chapter 15 water resources. chapter overview questions why is water so important, how much...

Chapter 15Chapter 15

Water ResourcesWater Resources

Chapter Overview QuestionsChapter Overview Questions

Why is water so important, how much Why is water so important, how much freshwater is available to us, and how much freshwater is available to us, and how much of it are we using?of it are we using?

What causes freshwater shortages, and what What causes freshwater shortages, and what can be done about this problem?can be done about this problem?

What are the advantages and disadvantages What are the advantages and disadvantages of withdrawing groundwater?of withdrawing groundwater?

What are the advantages and disadvantages What are the advantages and disadvantages of using dams and reservoirs to supply more of using dams and reservoirs to supply more water?water?

Chapter Overview Questions (cont’d)Chapter Overview Questions (cont’d)

What are the advantages and disadvantages What are the advantages and disadvantages of transferring large amounts of water from of transferring large amounts of water from one place to another?one place to another?

Can removing salt from seawater solve our Can removing salt from seawater solve our water supply problems?water supply problems?

How can we waste less water?How can we waste less water? How can we use the earth’s water more How can we use the earth’s water more

sustainably?sustainably? What causes flooding, and what can we do What causes flooding, and what can we do

about it?about it?

Core Case Study: Water Conflicts in Core Case Study: Water Conflicts in the Middle East - A Preview the Middle East - A Preview

of the Futureof the Future Many countries in Many countries in

the Middle East, the Middle East, which has one of which has one of the world’s highest the world’s highest population growth population growth rates, face water rates, face water shortages.shortages.

Water Conflicts in the Middle East: A Water Conflicts in the Middle East: A Preview of the FuturePreview of the Future

Most water in this dry region comes from the Most water in this dry region comes from the Nile, Jordan or Tigris rivers.Nile, Jordan or Tigris rivers.

Countries are in disagreement as to who has Countries are in disagreement as to who has water rights.water rights.

Currently, there are no cooperative Currently, there are no cooperative agreements for use of 158 of the world’s 263 agreements for use of 158 of the world’s 263 water basins that are shared by two or more water basins that are shared by two or more countries.countries.

WATER’S IMPORTANCE, WATER’S IMPORTANCE, AVAILABILITY, AND RENEWALAVAILABILITY, AND RENEWAL

Water keeps us alive, moderates climate, Water keeps us alive, moderates climate, sculpts the land, removes and dilutes wastes sculpts the land, removes and dilutes wastes and pollutants, and moves continually and pollutants, and moves continually through the hydrologic cycle.through the hydrologic cycle.

Only about 0.02% of the earth’s water supply Only about 0.02% of the earth’s water supply is available to us as liquid freshwater.is available to us as liquid freshwater.


Comparison of Comparison of population sizes and population sizes and shares of the world’s shares of the world’s freshwater among freshwater among the continents.the continents.


Some precipitation Some precipitation infiltrates the ground and is infiltrates the ground and is stored in soil and rock stored in soil and rock (groundwater).(groundwater).

• The zone of aeration is close to The zone of aeration is close to the surface, and pores/spaces the surface, and pores/spaces here contain a mixture of air here contain a mixture of air and water.and water.

In the zone of saturation, the In the zone of saturation, the spaces in the ground are spaces in the ground are filled with water.filled with water.

Water Table Drama!Water Table Drama!

The water table is located The water table is located at the top of the zone of at the top of the zone of saturation.saturation.

An aquifer is deeper down An aquifer is deeper down in the geologic layers and in the geologic layers and is like an elongated is like an elongated sponge with watertight sponge with watertight layers of rock or clay layers of rock or clay below the aquifer to keep below the aquifer to keep water from seeping out.water from seeping out.

How Aquifers RechargeHow Aquifers Recharge

A A natural recharge natural recharge replenishes an aquifer replenishes an aquifer through the precipitation through the precipitation that percolates down that percolates down through soil and rock. through soil and rock. This recharge occurs This recharge occurs extremely slowly.extremely slowly.

