Chapter 7Chapter 7Water: Hydrologic Cycle Water: Hydrologic Cycle

and Human Useand Human Use

THE ARAL SEATHE ARAL SEAIntroductionIntroduction

Death of the Aral SeaDeath of the Aral Sea

• Located in present-day Kazakhstan and Located in present-day Kazakhstan and Uzbekistan.Uzbekistan.

• 1930’s it was decided that the area 1930’s it was decided that the area surrounding the sea could be used to surrounding the sea could be used to grow cotton.grow cotton.

• By 1960, millions of acres of land were By 1960, millions of acres of land were irrigated using water from the two large irrigated using water from the two large rivers that fed the Aral Sea.rivers that fed the Aral Sea.

• The sea began to shrinkThe sea began to shrink

Aral Sea ImpactsAral Sea Impacts• Salinity increased as water was not replenishedSalinity increased as water was not replenished

– Hurt the 60,000 employee fishery industry.Hurt the 60,000 employee fishery industry.– 3x saltier than the ocean.3x saltier than the ocean.

• Lost 90% of it’s original volume.Lost 90% of it’s original volume.

• Many health impacts for the people as the dried Many health impacts for the people as the dried salt/pesticide/fertilizer/herbicide laden dust is salt/pesticide/fertilizer/herbicide laden dust is carried by windscarried by winds– Increased cancer, higher infant mortalityIncreased cancer, higher infant mortality

• Local climate changed, growing season Local climate changed, growing season shortened, switch from cotton to riceshortened, switch from cotton to rice

Other dry runs:Other dry runs:

• Aral sea not unique:Aral sea not unique:– Rio Grande shorter because of withdraw Rio Grande shorter because of withdraw

for domestic use and irrigation.for domestic use and irrigation.– Colorado river almost completely drained Colorado river almost completely drained

before it can reach Mexico leaving a dried before it can reach Mexico leaving a dried baked mud area in the gulf of California.baked mud area in the gulf of California.

– Dead Sea is being diverted by Israel and Dead Sea is being diverted by Israel and Jordan. May disappear by 2050 without Jordan. May disappear by 2050 without any action taking place to prevent it.any action taking place to prevent it.

WATER: A VITAL WATER: A VITAL RESOURCERESOURCE

Lesson 7.1Lesson 7.1

• Objectives for the chapter (Threefold)Objectives for the chapter (Threefold)

1.1.To understand the natural water cycle, To understand the natural water cycle, its capacities, and its limitationsits capacities, and its limitations

2.2.To understand how we are over drawing To understand how we are over drawing certain water sources and to understand certain water sources and to understand the consequences the consequences

3.3.To understand how water must be To understand how water must be handled if we are to achieve sustainable handled if we are to achieve sustainable suppliessupplies

Water is fundamental to lifeWater is fundamental to life

• Earth has about 325 million cubic miles/ Earth has about 325 million cubic miles/ covers about 71 % of its surfacecovers about 71 % of its surface– 97.5% of this water is salt water97.5% of this water is salt water

• Fresh water- water that has a salt Fresh water- water that has a salt content of less than 0.1%content of less than 0.1%

• 97.5% Salt water97.5% Salt water

• 2.5% Fresh water2.5% Fresh water– 1.7% Polar ice caps and glaciers1.7% Polar ice caps and glaciers– .77% Accessible fresh water.77% Accessible fresh water

Where does the 0.77% fresh Where does the 0.77% fresh water come from?water come from?

• LakesLakes

• WetlandsWetlands

• RiversRivers

• GroundwaterGroundwater

• BiotaBiota

• SoilSoil

• AtmosphereAtmosphere

•Human societies must draw fresh Human societies must draw fresh water for energy through water for energy through hydroelectric, transportation, hydroelectric, transportation, recreation, waste processing, and recreation, waste processing, and habitats for aquatic plants and habitats for aquatic plants and animals.animals.

•Over the past two centuries these Over the past two centuries these uses have led us to try to control the uses have led us to try to control the water through infrastructure: dams, water through infrastructure: dams, canals, reservoirs, sewer systems, canals, reservoirs, sewer systems, treatment plants, water towers, etc.treatment plants, water towers, etc.

