Chapter 9
Water as a Resource
http://snr-1349.unl.edu/navigation/waterdistribution.aspx
Groundwater
 Exists in aquifers (permeable layers of rock and
sediment)
a. confined aquifer
b. unconfined aquifer
• Water table
a. uppermost level where water still saturates rock or soil
b. “surface of the groundwater”
• Groundwater recharge
 Sources of aquifers
a. springs
- source of freshwater
- water naturally rises to the ground surface
b. artesian wells
- drilling in confined aquifer
- releases pressure on the water
http://www.ec.gc.ca/eau-water/default.asp?lang=En&n=300688DC-1
 Problems with water from unconfined aquifer
- recharge very quickly
- contamination with chemicals
• Largest aquifer
- Ogalla in the Great Plains
- lots of water is being withdrawn (problem!)
 Cone of Depression
a. an area where there is no longer any ground water
b. water table drops too low
c. comprises water quality
 Saltwater intrusion
a. drilling wells along coastline
b. rapid pumping lowering water table
c. adjacent saltwater infiltrates in
Surface Water
 Freshwater that exists above ground
- streams, rivers, ponds, lakes, and wetlands
• Rivers
a. 3 largest
- Amazon in SA
- Congo in Africa
- Yangtze in China
b. land surrounding rivers is typically fertile
c. floodwaters deposit nutrient-rich sediment onto the
floodplain
• Lakes
a. classified by level of primary productivity
b. oligotrophic v. eutrophic
• Wetlands
a. control flooding
Atmospheric Water
 Drought
a. long-term effects on soil
• Flooding
a. water input exceeds the ability of an area to absorb
the water
b. areas affected by drought-impermeable surfacesflood
Altering the Availability of
Water
 Levees
a. enlarged bank built up on each side of the river
b. Mississippi River – largest system of levees
c. major challenges
- floodwater no longer add fertility to floodplain
- sediments will deposit further down where river
meets ocean
- cause even worse flooding downstream
- can collapse
 Dikes
a. built to prevent ocean waters from flooding
adjacent land
b. common in Europe – farmland below sea level
 Dams
a. barrier that runs across the river or stream to control
the flow of water
b. reservoir
c. used to generate electricity
d. world’s largest – Three Gorges Dam in China
e. environmental problems
- interruption of natural flow of water (fish ladders)
 Aqueducts
a. canals/ditches used to carry water from one place to
another
b. concrete canals and pressurized steel pipes
c. In the US: NYC and LA
d. ensures clean water, but disturbs habitats
e. diversion project
- Soviet Union diverted two rivers that fed into the Aral
Sea
 Desalination (desalinization)
a. removing salt from sea water
b. 2 common techniques
1. distillation
2. reverse osmosis
- leaves behind a brine
(high salt concentration)
http://bcs.whfreeman.com/friedlandapes/#668210__690864__
Water Use
 Freshwater
a. 70% - agriculture
30% - industrial and household
http://www.data360.org/dsg.aspx?Data_Set_Group_Id=757
 Agriculture
a. largest use of water
b. US: 1/3 of freshwater is used for irrigation
1. furrow – 65% efficient
2. flood – 70-80% efficient
3. spray – 75-95% efficient
4. drip – over 95% efficient (reduces weed growth)
c. hydroponic agriculture
1. alternative to traditional agriculture
2. crops under greenhouse conditions
3. uses 95% less water than traditional irrigation
http://blog.syracuse.com/cny/2011/01/hydroponic_farming_satisifes_central_new_yorks_craving_for_local_greens_in_midwinter.ht
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 Industry
a. in US, ½ water goes towards electricity
b. cools machinery (steam)
c. refines metals
d. used to make paper
 Household
a. in US, 10% water used in homes
b. Indoor use
1. flushing toilets (41%), bathing (33%), laundry
(21%), and cooking/drinking (5%)
c. Outdoor use
1. watering lawns, washing cars, etc.
d. drinking water
Water Conservation
 A NECESSITY!
 Improved efficiencies in toilets and shower heads
 Plant vegetation that’s appropriate for your climate
a. Las Vegas, Nevada