Water ResourcesWater Resources

All water Fresh water Readily accessible fresh water

Oceans andsaline lakes97.4%

Fresh water2.6%

Groundwater0.592%

Ice capsand glaciers1.984%

Lakes0.007%

Soilmoisture0.005%

Biota0.0001%

Rivers0.0001%

Atmosphericwater vapor0.001%

0.014%

Oceans

Ice

Lakes

Soilmoisture

77 trillion gallons/person

240,000 gallons/person

Evaporation and transpiration

Evaporation

Stream

Infiltration

Water tableInfiltration

Unconfined aquifer

Confined aquifer

Lake

Well requiring a pump

Flowingartesian well

Runoff

Precipitation

ConfinedRecharge Area

Less permeable materialsuch as clay Confirming permeable rock layer

Watershed, water table, aquiferWatershed, water table, aquifer

Increasing Demand for WaterIncreasing Demand for Water

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

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Total use

Agricultural use

Industrial use

Domestic use

Year

Use of Water ResourcesUse of Water Resources

In U.S., 2000 gallons/day/person In U.S., 2000 gallons/day/person

Agriculture - 700 gallons Agriculture - 700 gallons

Industry/commercial- 1200 gallons

Industry/commercial- 1200 gallons

Home - 100 gallons- 3 X world average- 20 X developing nations

Home - 100 gallons- 3 X world average- 20 X developing nations

United States

Industry 11%

Public 10%

Powercooling

38%

Agriculture38%

Problem: Too Little WaterProblem: Too Little Water

Dry climateDry climate

Drought- 40% of people

Drought- 40% of people

Acute shortage

Adequate supply

Shortage

Metropolitan regions with population greater than 1 million

Problem: Too Much WaterProblem: Too Much Water

Natural phenomena Natural phenomena

Floodplain

Levee Floodwall

Dam

Reservoir

Renew and replenish Renew and replenish

Aggravated by human activities

Aggravated by human activities

Maintaining Adequate SuppliesMaintaining Adequate Supplies

Increase current supplyIncrease current supply

Reduce pollutionReduce pollution

Use water more efficientlyUse water more efficiently

Tapping GroundwaterTapping Groundwater

Year-round useYear-round use

No evaporation lossesNo evaporation losses

Often less expensiveOften less expensive

Potential Problems!Potential Problems!

Problems with Using GroundwaterProblems with Using Groundwater

Water table loweringWater table lowering

DepletionDepletion

Subsidence Subsidence

Saltwater intrusionSaltwater intrusion

Ogallala AquiferOgallala Aquifer

WYOMING

SOUTH DAKOTA

NEBRASKA

COLORADOKANSAS

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

Lowering the Water TableLowering the Water Table

Initial water table

Cone ofdepression

Originalwater table

Loweredwater table

Groundwater OveruseGroundwater Overuse

GroundwaterOverdrafts:

High

Moderate

Minor or none

Ground SubsidenceGround Subsidence

Subsidence:

High

Moderate

Minor or none

Major irrigationwell

Well contaminatedwith saltwater

SaltwaterIntrusion

NormalInterface

Freshgroundwater

aquifer

Interface Interface

Saltwater

Sea LevelWater table

Saltwater IntrusionSaltwater Intrusion

Using Dams and Reservoirs to Supply More WaterUsing Dams and Reservoirs to Supply More Water

Large lossesof water throughevaporation

Large lossesof water throughevaporation

Flooded land destroys forests or cropland anddisplaces people

Flooded land destroys forests or cropland anddisplaces people

Downstream flooding is reducedDownstream flooding is reduced

Downstream cropland andestuaries are deprived ofnutrient-rich silt

Downstream cropland andestuaries are deprived ofnutrient-rich silt

Reservoir is useful for recreation and fishing

Can produce cheap electricity (hydropower)

Migration and spawning of some fish are disruptedMigration and spawning of some fish are disrupted

Provides waterfor year-roundirrigation ofcropland

Transferring Water from One Place to AnotherTransferring Water from One Place to Another

North BayAqueductNorth BayAqueduct

South BayAqueductSouth BayAqueduct

California AqueductCalifornia Aqueduct

CALIFORNIANEVADA UTAH

MEXICO

Central ArizonaProject

Colorado RiverAqueduct

Los AngelesAqueduct

Shasta Lake

Sacramento

Fresno

Phoenix

Tucson

ARIZONA

ColoradoRiver

SacramentoRiverSacramentoRiver

San FranciscoSan Francisco

Los AngelesLos Angeles

San DiegoSan Diego

Watershed transferWatershed transfer

California Water Project

California Water Project

Central Arizona Project

Central Arizona Project

Converting Salt Water to Fresh Water and Making it RainConverting Salt Water to Fresh Water and Making it Rain

Distillation desalinationDistillation desalination

Reverse osmosis desalinationReverse osmosis desalination

Desalination is very expensiveDesalination is very expensive

Cloud seedingCloud seeding

Using Water More EfficientlyUsing Water More Efficiently

Reduce losses due to leakage (e.g., Boston) Reduce losses due to leakage (e.g., Boston)

Reform water laws (use it or lose it) Reform water laws (use it or lose it)

Improve irrigation efficiency Improve irrigation efficiency

Improving manufacturing processes Improving manufacturing processes

Water efficient landscaping Water efficient landscaping

Water efficient appliances Water efficient appliances

Solutions: Achieving a More Sustainable Water FutureSolutions: Achieving a More Sustainable Water Future

Efficient irrigationEfficient irrigation

Water-saving technologiesWater-saving technologies

Improving water managementImproving water management

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

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

Drip or Trickle 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.

Irrigation Methods

Saving Water in the BathroomSaving Water in the Bathroom

Gray Water and Dual SystemsGray Water and Dual Systems