ENVIRONMENTAL SCIENCE

1. ENVIRONMENTALSCIENCE CHAPTER 11:Water Resources and Water Pollution

2. Three Big Ideas from This Chapter: #1 One of the world’s major environmental problems is growing shortages of freshwater in parts of the world.

3. Three Big Ideas from This Chapter: • #2 We can use H2O more sustainably by: • cutting water waste • raising water prices • slowing population growth • protecting aquifers, forests, & other ecosystems that store & release water.

4. Three Big Ideas from This Chapter: • #3 Reducing water pollution requires: • preventing pollution • working with nature in treating sewage • cutting resource use & waste • reducing poverty • slowing population growth.

5. Colorado River Story • 1400 miles thru ___ states • ___ dams & reservoirs • Electricity for _____________ people • Water for ____% of U.S. crops & livestock

6. Fig. 11-2, p. 238

7. Fig. 11-1, p. 238

8. Colorado River Story • Water for desert cities • Very little reaches the

11. Will We Have Enough Usable Water? • We’re using freshwater unsustainably by: • Now: One of every ____ people insufficient access to clean water

12. Fig. 11-3, p. 240

13. Importance & Availability of Water • Earth as a watery world ____% • Poorly managed resource • Water access  global health issue • 3900 children < 5 yrs die each ____ from waterborne disease • Water is

14. Importance & Availability of Water • National and global security issue • Environmental issue • Freshwater availability –

16. Groundwater

17. Surface Water • Surface runoff • Watershed (drainage) basin • Reliable runoff – _____ of total • Runoff use • Domestic – ___% • Agriculture – ___% • Industrial – ___%

18. Freshwater Resources in United States • Uneven distribution • Contamination by agriculture & industry • Groundwater withdrawal: ~_____% of total use

19. Average annual precipitation (centimeters) 81-122 More than 122 Less than 41 41-81 Acute shortage Shortage Adequate supply Metropolitan regions with population greater than 1 million Stepped Art Fig. 11-4, p. 241

20. Freshwater Resources in United States • Arid & semiaridWest: • ____% of water to irrigate thirsty crops • Water hot spots • Southwest: “permanent drying” by _____ • Water tables are _________________ • ____ states to face water shortages by 2013

21. Washington North Dakota Montana Oregon Idaho South Dakota Wyoming Nebraska Nevada Utah Kansas Colorado California Oklahoma Arizona New Mexico Texas Highly likely conflict potential Substantial conflict potential Moderate conflict potential Unmet rural water needs Fig. 11-5, p. 242

22. Freshwater Shortages • Causes of water scarcity • ______________________ • ______________________ • ______________________ • ______________________ • 2050: ____ countries will face water stress! • 1 of 7 people – no regular access to clean water • Potential international conflicts over water

23. Natural capital degradation: stress on the world’s major river basins Asia Europe North America Africa South America Australia Stress None High Fig. 11-6, p. 243

24. How Can We Increase Water Supplies? • Groundwater (supply cities & grow food) • pumped from aquifers

25. Using dams, reservoirs, & transport systems • to provide water to arid regions: • - has increased H2O supplies in some areas • - but has disrupted ecosystems • - displaced _____________________ people.

26. How Can We Increase Water Supplies? Convert ocean water to freshwater Freezing:

27. Electrodialysis: porous membranes filter out (-) & (-) salt ions using an applied electric current.

28. Reverse Osmosis pressure from salt in water, forces water thru a water permeable membrane.

29. Convert ocean water to freshwater, but: • High cost • Resulting salty brine must be disposed of without harming ecosystems.

31. Increasing Freshwater Supplies • Withdrawing groundwater • Dams and reservoirs • Transporting surface water • Desalination • Water conservation

32. Trade-Offs Withdrawing Groundwater Advantages Disadvantages Useful for drinking and irrigation Aquifer depletion from overpumping Sinking of land (subsidence) from overpumping Available year-round Aquifers polluted for decades or centuries Exists almost everywhere Saltwater intrusion into drinking water supplies near coastal areas Renewable if not overpumped or contaminated Reduced water flows into surface waters No evaporation losses Increased cost and contamination from deeper wells Cheaper to extract than most surface waters Fig. 11-7, p. 244

33. Groundwater Withdrawal • Most aquifers are renewable

34. Groundwater Withdrawal • U.S. groundwater withdrawn _____ times faster then it’s replenished • _____________ aquifer

35. Groundwater Withdrawal • California’s Central Valley and agriculture

36. Groundwater Overdrafts: High Moderate Minor or none Fig. 11-8, p. 244

37. Solutions Groundwater Depletion Prevention Control Raise price of water to discourage waste Waste less water Tax water pumped from wells near surface waters Subsidize water conservation Limit number of wells Set and enforce minimum stream flow levels Divert surface water in wet years to recharge aquifers Do not grow water-intensive crops in dry areas Fig. 11-9, p. 245

38. Are Deep Aquifers the Answer? • Could have enough water to supply billions of • people for centuries • Concerns: • _______________________ • Geological and ecological impacts of pumping them __________________ • No treaties to govern water rights • Costs unknown

39. Provides irrigation water above and below dam Flooded land destroys forests or cropland and displaces people Large losses of water through evaporation Provides water for drinking Deprives downstream cropland and estuaries of nutrient-rich silt Reservoir useful for recreation and fishing Risk of failure and devastating downstream flooding Can produce cheap electricity (hydropower) Reduces downstream flooding Disrpupts migration and spawning of some fish Fig. 11-10, p. 246

41. Overtapped Colorado River Basin • Only small amount reaches Gulf of California • Threatened species • Climate change will likely ___________flows • Less water in Southwest • ______________________________ • ______ behind dams not reaching delta • and will eventually _____________________

42. 35 30 Hoover Dam completed (1935) 25 20 Flow (billion cubic meters) 15 Glen Canyon Dam completed (1963) 10 5 0 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Year Fig. 11-11, p. 247

43. California Water Project • Dams, pumps, aqueducts • Southern California would otherwise be desert • Climate change will reduce water availability in California • People in southern California may have to move • Groundwater already being depleted

44. CALIFORNIA NEVADA Shasta Lake UTAH Sacramento River Oroville Dam and Reservoir Feather River Lake Tahoe North Bay Aqueduct 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 California Aqueduct ARIZONA Colorado River Aqueduct Santa Barbara Central Arizona Project Los Angeles Phoenix Salton Sea San Diego Tucson MEXICO Fig. 11-12, p. 247

45. Aral Sea Disaster:

46. Aral Sea Disaster: • Large-scale water transfers in dry central Asia • Water loss and salinity increase • Wetland destruction and wildlife • Fish extinctions hurt fishing industry

47. 1976 2006 • Aral Sea Disaster: • Wind-blown salt • Water pollution • Climatic changes • Restoration efforts

48. How Can We Use Water More Sustainably? • cutting _________________________ • raising ________________________ • slowing population growth • protecting

49. Reducing Water Waste • Benefits of water conservation • Worldwide – __________% loss • Evaporation, leaks • Can be reduced to ____% • Increase cost of water use • End subsidies for wasteful water use • Provide subsidies for efficient water use

50. Reducing Water Waste • Improve irrigation efficiency: • Center pivot • Low-pressure sprinkler • Precision sprinklers • Drip irrigation • Use less in homes and businesses