LIVING IN THE ENVIRONMENT 17THMILLER/SPOOLMAN

Chapter 13Water Resources

Case Study: The Colorado River Basin— An Overtapped Resource

• Colorado River flows 1,400 miles (2,300 km) through 7 U.S. states to the Gulf of California.

• 14 dams and reservoirs to supply water to farmers, ranchers, industries and cities.

• Supplies water and electricity for about 30 million people• Las Vegas, Los Angeles, San Diego

• Located in a desert area, water supplied mostly from snowmelt of the Rocky Mountains.

• So much water is withdrawn that very little water reaches the Gulf of California

The Colorado River Basin

Fig. 13-1, p. 317

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

Fig. 13-2, p. 317

Freshwater Is an Irreplaceable Resource That We Are Managing Poorly

• Why is water so important?• Needed for survival• Takes huge amounts to produce food and energy• Sculpts the earth’s surface• Controls earth’s climate• Removes or dilutes pollutants and wastes that we produce

Freshwater Is an Irreplaceable Resource That We Are Managing Poorly

• Access to water is • A global health issue – about 3900 children under 5 die

from waterborne disease each day• An economic issue - vital to reduce poverty and produce

food and energy• A women’s and children’s issue - about 50% of people do

not have easy access to water• A national and global security issue - increase tension

between countries• An environmental issue – declining water quality problems

and overuse reduces aquifers and water tables

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

Fig. 13-3, p. 319

Most of the Earth’s Freshwater Is Not Available to Us

• About 70% of Earth is covered by water…97% of it is salt water

• Freshwater availability: 0.024%• Groundwater, lakes, rivers, streams

• Hydrologic cycle • Movement of water in the seas, land, and air• Driven by solar energy and gravity

• Not evenly distributed• Canada has .5% of world population but 20% of the liquid

freshwater; China has 19% of the population and 7% of the supply; Asia has 60% of the population and 30% supply.

Fig. 3-16, p. 67

Condensation Condensation

Ice and snow

Transpiration from plants

Precipitation to land Evaporation of

surface water Evaporation from ocean

Runoff

Lakes and reservoirs Precipitation

to oceanRunoff

Increased runoff on land covered with crops, buildings and pavementInfiltration and

percolation into aquifer

Increased runoff from cutting forests and filling wetlands

Runoff

Groundwater in aquifers

Overpumping of aquifers

RunoffWater pollution

Ocean

Natural process

Natural reservoir

Human impacts

Natural pathwayPathway affected by human activities

Groundwater and Surface Water Are Critical Resources

Case Study: Freshwater Resources in the United States

• More than enough renewable freshwater, unevenly distributed and polluted by agricultural and industrial wastes.

• In 2005 groundwater and surface water in the US was used for:• 41% cooling power plants, 37% crop irrigation (85% in

western US), 13% public water use, 9% industry and livestock.

• Problems include:• Flooding, clean water shortages, drought

Fig. 13-4, p. 322

Average annual precipitation (centimeters)Less than 41 81–122

More than 122

Acute shortageShortageAdequate supplyMetropolitan regions with population greater than 1 million

41–81

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

Fig. 13-6, p. 323

Groundwater is Being Withdrawn Faster Than It Is Replenished (1)

• Most aquifers are renewable

• Aquifers provide drinking water for half the world

• Water tables are falling in many parts of the world, primarily from crop irrigation (can cause subsidence)

• India, China, and the United States• Three largest grain producers• Overpumping aquifers for irrigation of crops

Fig. 13-7, p. 325

Trade-Offs

Withdrawing Groundwater

Advantages Disadvantages

Useful for drinking and irrigation

Aquifer depletion from overpumping

Exists almost everywhere

Sinking of land (subsidence) from overpumping

Renewable if not overpumped or contaminated

Pollution of aquifers lasts decades or centuries

Deeper wells are nonrenewable

Cheaper to extract than most surface waters

Case Study: Aquifer Depletion in the United States

• Ogallala aquifer: largest known aquifer• Irrigates the Great Plains• Very slow recharge• Water table dropping• Government subsidies to continue farming deplete

the aquifer further• Biodiversity threatened in some areas

• California Central Valley: serious water depletion

Subsidence in the San Joaquin Valley

Fig. 13-11, p. 327

Fig. 13-12, p. 327

Solutions

Groundwater Depletion

Prevention Control

Waste less water Raise price of water to discourage waste

Tax water pumped from wells near surface waters

Subsidize water conservation

Set and enforce minimum stream flow levels

Limit number of wells

Do not grow water-intensive crops in dry areas

Divert surface water in wet years to recharge aquifers

Deep Aquifers Might Be Tapped

• Deep aquifers may contain enough water to provide for billions of people for centuries.

