1. Chapter 14
Water

2. Core Case Study: Water Conflicts in the Middle East - A Preview of the Future
One of the world’s highest population growth rates
water shortages
Main supply: Nile, Tigris, Jordan
Figure 14-1

3. Water Conflicts in the Middle East: A Preview of the Future
Disagreement about water rights.
Currently
No cooperative agreements for use of 158 of the world’s 263 water basins that are shared by two or more countries.

4. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
Water: life, moderates climate, sculpts land, removes/dilutes wastes and pollutants, hydrologic cycle.
0.02% = liquid freshwater

5. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
Figure 14-2

6. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
The land from which the surface water drains into a body of water is called its watershed or drainage basin.
Groundwater exists too.

7. Unconfined Aquifer Recharge Area Evaporation and transpiration
Precipitation
Evaporation and transpiration
Evaporation
Confined Recharge Area
Runoff
Flowing artesian well
Recharge Unconfined Aquifer
Stream Well requiring a pump
Figure 14.3
Natural capital: groundwater system. An unconfined aquifer is an aquifer with a permeable water table. A confined aquifer is bounded above and below by less permeable beds of rock where the water is confined under pressure. Some aquifers are replenished by precipitation; others are not.
Infiltration
Water table
Lake
Infiltration
Unconfined aquifer
Less permeable material such as clay
Confined aquifer
Confining impermeable rock layer
Fig. 14-3, p. 308

8. Animation: Threats to the Aquifers
Animations/aquifers.html

9. WATER’S IMPORTANCE, AVAILABILITY, AND RENEWAL
70% water withdrawn from rivers, lakes, and aquifers is not returned to these sources.
Irrigation (70%), industries (20%) and cities and residences (10%).
Currently >50% of the world’s reliable runoff is used
70-90% by 2025.

10. Figure 14-4

11. Case Study: Freshwater Resources in the United States
17 western states face potential intense water conflict
urban growth, irrigation, recreation and wildlife.
Figure 14-5

12. TOO LITTLE FRESHWATER
41% of the world’s population lives in river basins that do not have enough freshwater.
Rivers running dry.
Lakes and seas shrinking.
Falling water tables (overpumped aquifers)

13. Stress on the World’s River Basins
Comparison of the amount of water available with the amount used by humans.
Figure 14-6

14. Case Study: Who Should Own and Manage Freshwater Resources
Controversy: government owned and managed or private corporations.
European-based water companies aim to control 70% of the U.S. water supply.

15. TOO LITTLE FRESHWATER Cities are outbidding farmers.
Countries are importing grain.
More crops used for biofuels.
Options:
Get more water from aquifers and rivers, desalinate ocean water, waste less water.

16. WITHDRAWING GROUNDWATER TO INCREASE SUPPLIES
Most aquifers are renewable
Unless water is removed faster than replenished
Or contaminated.
Groundwater depletion - growing problem
Irrigation.
One-fourth of the farms in India irrigated from overpumped aquifers.

17. Withdrawing Groundwater
Trade-Offs
Withdrawing Groundwater
Advantages
Disadvantages
Useful for drinking and irrigation
Aquifer depletion from overpumping
Sinking of land (subsidence) from overpumping
Available year-round
Exists almost everywhere
Polluted aquifers for decades or centuries
Renewable if not overpumped or contaminated
Saltwater intrusion into drinking water supplies near coastal areas
Figure 14.7
Trade-offs: advantages and disadvantages of withdrawing groundwater. QUESTION: Which two advantages and which two disadvantages do you think are the most important?
No evaporation losses
Reduced water flows into surface waters
Increased cost and contamination from deeper wells
Cheaper to extract than most surface waters
Fig. 14-7, p. 313

18. Groundwater Depletion: A Growing Problem
Areas of greatest aquifer depletion (overdraft)

19. OGALLALA

20. Other Effects of Groundwater Overpumping
Sinkholes (subsidence)
Contamination with saltwater. (salt water intrusion)
Figure 14-11

21. Other Effects of Groundwater Overpumping
Figure 14-10

22. Groundwater Pumping in Saudi Arabia (1986 – 2004)
Irrigation systems
Nonrenewable aquifer = green dots
Dried wells = Brown dots
Figure 14-9

23. Groundwater Depletion
Solutions
Groundwater Depletion
Prevention
Control
Waste less water
Raise price of water to discourage waste
Subsidize water conservation
Ban new wells in aquifers near surface waters
Tax water pumped from wells near surface waters
Buy and retire groundwater withdrawal rights in critical areas
Figure 14.12
Solutions: ways to prevent or slow groundwater depletion by using water more sustainably. QUESTION: Which two of these solutions do you think are the most important?
Set and enforce minimum stream flow levels
Do not grow water-intensive crops in dry areas
Fig , p. 316

24. USING DAMS AND RESERVOIRS TO SUPPLY MORE WATER
Large dams and reservoirs
cheap electricity
reduce downstream flooding
year-round water for irrigating cropland
displace people
disrupt aquatic systems.

