1. Chapter 11 Water

2. World Water Distribution
Total:
97% salt water
3% freshwater
Freshwater:
70% glaciers
29% aquifers
1% lakes, rivers, streams

3. Water is unequally distributed across Earth’s surface
Different regions possess vastly different amounts of groundwater, surface water, and precipitation
Many areas with high population density are water- poor and face serious water shortages

4. Surface Water Lakes, rivers, streams, wetlands, estuaries
Watershed: the area of land that is drained by a river
River system: the flowing network of water draining a river basin

5. Watersheds of the world (see pgs. 270-271)

6. Groundwater Groundwater: water that is beneath the earth’s surface
Water table: the upper level of water underground
Aquifer: underground formation that contains groundwater

7. Aquifers
Most are made of materials like rock, sand, gravel with spaces in which the water can be held like a sponge (see pgs )
Water can be tapped from aquifers for use by people; if used too much and too quickly, it can go dry (Ogallala Aquifer case study, pgs )

8. Aquifers
Aquifers can be refilled as water percolates down through the recharge zone, may take a long time
Porosity – amount of space between particles of the rock
Permeability – ability of the rock or soil to allow water to flow through it
Pollution can enter the groundwater through the recharge zone (think about Silent Spring) – it can then travel to other places through the underground water system, even showing up years later

9. The Ogallala Aquifer The world’s largest known aquifer
Underlies the Great Plains of the U.S.
Its water has allowed farmers to create the most bountiful grain-producing region in the world

10. Water Use
Which category has the highest
use overall in the world?

11. Water Use
1. Industrial – manufacturing, producing power (including reservoirs by dams), cooling of power plants

12. Global Water Use: Industry
How does water use compare in developing and developed countries?
Which countries have more than 50% of their water used by industries?

13. Water Use
2. Agricultural – irrigation of crops

14. Global Water Use: Agriculture
Which countries have the highest percent of their water use dedicated to agriculture?

15. Water Use
3. Residential (=municipal) –
drinking, cooking, cleaning

16. Residential Water Use

17. Guess the gallons it takes to…
Take a shower:
50 gallons
Flush the toilet:
6 gallons
Large load of laundry:
60 gallons
Brushing teeth, water running:
2 gallons
Dishwasher load:
10 gallons
Washing face/hands:
5 gallons

18. Water Use Caculator

19. Drinking Water Treatment
Steps (pgs ):
1. First filtration – removes large trash, objects, large organisms like fish and mussels

20. Drinking Water Treatment
2. Coagulation or flocculation – chemicals are added to the water; bacteria and other small impurities stick together to form flocs and settle out of the water

21. Drinking Water Treatment
3. Second filtration – layers of sand, gravel, coal used to filter remaining impurities

22. Drinking Water Treatment
4. Chlorination – chlorine added to stop bacterial growth

23. Drinking Water Treatment
5. Aeration – removes unwanted gases, improves odor and taste

24. Drinking Water Treatment
6. Additional Treatments - depends on the community: may include addition of fluoride which is good for teeth, addition of chemicals to soften hard waters

25. Drinking Water Treatment
7. Potable (=drinkable) water is pumped to homes for residential use.

26. Water Treatment Plant Virtual Tour

27. Water management
Water diversion projects bring water to areas that need it
Central Arizona Project Aqueduct – brings water from the Colorado River to dry areas of Arizona, multiple uses (drinking water, recreation, power, etc.)

28. We divert – and deplete – surface water
People have long diverted water to farm fields, homes, and cities
The once mighty Colorado River has been extensively dammed and diverted

29. The Colorado River is heavily diverted
What water is left after all the diversions comprises just a trickle into the Gulf of California
On some days, water does not reach the gulf
Diversion has drastically altered the river’s ecology

30. The Aral Sea Once the fourth-largest lake on Earth
It has lost more than 80% of its volume in just 45 years
The two rivers leading into the Aral Sea were diverted to irrigate cotton fields
Consequences of a shrinking sea
60,000 fishing jobs are gone
Pesticide-laden dust from the lake bed is blown into the air
The cotton cannot bring back the region’s economy

31. Can the Aral Sea be saved?
People may have begun saving the northern part of the Aral Sea

32. Water management Dams – purposes: flood control hydroelectric power
creation of reservoirs for drinking water, irrigation and recreation
Only a few major rivers remain undammed
In remote regions of Canada, Alaska, and Russia

33. A typical dam

34. Water management Case Study: Glen Canyon Dam, AZ List pros and cons

35. Water management Case Study: Three Gorges Dam, China
List pros and cons

36. Benefits and drawbacks of dams
Power generation
Emission reduction
Crop irrigation
Drinking water
Flood control
Shipping
New recreational opportunities
Drawbacks:
Habitat alteration
Fisheries declines
Population displacement
Sediment capture
Disruption of flooding
Risk of failure
Lost recreational opportunities

37. Are we running out of water?
Do you think water is a renewable resource?
It is a renewable resource because it can be replenished by nature (water cycle)
However, if it is made unusable by pollution or removed from the ground faster than nature can replenish it, then it is considered nonrenewable

38. Will we see a future of water wars?
Freshwater depletion leads to shortages, which can lead to conflict
261 major rivers cross national borders
Water is a key element in hostilities among Israel, Palestinians, and neighboring countries
Many nations have cooperated with neighbors to resolve disputes

39. Consequences of overuse of water resources:
Groundwater is easily depleted
Aquifers recharge slowly
1/3 of world population relies on groundwater
As aquifers become depleted
Water tables drop
Salt water intrudes in coastal areas
Sinkholes = areas where ground gives way unexpectedly
Some cities (Venice, Mexico City) are slowly sinking
Wetlands dry up

40. Solutions can address supply or demand
Increasing supply
Water can be transported through pipes and aqueducts
It can be forcibly appropriated from weak communities
Can we “make” more usable water?

41. Desalination
Desalination is the process of removing salt from salt water – may be answer to providing more water to a growing human population It is expensive, requires fossil fuels, and produces concentrated salty water

42. Solutions can address supply or demand
Best solution is to lower demand, that is to CONSERVE WATER
Politically difficult in the short term
Offers better economic returns
Causes less ecological and social damage

43. Water conservation
Agriculture – drip irrigation system

44. Water conservation
Industry – recycle water

45. Residential demand can be reduced outside
Water lawns at night, when evaporation is minimal
Xeriscaping = landscaping using plants adapted to arid conditions
Don’t wash driveways and sidewalks with water

46. Water conservation in the home
Residential – how can you conserve water?
Awareness of water use and conscious decisions to reduce water use (shorter showers, turn off water when brushing teeth, etc.)
Low flow faucets, shower heads and toilets
Don’t use toilet as a waste basket
Run dishwasher and washing machine only when full
Fix leaky plumbing