• Major concerns1. Nonrenewable2. Little is known about the geological and ecological

impacts of pumping deep aquifers3. Some flow beneath more than one country4. Costs of tapping are unknown and could be high

California Transfers Water from Water-Rich Areas to Water-Poor Areas

• Water transferred from north to south by• Tunnels• Aqueducts• Underground pipes

• California Water Project • Inefficient water use• Environmental damage to Sacramento River and San

Francisco Bay

The California Water Project and the Central Arizona Project

Fig. 13-16, p. 331

Fig. 13-13a, p. 328

Provides irrigation water above and below dam

Flooded land destroys forests or cropland and displaces people

Large losses of water through evaporation

Provides water for drinking

Deprives downstream cropland and estuaries of nutrient-rich silt

Reservoir useful for recreation and fishing

Risk of failure and devastating downstream flooding

Can produce cheap electricity (hydropower)

Reduces down-stream flooding of cities and farms Disrupts

migration and spawning of some fish

Natural Capital Degradation: The Aral Sea, Shrinking Freshwater Lake

Fig. 13-17, p. 332

Removing Salt from Seawater Is Costly, Kills Organisms, Creates Briny Wastewater (1)

• Desalination• Distillation: evaporate water, leaving salts behind• Reverse osmosis, microfiltration: use high pressure to

remove salts

• 14,450 plants in 125 countries• Saudi Arabia has the highest number

Removing Salt from Seawater Is Costly, Kills Organisms, Creates Briny Wastewater (2)

• Problems1. High cost and energy footprint2. Keeps down algal growth and kills many marine

organisms3. Large quantity of brine wastes

Reducing Water Waste Has Many Benefits

• One-half to two-thirds of water is wasted - subsidies mask the true cost of water by lower cost

• Water conservation• Improves irrigation efficiency to lower wasted water• Improves collection efficiency• Uses less in homes and businesses

Major Irrigation Systems

Fig. 13-18, p. 335

Less-Developed Countries Use Low-Tech Methods for Irrigation

• Human-powered treadle pumps• Harvest and store rainwater

17THMILLER/SPOOLMAN

LIVING IN THE ENVIRONMENT

Chapter 20Water Pollution

Water Pollution Comes from Point and Nonpoint Sources

• Water pollution • Change in water quality that can harm organisms or

make water unfit for human uses• Contamination with chemicals or heat

• Point sources• Located at specific places; Easy to identify, monitor,

and regulate• Nonpoint sources• Broad, diffuse areas; Difficult to identify and control;

Expensive to clean up

Water Pollution Comes from Point and Nonpoint Sources

• Leading causes of water pollution1. Agriculture activities• Sediment eroded from the lands• Fertilizers and pesticides• Bacteria from livestock and food processing wastes

2. Industrial facilities3. Mining• Runoff from waste rock

Nonpoint Sediment from Unprotected Farmland Flows into Streams

Fig. 20-4, p. 530

Lake Polluted with Mining Wastes

Fig. 20-5, p. 531

Plastic Wastes in Mountain Lake

Fig. 20-6, p. 531

Major Water Pollutants Have Harmful Effects

• Infectious disease organisms: contaminated drinking water

• The World Health Organization (WHO) • 1.6 million people die every year, mostly under the

age of 5

Common Diseases Transmitted to Humans through Contaminated Drinking Water

Table 20-2, p. 532

Science Focus: Testing Water for Pollutants • Variety of tests to determine water quality and

chemical analysis – check for Coliform bacteria: Escherichia coli

• Level of dissolved oxygen (DO) • Indicator species • Mayfly vs. leeches

• Bacteria and yeast glow in the presence of a particular toxic chemical

• Color and turbidity of the water

Water Quality as Measured by Dissolved Oxygen Content in Parts per Million

Fig. 20-A, p. 533

Streams Can Cleanse Themselves If We Do Not Overload Them

• Dilution• Biodegradation of wastes by bacteria takes time

Global Outlook: Stream Pollution in Developing Countries

• Half of the world’s 500 major rivers are polluted

• Untreated sewage, Industrial waste

• India’s and China’s rivers worst in the world

Natural Capital Degradation: Highly Polluted River in China

Fig. 20-8, p. 535

Trash Truck Disposing of Garbage into a River in Peru

Fig. 20-9, p. 536

Too Little Mixing and Low Water Flow Makes Lakes Vulnerable to Water Pollution

• Less effective at diluting pollutants than streams• Little of no water flow• Can take up to 100 years to change the water in a

lake• Biological magnification of pollutants

Cultural Eutrophication Is Too Much of a Good Thing (1)