What water does for land:What water does for land:

• Provides drinking water, water for Provides drinking water, water for industry, and water to irrigate crops.industry, and water to irrigate crops.

• Bodies of water provide energy Bodies of water provide energy through the hydroelectric power and through the hydroelectric power and control flooding by absorbing excess control flooding by absorbing excess water.water.

•There are two ways to consider There are two ways to consider water issues:water issues:– Quantity (this chapter)Quantity (this chapter)

•On the Global water cycle and how it On the Global water cycle and how it works, on the technolgies we use to works, on the technolgies we use to control and manage its use, and on control and manage its use, and on public policypublic policy

– Quality (chapter 17)Quality (chapter 17)•Water pollution and its Water pollution and its consequences, on sewage treatment consequences, on sewage treatment technologies, and on public policy for technologies, and on public policy for dealing with pollution issues.dealing with pollution issues.

Section TwoSection TwoThe Hydrologic Cycle:The Hydrologic Cycle:Natural Cycle, Human Natural Cycle, Human

ImpactsImpacts

Water cycle or Hydrologic Water cycle or Hydrologic cyclecycle- Hydrologic Cycle:Hydrologic Cycle:

- Consists of water rising to the Consists of water rising to the atmosphere through either atmosphere through either evaporation or transpiration and evaporation or transpiration and returning to the land and oceans returning to the land and oceans through condensation and through condensation and precipitation.precipitation.-Water vapor-green waterWater vapor-green water-Liquid water-blue waterLiquid water-blue water

Humidity:Humidity:•Humidity- amount of water vapor in Humidity- amount of water vapor in

the airthe air– measured as relative humiditymeasured as relative humidity

(amount of water vapor as a % (amount of water vapor as a % of what the air can hold of what the air can hold at a at a particular temperatureparticular temperature))

••Humidity increases as air warmsHumidity increases as air warms decreases as air coolsdecreases as air cools

Water cycleWater cycle

Water TermsWater Terms

•Table 7-1 page 172Table 7-1 page 172

•Add the following terms:Add the following terms:–PotablePotable–GrayGray–BlackBlack

Physical Processes and Physical Processes and LoopsLoops4 Physical Processes4 Physical Processes

• EvaporationEvaporation

• CondensationCondensation

• PrecipitationPrecipitation

• Gravitational flowGravitational flow

3 Physical Loops3 Physical Loops• Evapotranspiration loopEvapotranspiration loop

– Evaporates and returns as Evaporates and returns as precipitationprecipitation

• Surface runoff loopSurface runoff loop– Water runs across the ground Water runs across the ground

surface and becomes part of the surface and becomes part of the surface water systemsurface water system

• Ground water loopGround water loop– Water infiltrates, percolates down Water infiltrates, percolates down

to join the ground water traveling to join the ground water traveling through aquifers and then exiting through aquifers and then exiting through seeps, springs, or wellsthrough seeps, springs, or wells

Green House GasGreen House Gas

•Water is a powerful Water is a powerful greenhouse gas: it greenhouse gas: it provides about 2/3 of provides about 2/3 of the total warming from the total warming from all greenhouse gases.all greenhouse gases.

AerosolsAerosols

• • Microscopic liquid or solid particles Microscopic liquid or solid particles originating from land and water surfaces originating from land and water surfaces that attract water vapor and promote that attract water vapor and promote the formation of droplets of moisture the formation of droplets of moisture (AKA-condensation nuclei)(AKA-condensation nuclei)

May originate naturally through volcanic May originate naturally through volcanic eruption, wind-stirred dust and soil, and eruption, wind-stirred dust and soil, and sea salts or may occur sea salts or may occur anthropogenically through sulfates, anthropogenically through sulfates, carbon, and dust.carbon, and dust.

Natural water purificationNatural water purification•One very important aspect of One very important aspect of evaporation & condensation is evaporation & condensation is water water purification.purification.

•When water in an ocean or When water in an ocean or lake evaporates, only the water lake evaporates, only the water molecules leave the surface. molecules leave the surface. May pick up impurities again as May pick up impurities again as it falls.it falls.•Water turn over in the Water turn over in the atmosphere happens every 10 atmosphere happens every 10 days, so water is constantly days, so water is constantly being purified.being purified.

