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Chapter 14Chapter 14

WaterWater

Chapter Overview QuestionsChapter Overview Questions

Why is water so important, how muchWhy is water so important, how muchfreshwater is available to us, and how muchfreshwater is available to us, and how muchof it are we using?of it are we using?

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

What are the advantages and disadvantagesWhat are the advantages and disadvantagesof withdrawing groundwater?of withdrawing groundwater?

What are the advantages and disadvantagesWhat are the advantages and disadvantagesof using dams and reservoirs to supply moreof using dams and reservoirs to supply morewater?water?

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

What are the advantages and disadvantagesWhat are the advantages and disadvantagesof transferring large amounts of water fromof transferring large amounts of water fromone place to another?one place to another?

Can removing salt from seawater solve ourCan removing salt from seawater solve ourwater supply problems?water supply problems?

How can we waste less water?How can we waste less water?

How can we use the earthHow can we use the earth’’s water mores water moresustainably?sustainably?

What causes flooding, and what can we doWhat causes flooding, and what can we doabout it?about it?

Core Case Study: Water Conflicts inCore Case Study: Water Conflicts inthe Middle Eastthe Middle East -- A PreviewA Preview

of the Futureof the Future

Many countries inMany countries inthe Middle East,the Middle East,which has one ofwhich has one ofthe worldthe world’’s highests highestpopulation growthpopulation growthrates, face waterrates, face watershortages.shortages.

Figure 14Figure 14--11

Water Conflicts in the Middle East: AWater Conflicts in the Middle East: APreview of the FuturePreview of the Future

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

Countries are in disagreement as to who hasCountries are in disagreement as to who haswater rights.water rights.

Currently, there are no cooperativeCurrently, there are no cooperativeagreements for use of 158 of the worldagreements for use of 158 of the world’’s 263s 263water basins that are shared by two or morewater basins that are shared by two or morecountries.countries.

WATERWATER’’S IMPORTANCE,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 wastessculpts the land, removes and dilutes wastesand pollutants, and moves continuallyand pollutants, and moves continuallythrough the hydrologic cycle.through the hydrologic cycle.

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


Comparison ofComparison ofpopulation sizes andpopulation sizes andshares of the worldshares of the world’’ssfreshwater amongfreshwater amongthe continents.the continents.

Figure 14Figure 14--22 Fig. 14-2, p. 307

ContinentPercent of world's water resourcesand population

Asia60.5%

36%

Africa10%

8%Europe

North and CentralAmerica 7.3%

South America andCaribbean 6.4%

26%

15%

5%Oceania

11.3%

0.5%

14%


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

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

The land from which the surface water drains intoThe land from which the surface water drains intoa body of water is called itsa body of water is called its watershedwatershed orordrainage basindrainage basin..

2

Fig. 14-3, p. 308

Unconfined Aquifer Recharge Area

Precipitation Evaporation and transpiration Evaporation

ConfinedRechargeArea

Runoff

Flowingartesianwell

RechargeRechargeUnconfinedUnconfined

AquiferAquifer

Stream Wellrequiring apumpInfiltration Water

table LakeInfiltration

Unconfined aquifer

Confined aquiferConfining impermeable rock layerConfining impermeable rock layer

Less permeableLess permeablematerial such as claymaterial such as clay


We currently use more than half of theWe currently use more than half of theworldworld’’s reliable runoff of surface water ands reliable runoff of surface water andcould be using 70could be using 70--90% by 2025.90% by 2025.

About 70% of the water we withdraw fromAbout 70% of the water we withdraw fromrivers, lakes, and aquifers is not returned torivers, lakes, and aquifers is not returned tothese sources.these sources.

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

Water in theWater in theUnited StatesUnited States

AverageAverageprecipitation (top)precipitation (top)in relation toin relation towaterwater--deficitdeficitregions and theirregions and theirproximity toproximity tometropolitan areasmetropolitan areas(bottom).(bottom).