• Eutrophication• Natural enrichment of a shallow lake, estuary, or slow-

moving stream• Caused by runoff into lake that contains nitrates and

phosphates

• Oligotrophic lake• Low nutrients, clear water

Case Study: Pollution in the Great Lakes

• 1972: Canada and the United States: Great Lakes pollution control program• Decreased algal blooms• Increased dissolved oxygen• Increased fishing, swimming beaches reopened• Better sewage treatment plants• Fewer industrial wastes• Bans on phosphate-containing household products

• Problems still exist• Raw sewage• Nonpoint runoff of pesticides and fertilizers• Biological pollution• Atmospheric deposition of pesticides and Hg

Case Study: Pollution in the Great Lakes

• 2007 State of the Great Lakes report• New pollutants found• Wetland loss and degradation• Declining of some native species• Native carnivorous fish species declining • What should be done?

The Great Lakes of North America

Fig. 20-12, p. 538

Ground Water Cannot Cleanse Itself Very Well

• Source of drinking water• Common pollutants• Fertilizers and pesticides, Gasoline, Organic solvents

• Pollutants dispersed in a widening plume• Slower chemical reactions in groundwater due to• Slow flow: contaminants not diluted • Less dissolved oxygen• Fewer decomposing bacteria• Low temperatures

Principal Sources of Groundwater Contamination in the U.S.

Fig. 20-13, p. 540

Solutions: Groundwater Pollution, Prevention and Cleanup

Fig. 20-14, p. 541

Case Study: Is Bottled Water the Answer?

• U.S.: some of the cleanest drinking water

• Bottled water• Some from tap water• 40% bacterial contamination• Fuel cost to manufacture the plastic bottles• Recycling of the plastic• 240-10,000x the cost of tap water

• Growing back-to-the-tap movement

Reducing Surface Water Pollution from Nonpoint Sources

• Agriculture• Reduce erosion• Reduce the amount of fertilizers• Plant buffer zones of vegetation• Use organic farming techniques• Use pesticides prudently • Control runoff• Tougher pollution regulations for livestock operations• Deal better with animal waste

Laws Can Help Reduce Water Pollution from Point Sources

• 1972: Clean Water Act 1987: Water Quality Act

• EPA: experimenting with a discharge trading policy that uses market forces• Cap and trade system• Could this allow pollutants to build up?

Sewage Treatment Reduces Water Pollution

• Septic tank system – household waste

• Wastewater or sewage treatment plants• Primary sewage treatment• Physical process

• Secondary sewage treatment• Biological process with bacteria

• Tertiary or advance sewage treatment • Special filtering processes• Bleaching, chlorination

Sewage Treatment Reduces Water Pollution

• Many cities violate federal standards for sewage treatment plants

• Should there be separate pipes for sewage and storm runoff?

• Health risks of swimming in water with blended sewage wastes

What Can You Do? Reducing Water Pollution

Fig. 20-22, p. 554

Unit 4 test review

• Benefits provided by coral reefs.• How are coral reefs being damaged/destroyed?• The percentage of earth’s surface covered by water?• % of liquid freshwater available on Earth?• The 4 major problems associated with the use of the Colorado

River.• By 2025, how many of the world’s people will lack access to

clean water?• The US withdraws water from underground how much faster

than the recharge rate?• The 7 states using the Colorado River are supposed to do

what to help with the problems?

Unit 4 test review

• The Aral Sea case study- question and essay• Problems with desalination?• How can desalinization be improved?• Efficient means to delivery water to crops.• Leading cause of water pollution.• The WHO says how many people do not have access

to clean water?• Safe drinking water can contain ___ colonies of

coliform per 100 ml sample? How m uch for swimming water?

• Examples of point source and nonpoint source

Unit 4 test review

• Global Water Policy Project says ___% of untreated sewage is dumped by most cities in developing countries.

• Great Lakes hold ___% of surface water in the US?• Less than __% of water from Great Lakes leaves the St. Lawrence

River?• How long does it take for Great lakes to flush pollutants?• Effective ways to prevent groundwater?• % of bottled water from tap.• 3rd largest dead zone is found in Gulf of Mexico…what’s it caused by

and which river?• Essay: Could water shortages lead to wars? Should there be more

controls on water usage to help protect freshwater availability? Global warming can cause a lessening of freshwater…how will that change the downhill flow of freshwater?