Ground WaterGround Water• • Water that infiltrates the ground has two Water that infiltrates the ground has two

alternatives.alternatives.1.1. It may be held in the soil and returned It may be held in the soil and returned to the atmosphere through one of the to the atmosphere through one of the following methods…following methods…

• Transpiration: air picks up water vapor from Transpiration: air picks up water vapor from vegetation (green water flow)vegetation (green water flow)

• Evaporation: Air picks up water vapor from the Evaporation: Air picks up water vapor from the soil (green water flow)soil (green water flow)

• Evapotranspiration: the combination of the two Evapotranspiration: the combination of the two above terms.above terms.

2.2. Or it may percolate (blue water Or it may percolate (blue water system).system).

Salt LakesSalt Lakes

• Created as salts are picked up and Created as salts are picked up and carried to inland lakes the same way carried to inland lakes the same way that they are carried to the ocean.that they are carried to the ocean.

Hadley CellHadley CellRising air over the equator is pushed from beneath by more rising air causing a “spill over” to the North and South. The two halves of the system (rising and falling air) make up the Hadley cell

Rain ShadowRain Shadow

• Causes rising and falling air currents Causes rising and falling air currents when moisture laden trade winds when moisture laden trade winds encounter mountain rangesencounter mountain ranges

AquifersAquifers• Layers of porous material through Layers of porous material through

which groundwater moves through.which groundwater moves through.– Hold 99% of the liquid fresh waterHold 99% of the liquid fresh water– The rest is found in lakes, wetlands and The rest is found in lakes, wetlands and

riversrivers

Surface Runoff and Surface Runoff and Ground Water:Ground Water:•Both are blue water systems.Both are blue water systems.

•Both are the usual focus for Both are the usual focus for human resource management.human resource management.

•Infiltration-runoff ratio: the Infiltration-runoff ratio: the amount that soaks in compared amount that soaks in compared to the amount that runs offto the amount that runs off

Human ImpactsHuman Impacts•Four categories that either Four categories that either directly or indirectly directly or indirectly impact the water cycle:impact the water cycle:–Changes to Earth’s surfaceChanges to Earth’s surface–Changes to Earth’s climateChanges to Earth’s climate–Atmospheric pollutionAtmospheric pollution–Withdraws for human useWithdraws for human use

DeforestationDeforestation•As land is cleared or As land is cleared or

overgrazed, the pathway for overgrazed, the pathway for the water cycle shifts from the water cycle shifts from infiltration and groundwater infiltration and groundwater recharge to runoff.recharge to runoff.–Consequences include Consequences include flooding, decreased ground flooding, decreased ground water, increased salinization, water, increased salinization, loss of biodiversityloss of biodiversity

Section ThreeSection Three

Water: A Resource to Water: A Resource to Manage, a Threat to Manage, a Threat to ControlControl

Major UsesMajor Uses•Table 7.2Table 7.2•Homes/industry: Homes/industry:

– washing and flushing away washing and flushing away wastes. (nonconsumptive)wastes. (nonconsumptive)

– Irrigation. (consumptive)Irrigation. (consumptive)

•We use less water today than in We use less water today than in 1975…even though population 1975…even though population has increased.has increased.

Water UsageWater Usage

ConsumptiveConsumptive

• The applied water The applied water does not return to the does not return to the water sourcewater source– IrrigationIrrigation– Other agricultural useOther agricultural use

NonconsumptiveNonconsumptive

• Water is returned to Water is returned to its sourceits source– Electric power Electric power

generationgeneration– Industrial useIndustrial use– Domestic use (public Domestic use (public

and self-supplied)and self-supplied)

Trends in water use:Trends in water use:• US: industry followed by agriculture by US: industry followed by agriculture by

domesticdomestic

• World: agriculture, industry, domesticWorld: agriculture, industry, domestic

• Europe: similar to USEurope: similar to US

• South America & Africa: agriculture, South America & Africa: agriculture, domestic, industrydomestic, industry

• Asia: similar to world pattern of useAsia: similar to world pattern of use

• Figure 7-11 page 179Figure 7-11 page 179

SourcesSources•US: 40% ground, 60% surface for US: 40% ground, 60% surface for

domestic use.domestic use.•Developing countries: 90% of the Developing countries: 90% of the

waste water is released directly to waste water is released directly to surface waters without treatment…surface waters without treatment…cholera, etc. 1.1 billion people drink cholera, etc. 1.1 billion people drink this unsafe water.this unsafe water.

