Unit 4: Water, Food Production Systems & Society Flashcards
What are 4 reasons why water is important?
- keeps us alive
- moderates climate
- sculpts land
- removes and dilutes wastes and pollutants
How does water sculpt land?
erosion
What percent of the earth’s water supply is available to us as liquid freshwater?
1%
What percent of all water is saltwater?
97%
What percent of all water is freshwater?
2.6%
What percent of freshwater is frozen? (for now)
68.7%
What percent of freshwater is groundwater?
30.1%
What percent of Earth’s total water volume is available on the surface in lakes, rivers, and swamps?
0.3%
If 2.6% of all water is fresh, then why is only 1% of the earth’s water supply available to us?
2/3 of freshwater is frozen, so we cannot use it
What percent of the total Earth’s water volume is water vapor in the atmosphere?
0.001%
If all of the water in the atmosphere rained down at once, to what depth would it cover the ground?
2.5 cm
When is a resource renewable?
a resource is renewable if it is replenished on a human time scale
How long does it take a molecule of water to enter and leave a river storage?
12-20 days
How long does it take a molecule of water to enter and leave an atmospheric storage?
9 days
How long does it take a molecule of water to enter and leave a groundwater storage?
up to 300 years
How long does it take a molecule of water to enter and leave an ice cap storage?
16,000 years
How long does it take a molecule of water to enter and leave an ocean storage?
37,000 years
How can water easily go from being a renewable to a non-renewable resource?
poor management
Which water storages are renewable?
atmosphere and rivers
Which water storages are non-renewable?
oceans and icecaps
What water storage is a middle ground (either renewable or non-renewable)?
groundwater aquifers
What is the water cycle powered by?
solar radiation (the Sun)
What can water flows either be?
transfers or transformations
What are 5 types of transfers that occur in the water cycle?
- advection
- flooding
- surface run-off
- infiltration and percolation
- stream flow and current
advection
wind-blown movement
infiltration and percolation
when water runs into and through soil or rocks
What are 3 types of transformations that occur in the water cycle?
- evapotranspiration
- condensation
- freezing
evapotranspiration
liquid to water vapor
condensation
water vapor to liquid
What are the seven storages in the water cycle?
- oceans
- soil
- groundwater (aquifers)
- lakes
- rivers and streams
- atmosphere
- glaciers and icecaps
What are 4 ways humans impact the water cycle?
- withdrawals
- discharges
- changing flows (the speed at which water can flow and where it flows)
- diverting rivers
What are 3 uses for humans to withdraw water?
- domestic
- irrigation
- industry
How do humans interrupt the movement of water through discharges?
adding pollutants to water (chemicals from agriculture, fertilizers, sewage)
How do humans change flows in the water cycle?
creating dams, reservoirs, and channels
Why do humans divert rivers?
rivers are directed away from important areas or towards dams to improve storage
canalizing
converting a river into a navigable canal, leading to more rapid flow
permeable surfaces
allow water to percolate into the soil to filter out pollutants and recharge the water table
impermeable surfaces
solid surfaces that do not allow water to penetrate it, forcing it to run off
What has water from the Aral Sea mostly been used for?
irrigation
Since 1961, what has happened to the Aral Sea’s salinity levels?
The Aral Sea’s salinity levels have tripled.
How much has the water dropped in the Aral Sea?
22 meters
Where does most water from the Middle East come from?
the Nile, Jordan, Euphrates, or Tigris rivers
What percent has lake Chad in Africa shrunk by?
95%
What are 3 things many parts of the world experiencing?
- rivers running dry
- falling water tables from over pumped aquifers
- lake and seas shrinking
How many people live without clean drinking water?
1.1 billion
How many people lack adequate sanitation?
2.6 billion
How many people die every year from diarrheal diseases?
1.8 million
How many children die everyday from waterborne diseases?
3,900
How many river basins are shared by 2 or more countries mostly without adequate legal or institutional arrangements?
over 260
What quantity of water is needed to produce 1 kg of wheat?
1,000 liters
What quantity of water is needed to produce 1 kg of rice?
