UNIT 4 Water Resources and Pollution Chapter 13 and 20

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<p>UNIT 4 Water Resources and Pollution</p> <p>UNIT 4 Water Resources and PollutionChapter 13 and 20</p> <p>Freshwater Is an Irreplaceable Resource That We Are Managing PoorlyWhy is water so important?</p> <p>Earth as a watery world: 71%</p> <p>Freshwater availability: 0.024%</p> <p>Poorly managed resource</p> <p>Hydrologic cycle</p> <p>Water pollution2Freshwater Is an Irreplaceable Resource That We Are Managing Poorly Access to water is A global health issueAn economic issueA womens and childrens issueA national and global security issue</p> <p>3Freshwater ResourcesSurface water: rivers, lakes, wetlands, estuaries, ocean. -&gt; recharge from runoff</p> <p>Groundwater: -&gt; recharge from precipitation -&gt;lateral recharge: movement of water from rivers and streams.</p> <p>Fig. 13-3, p. 316Unconfined Aquifer Recharge AreaPrecipitationEvaporation and transpirationEvaporationConfined Recharge AreaRunoffFlowing artesian wellWell requiring a pumpStreamInfiltrationWater tableLakeInfiltrationUnconfined aquiferLess permeable material such as clayConfined aquiferConfining impermeable rock layerFigure 13.3Natural capital: groundwater system. An unconfined aquifer is an aquifer with a permeable water table. A confined aquifer is bounded above and below by less permeable beds of rock, and its water is confined under pressure. Some aquifers are replenished by precipitation; others are not.Water Equity, Shortages, and FloodsGlobal usage of groundwater and surface water: agriculture 70%Industry 20%Human consumption 10%</p> <p>Developing and Developed counties water usageEx: Canada uses 20% of the worlds liquid water(0.5% of world population)Asia- uses 30% (60% of worlds population)Water conflicts in the Middle EastThree Major River Basins in the Middle Eastcore case study-pg.313</p> <p>7</p> <p>Natural Capital Degradation: Irrigation in Saudi Arabia Using an Aquifer</p> <p>8Water usage in USWestern half of US = severe water shortage - arid, semi-arid; less precipitation and high evaporation; droughts-uses water withdrawals for irrigation </p> <p>Eastern half of US- high level of precipitation; reduced evaporation rate</p> <p>Fig. 13-4a, p. 317Average annual precipitation (centimeters)4181More than 122Less than 4181122Figure 13.4Average annual precipitation and major rivers (top) and water-deficit regions in the continental United States and their proximity to metropolitan areas having populations greater than 1 million (bottom). Question: Why do you think some areas with moderate precipitation still suffer from water shortages? (Data from U.S. Water Resources Council and U.S. Geological Survey)Surface Water and Groundwater DepletionGroundwater DepletionOverdraft of groundwater can cause sinkholes or saltwater intrusion (in coastal areas)</p> <p>Ogallala aquifer: largest known aquiferIrrigates the Great PlainsWater table lowered more than 30mCost of high pumping has eliminated some of the farmersGovernment subsidies to continue farming deplete the aquifer furtherBiodiversity threatened in some areasNatural Capital Degradation: Areas of Greatest Aquifer Depletion in the U.S.</p> <p>13</p> <p>Fig. 13-10, p. 323WYOMINGSOUTH DAKOTANEBRASKACOLORADOKANSASOKLAHOMANEW MEXICOMiles0100TEXASSaturated thickness of Ogallala AquiferLess than 61 meters (200 ft.)61183 meters (200600 ft.)More than 183 meters (600 ft.) (as much as 370 meters or 1,200 ft. in places)0160KilometersFigure 13.10Natural capital degradation: The Ogallala is the worlds largest known aquifer. If the water in this aquifer were above ground, it could cover all of the lower 48 states with 0.5 meter (1.5 feet) of water. Water withdrawn from this aquifer is used to grow crops, raise cattle, and provide cities and industries with water. As a result, this aquifer, which is renewed very slowly, is being depleted, especially at its thin southern end in parts of Texas, New Mexico, Oklahoma, and Kansas. (Data from U.S. Geological Survey)Groundwater Over-pumping Has Harmful Effects Limits future food productionLand subsidenceSinkholes Groundwater overdrafts near coastal regionsContamination of the groundwater with saltwaterUndrinkable and unusable for irrigation</p> <p>How to protect groundwater resourcesReduce number of water-intensive crops grown in arid and semi-arid regions;Increase the price of water -&gt; discourage waste;Implement water conservation practices in residential homes.Subsidize water conservationSurface Water Usage dams and water transfer projectsRivers are dammed to create freshwater reservoirs + hydroelectric powerAdvantagesDisadvantagesNo CO2 emissionProvides irrigation and drinking waterFlood controlCheap electricityReservoirs used for recreationDisplace people living behind the damDecreases nutrient-rich silt downstreamFish harvest below dam decreasesDisrupts migration patterns of some fishLoss of water by evaporationUseless after 50 yearsCH4 emissions</p> <p>18Examples of Major DamsExamples of Major DamsColorado River Basin-flows from Colorado