Saris used to filter cholera in Bangladesh.

Technologies for water Technologies for water collectioncollection• Industrialized countries: Industrialized countries:

– dams are built across rivers to create dams are built across rivers to create reservoirs (hole water in times of excess flow reservoirs (hole water in times of excess flow and can be drawn out in times of lower flow).and can be drawn out in times of lower flow).

– Water is piped to treatment plants.Water is piped to treatment plants.– Water is distributed through the water system Water is distributed through the water system

to homes, schools, and industry.to homes, schools, and industry.– Water is collected by sewage-treatment plant, Water is collected by sewage-treatment plant,

retreated, and sent back out for distributionretreated, and sent back out for distribution

Municipal Water Municipal Water TreatmentTreatment

•Figure 7-13 page 180.Figure 7-13 page 180.– Know the steps of the water Know the steps of the water

treatment plant…Alum, treatment plant…Alum, mixing tank, settling basin, mixing tank, settling basin, sand filter, lime/fluoride sand filter, lime/fluoride added, distribution.added, distribution.

Dam ImpactsDam Impacts•US: 75,000 dams at least six US: 75,000 dams at least six

feet in height, another 2 million feet in height, another 2 million smaller structures.smaller structures.

•Fresh water habitats lost, Fresh water habitats lost, increased salt concentration, increased salt concentration, etc. etc.

Glen CanyonGlen Canyon• Closed its gates in 1963 (meaning it became Closed its gates in 1963 (meaning it became

operational).operational).

• Stores excess water in Lake PowellStores excess water in Lake Powell

• Spans the Colorado River at Lee’s Ferry, AZ, Spans the Colorado River at Lee’s Ferry, AZ, just above Grand Canyon National Park.just above Grand Canyon National Park.

• Operated by Federal Bureau of Reclamation.Operated by Federal Bureau of Reclamation.

• Generates hydropower and stores water for Generates hydropower and stores water for distribution to CA, NE, AZ, and Mexico.distribution to CA, NE, AZ, and Mexico.

Glen Canyon ContinuedGlen Canyon Continued

• A study in the late 1980’s to early A study in the late 1980’s to early 1990’s concluded that the operation of 1990’s concluded that the operation of the dam had greatly impacted the the dam had greatly impacted the downstream ecology and its downstream ecology and its recreational resources.recreational resources.

• 1996, Secretary of the Interior issued 1996, Secretary of the Interior issued new rules that established minimum new rules that established minimum and maximum water-release rates and maximum water-release rates (GCMRC)(GCMRC)

GCMRCGCMRC

• 19961996

• Secretary of the Interior, Bruce BabbittSecretary of the Interior, Bruce Babbitt

• Grand Canyon Monitoring and Research Grand Canyon Monitoring and Research centercenter

• Provides scientific monitoring for the Provides scientific monitoring for the dam’s operations and operates within the dam’s operations and operates within the guidelines of adaptive ecosystem guidelines of adaptive ecosystem management.management.

• Outcome: successfulOutcome: successful

Dam building around the Dam building around the worldworld• US: 75,000 dams at least 6 feet in US: 75,000 dams at least 6 feet in

height and an estimated 2 million other height and an estimated 2 million other smaller structures.smaller structures.

• Around the world: more than 45,000 Around the world: more than 45,000 large dams (50ft high).large dams (50ft high).– 3,000 of these contain storage reservoirs 3,000 of these contain storage reservoirs

with volumes greater than 25 billion with volumes greater than 25 billion gallons, 120 million acres of land and gallons, 120 million acres of land and containing more than 1,500 micontaining more than 1,500 mi33 of water of water

CALFEDCALFED

• CALFED Bay-Delta ProgramCALFED Bay-Delta Program– Established to “develop and implement Established to “develop and implement

a lon-term comprehensive plan that will a lon-term comprehensive plan that will restore ecological health and improve restore ecological health and improve water management for beneficial uses water management for beneficial uses of the Bay-Delta System”of the Bay-Delta System”

– Bay-Delta is a huge estuary in the San Bay-Delta is a huge estuary in the San Francisco Bay. Francisco Bay.