Lateral recharge is Lateral recharge is replenished from the replenished from the side of nearby streams.side of nearby streams.

Surface Water and RunoffSurface Water and Runoff

Water that does not sink into the ground or Water that does not sink into the ground or evaporate into the air runs off (evaporate into the air runs off (surface runoffsurface runoff) ) into bodies of water.into bodies of water.

The land from which the surface water drains into The land from which the surface water drains into a body of water is called its a body of water is called its watershedwatershed or or drainage basindrainage basin..

Reliable runoff Reliable runoff – runoff that is stable from one – runoff that is stable from one year to the next – sweet water supplyyear to the next – sweet water supply

Unconfined Aquifer Recharge Area

Precipitation Evaporation and transpiration Evaporation

Confined Recharge Area

Runoff

Flowing artesian well

Recharge Recharge Unconfined Unconfined AquiferAquifer

Stream Well requiring a pumpInfiltration Water

table LakeInfiltration

Unconfined aquiferConfined aquifer

Confining impermeable rock layer Confining impermeable rock layer

Less permeable Less permeable material such as claymaterial such as clay

Unconfined aquifers receive recharge directly from rainfall and surface water infiltrating downward.

Confined aquifers are connected to unconfined areas where water can flow in.


We currently use more than half of the We currently use more than half of the world’s reliable runoff of surface water and world’s reliable runoff of surface water and could be using 70-90% by 2025.could be using 70-90% by 2025.

About 70% of the water we withdraw from About 70% of the water we withdraw from rivers, lakes, and aquifers is not returned to rivers, lakes, and aquifers is not returned to these sources.these sources.

Irrigation is the biggest user of water Irrigation is the biggest user of water (70-(70-85%), followed by industries (20%) and cities 85%), followed by industries (20%) and cities and residences (10%).and residences (10%).

East Coast vs. West CoastEast Coast vs. West Coast

West CoastWest Coast 85% for irrigation85% for irrigation Problems = too little Problems = too little

water! Drought!water! Drought!

East CoastEast Coast Energy production, Energy production,

manufacturing, cooling.manufacturing, cooling. Flooding, urban Flooding, urban

shortages, pollution!shortages, pollution!

Water in the Water in the United StatesUnited States

Average Average precipitation (top) precipitation (top) in relation to in relation to water-deficit water-deficit regions and their regions and their proximity to proximity to metropolitan areas metropolitan areas (bottom).(bottom).

Average annual precipitation (centimeters)

More than 122

Less than 41 81–122

41–81

Acute shortage

Metropolitan regions with population greater than 1 million

Shortage

Adequate supply

Case Study: Freshwater Resources in Case Study: Freshwater Resources in the United Statesthe United States

Water hot spots: 17 Water hot spots: 17 western states by western states by 2025 could face 2025 could face intense conflict over intense conflict over scarce water scarce water needed for urban needed for urban growth, irrigation, growth, irrigation, recreation and recreation and wildlife.wildlife.

Tee Time!Tee Time!

The daily minimum The daily minimum amount of water amount of water needed to support needed to support three-fourths of the three-fourths of the world’s people is equal world’s people is equal to the amount of water to the amount of water used to irrigate the used to irrigate the world’s golf courses.world’s golf courses.

DroughtDrought

Water scarcity arises from a dry climate, drought, dry soil, and too many people straining the water supply.

1. A drought occurs when precipitation is at least 70% lower than usual and evaporation is higher than normal for more than 21 days.

2.Increasing numbers of people relying on limited runoff produces a low per capita availability of water, which leads to water stress.

Harmful Effects of long-term severe droughtHarmful Effects of long-term severe drought Insect infestations and plant diseases, Insect infestations and plant diseases,

increased erosion, habitat degradation, a increased erosion, habitat degradation, a decrease in air quality and that of what water decrease in air quality and that of what water is present, as well as an increased risk of fire is present, as well as an increased risk of fire because of drier vegetation. because of drier vegetation.

