Water Flashcards
store
reservoirs where water is held
(oceans , lakes )
fluxes
way water moves between stores
flows
movement of water
hydrological cycle
a closed system driven by solar and gravitational potential energy
why the hydrological cycle is a closed system
no external outputs or inputs , the total volume of water is infinite and constant but can exist in different states
hydrosphere
water on surface
96.5% of total water
lithosphere
water in earths crust
1.7% of global water
atmosphere
water as vapour in earth above us
0.001% of total water
4 main stores of water
cryosphere
atmosphere
lithosphere
hydrosphere
cryosphere
areas of earth where water is frozen into snow or ice
1.7% of global water
how water is stored on land
rivers, streams , lakes and groundwater (blue water as visible)
or in plants in soil or vegetation itself
(green water as invisible)
how is water stored in the atmosphere
mainly as vapour ,
what is the carrying capacity in the atmosphere linked to
the temperature
ocean as a store
stores over 1 million
home to 96% of earths water
residence times
average time a water molecule will spend in that reservoir or store
what does residence time effect
-it impacts on turnover within the water system ,
-accesible stores ( rivers and lakes) are easily turned over due to evaporation or transpiration
- inaccessible stores ( deep ground water) can be stored for 10,000 years and become fossil water as it’s non renewable
fluxes - infiltration
water soaked into the ground
fluxes - precipitation
the movement of water from the atmosphere to the ground as droplets fall from clouds
fluxes - interception and transpiration
plants take water from the ground and return to atmosphere by transpiration
fluxes - accumulation
snow and ice melt back into liquid
fluxes - condensation
water vapour rises into the clouds after being evaporated
fluxes -evaporation
change in state of water from a liquid to a gas as water is heated by the sun
fossil water
deep ancient water from former wetter periods
main input and output of hydrological cycle
input - precipitation
output- evaporation , transpiration , discharge
flows - through flow
lateral movement of water down a slope
flows - groundwater flow
long process of percolated water into rivers
flows - infiltration
water soaking into plants and soil
flows - surface run off
movement of water overland
flows - percolation
- deep transfer of water into bedrock
flows - interception
retention of water by plants and soil
frontal rainfall
due to a weather front
warm air has to rise over weather front and cools as it rises causing heavy rain
convectional rainfall
occurs on warm days when warm air rises and cools and condenses as it does
relief rainfall
due to topography
air rises over a mountain and cools as it rises causing rain
availability of freshwater
only hydrosphere is accessible
only 2.5% of this is freshwater
only 1.2% of this is on surface
only 1% is accessible
drainage basin
an open system that is the area of land drained by a river and it’s tributaries
why the drainage basin is an open system
as it has external inputs and outputs that cause the amount of water in the drainage basin to vary
drainaige basin - watershed
the highland which divides and separates waters flowing to different rivers
outputs of drainage basin
transpiration from vegetation
evaporation
input of drainage basin
precipitation
source
top of river / origin
confluence
junction where two different rivers meet
tributary
small channel that flows into the main channel
distributary
small channel that flows out of main channel
mouth
end of river where the river flows out to the body of water
conditions needed for precipitation to fall
air cooled to a saturation point
temp below dew point
condensation to facilitate growth of water droplets in clouds
5 physical factors influencing drainage basin
- climate
- relief
- geology
-vegetation
-soil type
rain shadow
a dry area on the side of the mountain as mountain shelters it
interception loss
water retained by plant surfaces then lost due to evaporation or absorbed by plant and transpired
infiltration capacity
max rate which rain can be absorbed by soil in a given condition
5 factors effecting rate of infiltration
- decreases with persistent rainfall
- volume of water already in soil
- type of vegetation cover ( forest is best)
- nature of soil surface
- topography ( steep slopes encourage run off)
outputs of drainage basin - evapotranspiration
combined effect of evaporation and transpiration- accounts for nearly 100% of removal of precipitation in arid areas
physical factors affecting the drainage basin - climate
climate infleunces
- inputs and outputs
- evaporation and precipitation amount
physical factors affecting the drainage basin - soils
soils determine
- amount of infiltration
- sand soils infiltrate
- clay soils don’t
physical factors affecting the drainage basin - geology
impacts
- percolation
- soil formation
physical factors affecting the drainage basin - relief
impacts
- surface run off
- type of precipitation ( relief rainfall)
physical factors affecting the drainage basin - vegetation
imapacts
- interception
- infiltration
- transpiration
human impacts of drainage basin - river management