Fig. 14-4a, p. 309

Average annual precipitation (centimeters)

More than 122

Less than 41 81–122

41–81

Fig. 14-4b, p. 309

Acute shortage

Metropolitan regions with populationgreater than 1 million

Shortage

Adequate supply

Case Study: Freshwater Resources inCase Study: Freshwater Resources inthe United Statesthe United States

17 western states17 western statesby 2025 could faceby 2025 could faceintense conflict overintense conflict overscarce waterscarce waterneeded for urbanneeded for urbangrowth, irrigation,growth, irrigation,recreation andrecreation andwildlife.wildlife.


Fig. 14-5, p. 310

Wash.

MontanaOregon

N.D.

Idaho

Wyoming S.D.

Nevada Neb.

UtahColo.

Kansas

California Oak.

N.M.Texas

Highly likely conflict potential

Moderate conflict potential

Unmet rural water needs

Substantial conflict potential

TOO LITTLE FRESHWATERTOO LITTLE FRESHWATER

About 41% of the worldAbout 41% of the world’’s population lives ins population lives inriver basins that do not have enoughriver basins that do not have enoughfreshwater.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 fromFalling water tables from overpumpedoverpumped aquifers.aquifers.

Stress on the WorldStress on the World’’s River Basinss River Basins

Comparison of the amount of water availableComparison of the amount of water availablewith the amount used by humans.with the amount used by humans.


3

Fig. 14-6, p. 311

Europe

NorthAmerica

Asia

Africa

SouthAmerica

Australia

Stress

High None

Case Study: Who Should Own andCase Study: Who Should Own andManage Freshwater ResourcesManage Freshwater Resources

There is controversy over whether waterThere is controversy over whether watersupplies should be owned and managed bysupplies should be owned and managed bygovernments or by private corporations.governments or by private corporations.

EuropeanEuropean--based water companies aim tobased water companies aim tocontrol 70% of the U.S. water supply bycontrol 70% of the U.S. water supply bybuying up water companies and entering intobuying up water companies and entering intoagreements with cities to manage wateragreements with cities to manage watersupplies.supplies.

TOO LITTLE FRESHWATERTOO LITTLE FRESHWATER

Cities are outbidding farmers for waterCities are outbidding farmers for watersupplies from rivers and aquifers.supplies from rivers and aquifers.

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

More crops are being used to produceMore crops are being used to producebiofuelsbiofuels..

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 GROUNDWATERWITHDRAWING GROUNDWATERTO INCREASE SUPPLIESTO INCREASE SUPPLIES

Most aquifers are renewable resourcesMost aquifers are renewable resourcesunless water is removed faster than it isunless water is removed faster than it isreplenished or if they are contaminated.replenished or if they are contaminated.

Groundwater depletion is a growing problemGroundwater depletion is a growing problemmostly from irrigation.mostly from irrigation.

At least oneAt least one--fourth of the farms in India are beingfourth of the farms in India are beingirrigated fromirrigated from overpumpedoverpumped aquifers.aquifers.

Fig. 14-7, p. 313

Trade-Offs

Withdrawing Groundwater

Advantages Disadvantages

Useful for drinkingand irrigation

Aquifer depletion fromoverpumping

Available year-round

Sinking of land(subsidence) fromoverpumping

Exists almosteverywhere

Polluted aquifers fordecades or centuries

Renewable if notoverpumped orcontaminated

Saltwater intrusion intodrinking water suppliesnear coastal areas

Reduced water flowsinto surface waters

No evaporationlosses

Cheaper to extractthan most surfacewaters

Increased cost andcontamination fromdeeper wells

Groundwater Depletion:Groundwater Depletion:A Growing ProblemA Growing Problem

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

Areas ofAreas ofgreatest aquifergreatest aquiferdepletion fromdepletion fromgroundwatergroundwateroverdraft in theoverdraft in thecontinental U.S.continental U.S.


