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APES Ch 14

APES Ch 14 . Water. Water’s Importance , Availability and Renewal. You are made up of 60% water. Water is used in the production of food and building supplies. Water helps moderate climate, sculpt earths surface and dilutes pollution Water is a

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APES Ch 14

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  1. APES Ch 14 Water

  2. Water’s Importance , Availability and Renewal • You are made up of 60% water. • Water is used in the production of food and building supplies. • Water helps moderate climate, sculpt earths surface and dilutes pollution • Water is a • Global health issue- lack of water or sanitation systems is the single largest cause of illness. • Children’s issue- water is essential to healthy development • Economic issue – water is a key to poverty reduction, food production and energy production • Women’s issue- in developing countries water is found and carried by the women. • National and global security issue- tension increases between nations over limited or shared water • Environmental issue – removal of water and pollution leads to disappearing species, lower water tables, altered river flow, shrinking lakes, loss of wetlands, and declining water quality.

  3. Water’s Importance , Availability and Renewal • Only 0.024% of the world’s water is available to us as liquid freshwater. • Hydrologic cycle recycles available water • Can not recycle if water is overloaded with pollutants or it is removed faster then the hydrologic cycle can process. • Some countries have too much water and some don’t have enough for their population.

  4. Percent of world's water resources and population Continent 36% Asia 60.5% 10% Africa 14% 8% Europe 11.3% 15% North and Central America 7.3% 26% South America and Caribbean 6.4% 5% Oceania 0.5% Fig. 14-2, p. 307

  5. Water’s Importance , Availability and Renewal • Groundwater: • Zone of saturation: • Water table: • Aquifers: • Natural recharge:

  6. Water’s Importance , Availability and Renewal • Surface water: • Surface runoff: • Watershed (drainage basin): • There is a hydrological connection between surface and ground water. Most ground water makes its way into a lake, river or stream.

  7. Unconfined Aquifer Recharge Area Evaporation and transpiration Evaporation Precipitation Confined Recharge Area Runoff Flowing artesian well Recharge Unconfined Aquifer Stream Well requiring a pump Water table Infiltration Lake Infiltration Unconfined aquifer Less permeable material such as clay Confined aquifer Confining impermeable rock layer Fig. 14-3, p. 308

  8. Water’s Importance , Availability and Renewal • 2/3 of surface runoff is lost by floods and is not available for human use. • 1/3 is reliable runoff: • Due to population growth we now withdraw 34% of reliable runoff and use another 20% to transport goods, dilute pollution and sustain fisheries and wildlife. • About 70% of the water we withdraw from rivers, lakes and aquifers is not returned to these sources (consumptive use). Water is not destroyed but renewed in a different part of the world. • It isn’t the amount we use but the rate at which we use it. • Nonconsumptive use does not remove or only temporarily removes water from its source.

  9. Water’s Importance , Availability and Renewal • Irrigation uses 70% of the water we withdraw. • 85% is not returned to original source (lost through evaporation and seepage into growndwater) • Industries uses 20% • Cities and residence use 10%

  10. Case Study: Freshwater Resources in the United States • 17 western states by 2025 could face intense conflict over scarce water needed for urban growth, irrigation, recreation and wildlife. Figure 14-5

  11. Too Little Freshwater • Main factors causing water scarcity: • Dry climate, drought, too many people using and wasting water, lack of $ to drill wells and build dams. -“The fight for water will be more dramatic than the fight for oil in the long run. For oil we have substitutes, for water we have none.” –Gotthilf Hemple -1 in every 6 people lack regular access to clean water.

  12. Stress on the World’s River Basins • Comparison of the amount of water available with the amount used by humans. Figure 14-6

  13. Too Little Freshwater • Farmers and cities are competing for available water and farmers are losing because they require so much. • Plus, more crops are needed for the production of bio fuels. • How to get more water- • 1. Withdrawing groundwater • 2. Building dams and reservoirs • 3. bring freshwater from other areas • 4. Desalination

  14. Withdrawing Groundwater to Increase Supplies • Most aquifer are renewable unless their water is depleted faster then it can renew itself. • Most aquifers are being depleted mainly for irrigation. • Countries like India and China are rapidly depleting groundwater and it will eventually run out causing famine and economic, political and social chaos.