to Gulf of California- 7 states--water used for drinking (Los Angeles, San Diego, Las Vegas) and irrigation (15 % of US crops)-14 dams -&gt; volume reduction -&gt; not making his way to the Gulf of California or is too salty-&gt;&gt; international disputes-&gt; US constructed desalination plants -2 major dams: Hoover Dam (Lake Mead) and Glen Canyon Dam (Lake Powell)Aerial View of Glen Canyon Dam Across the Colorado River and Lake Powell</p> <p>21The Flow of the Colorado River Measured at Its Mouth Has Dropped Sharply</p> <p>22Examples of Major Dams2. Three Gorges Dam, China Worlds largest hydroelectric dam and reservoir</p> <p>2 km long across the Yangtze River</p> <p>BenefitsElectricity-producing potential is hugeHolds back the Yangtze River floodwatersAllows cargo-carrying shipsThree Gorges Dam, China Harmful effectsDisplaces about 5.4 million peopleBuilt over a seismic faultRotting plant and animal matter producing CH4Worse than CO2 emissions</p> <p>Water Transfer ProjectsThe Aral Sea - Asia(Uzbekistan)-irrigation canals for cotton and rice fields-loss of volume since 1960s-increase in salinity 7X-&gt; impacted local wetlands;altered local climate- summers hotter and drier, winters are colder;Negative impact on economy declining commercially valuable population and decrease crop productionFig. 13-18a, p. 331Stepped Art</p> <p>1976</p> <p>2006Figure 13.18Natural capital degradation: the Aral Sea was once the worlds fourth largest freshwater lake. Since 1960, it has been shrinking and getting saltier because most of the water from the rivers that replenish it has been diverted to grow cotton and food crops (Concept 13-4). These satellite photos show the sea in 1976 and in 2006. It has split into two major parts, little Aral on the left and big Aral on the right. As the lake shrank, it left behind a salty desert, economic ruin, increasing health problems, and severe ecological disruption. Question: What do you think should be done to help prevent further shrinkage of the Aral Sea?Ship Stranded in Desert Formed by Shrinkage of the Aral Sea</p> <p>27Water Transfer Projects2. California Water transfer projectMoves water from N California to S California;Transfers Water from Water-Rich Areas to Water-Poor AreasWater transferred byTunnelsAqueductsUnderground pipes</p> <p>May cause environmental problemsThe California Water Project and the Central Arizona Project</p> <p>29Water Transfer Projects3. Chinas water transfer projectSouth-North Water Transfer ProjectWater from three rivers to supply 0.5 billion peopleCompletion in about 2050ImpactEconomicHealthEnvironmental</p> <p>Water ConservationImprove irrigation practices-flood irrigation=pumping large volume of water into agricultural land; H2O flows by gravity into ditches into soil. -Drip irrigation- increase crop yields from 20% to 90%-Center pivot=metal frames rolling on wheels that extend large water pipes out over the crops.</p> <p>Fig. 13-20, p. 335Center pivot (efficiency 80% with low-pressure sprinkler and 9095% with LEPA sprinkler)Drip irrigation (efficiency 9095%)Water usually pumped from underground and sprayed from mobile boom with sprinklers.Gravity 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.Figure 13.20Major irrigation systems. Because of high initial costs, center-pivot irrigation and drip irrigation are not widely used. The development of new, low-cost, drip-irrigation systems may change this situation.Other methods of irrigation water conservationIrrigate crops using threated urban wastewaterIrrigate at nightDont grow water thirsty crops in arid and semi-arid regions;Increase government subsidies for efficient irrigation practicesIncrease polyculture instead of monoculture;Use soil monitor to irrigate only when needed.Developing Countries Use Low-Tech Methods for IrrigationHuman-powered treadle pumps</p> <p>Harvest and store rainwater</p> <p>Create a canopy over crops: reduces evaporation</p> <p>Fog-catcher nets34We Can Cut Water Waste in Industry and HomesRecycle water in industry</p> <p>Fix leaks in the plumbing systems</p> <p>Use water-thrifty landscaping: xeriscaping</p> <p>Use gray water</p> <p>Pay-as-you-go water use</p> <p>35</p> <p>Fig. 13-23, p. 337SOLUTIONSSustainable Water UseWaste less water and subsidize water conservation Preserve water qualityProtect forests, wetlands, mountain glaciers, watersheds, and other natural systems that store and release waterGet agreements among regions and countries sharing surface water resources Raise water prices Do not deplete aquifers Slow population growthFigure 13.23Methods for achieving more sustainable use of the earths water resources (Concept 13-6). Question: Which two of these solutions do you think are the most important? Why?Increasing freshwater suppliesDesalination-reverse osmosis (microfiltration)-distillationSome Areas Get Too Much Water from Flooding (1)Flood plains Highly productive wetlandsProvide natural flood and erosion controlMaintain high water qualityRecharge groundwater</p> <p>Benefits of floodplainsFertile soilsNearby rivers for use and recreationFlatlands