Fig. 14-8, p. 314

Groundwater Overdrafts:

High

Moderate

Minor or none

Other Effects of GroundwaterOther Effects of GroundwaterOverpumpingOverpumping

GroundwaterGroundwateroverpumpingoverpumping cancancause land to sink,cause land to sink,and contaminateand contaminatefreshwater aquifersfreshwater aquifersnear coastal areasnear coastal areaswith saltwater.with saltwater.


Majorirrigationwell

Well contaminatedwith saltwater

WatertableFresh

groundwateraquifer

Sea level

Saltwate

r

InterfaceSeaflo

or

Saltwaterintrusion

Interface

Normalinterface

4

Other Effects of GroundwaterOther Effects of GroundwaterOverpumpingOverpumping

Sinkholes form whenSinkholes form whenthe roof of anthe roof of anunderground cavernunderground caverncollapses after beingcollapses after beingdrained ofdrained ofgroundwater.groundwater.


Groundwater Pumping in SaudiGroundwater Pumping in SaudiArabia (1986Arabia (1986 –– 2004)2004)

Irrigation systems from the nonrenewableIrrigation systems from the nonrenewableaquifer appear as green dots. Brown dots areaquifer appear as green dots. Brown dots arewells that have gone dry.wells that have gone dry.


Solutions

Groundwater Depletion

Prevention Control

Waste less water Raise price of waterto discourage waste

Subsidize waterconservation

Ban new wells inaquifers nearsurface waters

Tax water pumpedfrom wells nearsurface waters

Buy and retiregroundwaterwithdrawal rightsin critical areas

Do not grow water-intensive crops indry areas

Set and enforceminimum streamflow levels

USING DAMS AND RESERVOIRSUSING DAMS AND RESERVOIRSTO SUPPLY MORE WATERTO SUPPLY MORE WATER

Large dams and reservoirs can produceLarge dams and reservoirs can producecheap electricity, reduce downstreamcheap electricity, reduce downstreamflooding, and provide yearflooding, and provide year--round water forround water forirrigating cropland, but they also displaceirrigating cropland, but they also displacepeople and disrupt aquatic systems.people and disrupt aquatic systems.

Figure 14Figure 14--1313 Fig. 14-13a, p. 317

Provides waterfor year-roundirrigation ofcropland

Flooded landdestroys forestsor cropland anddisplaces people

Large losses ofwater throughevaporation

Provideswater fordrinking Downstream

cropland andestuaries aredeprived ofnutrient-rich silt

Reservoir isuseful forrecreationand fishing

Risk offailure anddevastatingdownstreamflooding

Can producecheapelectricity(hydropower)

Downstreamflooding isreduced

Migration andspawning ofsome fish aredisrupted

Fig. 14-13b, p. 317

Powerlines

Reservoir

Dam

PowerhouseIntake

Turbine

Case Study: The Colorado BasinCase Study: The Colorado Basin –– ananOvertappedOvertapped ResourceResource

The Colorado River has so many dams andThe Colorado River has so many dams andwithdrawals that it often does not reach thewithdrawals that it often does not reach theocean.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 forProvides electricity from hydroelectric plants for30 million people (1/1030 million people (1/10thth of the U.S. population).of the U.S. population).

Case Study: The Colorado BasinCase Study: The Colorado Basin –– ananOvertappedOvertapped ResourceResource

Lake Powell, isLake Powell, isthe secondthe secondlargest reservoirlargest reservoirin the U.S.in the U.S.

It hosts one ofIt hosts one ofthe hydroelectricthe hydroelectricplants located onplants located onthe Coloradothe ColoradoRiver.River.


5

The Colorado River BasinThe Colorado River Basin

The areaThe areadrained by thisdrained by thisbasin is equal tobasin is equal tomore than onemore than one--twelfth of thetwelfth of theland area of theland area of thelower 48 states.lower 48 states.


Dam

Aqueduct orcanal

Upper Basin

LOWERBASIN

0 100 mi.

