1. Global Water Resources
Unit 4

2. Core Case Study: Water Conflicts in the Middle East: A Preview of the Future
Water shortages may be the biggest problem facing the Middle East
Most freshwater comes from three river basins:
Nile River
Jordan River
Tigris and Euphrates Rivers
Peacefully solving the problems will require shared sacrifice among all the countries in the region.

3. Three Major River Basins in the Middle East

4. The Nile

5. Jordan River

6. Tigris and Euphrates Rivers

7. Egypt and the Nile The Nile provides Egypt with 97% of its water.
The upstream countries of Ethiopia and Sudan plan to divert more water for their own use.
Egypt will be forced to take action by…..
Importing more food to reduce irrigation
Cutting its population growth
Working out water sharing agreements, OR
Going to war with Ethopia and Sudan.

8. Will We Have Enough Usable Water?
We are using available freshwater unsustainably by wasting it, polluting it, and charging too little for this irreplaceable natural resource.
One of every six people in the world does not have sufficient access to clean water, and this situation will almost certainly get worse.

9. Why is water so important?
The Earth is a watery world: 71% of the Earth’s surface is covered by water.
But only 0.024% is available to us as liquid freshwater.
With few exceptions, water is a poorly managed resource worldwide.
The United States is the world’s largest user of water.

10. Access to water is…
A global health issue: The world’s leading cause of illness is unsafe water
An economic issue: Water is essential for the functioning of modern economies.
A women’s and children’s issue: Women and children are the primary gatherers of water in the developing world
A national and global security issue: Future wars may be fought over water.

11. Girl Carrying Well Water over Dried Out Earth during a Severe Drought in India

12. Most of the Earth’s Freshwater Is Not Available to Us
People divided into
Water haves
Water have-nots
The lack of sufficient water to meet the needs of the people in a country or region is called hydrological poverty
Experts believe that developing water shortages around the world are one of the three primary problems the world faces during this century.

13. Groundwater Ground water is the water found underground in aquifers.
Water table is the depth at which groundwater is found. The water table can rise or fall depending on climate and extraction rates.
Aquifers are vast underground deposits of water that supply 50% of the world’s freshwater.
Aquifers are a geologic layer consisting of underground caverns and porous layers of sand gravel and bedrock where groundwater flows.

15. Surface Water
Surface runoff is the term used for the rain and groundwater that flows into streams and rivers
Watershed (drainage) basin is defined as the total area of land that flows into a particular river.
Only 1/3 of surface runoff is considered reliable runoff that can be used by humans. The other 2/3rds is lost to flooding or can’t be captured.

16. Flowing artesian well Well requiring a pump Water table
Unconfined Aquifer Recharge Area
Evaporation and transpiration
Evaporation
Precipitation
Confined Recharge Area
Runoff
Flowing artesian well
Well requiring a pump
Stream
Figure 13.3
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, and its water is confined under pressure. Some aquifers are replenished by precipitation; others are not.
Water table
Infiltration
Lake
Infiltration
Unconfined aquifer
Less permeable material such as clay
Confined aquifer
Confining impermeable rock layer
Fig. 13-3, p. 316

17. Worldwide Usage of Surface Runoff
Of the 1/3 of surface runoff that is usable. Throughout the world….
Cities and residences use 10%
Agriculture uses 70%, mostly for irrigation.
Industry uses 20%. For example, it takes 120,000 gallons of water to make one automobile!

18. Water shortages in the United States
By 2012 at least 36 states are likely to face water shortages due to
drought (exacerbated by global warming)
population growth
Urban sprawl (sprawling suburbs use much more water per capita than dense cities)
Waste of water. Experts believe that low prices are the leading case of water waste.

