Mrs. Sealy - APESMrs. Sealy - APES

Fig. 13.1, p. 294

MEDITERRANEANSEA

GAZAWEST BANK

LEBANON

EGYPT

AswanHigh Dam

Lake Nasser

SUDAN

ETHIOPIA

SOMALIA

SAUDIARABIA

YEMEN

UNITED ARABEMIRATES

QATAR

BAHRAIN

KUWAIT

JORDAN

OMAN

OMAN

IRANIRAQ

SYRIA

TURKEY ARMENIA

BLACK SEA GEORGIA

AZERBAIJAN TURKMENISTAN

CASPIANSEA

How much freshwater is How much freshwater is available and where is it?available and where is it?

• 97.4% of water is in the ocean, 97.4% of water is in the ocean, 2.6% is freshwater and of that 2.6% is freshwater and of that amount, Most is locked in icecaps amount, Most is locked in icecaps leaving .014% available for useleaving .014% available for use

Fig. 13.2, p. 296

Freshwater Readily accessible freshwater

Biota0.0001%

Rivers0.0001%

Atmosphericwater vapor

0.001%

Lakes0.007%

Soilmoisture0.005%

Groundwater0.592%

Ice capsand glaciers

1.984%

0.014%

Fig. 13.5, p. 298

United States China

Industry 11% Public 10%

Powercooling

38%

Agriculture41% Agriculture 87%

Public 6% Industry 7%

Fig. 13.4, p. 298

5,500

5,000

4,500

4,000

3,500

3,000

2,500

2,000

1,500

1,000

500

1900 1920 1940 1960 1980 2000

Wat

er u

se (

cub

ic k

ilom

eter

s p

er y

ear) Total use

Agricultural use

Industrial use

Domestic use

Year

Fig. 13.6, p. 298

1 automobile

1 kilogramcotton

1 kilogramaluminum

1 kilogramgrain-fed beef

1 kilogramrice

1 kilogramcorn

1 kilogrampaper

1 kilogramsteel

400,000 liters(106,000 gallons)

10,500 liters(2,400 gallons)

9,000 liters(2,800 gallons)

7,000 liters(1,900 gallons)

5,000 liters(1,300 gallons)

1,500 liters(400 gallons)

880 liters(230 gallons)

220 liters(60 gallons)

What causes water What causes water shortages?shortages?• Dry climateDry climate

• DroughtDrought• DesiccationDesiccation• Water stress (low per capita availability due to Water stress (low per capita availability due to

population growth)population growth)• 30 countries containing 500,000 million people 30 countries containing 500,000 million people

have chronic water shortageshave chronic water shortages• There is enough water, but often it is wasted, There is enough water, but often it is wasted,

polluted, is in areas where it is hard to get to.polluted, is in areas where it is hard to get to.• Two-thirds of the world live in water poverty Two-thirds of the world live in water poverty

where they do not have water coming into the where they do not have water coming into the home. home.

Competition for the Competition for the WorldWorld’’s Water s Water

• Cities are outbidding farmers for Cities are outbidding farmers for water supplies from rivers and water supplies from rivers and aquifersaquifers

• Some countries are importing grain Some countries are importing grain as a way to reduce their water as a way to reduce their water needsneeds

• More crops are being used for More crops are being used for biofuels increasing water demand. biofuels increasing water demand.

Fig. 13.7a, p. 299

0-25

25-50

50-75

0-25

25-50

50-75

Average annual precipitation (centimeters)

Fig. 13.8b, p. 299

Acute shortage

Adequate supply

Shortage

Metropolitan regions with populationgreater than 1 million

Fig. 13.8, p. 300

High None

NorthAmerica

SouthAmerica Stress

Africa

Europe

Asia

Australia

How can water supplies be How can water supplies be increased?increased?