0 150 km

Lower BasinUPPERBASIN

IDAHO

WYOMING

Salt Lake City

Grand Junction

Denver

UTAH

NEVADA

COLORADOLakePowell

Las Vegas

GrandCanyon Glen

Canyon Dam

Boulder CityNEW MEXICO

ARIZONALosAngeles

Albuquerque

PhoenixSanDiego

Mexicali

YumaTucson

All-AmericanCanal Gulf of

California

MEXICO

CALIFORNIA

PalmSprings

Colo

rado

Riv

er

Case Study:Case Study:ChinaChina’’s Three Gorges Dams Three Gorges Dam

There is a debate over whether theThere is a debate over whether theadvantages of the worldadvantages of the world’’s largest dam ands largest dam andreservoir 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 coalThe 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 transportationIt will facilitate ship travel reducing transportationcosts.costs.

Dam will displace 1.2 million people.Dam will displace 1.2 million people.

Dam is built overDam is built over seismaticseismatic fault and already hasfault and already hassmall cracks.small cracks.

Dam RemovalDam Removal

Some dams are being removed for ecologicalSome dams are being removed for ecologicalreasons and because they have outlived theirreasons and because they have outlived theirusefulness.usefulness.

In 1998 the U.S. Army Corps of EngineersIn 1998 the U.S. Army Corps of Engineersannounced that it would no longer build largeannounced that it would no longer build largedams and diversion projects in the U.S.dams and diversion projects in the U.S.

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

Removing dams can reestablish ecosystems, butRemoving dams can reestablish ecosystems, butcan also recan also re--release toxicants into therelease toxicants into theenvironment.environment.

TRANSFERRING WATER FROMTRANSFERRING WATER FROMONE PLACE TO ANOTHERONE PLACE TO ANOTHER

Transferring water can make unproductiveTransferring water can make unproductiveareas more productive but can causeareas more productive but can causeenvironmental harm.environmental harm.

Promotes investment, jobs and strong economy.Promotes investment, jobs and strong economy.

It encourages unsustainable use of water inIt encourages unsustainable use of water inareas water is not naturally supplied.areas water is not naturally supplied.

Case Study: The California ExperienceCase Study: The California Experience

A massiveA massivetransfer of watertransfer of waterfrom waterfrom water--richrichnorthernnorthernCalifornia toCalifornia towaterwater--poorpoorsouthernsouthernCalifornia isCalifornia iscontroversial.controversial.


Fig. 14-16, p. 321

CALIFORNIA

SacramentoRiver

North BayAqueduct

Lake Tahoe

San Francisco Sacramento

South BayAqueduct

Hoover Dam andReservoir (LakeMead)

NEVADAUTAH

Fresno

San Luis Damand Reservoir Los Angeles

Aqueduct

ColoradoRiver

California Aqueduct

Santa Barbara

Colorado RiverAqueduct Central Arizona

Project

ARIZONA

Los Angeles

Salton Sea PhoenixSan Diego

Tucson

MEXICO

San

Joaq

uin

Valley

FeatherRiver

Shasta Lake

Oroville Dam andReservoir

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

The Aral Sea was once the worldThe Aral Sea was once the world’’s fourths fourthlargest freshwater lake.largest freshwater lake.


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

Diverting water from the Aral Sea and its twoDiverting water from the Aral Sea and its twofeeder rivers mostly for irrigation has createdfeeder rivers mostly for irrigation has createda major ecological, economic, and healtha major ecological, economic, and healthdisaster.disaster.

About 85% of the wetlands have beenAbout 85% of the wetlands have beeneliminated and roughly 50% of the local bird andeliminated and roughly 50% of the local bird andmammal species have disappeared.mammal species have disappeared.

Since 1961, the seaSince 1961, the sea’’s salinity has tripled and thes salinity has tripled and thewater has dropped by 22 meters most likelywater has dropped by 22 meters most likelycausing 20 of the 24 native fish species to gocausing 20 of the 24 native fish species to goextinct.extinct.