In short-term droughts, natural environments In short-term droughts, natural environments can often reboundcan often rebound

When there are long term droughts, plant and When there are long term droughts, plant and animal species can suffer tremendously, and animal species can suffer tremendously, and over time desertification can happen with an over time desertification can happen with an extreme lack of moisture.extreme lack of moisture.

Americans and Water UsageAmericans and Water Usage

Most Americans are served by publicly owned water and sewer utilities.

Eleven percent of Americans receive water from private (so-called “investor-owned”) utilities.

In rural areas, cooperatives often provide drinking water.

Finally, up to 15 percent of Americans are served by their own wells

United States China

Industry 11% Public 10%

Powercooling38%

Agriculture41% Agriculture 87%

Public 6% Industry 7%

Figure 15-4Figure 15-4Page 309Page 309

TOO LITTLE FRESHWATERTOO LITTLE FRESHWATER

About 41% of the world’s population lives in About 41% of the world’s population lives in river basins that do not have enough river basins that do not have enough freshwater.freshwater.

Many parts of the world are experiencing:Many parts of the world are experiencing: Rivers running dry.Rivers running dry. Lakes and seas shrinking.Lakes and seas shrinking. Falling water tables from overpumped aquifers.Falling water tables from overpumped aquifers.

Stress on the World’s River BasinsStress on the World’s River Basins

Comparison of the amount of water available Comparison of the amount of water available with the amount used by humans.with the amount used by humans.

Case Study: Who Should Own and Case Study: Who Should Own and Manage Freshwater ResourcesManage Freshwater Resources

There is controversy over whether water There is controversy over whether water supplies should be owned and managed by supplies should be owned and managed by governments or by private corporations.governments or by private corporations.

European-based water companies aim to European-based water companies aim to control 70% of the U.S. water supply by control 70% of the U.S. water supply by buying up water companies and entering into buying up water companies and entering into agreements with cities to manage water agreements with cities to manage water supplies.supplies.

How Would You Vote?How Would You Vote?

Should private companies own or manage most of Should private companies own or manage most of the world's water resources?the world's water resources?

Some thoughts….Some thoughts…. a. No. Democratically elected governments, which are a. No. Democratically elected governments, which are

accountable to the voters, should own and manage water accountable to the voters, should own and manage water resources.resources.

b. Qualified yes. Governments should own the water, but b. Qualified yes. Governments should own the water, but expert private companies should manage it.expert private companies should manage it.

c. Depends. Each case must be decided independently. c. Depends. Each case must be decided independently. The record on private versus public ownership is mixed.The record on private versus public ownership is mixed.

d. Yes. Private companies have more expertise and d. Yes. Private companies have more expertise and experience in managing water resources than most experience in managing water resources than most government bureaucrats. government bureaucrats.

TOO LITTLE FRESHWATERTOO LITTLE FRESHWATER

Cities are outbidding farmers for water Cities are outbidding farmers for water supplies from rivers and aquifers.supplies from rivers and aquifers.

Countries are importing grain as a way to Countries are importing grain as a way to reduce their water use.reduce their water use.

More crops are being used to produce More crops are being used to produce biofuels.biofuels.

Our water options are:Our water options are: Get more water from aquifers and rivers, Get more water from aquifers and rivers,

desalinate ocean water, waste less water.desalinate ocean water, waste less water.

WITHDRAWING GROUNDWATER WITHDRAWING GROUNDWATER TO INCREASE SUPPLIESTO INCREASE SUPPLIES

Most aquifers are renewable resources Most aquifers are renewable resources unless water is removed faster than it is unless water is removed faster than it is replenished or if they are contaminated.replenished or if they are contaminated.

Groundwater depletion is a growing problem Groundwater depletion is a growing problem mostly from irrigation.mostly from irrigation. At least one-fourth of the farms in India are being At least one-fourth of the farms in India are being

irrigated from overpumped aquifers.irrigated from overpumped aquifers.