• Building dams and reserviorsBuilding dams and reserviors• Importing waterImporting water• Withdrawing groundwaterWithdrawing groundwater• DesalinationDesalination• improved efficiencyimproved efficiency

Dams and reservoirsDams and reservoirs

• Pros:Pros:• Can capture and store waterCan capture and store water• The water can be released as The water can be released as

desireddesired• Control flooding downstreamControl flooding downstream• Supply irrigation water year aroundSupply irrigation water year around• Provide electricityProvide electricity

Fig. 13.9, p. 301

Large lossesof water throughevaporation

Flooded landdestroys forestsor cropland anddisplaces people

Downstreamflooding is reduced

Downstreamcropland andestuaries aredeprived ofnutrient-rich silt

Reservoir isuseful forrecreationand fishing

Can producecheap electricity(hydropower)

Migration andspawning ofsome fish aredisrupted

Provides waterfor year-roundirrigation ofcropland

• Cons:Cons:• Silting behind the dam robs the Silting behind the dam robs the

downstream of nutrientsdownstream of nutrients• Loss of silt destroys deltasLoss of silt destroys deltas• Causes flooding behind the damCauses flooding behind the dam• They can fall downThey can fall down• Disturbs species like salmonDisturbs species like salmon• Causes landslides and earthquakesCauses landslides and earthquakes

Case Study: The Colorado Case Study: The Colorado RiverRiver

• Water laws in the Western United States are Water laws in the Western United States are governed by prior appropriation: governed by prior appropriation: ““First in First in time, first in righttime, first in right””, which means the first to , which means the first to use the water has the first rights. On the use the water has the first rights. On the Colorado River the Indians and the Ranchers Colorado River the Indians and the Ranchers were the first.were the first.

• The Colorado is divided into two parts:The Colorado is divided into two parts:

* Upper Basin: Wyoming, Utah, Colorado, * Upper Basin: Wyoming, Utah, Colorado, New MexicoNew Mexico

* Lower Basin: Arizona, Nevada and California* Lower Basin: Arizona, Nevada and California

Case Study: The Colorado Case Study: The Colorado RiverRiver

• In 1922 water was allocated to In 1922 water was allocated to these states by the Colorado River these states by the Colorado River compact, in 1944 Mexico was compact, in 1944 Mexico was allocated waterallocated water

• The problem was that the amount of The problem was that the amount of water was overestimated by 33%, water was overestimated by 33%, so when all the states start taking so when all the states start taking their water, there will not be enoughtheir water, there will not be enough

Fig. 13.10, p. 304

Dam

Aqueductor canal

Upper Basin

Lower Basin

IDAHO

WYOMING

UTAH

Salt Lake City

Las Vegas

CALIFORNIA

Boulder City

Los Angeles Palm

Springs

San DiegoMexicali

Yuma

Phoenix

Tucson

LOWERBASIN

ARIZONA

GrandCanyon

UPPERBASIN

Grand Junction

Denver

COLORADO

NEW MEXICO

Albuquerque

MEXICO

LakePowell

GlenCanyonDam

All-AmericanCanal Golf of

California

0

0

100 mi.

150 km

The Science of GroundwaterThe Science of Groundwater• Groundwater: rain that infiltrates the ground Groundwater: rain that infiltrates the ground

and percolates downward through spaces in and percolates downward through spaces in soil, water and rocksoil, water and rock

• Below a certain level the spaces are completely Below a certain level the spaces are completely filled with water, called the zone of saturation . filled with water, called the zone of saturation . The top of this zone is the water table.The top of this zone is the water table.

• Aquifer: porous layers of sand, gravel and rock Aquifer: porous layers of sand, gravel and rock through which water flows (from which water through which water flows (from which water can be extracted).can be extracted).

• Recharge rate: how fast an aquifer can refill. Recharge rate: how fast an aquifer can refill. Can take thousands of years.Can take thousands of years.

Tapping GroundwaterTapping Groundwater

• Pros:Pros:• Supplies 50 % of drinking waterSupplies 50 % of drinking water• Supplies 40% of irrigationSupplies 40% of irrigation• Usually very high qualityUsually very high quality

Tapping GroundwaterTapping Groundwater

• Aquifer depletion: currently US is Aquifer depletion: currently US is withdrawing groundwater at 4x itwithdrawing groundwater at 4x it’’s s replacement ratereplacement rate

• Aquifer subsidence: sinking of land Aquifer subsidence: sinking of land due to water removaldue to water removal

• Salt water intrusion: removing too Salt water intrusion: removing too much groundwater causes salt much groundwater causes salt water to seep into aquiferswater to seep into aquifers

