Chapter 13

Core Case Study: Water Conflicts in the
Middle East: A Preview of the Future
 Water shortages in the Middle East: hydrological poverty
 Nile River
 Jordan Basin
 Tigris and Euphrates Rivers
 Peacefully solving the problems

Three Major River Basins in the
Middle East

13-1 Will We Have Enough Usable Water?
 Concept 13-1A We are using available freshwater unsustainably by wasting it, polluting it, and charging too little for this irreplaceable natural resource.
 Concept 13-1B One of every six people does not have sufficient access to clean water, and this situation will almost certainly get worse.

Freshwater Is an Irreplaceable Resource
That We Are Managing Poorly (1)
 Why is water so important?
 Earth as a watery world: 71%
 Freshwater availability: 0.024%
 Poorly managed resource
 Hydrologic cycle
 Water pollution

Freshwater Is an Irreplaceable Resource
That We Are Managing Poorly (2)
 Access to water is
• A global health issue
• An economic issue
• A women’s and children’s issue
• A national and global security issue

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

Most of the Earth’s Freshwater Is Not
Available to Us
 Hydrologic cycle
• Movement of water in the seas, land, and air
• Driven by solar energy and gravity
 People divided into
• Water haves
• Water have-nots

We Get Freshwater from Groundwater and Surface Water (1)
 Ground water
 Zone of saturation
 Water table
 Aquifers
• Natural recharge
• Lateral recharge

We Get Freshwater from Groundwater and Surface Water (2)
 Surface Water
• Surface runoff
• Watershed (drainage) basin
• Reliable runoff
• 1/3 of total

Natural Capital: Groundwater System:
Unconfined and Confined Aquifer

Unconfined Aquifer Recharge Area
Evaporation and transpiration Evaporation
Precipitation
Confined
Recharge
Area
Runoff
Less permeable material such as clay
Flowing artesian well
Infiltration
Water table
Well requiring a pump Stream
Infiltration
Lake
Fig. 13-3, p. 316

We Use a Large and Growing Portion of the World’s Reliable Runoff
 2/3 of the surface runoff: lost by seasonal floods
 1/3 runoff usable
• Domestic: 10%
• Agriculture: 70%
• Industrial use: 20%
 Fred Pearce, author of When the Rivers Run Dry

Case Study: Freshwater Resources in the
United States
 More than enough renewable freshwater, unevenly distributed
 Effect of
• Floods
• Pollution
• Drought
 2007: U.S. Geological Survey projection
• Water hotspots

Average Annual Precipitation and Major
Rivers, Water-Deficit Regions in U.S.

Fig. 13-4a, p. 317

Average annual precipitation (centimeters)
Less than 41
41 –81
81 –122
More than 122
Fig. 13-4a, p. 317

Fig. 13-4b, p. 317

Acute shortage
Shortage
Adequate supply
Metropolitan regions with population greater than 1 million
Fig. 13-4b, p. 317

Water Hotspots in 17 Western U.S. States

Washington
Oregon
Idaho
Montana
Wyoming
North
Dakota
South
Dakota
Nevada Nebraska
Utah
Colorado
Kansas
California
Oklahoma
Arizona
New
Mexico
Texas
Highly likely conflict potential
Substantial conflict potential
Moderate conflict potential
Unmet rural water needs
Fig. 13-5, p. 318

Water Shortages Will Grow (1)
 Dry climate
 Drought
 Too many people using a normal supply of water

Water Shortages Will Grow (2)
 Wasteful use of water
 China and urbanization
 Hydrological poverty

Natural Capital Degradation: Stress on the World’s Major River Basins

Europe
Asia
North
America
South
America
Africa
Stress
High None
Australia
Fig. 13-6, p. 319

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

In Water-Short Areas Farmers and Cities
Compete for Water Resources
 2007: National Academy of Science study
• Increased corn production in the U.S. to make ethanol as an alternative fuel
• Decreasing water supplies
• Aquifer depletion
• Increase in pollution of streams and aquifers

Who Should Own and Manage
Freshwater Resources? (1)
 Most water resources
• Owned by governments
• Managed as publicly owned resources
 Veolia and Suez: French companies
• Buy and manage water resources
• Successful outcomes in many areas

Who Should Own and Manage
Freshwater Resources? (2)
 Bechtel Corporation
• Poor water management in Bolivia
 A subsidiary of Bechtel Corporation
• Poor water management in Ecuador
 Potential problems with full privatization of water resources
• Financial incentive to sell water; not conserve it
• Poor will still be left out

13-2 Is Extracting Groundwater the Answer?
 Concept 13-2 Groundwater that is used to supply cities and grow food is being pumped from aquifers in some areas faster than it is renewed by precipitation.