for urbanization and farming</p> <p>38Some Areas Get Too Much Water from Flooding (2)Dangers of floodplains and floodsDeadly and destructiveHuman activities worsen floodsFailing dams and water diversionHurricane Katrina and the Gulf CoastRemoval of coastal wetlands39Fig. 13-25a, p. 339</p> <p>Oxygen released by vegetationDiverse ecological habitatEvapotranspirationTrees reduce soil erosion from heavy rain and windTree roots stabilize soilVegetation releases water slowly and reduces floodingForested HillsideAgricultural landStepped Art</p> <p>Tree plantationRoads destabilize hillsidesOvergrazing accelerates soil erosion by water and windWinds remove fragile topsoilAgricultural land is flooded and silted upGullies and landslidesHeavy rain erodes topsoilSilt from erosion fills rivers and reservoirsRapid runoff causes floodingAfter DeforestationEvapotranspiration decreasesFigure 13.25Natural capital degradation: hillside before and after deforestation. Once a hillside has been deforested for timber, fuelwood, livestock grazing, or unsustainable farming, water from precipitation rushes down the denuded slopes, erodes precious topsoil, and can increase flooding and pollution in local streams. Such deforestation can also increase landslides and mudflows. A 3,000-year-old Chinese proverb says, To protect your rivers, protect your mountains. See an animation based on this figure at CengageNOW. Question: How might a drought in this area make these effects even worse?</p> <p>Fig. 13-26, p. 340SOLUTIONSReducing Flood DamagePreventionControlPreserve forests on watershedsStraighten and deepen streams (channelization)Preserve and restore wetlands in floodplainsTax development on floodplainsBuild levees or floodwalls along streamsUse floodplains primarily for recharging aquifers, sustainable agriculture and forestryBuild damsFigure 13.26Methods for reducing the harmful effects of flooding (Concept 13-7). Question: Which two of these solutions do you think are the most important? Why?Water Pollution Sources and TypesPoint-source pollution Located at specific placesEasy to identify, monitor, and regulateex: industry, sewage treatment plans, oil spills from tankers;Non-point pollution Broad, diffuse areasDifficult to identify and controlExpensive to clean up</p> <p>Point Source of Polluted Water in Gargas, France</p> <p>43Nonpoint Sediment from Unprotected Farmland Flows into Streams</p> <p>44Leading Sources of Water PollutionAgriculture water runoff with sediments, excess fertilizer, pesticides; animal waste (feedlots)Industrial acids, heavy metals, fertilizers, gasoline, food processing waste, PCBsMining sediments and chemicals like arsenic, cyanide, mercury.Pollution in Streams, Rivers and LakesDilution in fast moving rivers</p> <p>Biodegradation of wastes by bacteria takes time </p> <p>Oxygen sag curve -occurs in rivers-bacteria breaks down degradable wastes;-bacteria depletes the dissolved oxygen in the process.</p> <p>Fig. 20-5, p. 536Point sourcePollution-tolerant fishes (carp, gar)Types of organismsNormal clean water organisms (Trout, perch, bass, mayfly, stonefly)Fish absent, fungi, sludge worms, bacteria (anaerobic)Pollution-tolerant fishes (carp, gar)8 ppmNormal clean water organisms (Trout, perch, bass, mayfly, stonefly)Dissolved oxygen (ppm)8 ppmBiochemical oxygen demandClean ZoneRecovery ZoneSeptic ZoneDecomposition ZoneClean ZoneFigure 20.5Natural capital: dilution and decay of degradable, oxygen-demanding wastes (or heated water) in a stream, showing the oxygen sag curve (blue) and the curve of oxygen demand (red). Depending on flow rates and the amount of biodegradable pollutants, streams recover from oxygen-demanding wastes and from injection of heated water if they are given enough time and are not overloaded (Concept 20-2A). See an animation based on this figure at CengageNOW. Question: What would be the effect of putting another biodegradable waste discharge pipe to the right of the one in this picture?Pollution in freshwater lakesLess effective at diluting pollutants than streamsStratified layersLittle vertical mixingLittle of no water flowEutrophication</p> <p>Oligotrophic lakeLow nutrients, clear water </p> <p>Cultural eutrophication </p> <p>Remediation and Prevention of Cultural EutrophicationPrevent or reduce cultural eutrophicationRemove nitrates and phosphatesDiversion of lake water</p> <p>Clean up lakesRemove excess weedsUse herbicides and algaecides; down-side?Pump in airCase Study: Pollution in the Great Lakes (1)1960s: Many areas with cultural eutrophication</p> <p>1972: Canada and the United States: Great Lakes pollution control programWhat was done?</p> <p>Problems still existRaw sewageNonpoint runoff of pesticides and fertilizersBiological pollutionAtmospheric deposition of pesticides and Hg</p> <p>50Case Study: Pollution in the Great Lakes (2)2007 State of the Great Lakes reportNew pollutants foundWetland loss and degradation; significance?Declining of some native speciesNative carnivorous fish species declining What should be...</p>


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