Fig. 13.3, p. 297

Evaporation and transpiration

Evaporation

Stream

Infiltration

Water tableInfiltration

Unconfined aquifer

Confined aquifer

Lake

Well requiring a pump

Flowingartesian well

Runoff

Precipitation

ConfinedRecharge Area

Aquifer

Less permeable materialsuch as clay

Confining permeable rock layer

Unconfined Aquifer Recharge Area

Fig. 13.17, p. 308

Major irrigationwell

Well contaminatedwith saltwater

SaltwaterIntrusion

NormalInterface

Freshgroundwater

aquifer

Interface Interface

Saltwater

Sea LevelWater table

Fig. 13.15, p. 307

Initial water table

Cone ofdepression

Originalwater table

Loweredwater table

Fig. 13.16a, p. 308

GroundwaterOverdrafts:

High

Moderate

Minor or none

Fig. 13.16b, p. 308

Subsidence:

High

Moderate

Minor or none

Case Study: Ogallala Case Study: Ogallala AquiferAquifer

• The Ogallala aquifer stretches from The Ogallala aquifer stretches from Texas north to North Dakota. It was Texas north to North Dakota. It was deposited over several thousand years deposited over several thousand years duirng the last ice age. It is the largest duirng the last ice age. It is the largest aquifer in North America. It is non-aquifer in North America. It is non-renewable because it has a very slow renewable because it has a very slow recharge rate. One quarter of it will be recharge rate. One quarter of it will be depleted by 2020. This is because the depleted by 2020. This is because the farmers get tax breaks for depleting it. In farmers get tax breaks for depleting it. In the Midwest there is no such thing as the Midwest there is no such thing as water conservation.water conservation.

Fig. 13.18, p. 309

WYOMING SOUTH DAKOTA

NEBRASKA

COLORADO

KANSAS

OKLAHOMA

NEW MEXICO

TEXAS

0 100Miles

Kilometers

Less than 61 meters (200 ft)

61-183 meters (200-600 ft)

More than 183 meters (600 ft)(as much as 370 meters or 1,200 ft.in places)

0 160

Water TransferWater Transfer

• Pros: Pros: • Using tunnels, aquaducts and pipes Using tunnels, aquaducts and pipes

to transport water from watersheds to transport water from watersheds to water poor areasto water poor areas

• Allows for year-around irrigation of Allows for year-around irrigation of cropland in arid regionscropland in arid regions

• Has allowed L.A. to become what it Has allowed L.A. to become what it is (Owens Valley water transfer).is (Owens Valley water transfer).

Water TransferWater Transfer

• Robs other areas of waterRobs other areas of water• Can be environmentally harmful to areas Can be environmentally harmful to areas

where the water is being removedwhere the water is being removed• Threatens fisheriesThreatens fisheries• Causes rivers to flow backwardsCauses rivers to flow backwards• Takes away the flushing action of riversTakes away the flushing action of rivers• Lowers the level of inland seas and lakesLowers the level of inland seas and lakes• Causes inland seas to become more salty Causes inland seas to become more salty

and produces salt rain from blowing saltand produces salt rain from blowing salt• Hard on native speciesHard on native species

Areas already harmed:Areas already harmed:

• Aral Sea in RussiaAral Sea in Russia• Mono Lake in CaliforniaMono Lake in California• Sacramento River deltaSacramento River delta

Fig. 13.12, p. 305

KAZAKHSTAN

TURKMENISTAN

UZBEKISTAN

ARALSEA

2000

1989

1960

Fig. 13.13, p. 306

North BayAqueduct

South BayAqueduct

California Aqueduct

CALIFORNIA

NEVADA UTAH

MEXICO

Central ArizonaProject

Colorado RiverAqueduct

Los AngelesAqueduct

Shasta Lake

Oroville Dam andReservoir

FeatherRiver

Lake Tahoe

Sacramento

Fresno

Hoover Damand Reservoir(Lake Mead)

Salton SeaPhoenix

Tucson

ARIZONA

ColoradoRiver

SacramentoRiver

San Francisco

San Luis Damand Reservoir

Santa Barbara

Los Angeles

San Diego

DesalinationDesalination

• Removing salt from ocean water Removing salt from ocean water by distillation or reverse osmosisby distillation or reverse osmosis

• Problem is that it requires large Problem is that it requires large amounts of energy and it is very amounts of energy and it is very expensiveexpensive

Improved EfficiencyImproved Efficiency

• 60-70% of water is 60-70% of water is wasted worldwidewasted worldwide• Why is water wasted:Why is water wasted:

* artificially low prices in the US* artificially low prices in the US* government subsidies* government subsidies* outdated laws governing water * outdated laws governing water suppliessupplies* water management in watersheds is * water management in watersheds is divided into too many different hands. divided into too many different hands.