19. Average annual precipitation (centimeters)
Less than 41
81–122
41–81
More than 122
Figure 13.4
Average annual precipitation and major rivers (top) and water-deficit regions in the continental United States and their proximity to metropolitan areas having populations greater than 1 million (bottom). Question: Why do you think some areas with moderate precipitation still suffer from water shortages? (Data from U.S. Water Resources Council and U.S. Geological Survey)
Fig. 13-4a, p. 317

20. Metropolitan regions with population greater than 1 million
Figure 13.4
Average annual precipitation and major rivers (top) and water-deficit regions in the continental United States and their proximity to metropolitan areas having populations greater than 1 million (bottom). Question: Why do you think some areas with moderate precipitation still suffer from water shortages? (Data from U.S. Water Resources Council and U.S. Geological Survey)
Acute shortage
Shortage
Adequate supply
Metropolitan regions with population greater than 1 million
Fig. 13-4b, p. 317

21. Water “hot spots” in 17 Western States
Washington
North Dakota
Montana
Oregon
Idaho
South Dakota
Wyoming
Nevada
Nebraska
Utah
Colorado
Kansas
California
Oklahoma
New Mexico
Arizona
Figure 13.5
Water hotspots in 17 western states that, by 2025, could face intense conflicts over scarce water needed for urban growth, irrigation, recreation, and wildlife. Some analysts suggest that this is a map of places not to live during the next 25 years. Question: If you live in one of these hotspot areas, have you noticed any signs of conflict over water supplies? (Data from U.S. Department of the Interior)
Texas
Highly likely conflict potential
Substantial conflict potential
Moderate conflict potential
Unmet rural water needs
Fig. 13-5, p. 318

22. Long-Term Severe Drought Is Increasing
Causes
Extended period of below-normal rainfall
Diminished groundwater
Global warming?
Harmful environmental effects of drought
Dries out soils
Reduces stream flows
Decreases tree growth and biomass
Lowers net primary productivity and crop yields
Shift in biomes

23. Who Should Own and Manage Freshwater Resources?
Most water resources are owned by governments
And are managed as publicly owned resources
Veolia and Suez: Two French companies.
Actively buy and manage water resources around the world.
They have achieved successful outcomes in many areas but controversy follows.

24. Who Should Own and Manage Freshwater Resources?
Bechtel Corporation. Controversial water management in Bolivia led to riots that drove them from the country.
Potential problems with full privatization of water resources
Financial incentive to sell water; not conserve it
Poor will still be left out

25. Water Tables Fall When Groundwater Is Withdrawn Faster Than It Is Replenished
India, China, and the United States
Three largest grain producers in the world
All are over pumping aquifers for irrigation of crops
The United State is withdrawing groundwater at a rate that is 4-times faster than it can be recharged.

26. TRADE-OFFS Withdrawing Groundwater Advantages Disadvantages
Useful for drinking and irrigation
Aquifer depletion from overpumping
Sinking of land (subsidence) from overpumping
Available year-round
Aquifers polluted for decades or centuries
Exists almost everywhere
Saltwater intrusion into drinking water supplies near coastal areas
Renewable if not overpumped or contaminated
Figure 13.7
Advantages and disadvantages of withdrawing groundwater. Question: Which two advantages and which two disadvantages do you think are the most important? Why?
Reduced water flows into surface waters
No evaporation losses
Increased cost and contamination from deeper wells
Cheaper to extract than most surface waters
Fig. 13-7, p. 321

27. Aquifer Depletion in the United States
Ogallala aquifer: World’s largest known aquifer
Irrigates the Great Plains
Water table lowered more than 30 meters in many places.
Cost of high pumping has eliminated some of the farmers
Government subsidies to continue farming deplete the aquifer further
Biodiversity threatened in some areas

28. Natural Capital Degradation: Areas of Greatest Aquifer Depletion in the U.S.

29. Natural Capital Degradation: The Ogallala is the World’s Largest Known Aquifer

30. Groundwater Overpumping in Coastal Areas can cause Catastrophic Problems
Contamination of the groundwater with saltwater intrusion
Groundwater becomes undrinkable and unusable for irrigation
Growing problem in Florida and the Gulf Coast, including Texas.