  15. Trade-Offs Withdrawing Groundwater Advantages Disadvantages Useful for drinking and irrigation Aquifer depletion from overpumping Sinking of land (subsidence) from overpumping Available year-round Exists almost everywhere Polluted aquifers for decades or centuries Renewable if not overpumped or contaminated Saltwater intrusion into drinking water supplies near coastal areas Reduced water flows into surface waters No evaporation losses Increased cost and contamination from deeper wells Cheaper to extract than most surface waters Fig. 14-7, p. 313

  16. Groundwater Depletion: A Growing Problem • The Ogallala, the world’s largest aquifer, is most of the red area in the center (Midwest). • Areas of greatest aquifer depletion from groundwater overdraft in the continental U.S. Figure 14-8

  17. Other Effects of Groundwater Overpumping • Groundwater overpumping can cause land to sink, and contaminate freshwater aquifers near coastal areas with saltwater. Figure 14-11

  18. Solutions Groundwater Depletion Prevention Control Raise price of water to discourage waste Waste less water Subsidize water conservation Ban new wells in aquifers near surface waters Tax water pumped from wells near surface waters Buy and retire groundwater withdrawal rights in critical areas Set and enforce minimum stream flow levels Do not grow water-intensive crops in dry areas Fig. 14-12, p. 316

  19. Using Dams and Reservoirs • Main purpose is to capture and store runoff and release it as needed to control floods, generate electricity and to supply water for irrigation and for towns and cities. • There are more then 45,000 dams (22,000 in China). • Dams can reduce water downstream and prevent water from reaching the sea and altering the hydrologic cycle.

  20. 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 Fig. 14-13a, p. 317

  21. The Colorado River Basin • The area drained by this basin is equal to more than one-twelfth of the land area of the lower 48 states. Figure 14-14

  22. Using Dams and Reservoirs • Case Study: China’s 3 Gorges Dam • 1.4 miles long and cost $25 billion. • Good news: electrical output of 18 coal plants (reduce CO2), reduce floodwaters that kill 1,000s of people a year and it will allow cargo ships to travel further into China • Bad news: The huge reservoir behind the dam will displace 1.2 million people. It will flood 1,350 cities and towns • Mixed news: It is built on a seismic fault and could collapase during a earthquake and cause massive flooding. About 80 small cracks have already been found. Builders claim the dam can withstand a large earthquake.

  23. Dam Removal • Some dams are being removed for ecological reasons and because they have outlived their usefulness. • In 1998 the U.S. Army Corps of Engineers announced that it would no longer build large dams and diversion projects in the U.S. • 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.

  24. Transferring Water • Advantages: brings water to dry areas for crops, grazing, and other business. • Disadvantages: encourages unsustainable use of water in areas where water is naturally available.

  25. Transferring Water • Case Study: California Experience • California Water Project uses dams, pumps and aquaducts to transfer water from north California to south California • South wants more water from north to help grow more crops and support large cities. North claims that giving more water will degrade the rivers, threaten fisheries, and reduce flushing action that helps Sacramento Bay with pollutants.

  26. CALIFORNIA NEVADA Shasta Lake UTAH Sacramento River Oroville Dam and Reservoir Feather River North Bay Aqueduct Lake Tahoe Sacramento San Francisco Hoover Dam and Reservoir (Lake Mead) South Bay Aqueduct Fresno San Joaquin Valley San Luis Dam and Reservoir Colorado River Los Angeles Aqueduct ARIZONA California Aqueduct Colorado River Aqueduct Central Arizona Project Santa Barbara Los Angeles Salton Sea San Diego Phoenix Tucson MEXICO Fig. 14-16, p. 321