Wasting Less Water in Wasting Less Water in IrrigationIrrigation

• Currently we use flood irrigation or Currently we use flood irrigation or gravity flow, which wastes 50% of gravity flow, which wastes 50% of waterwater

• Drip irrigation delivers water Drip irrigation delivers water directly to plants with a 80-90% directly to plants with a 80-90% efficiencyefficiency

• Center-pivot-mobile boom moves Center-pivot-mobile boom moves over crops 70-80% efficient over crops 70-80% efficient

Gravity Flow(efficiency 60% and 80% with surge valves)

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

Drip Irrigation(efficiency 90–95%)

Above- or below-ground pipes or tubes deliver water to

individual plant roots.

Center Pivot(efficiency 80% with low-pressure

sprinkler and 90–95% with LEPA sprinkler)

Water usually pumped from underground and sprayed from

mobile boom with sprinklers.

Fig. 13.19, p. 311

Fig. 13.20, p. 313

• Lining canals bringing water to irrigation ditches

• Leveling fields with lasers

• Irrigating at night to reduce evaporation

• Using soil and satellite sensors and computer systems to monitor soil moisture and add water only when necessary

• Polyculture

• Organic farming

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

• Irrigating with treated urban waste water

• Importing water intensive crops and meat

Wasting Less in IndustryWasting Less in Industry

• Recycling water in the manufacturing Recycling water in the manufacturing processprocess

• Many companies already do this Many companies already do this because it saves them money and because it saves them money and they do not get government kickbacks they do not get government kickbacks on water like farmers doon water like farmers do

• Also companies have to pay for the Also companies have to pay for the amount of stuff that goes down the amount of stuff that goes down the sewersewer

Wasting Less in Businesses Wasting Less in Businesses and Homesand Homes

• Low flush toiletsLow flush toilets• Low flow shower headsLow flow shower heads• XeriscapingXeriscaping• Fix leaky pipesFix leaky pipes• Reusing gray water in Reusing gray water in

homes and to water homes and to water

lawnslawns

Too much water-FloodsToo much water-Floods

• Floodplain: the natural overflow area Floodplain: the natural overflow area of a river, these are very productive of a river, these are very productive areas with nutrient rich soilsareas with nutrient rich soils

• Floods are natural thing- they enrich Floods are natural thing- they enrich the soil, recharge groundwater and the soil, recharge groundwater and refill wetlandsrefill wetlands

• Humans make flooding worse by Humans make flooding worse by removing vegetation, draining removing vegetation, draining wetlands and living on floodplainswetlands and living on floodplains

Fig. 13.22, p. 314

Floodplain

Levee Floodwall

Dam

Reservoir

Fig. 13.24a, p. 316

Oxygenreleased byvegetation

Diverseecological

habitat

Trees reduce soilerosion from heavyrain and wind

Agriculturalland

Steadyriver flow

Leaf litterimprovessoil fertility

Tree rootsstabilize soil andaid water flow Vegetation releases

water slowly andreduces flooding

Forested Hillside

Evaporation increases

Tree plantation

Evapotranspiration decreases

Ranchingacceleratessoil erosion bywater and wind

Winds removefragile topsoil

Gullies andlandslides

Heavy rain leachesnutrients from soiland erodes topsoil Rapid runoff

causes flooding

After DeforestationFig. 13.24b, p. 316

Roadsdestabilizehillsides

Agriculture landis flooded andsilted up

Silt from erosion blocksrivers and reservoirs andcauses flooding downstream

Fig. 13.25, p. 317

Extremely severe

Very severe

Moderately severe

Somewhat severe

Not severe

Fig. 13.26, p. 317

• Not depleting aquifers

• Preserving ecological health of aquatic systems

• Preserving water quality

• Integrated watershed management

• Agreements among regions and countries sharing surface water resources

• Outside party mediation of water disputes between nations

• Marketing of water rights

• Wasting less water

• Decreasing government subsides for supplying water

• Increasing government subsides for reducing water waste

• Slowing population growth