Chapter 15 Water ResourcesChapter 15 Water Resources

G. Tyler Miller’sLiving in the Environment

14th Edition

Chapter 15

G. Tyler Miller’sLiving in the Environment

14th Edition

Chapter 15

Chapter 15 Key ConceptsChapter 15 Key Concepts

The physical properties of water The physical properties of water

Availability of fresh water Availability of fresh water

Methods of increasing freshwater supplies Methods of increasing freshwater supplies

Using water more efficiently Using water more efficiently

Problems associated with flooding Problems associated with flooding

Sections 1 and 2 Key IdeasSections 1 and 2 Key Ideas

• Why is water so important?

• What makes water unique?

• How much fresh water is available to humans?

• What are some of the sources of fresh water?

• How do we use the world’s fresh water?

• What are some water resource issues faced in the United States?

Water’s ImportanceWater’s Importance

• No species can live without water.

• Plays a key role in shaping the earth’s surface, moderating climate, removing and diluting wastes.

• Takes huge amount to provide food, shelter and other needs.

• 71% of our planet

Water’s Unique PropertiesWater’s Unique Properties

Hydrogen bonding: water’s unique properties comes from the strong attractive forces between molecules.

Hydrogen bonding: water’s unique properties comes from the strong attractive forces between molecules.

Water’s Unique PropertiesWater’s Unique Properties Liquid over wide

temperature range: without its high boiling point the oceans would have evaporated long ago.

Changes temperature slowly: high specific heat means slow temperature changes. Helps moderate climate.

Liquid over wide temperature range: without its high boiling point the oceans would have evaporated long ago.

Changes temperature slowly: high specific heat means slow temperature changes. Helps moderate climate.

Water’s Unique PropertiesWater’s Unique Properties

• High heat of evaporation: evaporation takes a lot of heat. This explains why sweating makes you feel cooler.

• Great dissolving power: known as the universal solvent because so may things dissolve well in it. Leads to pollution problems as well.

Water’s Unique PropertiesWater’s Unique Properties

• Filters out ultraviolet radiation: protecting aquatic organisms from sun’ rays.

• Adhesion and cohesion: strong forces of attraction between molecules allows water to rise up inside plants from roots to leaves.

Water’s Unique PropertiesWater’s Unique Properties

• Expands when it freezes: most substances contract when frozen, not water. Water expands and is less dense in its solid form. Hence, ice floats.

• Water is also one of few substances found commonly as a solid, liquid and gas.

How Much Water Is Available?How Much Water Is Available?• 71% of earth is water• 97.4% of that is in oceans• Most of the remaining

2.6% is in ice caps and glaciers.

• Only about 0.014% is easily available fresh water.

If earth’s water was 26 gallons, 2.5 teaspoons would be available.

Supply of WaterSupply of Water

Supply of Water ResourcesSupply of Water Resources

Fig. 15-2 p. 307Fig. 15-2 p. 307

FreshwaterFreshwater Readily accessible freshwaterReadily accessible freshwater

Biota0.0001%

Biota0.0001%

Rivers0.0001%Rivers

0.0001%

Atmosphericwater vapor

0.0001%

Atmosphericwater vapor

0.0001%

Lakes0.0007%

Soilmoisture0.0005%

Groundwater0.592%

Groundwater0.592%

Ice capsand glaciers

0.592%

0.014%0.014%

Water Cycle: Renewing WaterWater Cycle: Renewing Water

Surface WaterSurface Water

Surface runoff: precipitation that does not infiltrate the ground or return to the atmosphere.

Surface runoff: precipitation that does not infiltrate the ground or return to the atmosphere.

Reliable runoff: the amount of water that

can be counted on each year as a stable source.

Reliable runoff: the amount of water that

can be counted on each year as a stable source.

Surface RunoffSurface Runoff

Watershed: the region of land from which surface water drains into a river, lake, wetland or other body of water

WatershedWatershed

Delaware

River

Watershed

GroundwaterGroundwater • One of the most important source of water.

