Freshwater Resources and Water Pollution

1. Freshwater Resources and Water Pollution Chapter 10

2. Drought in Australia • The Murray-Darling Basin supports the city of Adelaide and provides 65% of water used by Australia’s agriculture • Currently threatened after 8 years of drought • About 40% of Australia’s crops are raised in this semi-arid region • Farmers compete with city residents • Environment is changing • Lakes become salty, native species die, wetlands become toxic, ethnologically important plants and animals have been lost • Environmental and economic damage

3. The Importance of Water Learning Objectives: • Explain how processes of the hydrologic cycle allow water to circulate through the abiotic environment • Describe the structure of a water molecule and explain how hydrogen bonds form between adjacent water molecules • List the unique properties of water

4. The Importance of Water • Life on Earth would be impossible without water • All living organisms contain water • Humans are approximately 60% water • Uses: • Drinking, cooking, washing, travel on it, agriculture, manufacturing, mining, energy production, waster disposal • Less than 3% of Earth’s water is consumable • 97% is salty • Uneven distribution - serious regional supply issues • By 2025, more than 1/3 of humans will live in areas with inadequate supply of drinking/irrigation water

5. The Importance of Water

6. The Importance of Water • The Hydrologic Cycle and Our Supply of Freshwater • Water circulates in the environment • Provides balance of water in ocean, land, atmosphere • Renews supply of freshwater on land

7. The Importance of Water

8. The Importance of Water

9. The Importance of Water • Surface Water: • Precipitation that remains on the surface of the land and does not seep down through the soil • Runoff: • Drainage basin/watershed: • Groundwater: • The supply of freshwater that is stored in underground aquifers (underground reservoirs) • Considered a non-renewable resource, takes 100s–1000s of years to form

10. The Importance of Water

11. The Importance of Water • Properties of Water • Molecules of H2O • Polar molecules • The O end of the molecule has negative charge • The H end of the molecule has positive charge • Hydrogen bonds • Form between 2 molecules of H2O due to opposite charges of the two ends of each molecule • Responsible for many physical properties of water

12. The Importance of Water

13. Global Climate Change • What is surface water? • How do hydrogen bonds form between adjacent water molecules? • What are the unique properties of water?

14. Water Resource Problems Learning Objectives • Relate some of the problems caused by aquifer depletion, overdrawing of surface waters, and salinization of irrigated soil • Relate the background behind the water problems of the Ogallala Aquifer and the Colorado River Basin • Briefly describe the role of international cooperation in managing shared water resources

15. Water Resource Problems Three categories: • Too much water • Too little water • Poor-quality water

16. Water Resource Problems • Flooding • Occurs when a river’s discharge cannot be contained within its normal channel • Humans remove water-absorbing plant cover and construct buildings on flood plains • Area bordering a river channel that has the potential to flood • Construction replaces flood-protecting plant cover

17. Water Resource Problems

18. Water Resource Problems

19. Water Resource Problems

20. Water Resource Problems • Too little water • Arid lands: desert • Plant growth is limited by lack of precipitation • Semiarid lands: • Receive more precipitation than deserts, but have long periods of drought • Farmers use irrigation to increase agricultural productivity of arid and semi-arid lands • Amount of irrigated land has tripled • 71% of world’s total water is used for irrigation

21. Water Resource Problems

22. Water Resource Problems • Aquifer Depletion • Results form excessive removal of groundwater, faster than it can be recharged by precipitation or melting snow • Lowers the water table • The upper surface of the saturated zone of groundwater • Subsidence (sinking of the land) • In areas with porous sediments • Saltwater intrusion • Movement of seawater into a freshwater aquifer near the coast

23. Water Resource Problems • The Ogallala Aquifer • Largest groundwater deposit in the world • Farmers are drawing water 40 times faster than it can be replaced by nature • Water table has been lowered 30m (100ft) • Water conservation esp. through water-saving irrigation will postpone aquifer depletion

24. Water Resource Problems

25. Water Resource Problems • Overdrawing of Surface Waters • Wetlands dry up • Estuaries become saltier • Serve as breeding grounds for many species • Play vital role in water cycle • Water shortages have great economic and ecological ramifications • Water supply and Water quality problems • West and Southwest US, Florida

26. Water Resource Problems • Colorado River Basin • Serious water problems in US • Provides water for 30 million people • Provides irrigation for 3.5 million acres • International and State laws and agreements • Insufficient water supply for upper Colorado populations and Mexico - violates agreements • Colorado river water is saltier than the ocean in some places • California has agreed to reduce the amount of water withdrawn

27. Water Resource Problems

28. Water Resource Problems • Salinization of Irrigated Soil • Gradual accumulation of slat in soil, often as a result of improper irrigation methods • Normally, precipitation runoff would carry away salts • Salt accumulation becomes poisonous for plants • May render soil unfit for crop production

29. Water Resource Problems • Global Water Issues

30. Water Resource Problems

31. Water Resource Problems

32. Water Resource Problems

33. Water Resource Problems

34. Water Resource Problems

35. Water Resource Problems

36. Water Resource Problems

37. Global Climate Change • What problems are associated with overdrawing surface water? With aquifer depletion? • What issues surround water problems of the Ogallala Aquifer? The Colorado River basin? • How does international cooperation affect shared water resources?

38. Water Management Learning Objectives: • Define sustainable water use • Contrast the benefits and drawbacks of dams and reservoirs • Give examples of water conservation in agriculture, industry, and individual homes and buildings

39. Water Management • Sustainable water use: • The wise use of water resources, without harming the essential functioning of the hydrologic cycle or the ecosystems on which present and future humans depend • Conservation: • Includes reusing and recycling water, improving water use efficiency. • Important part of sustainable use • Economic Policies: • If water is cheap, it tends to be wasted

40. Water Management • Dams and Reservoirs: • Dams generate electricity and ensure year-round supply of water • Costs vs. Benefits • Columbia River - 4th largest in North America • More than 100 dams generate electricity and provide water • Negative impact on fish populations

41. Water Management

42. Water Management

43. Water Management • Water Conservation • Reducing agricultural water waste • Reducing water waste in industry • Reducing municipal water waste

44. Water Management

45. Water Management

46. Global Climate Change • What is sustainable water use? • What are the benefits of dams on the Columbia River? The drawbacks? • How can individuals conserve and manage water resources?

47. Water Pollution Learning Objectives: • Define water pollution • Discuss how sewage is related to eutrophication, biochemical oxygen demand (BOD), and dissolved oxygen • Distinguish between the two types of pollution sources and give examples of each • Describe sources of groundwater pollution

48. Water Pollution • A physical or chemical change in water that adversely affects the health of humans and other organisms • Sewage • Disease-causing agents • Sediment pollution • Inorganic plant and algal nutrients • Organic compounds • Inorganic chemicals • Radioactive substances • Thermal pollution

49. Water Pollution

50. Water Pollution