Chapter 13Chapter 13

Water Resources

Supply of Water ResourcesSupply of Water Resources

FreshwaterFreshwater Readily accessible freshwaterReadily accessible freshwater

Biota0.0001%

Biota0.0001%

Rivers0.0001%Rivers

0.0001%

Atmosphericwater vapor

0.0001%

Atmosphericwater vapor

0.0001%

Lakes0.0007%

Soilmoisture0.0005%

Groundwater0.592%

Groundwater0.592%

Ice capsand glaciers

1.984%

0.014%0.014%

Core Case Study: Water Conflicts in the Middle East - A Preview of the Future

Core Case Study: Water Conflicts in the Middle East - A Preview of the Future

• Many countries in the Middle East, which has one of the world’s highest population growth rates, face water shortages.

Figure 14-1Figure 14-1

Water Conflicts in the Middle East: A Preview of the FutureWater Conflicts in the Middle East: A Preview of the Future

• Countries are in disagreement as to who has water rights.

• Currently, there are no cooperative agreements for use of 158 of the world’s 263 water basins that are shared by two or more countries.

Soil PropertiesSoil Properties

Infiltration Infiltration

Porosity/permeability Porosity/permeability

Texture Soil type here?

Texture Soil type here?

Water Water

High permeability Low permeability

Clay, graniteClay, graniteSand, gravelSand, gravel

Fig. 13-3,

Unconfined Aquifer Recharge Area

Precipitation Evaporation and transpiration Evaporation

Confined Recharge Area

Runoff

Flowing artesian well

Recharge Recharge Unconfined Unconfined AquiferAquifer

Stream Well requiring a pumpInfiltration Water

table LakeInfiltration

Unconfined aquifer

Confined aquiferConfining impermeable rock layer Confining impermeable rock layer

Less permeable material Less permeable material such as claysuch as clay

GroundwaterZone of aerationZone of saturation

Tapping GroundwaterTapping Groundwater

Year-round useYear-round use

No evaporation lossesNo evaporation losses

Often less expensiveOften less expensive

Other Effects of Groundwater Overpumping- Sea water intrusionOther Effects of Groundwater Overpumping- Sea water intrusion

• Groundwater overpumping can cause land to sink, and contaminate freshwater aquifers near coastal areas with saltwater.

Other Effects of Groundwater Overpumping-subsidenceOther Effects of Groundwater Overpumping-subsidence

• Sinkholes

• Chemical contamination.

Use of Water ResourcesUse of Water Resources

United StatesUnited States

Industry 11%Industry 11%

Public 10%Public 10%

Powercooling

38%

Agriculture41%

Case Study: The California ExperienceCase Study: The California Experience • A massive transfer

of water from water-rich northern California to water-poor southern California is controversial.

• Water rights– Prior appropriation– riparian

Figure 13-17Figure 13-17

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

Fig. 13-12

Provides water for year-round irrigation of cropland

Flooded land destroys forests or cropland and displaces people

Large losses of water through evaporation

Provides water for drinking Downstream

cropland and estuaries are deprived of nutrient-rich silt

Reservoir is useful for recreation and fishing

Risk of failure and devastating downstream flooding

Can produce cheap electricity (hydropower)

Downstream flooding is reduced

Migration and spawning of some fish are disrupted

Case Study: China’s Three Gorges DamCase Study: China’s Three Gorges Dam• There is a debate

– The electric output– It will facilitate ship travel reducing transportation

costs.– Dam will displace 1.2 million people.– Dam is built over seismatic fault and already has small

cracks.

Dam RemovalDam Removal

• Some dams are being removed for ecological reasons and because they have outlived their usefulness.– The Federal Energy Regulatory Commission has

approved the removal of nearly 500 dams.– Removing dams can reestablish ecosystems, but

can also re-release toxicants into the environment.

Using Water More EfficientlyUsing Water More Efficiently

Reduce losses due to leakage Reduce losses due to leakage

Reform water laws Reform water laws

Improve irrigation efficiency Improve irrigation efficiency

Improving manufacturing processes Improving manufacturing processes

Water efficient landscaping Water efficient landscaping

Water efficient appliances Water efficient appliances

INCREASING WATER SUPPLIES BY WASTING LESS WATERINCREASING WATER SUPPLIES BY WASTING LESS WATER

• Sixty percent of the world’s irrigation water

• Center-pivot, low pressure sprinklers sprays water directly onto crop.– It allows 80% of water to reach crop.

Fig. 13-20

Center pivotCenter pivot

Drip irrigationDrip irrigation

Gravity flowGravity 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.

(efficiency 90–95%)

(efficiency 80%–95%)

Water usually pumped from underground and sprayed from mobile boom with sprinklers.

Solutions: Getting More Water for Irrigation in Developing Countries – The Low-Tech Approach

Solutions: Getting More Water for Irrigation in Developing Countries – The Low-Tech Approach

• low-tech methods to pump groundwater

• Arsenic in India

Raising the Price of Water: A Key to Water ConservationRaising the Price of Water: A Key to Water Conservation• We can reduce water use and waste by raising the

price of water while providing low lifeline rates for the poor.– When Boulder, Colorado introduced water meters,

water use per person dropped by 40%.

What Can You Do?Water Use and Waste

• Use water-saving toilets, showerheads, and faucet aerators.

• Shower instead of taking baths, and take short showers.

• Stop water leaks.

• Turn off sink faucets while brushing teeth, shaving, or washing.

• Flush toilets only when necessary.

• Wash only full loads of clothes or use the lowest water-level for smaller loads.

• Use recycled (gray) water for lawn, gardens, house plants, car washing.

• Wash a car from a bucket of soapy water, and use the hose for rinsing only.

• If you use a commercial car wash, try to find one that recycles its water.

• Replace your lawn with native plants that need little if any watering and decorative gravel or rocks.

• Water lawns and gardens in the early morning or evening.

• Sweep or blow off driveways instead of hosing off with water.

• Use drip irrigation and mulch for gardens and flowerbeds.

Too Much Water: FloodsToo Much Water: Floods

Natural phenomena Natural phenomena

Floodplain

Levee Floodwall

Dam

Reservoir

Renew and replenish Renew and replenish

Aggravated by human activities

Aggravated by human activities

Flood zone

TOO MUCH WATERTOO MUCH WATER

• Comparison of St. Louis, Missouri under normal conditions (1988) and after severe flooding (1993).

Water ConservationWater Conservation

• The average American uses 90 gallons of water each day. European-53 and Sub-Saharan Africa-5

• Fix leaks, replace old toilets (trade ins), efficient washers (50% less water and energy).

• A switch to water efficient appliances family of 4- save 23,000 gallons a year.

• End chapter 13•