• Precipitation filters down through pores and cracks in soil and rocks.

• Groundwater found within 1km of the surface contains 100 times more water than all the rivers, streams and lakes

Evaporation and transpiration

Evaporation

Stream

Infiltration

Water tableInfiltration

Unconfined aquifer

Confined aquifer

Lake

Well requiring a pump

Flowingartesian well

Runoff

Precipitation

ConfinedRecharge Area

Aquifer

Less permeable materialsuch as clay Confirming permeable rock layer

Ground WaterGround Water

Fig. 15-3 p. 308

Use of Water ResourcesUse of Water Resources

Humans use about 54% of reliable runoff Humans use about 54% of reliable runoff

Agriculture: worldwide about 70% of water is used to irrigate crops.

85% of that is not returned to the water ways.

Agriculture: worldwide about 70% of water is used to irrigate crops.

85% of that is not returned to the water ways.

Fig. 15-4 p. 309Fig. 15-4 p. 309

United States

Industry 11%

Public 10%

Powercooling

38%

Agriculture38%

Use of Water ResourcesUse of Water Resources

• Industry: 20% of water withdrawn each year is used by industry.

• Domestic: 10% is used by cities and residencies.

Uses of WaterUses of Water

Water in US East vs. WestWater in US East vs. West

• Eastern US most water is used for energy production, manufacturing.

• Western US most water is used for irrigation.

Water in US East vs. WestWater in US East vs. West

Chapter 15 Sections 1-2 ReviewChapter 15 Sections 1-2 Review• Where is the world’s usable water located?

• Describe several properties of water that make it unique.

• How much water is available for human usage?

• What is runoff? What is a watershed? What is groundwater?

• Describe the water cycle.

• How is most of the world’s water used?

• What are some water differences between the eastern and western US?

Key Concepts Chapter 15 Sections 3, 4 and 5Key Concepts Chapter 15 Sections 3, 4 and 5

• What causes fresh water shortages?• How many people do not have access to clean

water?• How can we increase clean water supplies?• What are advantages and disadvantages of large

dams and reservoirs?• Case Studies: 1) Water Conflicts in the Middle East,

2) Colorado River Basin, 3) China’s Three Gorges Dam, 4) Aral Sea, 5) California Water Transfer, 6) Canada’s James Bay Watershed.

Access to FreshwaterAccess to Freshwater

• About 1 in 6 people (1 billion people) do not have access to regular, clean water supplies.

Too Little WaterToo Little Water

Acute shortage

Adequate supply

Shortage

Metropolitan regions with population greater than 1 million

Fig. 15-6 p. 310Fig. 15-6 p. 310

What causes fresh water shortages?

Areas of US where there are conflicts over water. “Water Wars” competing for a scarce resource.

Too Little Water: 4 Reasons Too Little Water: 4 Reasons Dry climate: people

living or growing crops in areas where little precipitation naturally falls

• San Diego averages just 8 inches of rain a year compared to over 35 inches in Camden.

Las Vegas averages less than 5 inches of rain yearly.

Too Little WaterToo Little Water

Drought: prolonged periods of below average precipitation.

Too Little WaterToo Little Water

Desiccation: drying of exposed soil because of activities such as deforestation and overgrazing.

Too Little WaterToo Little WaterWater stress: low per

capita availability of water due to increasing population demands.

• Some regions get plenty of water, but not near where people live

• Some regions get plenty of water, but not at the right time of year

• Some regions have no capacity to store water.

Natural Capital Degradation. Stress on the world’s river basins.

Increasing Water SuppliesIncreasing Water Supplies

1) Build dams and reservoirs

2) Transfer water to places it is needed

3) Withdraw groundwater

4) Desalinization

5) Reduce water waste

6) Import food from regions where irrigation is not needed.

Using Dams and ReservoirsUsing Dams and Reservoirs

Large dams can produce cheap electricity, reduce downstream flooding and provide a year-round source of water, but they completely alter the river ecosystem.

