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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