31. Saltwater Intrusion

32. SOLUTIONS Groundwater Depletion Prevention Control Waste less water
Raise price of water to discourage waste
Subsidize water conservation
Tax water pumped from wells near surface waters
Limit number of wells
Figure 13.11
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? Why?
Set and enforce minimum stream flow levels
Do not grow water-intensive crops in dry areas
Divert surface water in wet years to recharge aquifers
Fig , p. 324

33. Active Figure: Threats to aquifers

34. Large Dams and Reservoirs Have Advantages and Disadvantages
Main goals of a dam and reservoir system
Capture and store runoff
Release runoff as needed to control floods.
Generate electricity
Supply irrigation water
Provide recreational opportunities (reservoirs).
All the lakes in Texas are reservoirs except Caddo Lake

35. Advantages of Dams Increase the reliable runoff available
Reduce flooding
Grow crops in arid regions
Reliable carbon-free supply of electricity

36. China’s Three Gorges Dam

37. Large Dams and Reservoirs Have Advantages and Disadvantages (3)
Displaces people behind the dam
Leads to devastating flooding if there is a failure.
Impaired ecological services of rivers (disrupt migrations of fish)
Loss of plant and animal species
Fill up with sediment within 50 years
Reduces downstream flow of nutrients and sediments.

38. The Ataturk Dam Project in Eastern Turkey

39. Case Study: The Colorado River Basin— An Overtapped Resource
2,300 km through 7 U.S. states
14 Dams and reservoirs
Located in a desert area within the rain shadow of the Rocky Mountains
Water supplied mostly from snowmelt of the Rocky Mountains

40. Case Study: The Colorado River Basin— An Overtapped Resource
Four Major problems
Colorado River basin has very dry lands
Modest flow of water for its size
Legal pacts allocated more water for human use than it can supply
Amount of water flowing to the mouth of the river has dropped

41. What will happen if some of the reservoirs empty out?
Economic and ecological catastrophe.
Cities like Las Vegas, Phoenix and Los Angeles will run out of water
Political and legal battles over water will be intense.

42. The Colorado River Basin

43. Aerial View of Glen Canyon Dam Across the Colorado River and Lake Powell

44. The Flow of the Colorado River Measured at Its Mouth Has Dropped Sharply

45. The Aral Sea Disaster
Large-scale water transfer project in dry central Asia removed the source of the Aral Sea.
Surface level of the sea dropped by 22 meters
Salt and sand from the dry sea bottom have spread by wind as far as 300 miles.
Massive wetlands destruction. Populations of fish and wildlife have been driven to near extinction.

46. The Aral Sea Disaster– a Vanishing Freshwater Lake
1976
2006

47. Ship Stranded in Desert Formed by Shrinkage of the Aral Sea

48. Removing Salt from Seawater Seems Promising but Is Costly
Two primary methods of Desalination
Distillation turns water to vapor and condenses the vapor back to liquid (salt is left behind)
Reverse osmosis uses high pressure to force saltwater through a membrane filter that excludes salt ions.
Currently 15,000 plants in 125 countries.
Saudi Arabia: highest number

49. Desalination plant in Saudi Arabia

50. Problems with desalination
High cost and high energy footprint
Keeps down algal growth and kills many marine organisms
Large quantity of brine wastes (what do we do with all that salt?)

51. We Can Cut Water Waste in Irrigation
Flood irrigation is the most wasteful form of irrigation.
Center pivot, low pressure sprinkler are better
Low-energy, precision application sprinklers better still.
Drip or trickle irrigation offers the greatest conservation of water.