Trade-OffsWithdrawing Groundwater

Advantages Disadvantages

Useful for drinking and irrigation

Aquifer depletion from overpumping

Available year-round

Sinking of land (subsidence) from overpumping

Exists almost everywhere Polluted aquifers for

decades or centuries

Renewable if not overpumped or contaminated

Saltwater intrusion into drinking water supplies near coastal areas

Reduced water flows into surface waters

No evaporation losses

Cheaper to extract than most surface waters

Increased cost and contamination from deeper wells

Groundwater Depletion: Groundwater Depletion: A Growing Problem A Growing Problem

http://www.youtube.com/watch?v=nKnG1a2Q6BYhttp://www.youtube.com/watch?v=nKnG1a2Q6BY

The Ogallala, the world’s largest aquifer, is The Ogallala, the world’s largest aquifer, is most of the red area in the center (Midwest).most of the red area in the center (Midwest).

Areas of Areas of greatest aquifer greatest aquifer depletion from depletion from groundwater groundwater overdraft in the overdraft in the continental U.S.continental U.S.

Other Effects of Groundwater Other Effects of Groundwater OverpumpingOverpumping

Groundwater Groundwater overpumping can overpumping can cause land to sink, cause land to sink, and contaminate and contaminate freshwater aquifers freshwater aquifers near coastal areas near coastal areas with saltwater.with saltwater.

Other Effects of Groundwater Other Effects of Groundwater OverpumpingOverpumping

Sinkholes form when Sinkholes form when the roof of an the roof of an underground cavern underground cavern collapses after being collapses after being drained of drained of groundwater.groundwater.

Groundwater Pumping in Saudi Groundwater Pumping in Saudi Arabia (1986 – 2004)Arabia (1986 – 2004)

Irrigation systems from the nonrenewable Irrigation systems from the nonrenewable aquifer appear as green dots. Brown dots are aquifer appear as green dots. Brown dots are wells that have gone dry.wells that have gone dry.

Solutions

Groundwater Depletion

Prevention Control

Waste less water Raise price of water to discourage waste

Subsidize water conservation

Ban new wells in aquifers near surface waters

Tax water pumped from wells near surface waters

Buy and retire groundwater withdrawal rights in critical areas

Do not grow water-intensive crops in dry areas

Set and enforce minimum stream flow levels

USING DAMS AND RESERVOIRS USING DAMS AND RESERVOIRS TO TO SUPPLY MORE WATERSUPPLY MORE WATER

Large dams and reservoirs can produce Large dams and reservoirs can produce cheap electricity, reduce downstream cheap electricity, reduce downstream flooding, and provide year-round water for flooding, and provide year-round water for irrigating croplandirrigating cropland, but they also displace , but they also displace people and disrupt aquatic systems.people and disrupt aquatic systems.

Provides water for year-round irrigation of cropland

Flooded land destroys forests or cropland and displaces people

Large losses of water through evaporation

Provides water for drinking Downstream

cropland and estuaries are deprived of nutrient-rich silt

Reservoir is useful for recreation and fishing

Risk of failure and devastating downstream flooding

Can produce cheap electricity (hydropower)

Downstream flooding is reduced

Migration and spawning of some fish are disrupted

Powerlines

Reservoir

DamPowerhouse

Intake

Turbine

Case Study: The Colorado Basin – an Case Study: The Colorado Basin – an Overtapped ResourceOvertapped Resource

The Colorado River has so many dams and The Colorado River has so many dams and withdrawals that it often does not reach the withdrawals that it often does not reach the ocean.ocean. 14 major dams and reservoirs, and canals.14 major dams and reservoirs, and canals. Water is mostly used in desert area of the U.S.Water is mostly used in desert area of the U.S. Provides electricity from hydroelectric plants for Provides electricity from hydroelectric plants for

30 million people (1/1030 million people (1/10thth of the U.S. population). of the U.S. population).