construction of reservoirs disrupts the flow
human impact on drainage basin- deforestation
increases EVT
increases infiltration
increases surface run off
human impact on drainage basin - urbanisation
impermeable surfaces cause
decreases infiltration
increases SR
human impact on drainage basin - changing land use
arable to pastrol farming = increase soil compaction which increases SR
pastoral - arable farming = increase infiltration due to ploughing
6 main components affected by humans
- evaporation
- EVT
- SR
- infiltration
- interception
- groundwater
water budgets
the annual balance between precipitation , EVT and run off
balance between inputs and outputs
polar regions have low water budget
river regimes
the annual variation in discharge of a river at a particular point measured in cumecs
what is most of the river flow from
supplied from groundwater between periods of rain which feed steadily into the river system from base water flow
eg of river regime - Alaska
Apr- Aug= high flow due to snow melt
Sep - Mar = low flow as ice forms
large flow variability
few human influences
eg of river regime - Amazon
Dec - may = high flow
Jun - nov = low flow
moderate variability but human activity is increasing this
characteristics of river regime are influenced by 7 factors:
size of the river
where measurement is taken
amount and intenisty of precipiation
temps
geology
type of vegetation
human activity
case study - how human factors have affected amazon basin 7 ways
deforestation has disrupted basin by :
- lowering humidity
- increase SR
- increase infiltartion
- increase evaporation
-decreasing transpiration
- increasing soil erosion
- increasing silt in rivers
storm hydrographs
show variation of discharge within a short period of time ( storm, group of storms) not normally longer than a few days
storm hydrographs - lag time
time interval between peak rainfall and peak discharge
flashy storm hydrographs
- steep rising and falling limb
- short lag time
- high peak discharge
delayed hydrographs
- gentle rising limb
- lower peak discharge
- slightly steeper falling limb
- more manageable
Factors affecting shape of hydrograph - climate
flashy hydrographs are due to intense storms or low evaporation
delayed hydrographs are due to steady precipitation and high evaporation
Factors affecting shape of hydrograph - geology
flashy hydrographs will have impermeable rocks such as clay
delayed hydrographs will have permeable rocks that allow percolation
Factors affecting shape of hydrograph - relief
flashy hydrographs will have steep relief of land
delayed hydrographs will have gentle relief
Factors affecting shape of hydrograph - human activity
flashy hydrographs may be due to urbanisation and deforestation
delayed hydrographs will be due to limited human activity and afforestation
factors effecting shape of hydrograph - pre existing conditions
flashy hydrograph - fully saturated land or impermeable dry land
subdued - dry basin
factors affecting shape of hydrograph - shape of drainage basin
flashy hydrographs will have small circular drainage basin
subdued hydrographs will have a large elongated drainage basin
impact of urbanisation on hydrological cycle
- increase soil erosion as veg been cleared
- drains reduce lag time
- bridges restrain free discharge of flood waters
- channelized rivers makes flooding more dangerous when it does occur
normal % of inputs and outputs in non urbanised areas Vs Urbanised area
EVT- decreases by 10%
SR - increases by 45%
infiltration - decreases by 35%
meteorological drought
dry weather in an area due to shortfalls in precipitation
agricultural droughts
the rainfall deficiency from a meteorological drought leads to a deficiency of soil moisture which has a knock on effect of plant growth
hydrological droughts
reduced stream flow and groundwater levels because of little precipitation but high evaporation which show evidence of low water supply
Brazil drought 2014 causes
deforestation , a high pressure weather system which caused rain to be diverted away and over abstraction
Brazil drought 2014 - socio economic impacts
water rationing for 4 million
halt in HEP production
power cuts
reduced coffe bean crops - increased prices by 50%
Brazil drought 2014 - impacts on rainforest
forest stress
reduced canopy cover - can’t absorb as much c02
reduced humidity
Brazil drought 2014 - impact on wetland
reduced habitat
reduced space for cattle ranching
wild fires due to slash and burn technique
ENSO- El nino
trade winds weaken causing the ocean current to slow seeing rainfall over SA and droughts over eastern Aus
ENSO- normal conditions
trade winds blow from east to west
warm water in aus causing upwelling and evaporation
ENSO- La nina
exaggerated version of a normal years with a stronger trade winds causing strong ocean currents are upwelling , heavy rain over Aus , drought in SA
The Sahel region - desertification
desertification caused by changing rainfall patterns , wind erosion , soil erosion and lack of vegetation
annual rainfall fell by 30%
Human Influences on drought -
Human factors causing Sahel
- environmental degradation due to overgrazing
- deforestation for fuel wood
- high levels of poverty
- population doubling in 20 years
desertification
