1. Water Resources
“It is not until the well runs dry, that we know the worth of water.”
Benjamin Franklin

2. Properties of Water Strong hydrogen bonds
Remains liquid over wide temp range
High heat capacity
Protect living things from temp fluctuations
Moderates climate
Excellent coolant
Properties of Water video
Water-Liquid Awesome, Crash Course

3. Properties of Water con’t
Need a lot heat to evaporate water
Excellent solvent
Water molecules can ionize into H+ and OH- to help maintain balance between acids and bases in the cells
Filters out UV radiation from aquatic organisms
Capillary action
Expands when it freezes/ice has lower density

4. Fresh Water?
97% too salty
Most of 3% freshwater is locked up in ice caps or too deep to be used
.024% easily available

5. Unconfined & Confined Aquifer

6. Groundwater System Surface runoff Watershed or drainage basin
Zone of Saturation
Water table
Zone of aeration
Aquifer
Recharge area

7. Groundwater System

8. Uses of World’s Fresh Water
70% of water withdrawn=irrigation
About 57% of irrigated water evaporates or seeps into groundwater
20% of water withdrawn=energy production & industrial processing, cleaning, and waste removal
10% domestic and municipal use

9. Causes of Freshwater Shortages
Dry climate
Drought
Desiccation
Water stress

10. Causes of Flooding Removal of water absorbing vegetation
Living on floodplains
Urbanization-roads, buildings, parking lots

11. Reduce Risk of Flooding
Channelization
Building levees and dams
Restoring wetlands
Floodplain management to keep people out of flood prone areas = experts view this as best approach

12. Increase Water Supplies
Dams and reservoirs to store runoff
Bringing in surface water from other areas
Withdrawing groundwater
Desalination
Improving the efficiency of water use

13. Dams and Reservoirs
Used to capture and store runoff and release it as needed to
Control flooding
Produce electricity
Supply water for irrigation
Reservoirs used for recreation
number of large dams has increased from 5,700 to more than 45,000
24% of world’s freshwater fish species are threatened or endangered

14. Dams and Reservoirs cont
½ of the world’s major rivers either run dry part of the year and fail to reach the sea or have little water left in them
Major rivers that run dry: Colorado, Rio Grande, Yellow in northern China, Nile in the Middle East, Ganges and Indus in South Asia, and Amu Darya and Syr Darya in counties of the former Soviet Union

15. Transferring Water Uses tunnels, aqueducts, and underground pipes
One of world’s largest transfer projects is the California Water Project which transfers water to Southern California
Compare the transfer projects for the James Bay Watershed and the Aral Sea
Aral Sea

16. Advantages of Groundwater
Removed as needed
Water not lost to evaporation
Less expensive to use than surface water systems
Aquifers provide drinking water for 1/3 of world’s population
In U.S. 51% of water used for drinking & 43% used for irrigation

17. Disadvantages of Groundwater
Lowering of water table
Depletion of aquifer
Aquifer subsidence
Intrusion of salt water into aquifers
Case Study: Mining Groundwater: The Shrinking Ogallala Aquifer
Ogallala Aquifer

18. Using Water More Efficiently
Reduce water subsidies
Use more efficient irrigation practices
Xeriscaping-replace green lawns in arid & semiarid regions with vegetation adapted to that environment
Fix water leaks
Use water meters & charge for all municipal water use
Raise water prices
Water-saving toilets, showerheads, & washers