Case Study: The Colorado Basin – an Case Study: The Colorado Basin – an Overtapped ResourceOvertapped Resource

Lake Powell, is Lake Powell, is the second the second largest reservoir largest reservoir in the U.S.in the U.S.

It hosts one of It hosts one of the hydroelectric the hydroelectric plants located on plants located on the Colorado the Colorado River.River.

The Colorado River BasinThe Colorado River Basin

The area The area drained by this drained by this basin is equal to basin is equal to more than one-more than one-twelfth of the twelfth of the land area of the land area of the lower 48 states.lower 48 states.


Do the advantages of large dams outweigh Do the advantages of large dams outweigh their disadvantages?their disadvantages? a. No. Large dams inflict extensive environmental a. No. Large dams inflict extensive environmental

damage and humans must learn to meet their damage and humans must learn to meet their needs without them.needs without them.

b. Yes. Dams are critical in providing water and b. Yes. Dams are critical in providing water and electricity for people, especially in developing electricity for people, especially in developing countries. countries.

Case Study: Case Study: China’s Three Gorges DamChina’s Three Gorges Dam

There is a debate over whether the There is a debate over whether the advantages of the world’s largest dam and advantages of the world’s largest dam and reservoir will outweigh its disadvantages.reservoir will outweigh its disadvantages. The dam will be 2 kilometers long.The dam will be 2 kilometers long. The electric output will be that of 18 large coal-The electric output will be that of 18 large coal-

burning or nuclear power plants.burning or nuclear power plants. It will facilitate ship travel reducing transportation It will facilitate ship travel reducing transportation

costs.costs. Dam will displace 1.2 million people.Dam will displace 1.2 million people. Dam is built over seismatic fault and already has Dam is built over seismatic fault and already has

small cracks. small cracks.

Dam RemovalDam Removal

Some dams are being removed for ecological Some dams are being removed for ecological reasons and because they have outlived their reasons and because they have outlived their usefulness.usefulness. In 1998 the U.S. Army Corps of Engineers In 1998 the U.S. Army Corps of Engineers

announced that it would no longer build large announced that it would no longer build large dams and diversion projects in the U.S.dams and diversion projects in the U.S.

The Federal Energy Regulatory Commission has The Federal Energy Regulatory Commission has approved the removal of nearly 500 dams.approved the removal of nearly 500 dams.

Removing dams can reestablish ecosystems, but Removing dams can reestablish ecosystems, but can also re-release toxicants into the can also re-release toxicants into the environment.environment.

TRANSFERRING WATER FROM TRANSFERRING WATER FROM ONE PLACE TO ANOTHERONE PLACE TO ANOTHER

Transferring water can make unproductive Transferring water can make unproductive areas more productive but can cause areas more productive but can cause environmental harm.environmental harm. Promotes investment, jobs and strong economy.Promotes investment, jobs and strong economy. It encourages unsustainable use of water in It encourages unsustainable use of water in

areas water is not naturally supplied.areas water is not naturally supplied.

Case Study: The California ExperienceCase Study: The California Experience

A massive A massive transfer of water transfer of water from water-rich from water-rich northern northern California to California to water-poor water-poor southern southern California is California is controversial.controversial.

http://www.youtube.com/watch?v=dWzEQxD_zGs

Case Study: The Aral Sea DisasterCase Study: The Aral Sea Disaster

The Aral Sea was once the world’s fourth The Aral Sea was once the world’s fourth largest freshwater lake.largest freshwater lake.

http://www.youtube.com/watch?v=9HfkZXLRYu8

Case Study: The Aral Sea DisasterCase Study: The Aral Sea Disaster Diverting water from the Aral Sea and its two Diverting water from the Aral Sea and its two

feeder rivers mostly for irrigation has created feeder rivers mostly for irrigation has created a major ecological, economic, and health a major ecological, economic, and health disaster.disaster. About 85% of the wetlands have been About 85% of the wetlands have been

eliminated and roughly 50% of the local bird and eliminated and roughly 50% of the local bird and mammal species have disappeared.mammal species have disappeared.

