1. When the well is dry, we learn the worth of water... Benjamin Franklin
WATER RESOURCES
When the well is dry, we learn the worth of water...
Benjamin Franklin

2. FACTS 71% of the Earth’s surface is covered in oceans
97.5% of Earth’s water is saltwater; 2.5% is freshwater
Less than 1% (0.024%) of all freshwater is accessible for our daily use
Most freshwater is frozen in glaciers & icecaps or in underground aquifers

3. Water is not evenly distributed on Earth...
470 inches rainfall per year in Kauai, Hawaii
Virtually no rain per year in Atacama Desert, Chile
BUT...water is RENEWABLE...hydrologic cycle...water continually recycled
BUT...we do not use or manage water in a sustainable manner
Overload it with pollutants
Remove it/waste it faster than it can replenish
(it is thought that 30-50% of all water we use is wasted)
Every day we withdraw enough water to fill a convoy of large tankers that would stretch over 300,000 miles

4. What do we use water for?
AGRICULTURE...70% (92% OF Water footprint)...
Amount of irrigated land doubled in last 50 yrs
Irrigation is inefficient; crops absorb about 40% of the water
Over-irrigation leads to waterlogging & soil salinization
INDUSTRIAL...20%
RESIDENTIAL...10 %
Bottled drinking water
Why do you choose bottled water over water out of the tap?

5. POTABLE WATER…. drinkable water
VIRTUAL WATER
Water that is not directly consumed; used for production of food & other products
How much water do you think it takes to make 1 hamburger?
630 gallons...16 bathtubs
Look at page complete the table in your notes on the amount of water needed to produce various products
Major uses of water in United States
Cooling of electric power plants....41%
Irrigation...37%
Public water...13%
Industry...5%
Raising livestock...4%
POTABLE WATER…. drinkable water

6. Where does our water come from?
GROUND WATER
Water that soaks into ground
Held within pores of soil/rock
Aquifers: large amounts of water found in underground rocks; underground reservoirs
Largest in US: Ogalalla
Recharge zone...area of land from which groundwater originates
Water table: upper limit of groundwater
¼ of water used in US...but supplies ½ drinking water
SURFACE WATER
Above ground
Lakes, ponds, rivers, streams, wetlands
WATERSHED: entire area of land that is drained by a river; drainage basin
¾ of water used in US...electricity; municipalities, industrial, irrigation

7. flooding Can be beneficial Nutrient rich soil Recharge groundwater
Maintain wetland biodiversity
Freshwater overflows its natural channels to FLOODPLAIN...
Fertile soil
Flat land
Plenty of freshwater
Rivers narrowed/channelized; build dikes/levees/dams
Increases the impact of flooding....along with other human impacts:
Deforestation
Draining of wetlands
Climate change /sea level rise

8. CASE STUDIES The Colorado River Story...p. 318
Freshwater Resources in the US...p
Overpumping the Ogallala...p
How Dams Can Kill an Estuary...p. 331
Aral Sea Disaster: Glaring Example of Unintended Consequences...p
Living Dangerously on Floodplains in Bangledesh...p

9. Complete the survey based on your personal water use
Water we going to do?
Complete the survey based on your personal water use

10. Water promises to be to the 21st century what oil was to the 20th century: the precious commodity that determines the wealth of nations
Fortune magazine may 2000

11. Solutions addressing freshwater depletion issues
Reduce the use & demand
focus on water conservation
increase efficiency of water use
Efficient irrigation...
drip irrigation
low pressure spray irrigation
Line irrigation canals
Match crops with land & climate
Selective breeding & GMOs (crops that require less water)
Recycling treated municipal wastewater (for irrigation of lawns, golf courses, etc
Use gray water (wastewater from showers & sinks) to water lawns
Install low flow faucets/showerheads/toilets/washing machines
Repair leaks in pipes & water mains
Automatic dishwashers

12. Solutions con’t Increase water supply Market based approaches
Desalination (but there are several disadvantages: expensive; requires large inputs of fossil fuels; generates salty waste; kill aquatic life at intake
Reverse osmosis & distillation
Market based approaches
End gov’t subsidies of inefficient practices
Allow water to become a commodity
Privatization of water
Individual control; not government control
buy, sell, trade water rights
Disadvantages:
Undersupply the consumer
Inequitable distribution
Wealthy vs. poor