land degradation in arid and dry regions due to various factors such as climate and human activities
Human causes of desertification - Increased animals in Sahel region
livestock increased by 40% - overgrazing causes soil to be drained of nutrients - no protective grass cover - increase evaporation from soil - even more soil erosion
Human causes of desertification - Increased population in Sahel region -
farmers had to change methods as higher food demands - which led to over cultivation of land and soil erosion
Australian Droughts 2006 - physical causes of droughts
30% of Aus is in rainfall deficit , meaning droughts are reocurrent
2006 an El nino event worsened this but supplies were managed by water recyclying and desalination
Human causes of desertification - Increased deforestation in Sahel region
increased demand for wood for cooking/heating - led to deforestation - vegetation removed - increased risk of soil erosion
impacts of droughts on wetland
- drought causes decrease infiltration which decreases water table
- this decreases the functions of the wetlands
- they are resistant to human activity and can adapt
wetlands perform a number of key functions
- temporary water stores protecting land from erosion
- act as giant water filters by trapping and recycling nutrients
- high biological productivity
- provide resources for humans ( fish /fuelwood)
impacts of droughts on forests
- responsible for interception which decreases flooding
- droughts increase likelihood of fungal diseases which kill the trees
- they are resilient but human interference is high
3 meteorological causes of flood
- intense storms
- prolonged heavy rainfall (monsoons/depression)
- rapid snow melt
6 human factors increasing risk of flooding
- over cultivation
-over grazing - deforestation
-urbanisation - river channelization
- dams
3 mis management of rivers factors that cause flooding
- channelization - decreases in one area whilst over whelming another area
- Dams - block flow of sediment so reservoir fills with silt
- river embankments - if a river does flood they fall and worsen it
why there has been an increase in human factors causing flooding
economic and population growth since the 20th century has caused flood plains to be built on , changing land use and urbanisation
4 physical factors that can cause flooding
- topography
- volcanic activity
- geology
- eq rupturing dams
groundwater flooding
flooding that occurs after the ground has become saturated from prolonged heavy rainfall
surface water flooding
flooding that occurs after intense rainfall has insufficent time to infiltrate the soil
flash flooding
a flood with exceptionally short lag time
causes of flooding in southern and eatsern asia
intense monsoon rainfall results in wide spread flooding as they receive 70% of anual rainfall in 100 days
causes of flooding in Asia and America - climate change influence
snow and ice melt in late spring , ground remains frozen so water can’t infiltrate which increases surface run off
Storm Desmond 2015 Cumbria - meteorological causes
deep Atlantic low-pressure system (depression)
Fronts also brought heavy rainfall across the UK.
Storm Desmond 2015 Cumbria - human contributions
changing land use - trees no longer intercepted - higher run off rates - reduced lag time
mismanaging rivers- riverbanks, pumping stations and diversion channels carried surplus water away but they have limited capacity
Storm Desmond 2015 Cumbria - impacts
- 5200 homes flooded
- landslide between aliston and Carsile
- 61,000 without electricity
Storm Desmond 2015 Cumbria - how flood risk could’ve been reduced
- afforestation of upland areas
- ## restoration of river channels to return to natural meandering
How urbanisation causes flooding
- creation of impermeable surface
- drains (decrease lag time)
- channelization ( faster rate of water)
- changing land use ( deforestation, overgrazing )
climate change effects on precipitation
- warmer atmosphere holds more water
- rainfall increase in tropic
- decrease in deserts
-length and frequency of heat waves increase
climate change impact on evaporation
- North America and Asia have seen an increase in evaporation and transpiration
- decrease soil moisture which decreases crop yields
climate change and flows - Surface run off
- exaggerated low flows ( droughts) and high flows ( floods)
climate change and stores - cryosphere
- glacial retreat
- decrease in snow cover
- decrease overall store
climate change and stores - permaforst
- melting takes place
- deepens active layer
- releases C02
climate change and stores - resevoirs, lakes and wetlands
- increase temp means increase evaporation
- storage of these will decrease
Flood and future
hydrological cycle will intensify ,
extremes will be more common as the moisture holding capacity of atmosphere increases due to climate change causing heavier precipitation
uncertainties caused by climate change -
- increase EVT as forests die
- ENSO will become more common
- more frequent cyclones ( ocean temp)
low flows and drought in future
climate change influences precipitation, temp and potential evapotranspiration which increase frequency and severity of droughts
physical distribution of water
there is a mismatch between where water supplies are and the demand.
