2Key Concepts The physical properties of water Availability of fresh waterMethods of increasing freshwater suppliesUsing water more efficientlyProblems associated with flooding
3Water’s Unique Properties Hydrogen bondingLiquid over wide temperature rangeChanges temperature slowlyHigh heat of evaporationGreat dissolving powerFilters out ultraviolet radiationAdhesion and cohesionExpands when it freezes
9Evaporation and transpiration Ground WaterEvaporation and transpirationEvaporationStreamInfiltrationWater tableUnconfined aquiferConfined aquiferLakeWell requiring a pumpFlowingartesian wellRunoffPrecipitationConfinedRecharge AreaAquiferLess permeable materialsuch as clayConfirming permeable rock layer
18Using Dams and Reservoirs to Supply More Water: The Trade-offs Large lossesof water throughevaporationFlooded land destroys forests or cropland anddisplaces peopleDownstream flooding is reducedDownstream cropland andestuaries are deprived ofnutrient-rich siltReservoir is useful for recreation and fishingCan produce cheap electricity (hydropower)Migration and spawning of some fish are disruptedProvides waterfor year-roundirrigation ofcropland
23Europe North America Asia Africa South America Australia Stress HighNone
24Transferring Water from One Place to Another Watershed transferNorth BayAqueductSouth BayCalifornia AqueductCALIFORNIANEVADAUTAHMEXICOCentral ArizonaProjectColorado RiverLos AngelesShasta LakeSacramentoFresnoPhoenixTucsonARIZONAColoradoRiverSan FranciscoSan DiegoCalifornia Water ProjectCentral Arizona ProjectJames Bay
26CANADA II I II UNITED STATES HudsonBayChisasibiNEWFOUNDLANDIIJamesBayIONTARIOIIQUEBECNew YorkCityATLANTICOCEANChicagoUNITED STATES
27IDAHO WYOMING Dam Aqueduct or canal Salt Lake City Upper Basin Grand JunctionLower BasinDenverUPPERBASINUTAHCOLORADOLakePowellGrandCanyonGlenCanyonDamLas VegasNEW MEXICOBoulder CityARIZONACALIFORNIAAlbuquerqueLosAngelesLOWERBASINPalmSpringsPhoenix100 mi.San DiegoYuma150 kmMexicaliTucsonAll-AmericanCanalGulf ofCaliforniaMEXICO
28China’s Three Gorges Dam Trade-OffsChina’s Three Gorges DamAdvantagesDisadvantagesWill generate about 10%of China’s electricityReduces dependenceon coalReduces air pollutionReduces CO2 emissionsReduces chances ofdownstream floodingfor 15 million peopleReduces river sittingbelow dam by erodedsoilIncreases irrigation waterfor cropland belowdamFloods large areas ofcropland and forestsDisplaces 1.9 million peopleIncreases water pollutionbecause of reduced waterflowReduces deposits of nutrient-rich sediments below damIncreases saltwaterIntroduced into drinking waternear mouth of river becauseof decreased water flowDisrupts spawning andmigration of some fishbelow damHigh cost
29Tapping Groundwater Year-round use No evaporation losses Often less expensivePotential Problems!