52. Major Irrigation Systems

53. (efficiency 60% and 80% with surge valves)
Figure 13.20
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
(efficiency 80% with low-pressure sprinkler and 90–95% with LEPA sprinkler)
Drip irrigation
(efficiency 90–95%)
Gravity flow
(efficiency 60% and 80% with surge valves)
Above- or below-ground pipes or tubes deliver water to individual plant roots.
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. 335

54. (efficiency 60% and 80% with surge valves)
Center pivot
(efficiency 80% with low-pressure sprinkler and 90–95% with LEPA sprinkler)
Water usually pumped from underground and sprayed from mobile boom with sprinklers.
Drip irrigation
(efficiency 90–95%)
Above- or below-ground pipes or tubes deliver water to individual plant roots.
Gravity flow
(efficiency 60% and 80% with surge valves)
Water usually comes from an aqueduct system or a nearby river.
Figure 13.20
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.
Stepped Art
Fig , p. 335

55. Solutions: Reducing Irrigation Water Waste

56. Flood Plains Highly productive wetlands
Provide natural flood and erosion control
Maintain high water quality
Recharge groundwater
Benefits of floodplains
Fertile soils
Nearby rivers for use and recreation
Flatlands for urbanization and farming

57. Dangers of floodplains and Floods
Floods are deadly and destructive
Human activities worsen floods
Failing dams and water diversion can be catastrophic (Johnstown Flood)
Hurricane Katrina and the Gulf Coast
Removal of coastal wetlands

58. Natural Capital Degradation: Hillside Before and After Deforestation

59. Forested Hillside Oxygen released by vegetation
Diverse ecological habitat
Evapotranspiration
Trees reduce soil erosion from heavy rain and wind
Agricultural land
Figure 13.25
Natural capital degradation: hillside before and after deforestation. Once a hillside has been deforested for timber, fuelwood, livestock grazing, or unsustainable farming, water from precipitation rushes down the denuded slopes, erodes precious topsoil, and can increase flooding and pollution in local streams. Such deforestation can also increase landslides and mudflows. A 3,000-year-old Chinese proverb says, “To protect your rivers, protect your mountains.” See an animation based on this figure at CengageNOW. Question: How might a drought in this area make these effects even worse?
Tree roots stabilize soil
Vegetation releases water slowly and reduces flooding
Forested Hillside
Fig a, p. 339

60. After Deforestation Tree plantation Evapotranspiration decreases
Roads destabilize hillsides
Overgrazing accelerates soil erosion by water and wind
Winds remove fragile topsoil
Agricultural land is flooded and silted up
Gullies and landslides
Figure 13.25
Natural capital degradation: hillside before and after deforestation. Once a hillside has been deforested for timber, fuelwood, livestock grazing, or unsustainable farming, water from precipitation rushes down the denuded slopes, erodes precious topsoil, and can increase flooding and pollution in local streams. Such deforestation can also increase landslides and mudflows. A 3,000-year-old Chinese proverb says, “To protect your rivers, protect your mountains.” See an animation based on this figure at CengageNOW. Question: How might a drought in this area make these effects even worse?
Heavy rain erodes topsoil
Silt from erosion fills rivers and reservoirs
Rapid runoff causes flooding
After Deforestation
Fig b, p. 339

61. Forested Hillside After Deforestation Oxygen released by vegetation
Diverse ecological habitat
Evapotranspiration
Trees reduce soil erosion from heavy rain and wind
Tree roots stabilize soil
Vegetation releases water slowly and reduces flooding
Forested Hillside
Agricultural land
Stepped Art
Tree plantation
Roads destabilize hillsides
Overgrazing accelerates soil erosion by water and wind
Winds remove fragile topsoil
Agricultural land is flooded and silted up
Gullies and landslides
Heavy rain erodes topsoil
Silt from erosion fills rivers and reservoirs
Rapid runoff causes flooding
After Deforestation
Evapotranspiration decreases
Figure 13.25
Natural capital degradation: hillside before and after deforestation. Once a hillside has been deforested for timber, fuelwood, livestock grazing, or unsustainable farming, water from precipitation rushes down the denuded slopes, erodes precious topsoil, and can increase flooding and pollution in local streams. Such deforestation can also increase landslides and mudflows. A 3,000-year-old Chinese proverb says, “To protect your rivers, protect your mountains.” See an animation based on this figure at CengageNOW. Question: How might a drought in this area make these effects even worse?
Fig a, p. 339

62. Solutions: Reducing Flood Damage