60% of water lies in 10 countries
Countries experiencing shortages due to over abstraction
USA - ogallala aquifer
Mexico- Mexico city
Middle east - Yemen
gap in water usage between countries
richer countries use up to 10x more water per head than developing countries
virtual flow
the hidden flow of water when food or other commodities are traded
prediction of water vulnerability
predicted by 2025 , 50% of world’s population will be water vulnerable
water insecurity
a country with a lack of adequate and safe water for a healthy and productive life
water stress
when water resources are between below 1700m3 per capita
water scarcity
when water resources are below 1000m3 per capita
economic scarcity
when the water is there but the technology isn’t to extract it
caused by poverty
1 billion people don’t have access to water due to poverty
physical scarcity
when more than 75% of a countries blue water is being used
applies to 25% of worlds pop
( Middle east , north Africa)
physical causes of water insecurity - saltwater encroachment
when too much freshwater is pumped from the aquifer system, causing saltwater to migrate into the aquifer
physical causes of water insecurity - climate change
summers will become hotter and drier. Reduced precipitation and increase evaporation will diminish water supplies
physical causes of water insecurity - Geology
geology controls the distribution of aquifers (permeable rocks store water)
human causes of water insecurity - contamination
agriculture and industry use large amounts of water , often industry is responsible for water pollution which increases water insecurity
human causes of water insecurity - over abstraction
increase demand of water for humans has led to an increase abstraction from rivers lakes and aquifers which leads to water insecurity
Pollution of water sources figures
industrial waste cause eutrophication and disease.
This water then cannot be used or is expensive to clean.
WHO estimates 2.3bn lack proper sanitation.
3 pressures increasing water insecurity
- diminishing supply ( climate change , water quality)
- rising demands
- competeing demands
rising demand of water - caused by 3 factors
- population growth
- economic development
- improving living standards
Impacts of water insecurity - The Aral sea - Where and Why
-Aral sea in Asia used to be 4th largest inland sea
-the diversion of two main rivers for agriculture and industry meant by 2007 the sea lost 10% of it’s size
-
Impacts of water insecurity - The Aral sea - Impacts
- lost 150 bird species
- lost 38 mammal species
- collapse of fishing industry that employed 6000
- health issues caused by wind blown salt
water scarcity
the amount of water that can be physically assessed as supply and demand varies.
water as a commodity
water can now be brought and is seen as something people should pay for meaning water supply is in the hands of private companies
climate change and California
- precipitation levels fell - led to desertification
- temp increased - drier periods and droughts
- drinking water is decreasing so ground water is being over abstracted
Importance of water for economic development - industry and energy production
20% of all freshwater is used for industry and energy production
water pollution is a major product of this
Importance of water for economic development - agriculture
accounts for 3770 km of water extraction a year
20% of land is irrigated
much of this water is pumped from aquifers leading to depletion
importance of water for human well being
polluted water is a breeding ground for diseases such as cholerae and typhoid
water is vital for cooking and cleaning
Water conflict
– a conflict between countries or groups over the rights to access water resources.
The river Nile - Transboundary conflict - Background of river
Flows through 11 countries
is 67,000km long
The river Nile - Transboundary conflict - growing demand
1929 agreement gave Egypt and Sudan split ownership of the river however as the other countries became independent they fought for their rights.
This caused the 1999 Nile basin initiative which aimed to ensure sufficient management and cooperation
Ethiopia - internal water conflict
Ethiopia has built a controversial Dam to stimulate economic growth , cost $1.8 billion and environmental impacts weren’t published til 2 years after meaning production was halted as it going to harm tribes
Hard engineering - Mega Damns facts
In 2010 there were 845,000 dams that store 15% of global runoff
Hard engineering - Mega Dams - 3 Advantages
Greater source of renewable energy.
divert and hold water strategically
can reduce flooding
Hard engineering - Mega Dams - disadvantages
high costs
high evaporation loses
displacement of people
Eg of mega dam - Three gorges
-built in 2009 along the Yangtze River costing $31bn.
-Designed to control flooding, improve water supply.
-Most productive HEP dam
- 600km2 land flooded and water is still polluted.