Using Dams and Reservoirs to Supply More Water: The Trade-offsUsing Dams and Reservoirs to Supply More Water: The Trade-offs

Large lossesof water throughevaporation

Large lossesof water throughevaporation

Flooded land destroys forests or cropland anddisplaces people

Flooded land destroys forests or cropland anddisplaces people

Downstream flooding is reducedDownstream flooding is reduced

Downstream cropland andestuaries are deprived ofnutrient-rich silt

Downstream cropland andestuaries are deprived ofnutrient-rich silt

Reservoir is useful for recreation and fishing

Can produce cheap electricity (hydropower)

Migration and spawning of some fish are disruptedMigration and spawning of some fish are disrupted

Provides waterfor year-roundirrigation ofcropland

Fig. 15-9 p. 313Fig. 15-9 p. 313

Transferring Water from One Place to AnotherTransferring Water from One Place to Another

North BayAqueductNorth BayAqueduct

South BayAqueductSouth BayAqueduct

California AqueductCalifornia Aqueduct

CALIFORNIANEVADA UTAH

MEXICO

Central ArizonaProject

Colorado RiverAqueduct

Los AngelesAqueduct

Shasta Lake

Sacramento

Fresno

Phoenix

Tucson

ARIZONA

ColoradoRiver

SacramentoRiverSacramentoRiver

San FranciscoSan Francisco

Los AngelesLos Angeles

San DiegoSan Diego

Watershed transferWatershed transfer

California Water Project

California Water Project

Central Arizona Project

Central Arizona Project

James BayJames Bay Fig. 15-13 p. 317Fig. 15-13 p. 317

Sections 3,4 and 5 ReviewSections 3,4 and 5 Review• What causes fresh water shortages?

• How can we increase clean water supplies?

• What are advantages and disadvantages of large dams and reservoirs?

• Case Studies: 1) Water Conflicts in the Middle East, 2) Colorado River Basin, 3) China’s Three Gorges Dam, 4) Aral Sea, 5) California Water Transfer, 6) Canada’s James Bay Watershed.

Key Concepts Chapter 15 Sections 6 and 7Key Concepts Chapter 15 Sections 6 and 7

• What are advantages and disadvantages of using groundwater?

• Deep water or shallow water aquifers, what about desalinization?

• “Weird” Water Solutions?

• What are the benefits of reducing water waste?

• How can we reduce wasting irrigation water? What about in homes, industry and businesses?

Tapping Groundwater: BenefitsTapping Groundwater: Benefits

Most aquifers are renewable sources unless the water is removed faster than it is replenished

Tapping Groundwater: BenefitsTapping Groundwater: Benefits

Year-round use: aquifers provide reliable year-round use.

• ¼ of world’s drinking water

• In US groundwater is being withdrawn 4 times its replacement rate.

Tapping Groundwater: BenefitsTapping Groundwater: Benefits

Little Water Loss: there is no loss of water due to evaporation.

Often Cheaper: groundwater is often cheap to extract.

Tapping Groundwater: CostsTapping Groundwater: Costs

Using ground water has tradeoffs.

Water tables around the world are falling.

Problems Using GroundwaterProblems Using Groundwater

Problems with Using GroundwaterProblems with Using Groundwater

Water table lowering Water table lowering

Depletion Depletion

Subsidence Subsidence

Saltwater intrusion Saltwater intrusion

Chemical contaminationChemical contamination

Reduced stream flowsReduced stream flows

Potential Sources of Groundwater Contamination

Problems with Using GroundwaterProblems with Using Groundwater

As groundwater is pumped out of the ground, the ground may subside.

This picture shows ground subsidence in CA.

Problems Using GroundwaterProblems Using Groundwater

Salt Water Intrusion: As water is pumped out of ground, saltwater can move inland to “pollute” the well.

Problems Using GroundwaterProblems Using Groundwater

Increasing Water Supplies Increasing Water Supplies

Distillation desalination: removing salt from seawater by evaporation of water leaving salt behind.