  27. Transferring Water • Case Study: The Aral Sea Disaster • Aral Sea is shrinking b/c its waters have been transferred to drier areas for irrigation • Salinity has tripled, average level has dropped by 22 meters, lost 90% of its volume and has split in 2. • 85% of wetlands have vanished and ½ of the bird and mammal species have disappeared. • Many more effects (pg 321-322)

  28. Case Study: The Aral Sea Disaster • The Aral Sea was once the world’s fourth largest freshwater lake. Figure 14-17

  29. Desalination • Desalination: • Methods- • Distillation: • Reverse Osmosis:

  30. Desalination • 13,400 desalination plants mostly in countries that have dry, arid areas and are wealthy • 2 major problems: • High cost b/c it takes a lot of energy • Produces large amount of briny waste water very high in salt

  31. Increasing Water Supplies by Wasting Less Water • Estimated that 65-70% of the water used is lost through evaporation, leaks, and other losses. • If we could reduce water loss by 15% we could meet the world’s water needs. • Decrease burden on wastewater plants, reduce the need for expensive dams and water transfer projects, slow depletion of groundwater aquifers.

  32. Increasing Water Supplies by Wasting Less Water • 2 Causes of water waste • Main cause of water waste is we charge too little for water. Gives users no financial incentive to safe water. • Lack of gov’t subsides for improving the efficiency of water use.

  33. Increasing Water Supplies by Wasting Less Water • Solutions: • More efficient and environmentally sound irrigation technology • Center-pivot, low pressure sprinkler: • Low-energy, precision application sprinkler: • Drip irrigation: • DRiWATER:

  34. Drip irrigation (efficiency 90–95%) Gravity flow (efficiency 60% and 80% with surge valves) Center pivot (efficiency 80%–95%) Water usually pumped from underground and sprayed from mobile boom with sprinklers. Above- or below-ground pipes or tubes deliver water to individual plant roots. Water usually comes from an aqueduct system or a nearby river. Fig. 14-18, p. 325

  35. Solutions Reducing Irrigation Water Waste • Line canals bringing water to irrigation ditches • Level fields with lasers • Irrigate at night to reduce evaporation • Monitor soil moisture to add water only when necessary • Polyculture • Organic farming • Don't grow water-thirsty crops in dry areas • Grow water-efficient crops using drought resistant and salt-tolerant crop varieties • Irrigate with treated urban waste water • Import water-intensive crops and meat Fig. 14-19, p. 326

  36. Solutions Reducing Water Waste • Redesign manufacturing processes • Repair leaking underground pipes • Landscape yards with plants that require little water • Use drip irrigation • Fix water leaks • Use water meters • Raise water prices • Use waterless composting toilets • Require water conservation in water-short cities • Use water-saving toilets, showerheads, and front loading clothes washers • Collect and reuse household water to irrigate lawns and nonedible plants • Purify and reuse water for houses, apartments, and office buildings • Don't waste energy Fig. 14-21, p. 327

  37. Too Much Water • Caused by heavy rain or rapid melting of snow. • To reduce flooding rivers have been narrowed and straightened, equipped with protective levees and walls and dammed. • Human activities that have increased floods include removal of water absorbing vegetation, draining and building on wetlands

  38. TOO MUCH WATER • Human activities have contributed to flood deaths and damages. Figure 14-23

  39. Solutions: Using Water More Sustainably • Expand and improve monitoring of river flows, aquifer levels, sizes and recharge rate and watershed health. • Overhaul water policy to protect natural ecosystems that help store water, slow erosion, help groundwater recharge, provide flood control. • Regulate aquifer withdrawals • Leave enough water in rivers to protect wildlife, ecological processes and services • Remove gov’t subsides that allow water to be underpriced and add subsides that reward water conservation • Switch to waste treatment plants that only accept non-toxic waste, use less water to treat waste • Get very serious about slowing global warming • Slow population growth.

  40. SOLUTIONS: USING WATER MORE SUSTAINABLY • We can use water more sustainably by cutting waste, raising water prices, preserving forests and wetlands in water basins, and slowing population growth. Figure 14-25

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