1,400 liters
What quantity of water is needed to produce 1 kg of beef?
13,000 liters
What is the daily water usage per person in residential areas in North America and Japan?
350 liters
What is the daily water usage per person in residential areas in Europe?
200 liters
What is the daily water usage per person in residential areas in sub-Saharan Africa?
20 liters or less
What is the leading human use of water?
agriculture
What are the 6 human uses of water?
- domestic
- agriculture
- industry
- electricity
- transportation
- boundaries
How do humans use water for transportation?
ships on lakes and rivers
How do humans use water for domestic purposes?
water used at home for drinking, washing, cleaning, etc.
How do humans use water for agriculture?
irrigation, for animals to drink
How do humans use water for industry purposes?
manufacturing, mining, cooling
How do humans use water for electricity purposes?
most turbines are powered by steam
How do humans use water as boundaries?
rivers and lakes mark boundaries between nation states
How much higher is agriculture water use than domestic water use?
agriculture water use is 10 times higher than domestic water use
What percent of human water use is for irrigation and electricity?
70%
What percent of human water use is for industries?
20%
What percent of human water use is for cities or residences?
10%
What term does the UN use to refer to our current situation?
“water crisis”
What percent of humans alive today deal with some level of water scarcity?
up to 40%
It isn’t that there’s not enough water world wide…
it’s that the water isn’t evenly distributed
water scarcity
the demand for water exceeds available resources
physical water scarcity
when the demand of the population exceeds the available water resources of a region
economic water scarcity
when human, institutional, or financial capital limit our access to water even though water in nature is available for human needs
Do poor households in developing countries or families in industrialized nations spend higher portions of their income on water?
poor households in developing countries spend more money on water
What would sustainable use allow for?
full natural replacement of the resources exploited and full recovery of the ecosystems
What are two sources of freshwater?
surface water and aquifers
What are examples of surface water?
rivers, streams, reservoirs, and lakes
aquifer
a layer of porous rock (holds water) adjacent to a layer of impermeable rock (does not let water through)
What do aquifers hold?
groundwater that can be extracted directly from the surface or via wells
watershed/drainage basin
land where surface runoff drains downhill into a body of water
reliable runoff
amount of surface runoff that is consistently available for use from year to year
What happens to reliable runoff?
it soaks into the ground and becomes groundwater
In what kind of places can aquifers be refilled?
aquifers can only be refilled in places where the porous rock is exposed at the surface and infiltration from precipitation
What happens to “fossil aquifers” that are no longer exposed at the surface?
the “fossil aquifers” are never recharged
How is the flow in an aquifer?
VERY slow
What can be done to aquifers?
aquifers can be opened or confined
What are the two types of aquifers?
renewable aquifers and non-renewable aquifers
natural recharge
aquifers are replenished naturally by precipitation and percolation
lateral recharge
aquifers are recharged from the side by nearby streams and lakes
At what speed do renewable aquifers recharge?
slowly
Where are non-renewable aquifers located?
deep underground
How long ago did non-renewable aquifers form?
formed tens of thousands of years ago
What is an example of a non-renewable aquifer?
Ogalla
Where is the Ogalla aquifer located?
under the Great Plains
What are the effects of over pumping groundwater?
subsidence and salt water intrusion
salt water intrusion
when the water table is lowered the normal interface moves inland, allowing saline water to penetrate freshwater aquifers
subsidence
the gradual caving in or sinking of an area of land, which can lead to sink holes
What percent of water that we withdraw from rivers, lakes, and aquifers is not returned to these sources?
70%
consumptive use
water does not return to its original source, instead it returns to a different stage in the hydrologic cycle
nonconsumptive use
water is used and returned, and only temporarily removed
What are seven issues related to freshwater use?
- climate change
- low water levels in lakes and rivers
- slow water flow
- pumping too fast from aquifers
- pollution (freshwater is contaminated)
- irrigation degrades soil
- thermal pollution
How do low water levels in lakes and rivers affect the economy?
low water levels can make navigation impossible