Chapter 17: Water Use and Management. Surface Water, Bosnia.

Chapter 17: Water Useand Management

Surface Water, Bosnia

17.1 Water Resources

• The hydrologic cycle constantly redistributes water

• Water supplies are unevenly distributed

The Hydrologic Cycle

17.2 Major Water Compartments

• Oceans hold 97 percent of all water on earth • Glaciers, ice, and snow contain most surface

fresh water (69%)• Groundwater Stores Large Resources (30%)• Rivers, lakes, and wetlands cycle quickly (1%)• The atmosphere is among the smallest of

compartments (1 ppm)

17.3 Water Availability And Use

• Many Countries Suffer Water Scarcity And Water Stress

• Water Consumption Is Less Than Withdrawal– Withdrawal: What’s Taken Out. Much May Return

Quickly To Source– Some Returned Water May Be Degraded– Consumed: Not Easily Returnable To Source– Very Little Water Is Actually Destroyed– What Is Destroyed Is Easily Reconstituted

17.3 Water Availability And Use

• Water Use Is Increasing • Agriculture Is The Greatest Water Consumer

Worldwide– Water Recycles Quickly But Not Necessarily Where

It Came From• Domestic And Industrial Water Use Are

Greatest In Wealthy Countries

17.4 Freshwater Shortages

• Many people lack access to clean water • Groundwater is being depleted • Climate change threatens water supplies • Rivers are shrinking • Would you fight for water?

All-Time Life Savers• Clean Water• Food Preservation• Antiseptics• Antibiotics• Vaccination• Surgery• Green revolution• Mosquito Control

Green Bay Case Study Deep Aquifers of the Green Bay Area

Green Bay Piezometric Surface1957 1960

Green Bay Piezometric Surface1957 2003

The Russian Radioactive Waste Injection Program

Center-Pivot Irrigation

Center-Pivot Irrigation

Some Places Have Too Much Water

Soluble Rocks

Karst in Wisconsin

Geothermal Systems: Mammoth Hot Springs, Yellowstone

Yellowstone Canyon

Old Faithful Geyser, Yellowstone

17.5 Dams And Diversions• Dam failure can be disastrous • Dams often displace people and damage

ecosystems • Dams kill fish • Sedimentation limits reservoir life • What Do You Think? Should We Remove

Dams? – Near end of useful life– Too small to contribute meaningfully

Banqiao Dam Failures, China, 1975

• Built 1950’s for power and flood control• Hydrologist critical of design was sacked,

reinstated, and sacked again• Designed to survive 1000 year flood (30 cm =

12 inches rain per day)• In 1975, >2000 year flood occurred– 19 cm (8 inches) in one hour– 106 cm (40 inches) in one day

Banqiao Dam Failures, China, 1975

• August 1975: Cold Front collides with Super Typhoon Nina

• Delay in opening gates because of communications failures and concern about downstream flooding

• Gates blocked by sediment• August 8, 12:30 AM: Dam upstream fails– Designed for 500 year flood but exceeded capacity

Banqiao Dam Failures, China, 1975

• August 8, 1 AM, Banqiao Dam overtopped and failed

• Precipitated the failure of 62 dams• Flood wave 10 km wide, 3-7 m high, moving

50 km/hour• Numerous dams opened by air strikes to

control flow

Banqiao Dam Failures, China, 1975

• One commune of 9600 people was entirely annihilated

• 26,000 people died from flooding • 145,000 died from subsequent epidemics and

famine. • 9 days after the flood a million people were

still stranded• About 6,000,000 buildings collapsed• Details declassified in 2005

Banqiao Dam After Failure

17.7 Increasing Water Supplies

• Desalination Provides Expensive Water• Domestic Conservation Can Save Water• Recycling Can Reduce Consumption • Prices And Policies Have Often Discouraged

Conservation (Encouraged Waste)• What Can You Do? Saving Water And

Preventing Pollution

Desalination

• Passive Distillation– Slow

• Active Distillation– Energy Intensive

• Reverse Osmosis– Energy Intensive– Fragile Filters

Reverse Osmosis