Water Tables Fall When Groundwater Is
Withdrawn Faster Than It Is Replenished
 India, China, and the United States
• Three largest grain producers
• Overpumping aquifers for irrigation of crops
 India and China
• Small farmers drilling tubewells
• Effect on water table
 Saudi Arabia
• Aquifer depletion and irrigation

Trade-Offs: Withdrawing Groundwater,
Advantages and Disadvantages

TRADE-OFFS
Withdrawing Groundwater
Advantages
Useful for drinking and irrigation
Disadvantages
Aquifer depletion from overpumping
Available year-round
Exists almost everywhere
Sinking of land
(subsidence) from overpumping
Aquifers polluted for decades or centuries
Renewable if not overpumped or contaminated
Saltwater intrusion into drinking water supplies near coastal areas
No evaporation losses
Reduced water flows into surface waters
Cheaper to extract than most surface waters
Increased cost and contamination from deeper wells
Fig. 13-7, p. 321

Natural Capital Degradation: Irrigation in
Saudi Arabia Using an Aquifer

Case Study: Aquifer Depletion in the
United States
 Ogallala aquifer: largest known aquifer
• Irrigates the Great Plains
• Water table lowered more than 30m
• Cost of high pumping has eliminated some of the farmers
• Government subsidies to continue farming deplete the aquifer further
• Biodiversity threatened in some areas
 California Central Valley: serious water depletion

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

Groundwater
Overdrafts:
High
Moderate
Minor or none
Fig. 13-9, p. 322

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

WYOMING
SOUTH DAKOTA
COLORADO
NEBRASKA
KANSAS
Saturated thickness of Ogallala Aquifer
OKLAHOMA
NEW MEXICO
TEXAS 0
Miles
100
0 160
Kilometers
Less than 61 meters (200 ft.)
61 –183 meters (200–600 ft.)
More than 183 meters (600 ft.)
(as much as 370 meters or 1,200 ft. in places)
Fig. 13-10, p. 323

Groundwater Overpumping Has Other
Harmful Effects (1)
 Limits future food production
 Bigger gap between the rich and the poor
 Land subsidence
• Mexico City
 Sinkholes

Groundwater Overpumping Has Other
Harmful Effects (2)
 Groundwater overdrafts near coastal regions
• Contamination of the groundwater with saltwater
• Undrinkable and unusable for irrigation

Solutions: Groundwater Depletion, Using
Water More Sustainably

SOLUTIONS
Groundwater Depletion
Prevention
Waste less water
Subsidize water conservation
Limit number of wells
Do not grow waterintensive crops in dry areas
Control
Raise price of water to discourage waste
Tax water pumped from wells near surface waters
Set and enforce minimum stream flow levels
Divert surface water in wet years to recharge aquifers
Fig. 13-11, p. 324

Science Focus: Are Deep Aquifers the Answer?
 Locate the deep aquifers; determine if they contain freshwater or saline water
 Major concerns
• Geological and ecological impact of pumping water from them
• Flow beneath more than one country
• Who has rights to it?

Active Figure: Threats to aquifers

13-3 Is Building More Dams the Answer?
 Concept 13-3 Building dam and reservoir systems has greatly increased water supplies in some areas, but it has disrupted ecosystems and displaced people.

Large Dams and Reservoirs Have
Advantages and Disadvantages (1)
 Main goals of a dam and reservoir system
• Capture and store runoff
• Release runoff as needed to control:
• Floods
• Generate electricity
• Supply irrigation water
• Recreation (reservoirs)

Large Dams and Reservoirs Have
Advantages and Disadvantages (2)
 Advantages
• Increase the reliable runoff available
• Reduce flooding
• Grow crops in arid regions

Large Dams and Reservoirs Have
Advantages and Disadvantages (3)
 Disadvantages
• Displaces people
• Flooded regions
• Impaired ecological services of rivers
• Loss of plant and animal species
• Fill up with sediment within 50 years

Advantages and Disadvantages of Large
Dams and Reservoirs

The Ataturk Dam Project in
Eastern Turkey

Some Rivers Are Running Dry and Some
Lakes Are Shrinking
 Dams disrupt the hydrologic cycle
 Major rivers running dry part of the year
• Colorado and Rio Grande, U.S.
• Yangtze and Yellow, China
• Indus, India
• Danube, Europe
• Nile River-Lake Victoria, Egypt
 Lake Chad Africa: disappearing