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DESALTING SEAWATER, SEEDINGDESALTING SEAWATER, SEEDINGCLOUDS, AND TOWING ICEBERGSCLOUDS, AND TOWING ICEBERGS

AND GIANT BAGGIESAND GIANT BAGGIES

Removing salt from seawater by currentRemoving salt from seawater by currentmethods is expensive and produces largemethods is expensive and produces largeamounts of salty wastewater that must beamounts of salty wastewater that must bedisposed 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 forcesaltwater through a membrane filter.saltwater through a membrane filter.

DESALTING SEAWATER, SEEDINGDESALTING SEAWATER, SEEDINGCLOUDS, AND TOWING ICEBERGSCLOUDS, AND TOWING ICEBERGS

AND GIANT BAGGIESAND GIANT BAGGIES

Seeding clouds with tiny particles ofSeeding clouds with tiny particles ofchemicals to increase rainfall towing icebergschemicals to increase rainfall towing icebergsor huge bags filled with freshwater to dryor huge bags filled with freshwater to drycoastal areas have all been proposed but arecoastal areas have all been proposed but areunlikely to provide significant amounts ofunlikely to provide significant amounts offreshwater.freshwater.

INCREASING WATER SUPPLIES BYINCREASING WATER SUPPLIES BYWASTING LESS WATERWASTING LESS WATER

We waste about twoWe waste about two--thirds of the water wethirds of the water weuse, but we could cut this waste to 15%.use, but we could cut this waste to 15%.

6565--70% of the water people use throughout the70% of the water people use throughout theworld is lost through evaporation, leaks, andworld is lost through evaporation, leaks, andother losses.other losses.

Water is underpriced through governmentWater is underpriced through governmentsubsidies.subsidies.

The lack of government subsidies for improvingThe lack of government subsidies for improvingthe efficiency of water use contributes to waterthe efficiency of water use contributes to waterwaste.waste.

INCREASING WATER SUPPLIES BYINCREASING WATER SUPPLIES BYWASTING LESS WATERWASTING LESS WATER

Sixty percent of the worldSixty percent of the world’’s irrigation water iss irrigation water iscurrently wasted, but improved irrigationcurrently wasted, but improved irrigationtechniques could cut this waste to 5techniques could cut this waste to 5--20%.20%.

CenterCenter--pivot, low pressure sprinklers sprayspivot, low pressure sprinklers sprayswater 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 inHas reduced depletion of Ogallala aquifer inTexas High Plains by 30%.Texas High Plains by 30%.

Fig. 14-18, p. 325

Center pivotCenter pivot

Drip irrigationDrip irrigation

Gravity flowGravity flow

(efficiency 60% and80% with surge

valves)

Above- or below-ground pipes or tubesdeliver water toindividual plant roots.

Water usually comes froman aqueduct system or anearby river.

(efficiency 90–95%)

(efficiency 80%–95%)

Water usually pumpedfrom underground andsprayed from mobileboom with sprinklers.

Fig. 14-19, p. 326

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 onlywhen necessary

• Polyculture

• Organic farming

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

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

• Irrigate with treated urban waste water

• Import water-intensive crops and meat

Solutions: Getting More Water forSolutions: Getting More Water forIrrigation in Developing CountriesIrrigation in Developing Countries ––

The LowThe Low--Tech ApproachTech Approach

Many poor farmers inMany poor farmers indeveloping countriesdeveloping countriesuse lowuse low--tech methodstech methodsto pump groundwaterto pump groundwaterand make moreand make moreefficient use of rainfall.efficient use of rainfall.


Solutions

Reducing Water Waste

• Redesign manufacturing processes

• Repair leaking underground pipes

• Landscape yards with plants thatrequire 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 toirrigate 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 ConservationA Key to Water Conservation

We can reduce water use and waste byWe can reduce water use and waste byraising the price of water while providing lowraising the price of water while providing lowlifeline rates for the poor.lifeline rates for the poor.