Since 1961, the sea’s salinity has tripled and the Since 1961, the sea’s salinity has tripled and the water has dropped by 22 meters most likely water has dropped by 22 meters most likely causing 20 of the 24 native fish species to go causing 20 of the 24 native fish species to go extinct.extinct.

China’s S-N Water Transfer ProjectChina’s S-N Water Transfer Project http://www.youtube.com/watch?v=SPq9Sapi5OU

http://www.youtube.com/watch?v=SPq9Sapi5OU

DESALTING SEAWATER, SEEDING DESALTING SEAWATER, SEEDING CLOUDS, AND TOWING ICEBERGS CLOUDS, AND TOWING ICEBERGS

AND GIANT BAGGIESAND GIANT BAGGIES Removing salt from seawater by current Removing salt from seawater by current

methods is expensive and produces large methods is expensive and produces large amounts of salty wastewater that must be amounts of salty wastewater that must be disposed of safely.disposed of safely. DistillationDistillation: heating saltwater until it evaporates, : heating saltwater until it evaporates,

leaves behind water in solid form.leaves behind water in solid form. Reverse osmosisReverse osmosis: uses high pressure to force : uses high pressure to force

saltwater through a membrane filter.saltwater through a membrane filter.

DESALTING SEAWATER, SEEDING DESALTING SEAWATER, SEEDING CLOUDS, AND TOWING ICEBERGS CLOUDS, AND TOWING ICEBERGS

AND GIANT BAGGIESAND GIANT BAGGIES Seeding clouds with tiny particles of Seeding clouds with tiny particles of

chemicals to increase rainfall towing icebergs chemicals to increase rainfall towing icebergs or huge bags filled with freshwater to dry or huge bags filled with freshwater to dry coastal areas have all been proposed but are coastal areas have all been proposed but are unlikely to provide significant amounts of unlikely to provide significant amounts of freshwater.freshwater.

Homework for DiscussionHomework for Discussion

Check desalination pdf on Weebly site.Check desalination pdf on Weebly site. Take some good notes and come to class ready Take some good notes and come to class ready

to discuss some of the methods, advantages and to discuss some of the methods, advantages and disadvantages of desalination.disadvantages of desalination.

INCREASING WATER SUPPLIES BY INCREASING WATER SUPPLIES BY WASTING LESS WATERWASTING LESS WATER

We waste about two-thirds of the water we We waste about two-thirds of the water we useuse, but we could cut this waste to 15%., but we could cut this waste to 15%. 65-70% of the water people use throughout the 65-70% of the water people use throughout the

world is lost through evaporation, leaks, and world is lost through evaporation, leaks, and other losses.other losses.

Water is underpriced through government Water is underpriced through government subsidies.subsidies.

The lack of government subsidies for improving The lack of government subsidies for improving the efficiency of water use contributes to water the efficiency of water use contributes to water waste.waste.


Should water prices be raised sharply to help Should water prices be raised sharply to help reduce water waste?reduce water waste? a. No. Poor people, farmers, ranchers, and small a. No. Poor people, farmers, ranchers, and small

businesses would suffer from price increases. businesses would suffer from price increases.

b. Yes. People would be more likely to conserve b. Yes. People would be more likely to conserve water if it is more expensive. water if it is more expensive.

INCREASING WATER SUPPLIES BY INCREASING WATER SUPPLIES BY WASTING LESS WATERWASTING LESS WATER

Sixty percent of the world’s irrigation water is Sixty percent of the world’s irrigation water is currently wasted, but improved irrigation currently wasted, but improved irrigation techniques could cut this waste to 5-20%.techniques could cut this waste to 5-20%.

Center-pivot, low pressure sprinklers sprays Center-pivot, low pressure sprinklers sprays water directly onto crop.water directly onto crop. It allows 80% of water to reach crop.It allows 80% of water to reach crop. Has reduced depletion of Ogallala aquifer in Has reduced depletion of Ogallala aquifer in

Texas High Plains by 30%.Texas High Plains by 30%.