Case Study: The Colorado River Basin —
An Overtapped Resource (1)
 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

Case Study: The Colorado River Basin —
An Overtapped Resource (2)
 Supplies water and electricity for more than 25 million people
 Irrigation of crops
 Recreation

Case Study: The Colorado River Basin —
An Overtapped Resource (3)
 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

Case Study: The Colorado River Basin —
An Overtapped Resource (4)
 What will happen if some of the reservoirs empty out?
• Economic and ecological catastrophe
• Political and legal battles over water

The Colorado River Basin

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

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

15
10
5
25
20
35
30
Hoover Dam completed (1935)
Glen Canyon
Dam completed
(1963)
0
1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Year
Fig. 13-16, p. 328

Case Study: China’s Three
Gorges Dam (1)
 World’s largest hydroelectric dam and reservoir
 2 km long across the Yangtze River
 Benefits
• Electricity-producing potential is huge
• Holds back the Yangtze River floodwaters
• Allows cargo-carrying ships

Case Study: China’s Three
Gorges Dam (2)
 Harmful effects
• Displaces about 5.4 million people
• Built over a seismic fault
• Significance?
• Rotting plant and animal matter producing CH
4
• Worse than CO
2 emissions
• Will the Yangtze River become a sewer?

13-4 Is Transferring Water from One
Place to Another the Answer?
 Concept 13-4 Transferring water from one place to another has greatly increased water supplies in some areas, but it has also disrupted ecosystems.

CA, U.S., Transfers Water from Water-
Rich Areas to Water-Poor Areas
 Water transferred by
• Tunnels
• Aqueducts
• Underground pipes
 May cause environmental problems
 California Water Project

The California Water Project and the
Central Arizona Project

Sacramento
River
North Bay
Aqueduct
CALIFORNIA
Shasta Lake
Oroville Dam and
Reservoir
NEVADA
Feather
River
Lake Tahoe
Sacramento
San Francisco
South Bay
Aqueduct
San Luis Dam and Reservoir
Fresno
Hoover Dam and Reservoir
(Lake Mead)
California Aqueduct
Santa Barbara
Los Angeles
Aqueduct
Colorado River
Aqueduct
Los Angeles
UTAH
Phoenix
Colorado
River
ARIZONA
Central Arizona
Project
San Diego
Salton Sea
Tucson
MEXICO
Fig. 13-17, p. 330

Case Study: The Aral Sea Disaster (1)
 Large-scale water transfers in dry central Asia
 Salinity
 Wetland destruction and wildlife
 Fish extinctions and fishing

Case Study: The Aral Sea Disaster (2)
 Wind-blown salt
 Water pollution
 Climatic changes
 Restoration efforts

Natural Capital Degradation: The Aral
Sea, Shrinking Freshwater Lake

1976 2006
Stepped Art
Fig. 13-18a, p. 331

Ship Stranded in Desert Formed by
Shrinkage of the Aral Sea

China Plans a Massive Transfer of Water
 South-North Water Transfer Project
 Water from three rivers to supply 0.5 billion people
 Completion in about 2050
 Impact
• Economic
• Health
• Environmental

13-5 Is Converting Salty Seawater to
Freshwater the Answer?
 Concept 13-5 We can convert salty ocean water to freshwater, but the cost is high, and the resulting salty brine must be disposed of without harming aquatic or terrestrial ecosystems.

Removing Salt from Seawater Seems
Promising but Is Costly (1)
 Desalination
• Distillation
• Reverse osmosis, microfiltration
 15,000 plants in 125 countries
• Saudi Arabia: highest number

Removing Salt from Seawater Seems
Promising but Is Costly (2)
 Problems
• High cost and energy footprint
• Keeps down algal growth and kills many marine organisms
• Large quantity of brine wastes
 Future economics

Science Focus: The Search for Improved
Desalination Technology
 Desalination on offshore ships
• Solar or wind energy
 Better membranes
 Better disposal options for the brine waste
 Reduce water needs, conserve water

13-6 How Can We Use Water More
Sustainably?
 Concept 13-6 We can use water more sustainably by cutting water waste, raising water prices, slowing population growth, and protecting aquifers, forests, and other ecosystems that store and release water.

Reducing Water Waste Has Many
Benefits (1)
 Water conservation
• Improves irrigation efficiency
• Improves collection efficiency
• Uses less in homes and businesses

Reducing Water Waste Has Many
Benefits (2)
 Worldwide: 65 –70% loss
• Evaporation, leaks, etc.
 Water prices: low cost to user
 Government subsidies: more needed?