- over 1 million people had to be relocated
Hard engineering - Water Transfer impacts on source
- reduce water flow by 60% which reduces floods
- low flow means increase pollution and damage to ecosystems
Hard engineering - Water transfer advantages
Increased water use for economic development, reduces abstraction and risk of water shortages.
Eg of water transfer - China south to north water transfer project
Aims to divert 44.8 billion tonnes of water
- It will cost $62bn,
-345000 people have to relocate
- but reduces deficit in the north so can be used for industry
- taken 50 years to build
Hard engineering - desalination - facts
Desalination Removing salt from seawater and is reliable and predictable.
there is a huge abundance of sea water
however v expensive and effects marine life
Hard engineering - desalination - Israel
5 plants opened in 2013 , aims to supply 70% of israels water by 2020
produces 600 tonnes of potable water an hour
- however each plants requires it own power station which releases large amounts of c02
waste products of brine harms ecosystems
Soft engineering - smart irrigation - how it works ( Blossom 8)
Automated spray system detecting temperature and humidity.
Soft engineering - smart irrigation - advantages ( Blossom 8)
Conserves water, lowers bills, less water lost by evaporation.
Soft engineering - smart irrigation -disadvantages ( Blossom 8)
Unattractive, small scale, uses freshwater, costs $199 to set up.
Soft engineering - drip irrigation - how it works (Metafim, Israel.)
Micro-irrigation focused on roots, reducing evaporation.
Soft engineering - drip irrigation - advantages (Metafim, Israel.)
Preserves water, saves 50% of water, more productive.
Soft engineering - drip irrigation - disadvantages (Metafim, Israel.)
Still expensive, impacted by drought, hard on a large scale.
Soft engineering - Grey water recycling - how it works ( China)
Reusing treated wastewater for irrigation (not humans).
Soft engineering - Grey water recycling - advantages ( China)
Multiple uses, if treated can be drinkable.
Soft engineering - Grey water recycling - disadvantages( China)
Not potable, can harbour bacteria/ viruses.
Soft engineering - restoration of aquifers - how it works (Saudi Arabia)
Not using aquifers, letting them be naturally replenished.
Soft engineering - restoration of aquifers - advantages(Saudi Arabia)
Growing crops elsewhere takes the pressure off aquifers.
Soft engineering - restoration of aquifers - disadvantages(Saudi Arabia)
They won’t be restored if rainwater is low.
Soft engineering - holistic water management - how it works - (Singapore.)
Managing all the water resources in an economy to keep prices down, desalinate water and catch local rainwater.
Soft engineering - holistic water management - advantages (Singapore.)
Effective, people use less water, less leakages, less imports of water.
Soft engineering - holistic water management - disadvantages (Singapore.)
People may ignore and pay more for water, desalination is expensive, still importing water from Malaysia.
Integrated Drainage basin management
- emphasises river basin as unit of management for resources
treated holistically to achieve - environmental quality
- water used with max efficiency
- equitable distribution
works well at community level but not transboundary
Colorado river - Integrated water management - allocated water usage
- In 2021, there was a water shortage on - The 1992 agreement in place was made in different conditions.
- Mexico takes 10% of the total flow,
-lower basin states take 50%
-upper basin states fall short by 10%. - California takes 20% more than its allocated
Colorado river -how many it supplies
- The river supplies 7 states, 50 million people and 1.4 million hectares of farmland
Colorado river - what’s being done
California have set up a desalination plant,
-Arizona has set up a water bank authority but no new agreement has been made yet.
water treaty
a agreement signed by a number of countries regarding the rights of water to attempt to resolve conflicts
The 1992 water convention - who
UN economic comissions for Europe water aims to protect and ensure the quantity, quality and sustainable use of transboundary water resources in Europe by helping with cooperation and resolving issues.
The 1992 water convention - aim
Aimed to prevent transboundary impact and use water in an equitable way
The 1992 water convention - how
includes provisions on monitoring, research and development, consultations, warning and alarm systems, mutual assistance, and exchange of information, as well as access to information by the public.
case study - how human factors have affected amazon basin 7 ways
deforestation has disrupted basin by :
- lowering humidity
- increase SR
- increase infiltartion
- increase evaporation
-decreasing transpiration
- increasing soil erosion
- increasing silt in rivers
Importance of water for economic development - agriculture
accounts for 3770 km of water extraction a year
20% of land is irrigated
much of this water is pumped from aquifers leading to depletion
4 water sharing treaties
- Helsiniki
- UN commission for europe
- UN water course convention
- EU water framework