25. Provides water for year-round irrigation of cropland
Flooded land destroys forests or cropland and displaces people
Large losses of water through evaporation
Provides water for drinking
Downstream cropland and estuaries are deprived of nutrient-rich silt
Reservoir is useful for recreation and fishing
Risk of failure and devastating downstream flooding
Can produce cheap electricity (hydropower)
Figure 14.13
Trade-offs: advantages (green) and disadvantages (orange) of large dams and reservoirs. The world’s 45,000 large dams (higher than 15 meters or 50 feet) capture and store 14% of the world’s runoff, provide water for almost half of all irrigated cropland, and supply more than half the electricity used by 65 countries. The United States has more than 70,000 large and small dams, capable of capturing and storing half of the country’s entire river flow. QUESTION: Which single advantage and which single disadvantage do you think are the most important?
Downstream flooding is reduced
Migration and spawning of some fish are disrupted
Fig a, p. 317

26. Powerlines Reservoir Dam Powerhouse Intake Turbine Fig. 14-13b, p. 317
CLICK ON THIS:
Dam
Powerhouse
Intake
Turbine
Figure 14.13
Trade-offs: advantages (green) and disadvantages (orange) of large dams and reservoirs. The world’s 45,000 large dams (higher than 15 meters or 50 feet) capture and store 14% of the world’s runoff, provide water for almost half of all irrigated cropland, and supply more than half the electricity used by 65 countries. The United States has more than 70,000 large and small dams, capable of capturing and storing half of the country’s entire river flow. QUESTION: Which single advantage and which single disadvantage do you think are the most important?
Fig b, p. 317

27. Case Study: The Colorado Basin – an Overtapped Resource
The Colorado River
14 major dams and reservoirs, and canals.
Used in desert area of the U.S.
Hydroelectric plants for 30 million people (1/10th of the U.S. population).
Often doesn’t reach Gulf of California

28. Case Study: The Colorado Basin – an Overtapped Resource
Lake Powell, 2nd largest reservoir in the U.S.
Hydroelectric plant
Figure 14-15

29. The Colorado River Basin
Drainage basin covers more than one-twelfth of the land area of the lower 48 states.
Figure 14-14

30. Case Study: China’s Three Gorges Dam
DEBATE – world’s largest dam
Dam 2 km long.
The electric output = 18 large coal-burning or nuclear power plants.
Facilitate ship travel, reduce transportation costs.
Displace 1.2 million people.
Built over seismatic fault, already has small cracks.

31. Dam Removal Some for ecological reasons
Some outlived their usefulness.
In 1998 the U.S. Army Corps of Engineers – no more large dam projects in US
Federal Energy Regulatory Commission has approved the removal of nearly 500 dams.
Can reestablish ecosystems
Can re-release toxicants into the environment.

32. TRANSFERRING WATER FROM ONE PLACE TO ANOTHER
makes unproductive areas more productive
can cause environmental harm.
Promotes investment, jobs and strong economy.
It encourages unsustainable use

33. Case Study: The California Experience
A massive transfer of water from water-rich northern California to water-poor southern California is controversial.
Figure 14-16

34. Case Study: The Aral Sea Disaster
The Aral Sea was once the world’s fourth largest freshwater lake.
Figure 14-17

35. Case Study: The Aral Sea Disaster
Diverting water from the Aral Sea and its two feeder rivers
Mostly for irrigation
85% of the wetlands have been eliminated
50% of the local bird and mammal species have disappeared.
Since 1961,
sea’s salinity has tripled
water has dropped by 22 meters most likely causing 20 of the 24 native fish species to go extinct.

36. DESALTING SEAWATER, SEEDING CLOUDS, AND TOWING ICEBERGS AND GIANT BAGGIES
Removing salt from seawater = expensive, & large amounts of salty wastewater
Distillation: heating saltwater until it evaporates, leaves behind water in solid form.
Reverse osmosis: uses high pressure to force saltwater through a membrane filter.

37. DESALTING SEAWATER, SEEDING CLOUDS, AND TOWING ICEBERGS AND GIANT BAGGIES
Seeding clouds with tiny particles of chemicals to increase rainfall – AgNO3
towing icebergs or huge bags filled with freshwater to dry coastal areas
unlikely to provide significant amounts of freshwater.