30Problems with Using Groundwater Water table loweringDepletionSubsidenceSaltwater intrusionChemical contaminationReduced stream flows
32Withdrawing Groundwater Trade-OffsWithdrawing GroundwaterAdvantagesDisadvantagesGood source of water fordrinking and irrigationAvailable year-roundExists almost everywhereRenewable if not over-pumped or contaminatedNo evaporation lossesCheaper to extract thanmost surface watersAquifer depletion from over-pumpingSinking of land (subsidence)when water removedPolluted aquifers unusablefor decades or centuriesSaltwater intrusion intodrinking water supplies nearcoastal areasReduced water flows intostreams, lakes, estuaries,and wetlandsIncreased cost, energy use,and contamination fromdeeper wells
40Using Water More Efficiently Reduce losses due to leakageReform water lawsImprove irrigation efficiencyImproving manufacturing processesWater efficient landscaping (xeriscaping)Water efficient appliances
41Too Much Water: Floods Natural phenomena Aggravated by human activitiesReservoirDamLeveeFloodwallFloodplain
48Groundwater Depletion SolutionsGroundwater DepletionPreventionControlWaste less waterSubsidize waterconservationBan new wells inaquifers near surfacewatersBuy and retire ground-water withdrawal rights incritical areasDo not grow water-intensive crops in dryareasReduce birth ratesRaise price of water todiscourage wasteTax water pumpedfrom Wells nearsurface waterSet and enforceminimum stream flowlevels
49WYOMING SOUTH DAKOTA NEBRASKA KANSAS COLORADO OKLAHOMA NEW MEXICO Less than 61 meters (200 ft)meters ( ft)More than 183 meters (600 ft)(as much as 370 meters or 1,200 ft.in places)NEBRASKAKANSASCOLORADOOKLAHOMANEW MEXICOTEXASMiles100160Kilometers
50Solutions: Achieving a More Sustainable Water Future Efficient irrigationWater-saving technologiesImproving water management
51Center Pivot Drip Irrigation Gravity Flow (efficiency 80% with low-pressuresprinkler and 90–95% withLEPA sprinkler)Water usually pumped fromunderground and sprayed frommobile boom with sprinklers.Drip Irrigation(efficiency 90-95%)Above- or below-ground pipesor tubes deliver water toindividual plant roots.Gravity Flow(efficiency 60% and 80% with surge valves)Water usually comes from anaqueduct system or a nearby river.
57Reducing Irrigation Water Waste SolutionsReducing Irrigation Water WasteLining canals bring water to irrigation ditchesLeveling fields with lasersIrrigating at night to reduce evaporationUsing soil and satellite sensors and computer systems to monitor soil moisture and add water only when necessaryPolycultureOrganic FarmingGrowing water-efficient crops using drought-resistant and salt tolerant crops varietiesIrrigating with treated urban waste waterImporting water-intensive crops and meat
58Solutions Reducing Water Waste Redesign manufacturing processesLandscape yards with plants that require little waterUse drip irrigationFix water leaksUse water meters and charge for all municipal water useUse waterless composting toiletsRequire water conservation in water-short citiesUse water-saving toilets, showerheads, and front-loading clothes washersCollect and reuse household water to irrigate lawns and non-edible plantsPurify and reuse water for houses, apartments, and office buildings
61Forested Hillside Oxygen released by vegetation Diverse ecological habitatEvapotranspirationTrees reduce soilerosion from heavyrain and windAgriculturallandSteadyriver flowLeaf litterimprovessoil fertilityTree rootsstabilize soil andaid water flowVegetation releaseswater slowly andreduces floodingForested Hillside
62Evapotranspiration decreases Tree plantationEvapotranspiration decreasesRoadsdestabilizehillsidesRanchingacceleratessoil erosion bywater and windWinds removefragile topsoilAgriculture landis flooded andsilted upGullies andlandslidesHeavy rain leachesnutrients from soiland erodes topsoilRapid runoffcauses floodingSilt from erosion blocksrivers and reservoirs andcauses flooding downstreamAfter Deforestation
63Solutions Sustainable Water Use Not depleting aquifers Preserving ecological health of aquatic systemsPreserving water qualityIntegrated watershed managementAgreements among regions and countries sharing surface water resourcesOutside party mediation of water disputes between nationsMarketing of water rightsRaising water pricesWasting less waterDecreasing government subsides for supplying waterIncreasing government subsides for reducing water wasteSlowing population growth
64What Can You Do? Water Use and Waste Use water-saving toilets, showerheads, and faucet aeratorsShower instead of taking baths, and take short showers.Repair water leaks.Turn off sink faucets while brushing teeth, shaving, or washing.Wash only full loads of clothes or use the lowest possible water-level setting for smaller loads.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.Water lawns and garden in the early morning or evening.Use drip irrigation and mulch for gardens and flowerbeds.Use recycled (gray) water for watering lawns and houseplants and for washing cars.