Ground WaterGround Water•Can be nonrenewable, such is Can be nonrenewable, such is

the case for the Ogallala aquifer.the case for the Ogallala aquifer.– Originally charged during the last Originally charged during the last

ice age melt (fossil water).ice age melt (fossil water).– Used to irrigate 1/5 of US land. Used to irrigate 1/5 of US land.

Cannot recharge at a fast enough Cannot recharge at a fast enough rate to be sustainable.rate to be sustainable.

Falling water tableFalling water table•Wet lands dry up.Wet lands dry up.

•Structural support is lost.Structural support is lost.– Land subsistence.Land subsistence.– Sink holes.Sink holes.– Salt water intrusion (figure 7-18 Salt water intrusion (figure 7-18

page 184).page 184).

SubsidenceSubsidence• Land subsidence is Land subsidence is

where ground water where ground water has leached into has leached into cavities in the ground, cavities in the ground, helping to support the helping to support the above lying rock and above lying rock and soil. As the water soil. As the water table drops, the table drops, the support is lost. This is support is lost. This is the gradual settling of the gradual settling of the land.the land.

Sink holeSink hole• Type of land subsidence Type of land subsidence

that happens rapidly and that happens rapidly and dramaticallydramatically

Salt water intrusionSalt water intrusion

• Results from dropping water tables.Results from dropping water tables.

• Springs of outflowing ground water may Springs of outflowing ground water may lie under the ocean. As long as the lie under the ocean. As long as the water table is high it will maintain water table is high it will maintain enough head pressure in the aquifer and enough head pressure in the aquifer and water will flow into the ocean. When water will flow into the ocean. When tables are low the pressure is not tables are low the pressure is not enough and ocean water flows backward enough and ocean water flows backward into the aquiferinto the aquifer

Salt water intrusionSalt water intrusion

Section FourSection FourWater Stewardship: Water Stewardship: Public Policy ChallengesPublic Policy Challenges

How is there not enough?How is there not enough?

• If the water cycle is sufficient to If the water cycle is sufficient to provide water for all human needs, provide water for all human needs, why do some go without?why do some go without?– Not distributed evenlyNot distributed evenly– Scarcity of water in many parts of the Scarcity of water in many parts of the

worldworld– Deficit in infrastructureDeficit in infrastructure– Expanding populationsExpanding populations

How can we make How can we make water use sustainable:water use sustainable:

1.1.Capture more runoffCapture more runoff

2.2.Gain better access to Gain better access to groundwater aquifersgroundwater aquifers

3.3.Desalt seawater Desalt seawater (microfiltration/reverse osmosis)(microfiltration/reverse osmosis)

4.4.Conserve present supplies by Conserve present supplies by using less water. (drip irrigation)using less water. (drip irrigation)

Why build dams?Why build dams?

• Combination of flood control, water Combination of flood control, water storage, and hydropower.storage, and hydropower.

Three Georges Dam

Three Georges DamThree Georges Dam• Yangtze River in ChinaYangtze River in China

• Completed in 2006Completed in 2006

• Largest hydroelectric project in the worldLargest hydroelectric project in the world

• Generates 22,000 MW of electricityGenerates 22,000 MW of electricity

• More than 1.2 million people have been More than 1.2 million people have been displaceddisplaced

• Critics point to the huge human, ecological, Critics point to the huge human, ecological, and aesthetic costs of the dam and claim and aesthetic costs of the dam and claim alternative sources of energy are cheaperalternative sources of energy are cheaper

US Dam RemovalUS Dam Removal

• 500 dams have already been removed in 500 dams have already been removed in the US and many await the same fate.the US and many await the same fate.

• Pros for removal: reestablish historic Pros for removal: reestablish historic fisheries and reestablish the river for fisheries and reestablish the river for recreational and aesthetic valuerecreational and aesthetic value

• Cons: massive sediment from upriver Cons: massive sediment from upriver that will be washed downstream, difficult.that will be washed downstream, difficult.

Wild and Scenic Rivers ActWild and Scenic Rivers Act

• 19681968

• Keeps rivers labeled as “wild and scenic” Keeps rivers labeled as “wild and scenic” from being dammed or affected by other from being dammed or affected by other harmful operations.harmful operations.