Center pivotCenter pivot

Drip irrigationDrip irrigation

Gravity flowGravity flow(efficiency 60% and

80% with surge valves)

Above- or below-ground pipes or tubes deliver water to individual plant roots.

Water usually comes from an aqueduct system or a nearby river.

(efficiency 90–95%)

(efficiency 80%–95%)Water usually pumped from underground and sprayed from mobile boom with sprinklers.

Solutions

Reducing Irrigation Water Waste

• Line canals bringing water to irrigation ditches

• Level fields with lasers

• Irrigate at night to reduce evaporation

• Monitor soil moisture to add water only when necessary

• Polyculture

• Organic farming

• Don't grow water-thirsty crops in dry areas

• Grow water-efficient crops using drought resistant and salt-tolerant crop varieties

• Irrigate with treated urban waste water

• Import water-intensive crops and meat

Solutions: Getting More Water for Solutions: Getting More Water for Irrigation in Developing Countries – Irrigation in Developing Countries –

The Low-Tech ApproachThe Low-Tech Approach Many poor farmers in Many poor farmers in

developing countries developing countries use low-tech methods use low-tech methods to pump groundwater to pump groundwater and make more and make more efficient use of rainfall.efficient use of rainfall.

SolutionsReducing Water Waste

• Redesign manufacturing processes• Repair leaking underground pipes• Landscape yards with plants that require little water

• Use drip irrigation• Fix water leaks• Use water meters• Raise water prices• Use waterless composting toilets• Require water conservation in water-short cities

• Use water-saving toilets, showerheads, and front loading clothes washers

• Collect and reuse household water to irrigate lawns and nonedible plants

• Purify and reuse water for houses, apartments, and office buildings

• Don't waste energy

Raising the Price of Water:Raising the Price of Water: A Key to Water Conservation A Key to Water Conservation

We can reduce water use and waste by We can reduce water use and waste by raising the price of water while providing low raising the price of water while providing low lifeline rates for the poor.lifeline rates for the poor. When Boulder, Colorado introduced water When Boulder, Colorado introduced water

meters, water use per person dropped by 40%.meters, water use per person dropped by 40%. A 10% increase in water prices cuts domestic A 10% increase in water prices cuts domestic

water use by 3-7%.water use by 3-7%.

Solutions: Using Less Water to Remove Solutions: Using Less Water to Remove Industrial and Household WastesIndustrial and Household Wastes

We can mimic the way nature deals with We can mimic the way nature deals with wastes instead of using large amounts of wastes instead of using large amounts of high-quality water to wash away and dilute high-quality water to wash away and dilute industrial and animal wastes.industrial and animal wastes. Use nutrients in wastewater before treatment as Use nutrients in wastewater before treatment as

soil fertilizer.soil fertilizer. Use waterless and odorless composting toilets Use waterless and odorless composting toilets

that convert human fecal matter into a small that convert human fecal matter into a small amount of soil material.amount of soil material.

FloodplainsFloodplains

A flood happens when A flood happens when water in a stream water in a stream overflows its normal overflows its normal channel into the channel into the adjacent adjacent floodplain.floodplain.

Floodplains = fertile Floodplains = fertile soil, ample water for soil, ample water for irrigation, water for irrigation, water for transportation, transportation, recreation, flat land!recreation, flat land!

FloodplainsFloodplains

Each year floods kill Each year floods kill up to 25,000 people up to 25,000 people and cause tens of and cause tens of billions of dollars in billions of dollars in property damage.property damage.

