1. Water: A Limited Resource

2. What are some properties of water (think chemistry)?
Questions of the day:
Why is water important?
What are some properties of water (think chemistry)?
What are the major uses of water?

3. Importance of Water Cooking Washing Use large amounts for:
Agriculture
Manufacturing
Mining
Energy production
Waste disposal
Use of freshwater is increasing

4. Properties of Water Composed of 2 Hydrogen and 1 oxygen
Exists as solid, liquid or gas
High heat capacity
Polar
One end has (+) charge, one end has (-) charge
Forms Hydrogen bond between 2 water molecules
H-bonds define water’s physical properties

5. Properties of Water Water is never completely pure in nature
Content of seawater (left)
Many substances water dissolves cause water pollution
Universal dissolver

6. Hydrologic Cycle

7. Distribution of Water Only 2.5% of water on earth is freshwater
2% is in the form of ice!
Only ~0.5% of water on earth is available freshwater
97.5% is saltwater

8. Freshwater Terminology
Surface water
Precipitation that remains on the surface and does not seep into soil
Runoff
Movement of surface water to lakes, rivers, etc.
Watershed (drainage basin)
Land area that delivers water into a stream or river system
Groundwater
Freshwater under the earth’s surface stored in aquifers
Aquifer
Underground caverns and porous layers of sand, gravel and rock in which groundwater is stored

9. Freshwater Aquifer/Groundwater

10. Q of Day- To be discussed, don’t need to write down
What are three main problems with water?
How much water do you think you use in one day? (In gallons)

11. Water Use and Resource Problems
Fall into Three Categories
Too much water
Too little water
Poor quality/contamination

12. Too Much Water Flooding
Both natural and human-induced
Modern floods are highly destructive because humans:
Remove water-absorbing plant cover from soil
Construct buildings on floodplains
Floodplain
Area bordering a river channel that has the potential to flood

13. Coastal flooding

14. Flooding of Rivers

15. Urban vs. Pre-Urban Floodplains

16. Floodplain Government restrictions on building
Levees can fail
Rather than rebuild levees adjacent to rivers, experts suggest allowing some flooding of floodplains during floods
(next slide)

17. Left: Traditional levees adjacent to river
Right: Suggested levee style, set back from river

18. Journey to Planet Earth video segments- Create this table on last page of notes
Too much water-Mississippi River
Too little water-Ogallalla Aquifer
Too many obstacles- Klamath River
Too little water- Aral Sea/ Salton Sea

19. Too Little Water Typically found in arid land Problems Drought
Overdrawing water
for irrigation
purposes
Aquifer depletion
Subsidence
Sinkholes

20. Too Little Water
Problems (continued)
Saltwater Intrusion

21. Water Problems in US and Canada
Water shortages in West and Southwest
Water is diverted and transported via aqueducts

22. Water Problems in US and Canada- Surface Water
Mono Lake (Eastern CA)
Rivers and streams that once fed this lake are diverted to Los Angeles (275mi away)
Becoming highly saline
Court ordered water diversion reduction
Colorado River Basin
Provides water for 27-million people
Numerous dams for Hydropower
Colorado River no longer reaches ocean

23. Colorado River bed in Mexico

24. Water Problems in US and Canada- Groundwater
Aquifer Depletion