• 11,300 miles of rivers have been 11,300 miles of rivers have been protected, 60,000 more miles are eligible.protected, 60,000 more miles are eligible.

• Like national parks, they need supporters Like national parks, they need supporters and defenders such as the organization and defenders such as the organization American RiversAmerican Rivers

Threats to irrigated Threats to irrigated agricultureagriculture

• Greatest: ground water depletionGreatest: ground water depletion– Happening in many parts of the worldHappening in many parts of the world

• Other threats: pollution from Other threats: pollution from fertilizers, pesticides, animal wastes, fertilizers, pesticides, animal wastes, and industrial chemicals.and industrial chemicals.

Genetically modify plants?Genetically modify plants?• Scientists are trying to modify plants to be tolerant Scientists are trying to modify plants to be tolerant

of salts.of salts.

• The trend however is to desalinate until this is an The trend however is to desalinate until this is an actual possibility.actual possibility.

• Desalinating: microfiltration (reverse osmosis)-Desalinating: microfiltration (reverse osmosis)-great pressure forces seawater through a great pressure forces seawater through a membrane filter fine enough to remove salt…and membrane filter fine enough to remove salt…and distillation-evaporation and recondensation of distillation-evaporation and recondensation of water vaporwater vapor

• Under the best circumstance it costs $2 per 1,000 Under the best circumstance it costs $2 per 1,000 gallons (2-4 x’s as much as US city dwellers pay gallons (2-4 x’s as much as US city dwellers pay but by far cheaper than bottled waterbut by far cheaper than bottled water

• Cost efficient for city dwellers but not for crop Cost efficient for city dwellers but not for crop owners who need to irrigate.owners who need to irrigate.

Water used per day per Water used per day per personperson

• Developing nation: 1 gallon (includes Developing nation: 1 gallon (includes cooking and washing)cooking and washing)

• US: 100 gallons per person per dayUS: 100 gallons per person per day– If all indirect uses such as irrigation are If all indirect uses such as irrigation are

added in it goes up to 1,300 gallonsadded in it goes up to 1,300 gallons

Agricultural water Agricultural water conservationconservation

• Drip irrigation: network of Drip irrigation: network of plastic pies with pin holes plastic pies with pin holes in them that literally drip in them that literally drip water at the base of the water at the base of the plant.plant.

• Treadle pump: works like Treadle pump: works like an exercise machine an exercise machine pumping water from just pumping water from just a few feet below the a few feet below the surface.surface.

Municipal water Municipal water conservationconservation• Flushing 3-5 gallonsFlushing 3-5 gallons

• Showering 2-3 gallons per minuteShowering 2-3 gallons per minute

• Laundry 20-30 gallons per loadLaundry 20-30 gallons per load

• Conserve: fix leaky faucets, low-flow Conserve: fix leaky faucets, low-flow shower heads and faucets, replace shower heads and faucets, replace lawns with xeriscaping, ban use of lawns with xeriscaping, ban use of water during draughts, gray-water water during draughts, gray-water recycling.recycling.

xeriscapingxeriscaping

• Landscaping with desert species that Landscaping with desert species that require no extra watering (lawn require no extra watering (lawn replacement)replacement)

US water policyUS water policy

• No US water policy No US water policy • Clean water act and its subsequent Clean water act and its subsequent

amendments authorize the US EPA to amendments authorize the US EPA to develop programs and rules to carry develop programs and rules to carry out its mandate for oversight of the out its mandate for oversight of the nation’s water quality.nation’s water quality.

• EPA does not deal with water EPA does not deal with water quantity.quantity.

Issues to be addressedIssues to be addressed• The last time a water policy report was The last time a water policy report was

issued was in 1950 by Harry S. Trumanissued was in 1950 by Harry S. Truman

• The issues that need to be addressed by The issues that need to be addressed by a water policy report…7 on page 190a water policy report…7 on page 190– Promote efficiencyPromote efficiency– Water subsidies reduced or eliminatedWater subsidies reduced or eliminated– Polluters charged according to effluentsPolluters charged according to effluents– Watershed managementWatershed management– Regulate dam operationsRegulate dam operations– International development aidInternational development aid– More research and monitoringMore research and monitoring