ice-forming seasons
- Sea ice breaking off into smaller icebergs
130
In what year was there the smallest amount of winter ice recorded?
2018
131
How will climate change affect permafrost?
- If soil temperatures go above freezing permafrost can thaw
- This leads to percolation and throughflow
132
How will climate change affect soil?
- Soil moisture levels decrease as less infiltration
- This is because of droughts as well as more intense rainfall
133
What happens in a La Nina year?
- Increased drought risk in South America
- Increased flood risk in Australia
134
What areas are most at risk for future droughts?
USA
Central America
Mediterranean
135
Why are Spain and Greece at high risk of drought?
- High population
- Over-reliance on tourism
136
What percentage of Bangladesh is on a floodplain?
70%
137
Why is Bangladesh at high risk of flooding?
- Himalayan glaciers melt
- Very low lying
- Sea level rise
- Cyclones more common
138
Is the Sahel becoming wetter or dryer?
There have been five significantly wetter years. Locals have taken advantage of this and replenished water.
139
How much precipitation does the Sahel get?
100-600mm per year
140
When is the Sahel rainy season?
July to September
90% annual rainfall during this period
141
How much did rainfall decrease during the 70s and 80s in Sahel?
Around 40%. This led to civil war in Ethiopia
142
What is water stress?
An area with less than 1,700 cubic metres per person of water
143
What is water scarcity?
An area with less than 1,000 cubic metres per person of water
144
What human factors are causing increased water stress?
- Rising population
- Increased living standards
- Agriculture insufficiency
- Industrialisation
145
How do farmers in Tanzania access water?
- Pay a one-off annual fee to use a source (e.g. well)
- This leads to farmers using more than necessary because they 'paid for it'
146
Why does industry use so much water?
- Energy production is very water-intensive as steam is needed to power turbines
- Water is needed to clean products
147
Why are countries like Morocco and UAE most at risk from water stress?
- Found at 30 degrees north, where Hadley and Ferrell cells meet
- When these cells meet there is an area of high pressure
- There is no cloud formation and minimal rainfall
148
What countries are least at risk from water stress?
- Brazil, gets lots of rainfall due to area of low pressure
- Canada, lots of ice
149
Why does the USA have high water stress?
- High living standards, largest consumption of water per capita in the world
- High amount of water used for industry
150
Why does Russia have low water stress?
- High landmass compared to population
- Regular precipitation
151
What are some physical causes of water insecurity?
- Climate
- Salt water encroachment
152
What is salt water encroachment?
Groundwater near the coast contaminated with salt water
Caused by:
- Coastal erosion
- Local overabstraction of groundwater
153
Why is Tuvalu at risk from climate change?
- Highest point is 3m above sea level
- Sea level rise has lead to salt water encroachment
- This has destroyed much of the farming land, hurting their food supply
154
What are some human causes of water insecurity?
- Over-abstraction of aquifers
- Water contamination from agriculture
- Water pollution from industry
155
What are some human causes of water insecurity?
- Over-abstraction of aquifers
- Water contamination from agriculture
- Water pollution from industry
156
What percentage of aquifers are said to be over-abstracted?
20%
157
How has Rajasthan, India suffered from over-abstraction of aquifers?
- Coca-cola bottling factory abstracted so much water that the water table fell 15m in 10 years
- This led to many farmers protesting
158
How can agriculture pollute water?
Excess fertilisers and pesticides can be washed away by rainwater. This makes the water unsafe for human use.
159
What percentage of water in the world is used in agriculture?
70%
160
How can industry cause water pollution?
- Lack of regulation allows chemicals to enter water
- Mining causes dangerous metals to enter waterways
- Untreated sewage can spread harmful bacteria through water
161
Why does the privitisation of water companies make water more expensive?
Often water companies want to make a profit so charge more for water
162
Why did the privitisation of the water company fail in Bolivia?
- Company raised prices to around 20% of the average income
- Poorest could not afford and began to illegally tap into the water supply
- Protests led to the government cancelling the contract
163
5 principles of the Water Poverty Index
- Availability
- Accessibility (distance to safe water access)
- Handling capacity (management techniques)
- Use and efficiency
- Environmental sustainability
164
How much will food production need to rise to feed the population by 2050?