We Can Cut Water Waste in Irrigation
 Flood irrigation
• Wasteful
 Center pivot, low pressure sprinkler
 Low-energy, precision application sprinklers
 Drip or trickle irrigation, microirrigation
• Costly; less water waste

Major Irrigation Systems

Gravity flow
(efficiency 60% and 80% with surge valves)
Water usually comes from an aqueduct system or a nearby river.
Drip irrigation
(efficiency 90 –95%)
Above- or below-ground pipes or tubes deliver water to individual plant roots.
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.
Fig. 13-20, p. 335

Gravity flow
(efficiency 60% and 80% with surge valves)
Water usually comes from an aqueduct system or a nearby river.
Drip irrigation
(efficiency 90 –95%)
Above- or below-ground pipes or tubes deliver water to individual plant roots.
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.
Stepped Art
Fig. 13-20, p. 335

Solutions: Reducing Irrigation
Water Waste

Developing Countries Use Low-Tech
Methods for Irrigation
 Human-powered treadle pumps
 Harvest and store rainwater
 Create a canopy over crops: reduces evaporation
 Fog-catcher nets

We Can Cut Water Waste in Industry and Homes
 Recycle water in industry
 Fix leaks in the plumbing systems
 Use water-thrifty landscaping: xeriscaping
 Use gray water
 Pay-as-you-go water use

Solutions: Reducing Water Waste

We Can Use Less Water to
Remove Wastes
 Can we mimic how nature deals with waste?
 Waterless composting toilets

We Need to Use Water More Sustainably
 “The frog does not drink up the pond in which it lives”
 Blue revolution

Solutions: Sustainable Water Use

SOLUTIONS
Sustainable Water Use
Waste less water and subsidize water conservation
Do not deplete aquifers
Preserve water quality
Protect forests, wetlands, mountain glaciers, watersheds, and other natural systems that store and release water
Get agreements among regions and countries sharing surface water resources
Raise water prices
Slow population growth
Fig. 13-23, p. 337

What Can You Do? Water Use and Waste

13-7 How Can We Reduce the Threat of Flooding?
 Concept 13-7 We can lessen the threat of flooding by protecting more wetlands and natural vegetation in watersheds and by not building in areas subject to frequent flooding.

Some Areas Get Too Much Water from
Flooding (1)
 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

Some Areas Get Too Much Water from
Flooding (2)
 Dangers of floodplains and floods
• Deadly and destructive
• Human activities worsen floods
• Failing dams and water diversion
• Hurricane Katrina and the Gulf Coast
• Removal of coastal wetlands

Natural Capital Degradation: Hillside
Before and After Deforestation

Oxygen released by vegetation
Diverse ecological habitat
Evapotranspiration
Trees reduce soil erosion from heavy rain and wind
Agricultural land
Tree roots stabilize soil
Forested Hillside
Vegetation releases water slowly and reduces flooding
Fig. 13-25a, p. 339

Tree plantation
Roads destabilize hillsides
Gullies and landslides
Heavy rain erodes topsoil
Silt from erosion fills rivers and reservoirs
After Deforestation
Evapotranspiration decreases
Overgrazing accelerates soil erosion by water and wind
Winds remove fragile topsoil
Agricultural land is flooded and silted up
Rapid runoff causes flooding
Fig. 13-25b, p. 339

Oxygen released by vegetation
Tree plantation
Diverse ecological habitat
Tree roots stabilize soil
Evapotranspiration
Trees reduce soil erosion from heavy rain and wind
Vegetation releases water slowly and reduces flooding
Agricultural land
Roads destabilize hillsides
Evapotranspiration decreases
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
Forested Hillside After Deforestation
Stepped Art
Fig. 13-25a, p. 339

Case Study: Living Dangerously on
Floodplains in Bangladesh
 Dense population
 Located on coastal floodplain
 Moderate floods maintain fertile soil
 Increased frequency of large floods
 Effects of development in the Himalayan foothills
 Destruction of coastal wetlands

We Can Reduce Flood Risks
 Rely more on nature’s systems
• Wetlands
• Natural vegetation in watersheds
 Rely less on engineering devices
• Dams
• Levees

Solutions: Reducing Flood Damage

SOLUTIONS
Reducing Flood Damage
Prevention
Preserve forests on watersheds
Preserve and restore wetlands in floodplains
Tax development on floodplains
Use floodplains primarily for recharging aquifers, sustainable agriculture and forestry
Control
Straighten and deepen streams
(channelization)
Build levees or floodwalls along streams
Build dams
Fig. 13-26, p. 340

Active Figure: Effects of deforestation