38. INCREASING WATER SUPPLIES BY WASTING LESS WATER
We waste about two-thirds of the water we use
65-70% lost through evaporation, leaks, and other losses.
Water is underpriced thru government subsidies.
Lack of subsidies for improving efficiency contributes to water waste.

39. INCREASING WATER SUPPLIES BY WASTING LESS WATER
60% of the world’s irrigation water is currently wasted
Improved techniques could cut this to 5-20%.
Center-pivot, low pressure sprinklers sprays water directly onto crop.
It allows 80% of water to reach crop.
Has reduced depletion of Ogallala aquifer in Texas High Plains by 30%.

40. (efficiency 60% and 80% with surge valves)
Drip irrigation
Gravity flow
(efficiency 60% and 80% with surge valves)
Figure 14.18
Major irrigation systems: because of high initial costs, center-pivot irrigation and drip irrigation are not widely used. The development of new low-cost drip-irrigation systems may change this situation.
Center pivot
Above- or below-ground pipes or tubes deliver water to individual plant roots.
(efficiency 80%–95%)
Water usually pumped from underground and sprayed from mobile boom with sprinklers.
Water usually comes from an aqueduct system or a nearby river.
Fig , p. 325

41. Reducing Irrigation Water Waste
Solutions
Reducing Irrigation Water Waste
• Line canals bringing water to irrigation ditches
• Level fields with lasers
• Irrigate at night to reduce evaporation
• Monitor soil moisture to add water only when necessary
• Polyculture
• Organic farming
Figure 14.19
Solutions: methods for reducing water waste in irrigation. QUESTION: Which two of these solutions do you think are the most important?
• Don't grow water-thirsty crops in dry areas
• Grow water-efficient crops using drought resistant and salt-tolerant crop varieties
• Irrigate with treated urban waste water
• Import water-intensive crops and meat
Fig , p. 326

42. Solutions: Getting More Water for Irrigation in Developing Countries – The Low-Tech Approach
Many poor farmers in developing countries use low-tech methods to pump groundwater and make more efficient use of rainfall.
Figure 14-20

43. Solutions Reducing Water Waste • Redesign manufacturing processes
• Repair leaking underground pipes
• Landscape yards with plants that require little water
• Use drip irrigation
• Fix water leaks
• Use water meters
• Raise water prices
• Use waterless composting toilets
• Require water conservation in water-short cities
Figure 14.21
Solutions: methods of reducing water waste in industries, homes, and businesses. QUESTION: Which three of these solutions do you think are the most important?
• Use water-saving toilets, showerheads, and front loading clothes washers
• Collect and reuse household water to irrigate lawns and nonedible plants
• Purify and reuse water for houses, apartments, and office buildings
• Don't waste energy
Fig , p. 327

44. Raising the Price of Water: A Key to Water Conservation
Reducing water use and waste
Raising the price of water
When Boulder, Colorado introduced water meters, water use per person dropped by 40%.
A 10% increase in water prices cuts domestic water use by 3-7%.
Provide low lifeline rates for the poor.

45. Solutions: Using Less Water to Remove Industrial and Household Wastes
Mimic the way nature deals with wastes
Instead of using large amounts of high-quality water to wash and dilute industrial and animal wastes.
Use nutrients in wastewater as soil fertilizer.
Composting toilets convert human fecal matter into a small amount of soil material.

46. TOO MUCH WATER
FLOODS
Heavy rainfall
rapid snowmelt
removal of vegetation
destruction of wetlands
Natural flood mitigation - Floodplains/wetlands = natural flood and erosion control, maintain high water quality, and recharge groundwater.
Artificial flood mitigation
narrowing rivers with levees and walls
damming to store water.

47. TOO MUCH WATER
Comparison of St. Louis, Missouri under normal conditions (1988) and after severe flooding (1993).
Figure 14-22

48. TOO MUCH WATER
Human activities have contributed to flood deaths and damages.
Figure 14-23

49. Animation: Effects of Deforestation
Animations/effects_deforestation.html

50. Preserve forests on watersheds
Solutions
Reducing Flood Damage
Prevention
Control
Preserve forests on watersheds
Strengthen and deepen streams (channelization)
Preserve and restore wetlands in floodplains
Build levees or floodwalls along streams
Tax all development on floodplains
Figure 14.24
Solutions: methods for reducing the harmful effects of flooding. QUESTION: Which two of these solutions do you think are the most important?
Use floodplains primarily for recharging aquifers, sustainable agriculture and forestry, and recreation
Build dams
Fig , p. 331

51. SOLUTIONS: USING WATER MORE SUSTAINABLY
cutting waste
raising water prices
preserving forests and wetlands
slowing population growth.
Figure 14-25