Distillation desalination: removing salt from seawater by evaporation of water leaving salt behind.

Increasing Water SuppliesIncreasing Water SuppliesReverse osmosis desalination: pumping

saltwater under high pressure through a membrane to take out salt.

Increasing Water SuppliesIncreasing Water Supplies

Desalination is very expensive: only several oil-rich and water poor countries use large-scale desalinization.

TAKES TREMENDOUS AMOUNT OF ENERGY

• Future Potential???

Increasing Water SuppliesIncreasing Water Supplies

Cloud Seeding: releasing tiny particles into air to produce rain clouds.

Towing Icebergs: moving ice around world.

Using Oil Tankers Filled with water.

Using Water More EfficientlyUsing Water More Efficiently

Reduce losses due to leakage: we waste about 2/3rd of the water we use, but simple steps could reduce that to 15%.

Reduce losses due to leakage: we waste about 2/3rd of the water we use, but simple steps could reduce that to 15%.

Using Water More EfficientlyUsing Water More Efficiently

Reform water laws:• Higher water prices• Typically US farmers

only pay 1/5th of true water costs.

• Encouraging conservation

• Reward people for using less water

Using Water More EfficientlyUsing Water More Efficiently

Improve irrigation efficiency: 60% of water applied to land does not reach crops.

• Evaporation

• Seepage

• Runoff

Using Water More EfficientlyUsing Water More Efficiently

Improve irrigation efficiency:

• Center pivot sprinklers

• Time controlled irrigation

• Soil moisture detectors• Drip Irrigation

Using Water More EfficientlyUsing Water More Efficiently

Water efficient landscaping (xeriscaping): using vegetating that does not require much water.

• About 1/5th of all US water houses do not have water meters and pay a flat rate.

Using Water More EfficientlyUsing Water More Efficiently

Water efficient appliances:

• Low Flow Toilets• Washers that use less

water

Reusing water:

Using “brownwater” for non-drinking water usages.

Chapter 15 Sections 6, 7 ReviewChapter 15 Sections 6, 7 Review

• What are advantages and disadvantages of using groundwater?

• Deep water or shallow water aquifers, what about desalinization?

• “Weird” Water Solutions?

• What are the benefits of reducing water waste?

• How can we reduce wasting irrigation water? What about in homes, industry and businesses?

Chapter 15 Section 8 and 9Chapter 15 Section 8 and 9

• What causes flooding?

• How do humans exacerbate flooding?

• How can flood risks be minimized?

• What are solutions for sustainable water use?

Too Much Water: FloodsToo Much Water: Floods

Natural phenomena Natural phenomena

Floodplain

Levee Floodwall

Dam

Reservoir

Aggravated by human activities Aggravated by human activities

Fig. 15-24 p. 327

Natural floodplain, altered floodplain and flooded.

Too Much Water: FloodsToo Much Water: Floods

Natural Events: heavy rainfall, melting snow are major causes of flooding.

Floodplain: the natural area around a river where flooding normally occurs.

Too Much Water: FloodsToo Much Water: Floods

Floodplains are usually fertile, have ample water for irrigation and therefore often developed.

Floods bring nutrients onto surrounding land.

Too Much Water: FloodsToo Much Water: Floods

Flooding Worsens With Human Impacts:

• Removing wetlands

• Building levees

• Making more land impermeable (development)

Downstream ImpactsDownstream Impacts

Too Much Water: FloodsToo Much Water: FloodsReducing Risks:

• Channelization

• Floodwalls

• Build Dams

• Preserve wetlands

• Identify and restrict building in floodplains

• Restore natural land

Solutions: Achieving a More Sustainable Water FutureSolutions: Achieving a More Sustainable Water Future

Efficient irrigationEfficient irrigation

Water-saving technologiesWater-saving technologies

Improving water managementImproving water management

See Fig. 15-26 p. 329See Fig. 15-26 p. 329