When Boulder, Colorado introduced waterWhen Boulder, Colorado introduced watermeters, water use per person dropped by 40%.meters, water use per person dropped by 40%.

A 10% increase in water prices cuts domesticA 10% increase in water prices cuts domesticwater use by 3water use by 3--7%.7%.

7

Solutions: Using Less Water to RemoveSolutions: Using Less Water to RemoveIndustrial and Household WastesIndustrial and Household Wastes

We can mimic the way nature deals withWe can mimic the way nature deals withwastes instead of using large amounts ofwastes instead of using large amounts ofhighhigh--quality water to wash away and dilutequality water to wash away and diluteindustrial and animal wastes.industrial and animal wastes.

Use nutrients in wastewater before treatment asUse nutrients in wastewater before treatment assoil fertilizer.soil fertilizer.

Use waterless and odorless composting toiletsUse waterless and odorless composting toiletsthat convert human fecal matter into a smallthat convert human fecal matter into a smallamount of soil material.amount of soil material.

TOO MUCH WATERTOO MUCH WATER

Heavy rainfall, rapid snowmelt, removal ofHeavy rainfall, rapid snowmelt, removal ofvegetation, and destruction of wetlandsvegetation, and destruction of wetlandscause flooding.cause flooding.

Floodplains, which usually include highlyFloodplains, which usually include highlyproductive wetlands, help provide naturalproductive wetlands, help provide naturalflood and erosion control, maintain high waterflood and erosion control, maintain high waterquality, and recharge groundwater.quality, and recharge groundwater.

To minimize floods, rivers have beenTo minimize floods, rivers have beennarrowed with levees and walls, andnarrowed with levees and walls, anddammed to store water.dammed to store water.


Comparison of St. Louis, Missouri underComparison of St. Louis, Missouri undernormal conditions (1988) and after severenormal conditions (1988) and after severeflooding (1993).flooding (1993).



Human activities have contributed to floodHuman activities have contributed to flooddeaths and damages.deaths and damages.

Figure 14Figure 14--2323 Fig. 14-23a, p. 330

Oxygenreleased byvegetation

DiverseDiverse

ecologicalecologicalhabitathabitat

Evapotranspiration

Trees reduce soilerosion from heavyrain and wind

AgriculturallandSteady

river flow

Leaf litterimproves soilfertility

Tree roots stabilizesoil and aid waterflow

Vegetation releaseswater slowly andreduces flooding

Forested Hillside

Fig. 14-23b, p. 330

Tree plantation

RoadsRoadsdestabilizedestabilizehillsideshillsides

Evapotranspiration decreases

Ranching acceleratessoil erosion by waterand wind

Winds remove fragiletopsoil

Agricultural land isflooded and silted up

Gullies andGullies andlandslideslandslides

Heavy rain leachesnutrients from soil anderodes topsoil

Silt from erosion blocks rivers and reservoirsand causes flooding downstream

Rapid runoffcauses flooding

After Deforestation

Fig. 14-24, p. 331

Solutions

Reducing Flood Damage

Prevention Control

Preserve forests onwatersheds

Strengthen anddeepen streams(channelization)

Preserve andrestore wetlandsin floodplains

Tax all developmenton floodplains

Build levees orfloodwalls alongstreams

Use floodplainsprimarily forrecharging aquifers,sustainableagriculture andforestry, andrecreation

Build dams

SOLUTIONS: USINGSOLUTIONS: USINGWATER MOREWATER MORESUSTAINABLYSUSTAINABLY

We can use water moreWe can use water moresustainably by cuttingsustainably by cuttingwaste, raising waterwaste, raising waterprices, preservingprices, preservingforests and wetlands inforests and wetlands inwater basins, andwater basins, andslowing populationslowing populationgrowth.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 forsmaller 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 forrinsing only.

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

• Replace your lawn with native plants that need little if any wateringand 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.

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