1. Water
Chapters 13, 8, & 20

2. Water
Covers 71% of Earth’s surface

3. Water’s Importance Regulates climate Dilutes waste
Sculpts Earth’s surface
Major habitat

4. Water Supply 97% salt 3% fresh 2.976% in ice caps 0.024% available
Groundwater, lakes, & rivers

5. Access to Water Supply Women and children’s issue Global health issue
Economic issue
National security issue

6. Hydrologic Cycle Natural recycling and purification
Driven by solar energy and gravity

7. Human Affects on Hydrological Cycle

8. Water Supply: Groundwater
Zone of Saturation
Space in soil filled with water
Water Table
Top of zone of saturation
Aquifers
Natural recharge
Lateral recharge

9. Water Supply: Surface Water
Water flows across the earth’s surface
Sources: precipitation & snow melt
Watershed (drainage basin)
Land from where water drains into a particular waterway

10. Case Study: US Freshwater Resources
More than enough freshwater but…
Unevenly distributed
Polluted
Droughts

11. Case Study: US Freshwater Resources
Water hotspots
Identified areas where competition for water may cause conflicts

12. Case Study: US Freshwater Resources
Storages will grow due to:
Dry climate
Droughts
Population
increases
Wasteful use

13. Case Study: The Colorado River Basin
Spans 7 states
14 dams & reservoirs
Supplied from snow melt of Rockies

14. Case Study: The Colorado River Basin
Many uses include:
Drinking water
Electricity
Crop irrigation
Recreation
~30 million people
Las Vegas
Los Angeles
San Diego

15. Case Study: The Colorado River Basin
Major Problems:
Colorado basin has dry lands
Modest flow for size
Legal pacts allocate for more water for human use than it can supply
Amount of water reaching the mouth (Gulf of California) has dropped since 1960

16. How can we increase our water supply?
Groundwater

17. Groundwater Most are renewable
Provides drinking water for half the world
Most are renewable

19. US Groundwater Supplies: Withdrawn at 4 times the replacement level
Almost all rural drinking water
1/5 of urban water
37% irrigation
Withdrawn at 4 times the replacement level

20. High Moderate Minor or none
Groundwater
Overdrafts:
High
Moderate
Fig a, p. 308
Minor or none

21. Case Study: Ogallala Aquifer
Largest known aquifer
Spans 8 states
Irrigates the Great Plains
Slow recharge = dropping water table
Supplies springs – vital habitats

22. Case Study: California Central Valley
Serious aquifer depletion
Supplies ½ the country’s fruits & veggies

23. How can we increase our water supply?
Groundwater
Dams & reservoirs

24. Main goal of Dams Capture & store runoff Release runoff:
Control floods
Generate electricity
Supply irrigation
Recreation

25. Three Gorges Dam Yangtze River, China World’s largest power station
Video in picture

27. How can we increase our water supply?
Groundwater
Dams & reserviors
Desalination

28. Desalination Removal of salt from ocean water Processes:
Distillation (evaporate & condensate)
Reverse osmosis (microfilter)
Middle east the most; US #4

30. Desalination Problems: Expensive Large amounts of energy
Disrupts marine ecosystems
Brine waste

31. Ways that Humans Use Water

32. Ways that Humans Use Water

33. Ways that Humans Use Water
70% is used for agriculture
1/3rd of US water – irrigation

34. Ways that Humans Use Water
70% is used for agriculture
20% industry
Electricity generation
Cooling machinery
Refining metals/paper

35. Ways that Humans Use Water
70% is used for agriculture
20% industry
10% household uses

39. Water Conservation Estimated 2/3rds of water wasted Why? Low cost
Lack of government
incentives

40. Irrigation Conservation

41. Household Conservation
Fix leaks
Landscape smart
Water efficient appliances
Recycle greywater