Chapter 13

Water Resources

Supply of Water Resources

Freshwater Readily accessible freshwater Groundwater 0.592% Biota 0.0001% Lakes 0.0007% Rivers 0.0001% 0.014% Ice caps and glaciers 1.984% Soil moisture 0.0005% Atmospheric water vapor 0.0001%

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 14-1

Water 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 Properties

Water Water

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Infiltration

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Porosity/permeability

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Texture Soil type here?

High permeability Sand, gravel Low permeability Clay, granite

Zone of aeration Zone of saturation Precipitation Confined Recharge Area Runoff Groundwater Unconfined Aquifer Recharge Area Evaporation and transpiration Evaporation Flowing artesian well Infiltration Water table Recharge Unconfined Aquifer Infiltration Stream Well requiring a pump Lake Fig. 13-3,

Tapping Groundwater

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Year-round use

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No evaporation losses

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Often less expensive

Other 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-subsidence

• Sinkholes • Chemical contamination.

Use of Water Resources

United States Power cooling 38% Agriculture 41% Industry 11% Public 10%

Case 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 13-17

Converting Salt Water to Fresh Water and Making it Rain

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Distillation desalination

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Reverse osmosis desalination

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Desalination is very expensive

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Cloud seeding

Provides water for year-round irrigation of cropland Provides water for drinking Reservoir is useful for recreation and fishing Can produce cheap electricity (hydropower) Downstream flooding is reduced Flooded land destroys forests or cropland and displaces people Large losses of water through evaporation Downstream cropland and estuaries are deprived of nutrient-rich silt Risk of failure and devastating downstream flooding Migration and spawning of some fish are disrupted Fig. 13-12

Case 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 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 Efficiently

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Reduce losses due to leakage

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Reform water laws

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Improve irrigation efficiency

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Improving manufacturing processes

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Water efficient landscaping

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Water efficient appliances

INCREASING 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.

Gravity flow (efficiency 60% and 80% with surge valves) Drip irrigation (efficiency 90–95%) Water usually comes from an aqueduct system or a nearby river.

Above- or below-ground pipes or tubes deliver water to individual plant roots.

Center pivot (efficiency 80%–95%) Water usually pumped from underground and sprayed from mobile boom with sprinklers.

Fig. 13-20

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 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: Floods

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Natural phenomena

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Renew and replenish Reservoir Levee

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Aggravated by human activities Dam Flood wall Flood zone Floodplain

TOO MUCH WATER

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

Water 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