Removal of water Removal of water absorbing vegetationabsorbing vegetation

Paving and building Paving and building impervious surfacesimpervious surfaces

How we make it worse:

Bangladesh – Danger for the poor!Bangladesh – Danger for the poor! Upstream deforestation of Himalayan mountain Upstream deforestation of Himalayan mountain

slopes and the clearing of mangrove forests on slopes and the clearing of mangrove forests on coastal floodplainscoastal floodplains

Bangladesh is densely populated and poor!Bangladesh is densely populated and poor! 50 year floods now occur every 4 years50 year floods now occur every 4 years

Without sponge-like Himalayan forests to absorb Without sponge-like Himalayan forests to absorb runoff from monsoon rainsrunoff from monsoon rains• Quick and massive floods/sediment flowQuick and massive floods/sediment flow

Kills 2000 and leaves 30 million homeless in 1998.Kills 2000 and leaves 30 million homeless in 1998.

TOO MUCH WATERTOO MUCH WATER Heavy rainfall, rapid snowmelt, removal of Heavy rainfall, rapid snowmelt, removal of

vegetation, and destruction of wetlands vegetation, and destruction of wetlands cause flooding.cause flooding.

Floodplains, which usually include highly Floodplains, which usually include highly productive wetlands, help provide natural productive wetlands, help provide natural flood and erosion control, maintain high water flood and erosion control, maintain high water quality, and recharge groundwater.quality, and recharge groundwater.

To minimize floods, rivers have been To minimize floods, rivers have been narrowed with levees and walls, and narrowed with levees and walls, and dammed to store water.dammed to store water.

TOO MUCH WATERTOO MUCH WATER

Comparison of St. Louis, Missouri under Comparison of St. Louis, Missouri under normal conditions (1988) and after severe normal conditions (1988) and after severe flooding (1993).flooding (1993).

TOO MUCH WATERTOO MUCH WATER

Human activities have contributed to flood Human activities have contributed to flood deaths and damages.deaths and damages.

Oxygen released by vegetation

Diverse Diverse ecological ecological habitathabitat

Evapotranspiration

Trees reduce soil erosion from heavy rain and wind

Agricultural landSteady

river flow

Leaf litter improves soil fertility

Tree roots stabilize soil and aid water flow

Vegetation releases water slowly and reduces flooding

Forested Hillside

Tree plantation

Roads Roads destabilize destabilize hillsideshillsides

Evapotranspiration decreases

Ranching accelerates soil erosion by water and wind

Winds remove fragile topsoil

Agricultural land is flooded and silted up

Gullies and Gullies and landslideslandslides

Heavy rain leaches nutrients from soil and erodes topsoil

Silt from erosion blocks rivers and reservoirs and causes flooding downstream

Rapid runoff causes flooding

After Deforestation

Solutions

Reducing Flood Damage

Prevention Control

Preserve forests on watersheds

Strengthen and deepen streams (channelization)

Preserve and restore wetlands in floodplains

Tax all development on floodplains

Build levees or floodwalls along streams

Use floodplains primarily for recharging aquifers, sustainable agriculture and forestry, and recreation

Build dams

SOLUTIONS: USING SOLUTIONS: USING WATER MORE WATER MORE SUSTAINABLYSUSTAINABLY

We can use water more We can use water more sustainably by cutting sustainably by cutting waste, raising water waste, raising water prices, preserving prices, preserving forests and wetlands in forests and wetlands in water basins, and water basins, and slowing population slowing population growth.growth.

What Can You Do?Water Use and Waste

• Use water-saving toilets, showerheads, and faucet aerators.

• Shower instead of taking baths, and take short showers.

• Stop water leaks.

• Turn off sink faucets while brushing teeth, shaving, or washing.

• Flush toilets only when necessary.

• Wash only full loads of clothes or use the lowest water-level for smaller loads.

• Use recycled (gray) water for lawn, gardens, house plants, car washing.

• Wash a car from a bucket of soapy water, and use the hose for rinsing only.

• If you use a commercial car wash, try to find one that recycles its water.

• Replace your lawn with native plants that need little if any watering and decorative gravel or rocks.

• Water lawns and gardens in the early morning or evening.

• Sweep or blow off driveways instead of hosing off with water.

• Use drip irrigation and mulch for gardens and flowerbeds.

chapter 15 water resources. chapter overview questions why is water so important, how much...

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