- 60%
- This will need 140% more water
165
How many children die of water-borne diseases in Nigeria each year?
335,000
166
Why is water needed for energy production?
Steam is used to turn turbines to generate electricity
167
By what percentage is water needed for industrial use set to increase 2000-2050?
4000%
168
How many countries does the river Nile pass through?
11
169
Why has Egypt threatened other nations with war in relation to the river Nile?
Any country upstream that tries to dam the river would limit Egypt's already fragile water supply
170
What year did Ethiopia begin building a dam on the Nile?
2011
171
How many countries does the river Mekong provide water to?
6
172
What is a consequence of China damming the river Mekong?
Other countries water supply will be affected
173
Name of dam on Omo river in Ethiopia?
Gilgel Gibe III Dam
174
Advantage and disadvantage of the dam in Ethiopia on the Omo river?
Advantage: Provides sustainable electricity
Disadvantage: 200,000 people, largely indigenous, rely on the seasonal floods for farming
175
Aim of China's South-North water transfer project?
Aims to deliver 25bn cubic metres of water to the North through two routes
176
Why is the South-North water transfer project needed?
- 2/3 farmland in the North of China
- 80% of water is in the South
177
Economic cons of the South-North water transfer project
- Expensive ($80bn)
- Likely that the water will be expensive for farmers to use in high volumes, so they will likely still use groundwater
178
Social con of the South-North water transfer project
- Over 300,000 people displaced
179
Environmental cons of the South-North water transfer project
- Water shortages in the North largely caused by water pollution. This issue should be fixed instead of artificially transferring water
- Removing water from the Yangtze could be devastating for ecosystems
180
Cons of the Three Gorges Dam
- 1.3m people relocated
- 1,500 villages lost
- Water quality is poor due to pollutant runoff
- Many ecosystems flooded, harming local animals
181
Pros of the Three Gorges Dam
- Can control flooding on the Yangtze
- Provides HEP energy, reduction in fossil fuels
- Can help with the South-North water transfer
182
What are desalination plants?
Removing salt from seawater to make clean drinking water
183
What country has 70% of its water from desalination?
Israel
184
Pros of desalination
- Endless supply of water from the sea
- Can produce up to 600 tonnes of clean drinking water an hour
185
Cons of desalination
- Extremely energy exhaustive, requires a power station for each plant
- By-product brine is extremely damaging to local ecosystems
186
What is smart irrigation?
A method of providing crops with the optimum level of water
187
Example of a smart irrigation technique
Drip feeding:
Water goes directly into the soil, minimising the loss to evaportation
188
How has smart irrigation helped Australia?
- 60% increase in water productivity
- Improvements in fruit quality
189
Why does Singapore struggle with water scarcity?
- City state with population 5.4m
- Extremely densely populated
- High temperature = high evaporation
- Limited land available for water collection and storage
190
How does Singapore sustainably manage its water?
Their NEWater scheme purifies used water into high-grade drinking water. Currently around 30% of water is recycled
191
Singapore imports water from which country?
Malaysia
192
What is Integrated Water Resource Management (IWRM)
- Focus on both conservation and development of the river
- Aim to maximise socio-economic potential while protecting ecosystems
193
Why does the Colorado river basin need a IWRM plan?
- Travels through two countries (US and Mexico)
- Across many ecosystems (Such as Rocky Mountains and semi-arid areas of Mexico)
- The population is growing which is increasing water insecurity
- Climate change is adding further pressure
194
What year was the Colorado River Storage Project?
1956
195
What did the Colorado River Storage Project provide?
Allowed for irrigation development as well as HEP production
196
What did the Colorado River Storage Project provide?
Allowed for irrigation development as well as HEP production
197
How many dams are there along the Colorado river?
29
198
Year of Helsinki Water Convention?
1992
199
Aim of Helsinki Water Convention
- To improve and protect water quality
- Ensuring this was done in a sustainable manner
- Improving co-operation for transboundary water conflicts
200
Result of the Helsinki Water Convention
Established IWRM
201
Year of the Berlin Rules agreement
2004
202
Aim of the Berlin Rules agreement
To state how freshwater resources should be shared and adopts nine water management principles
203
Examples of principles from the Berlin rules
1. Environmental, social and economic needs must be met
2. Everyone must co-operate over shared resources
3. Upstream developments must be controlled
