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Environmental Sciences: Towards a Sustainable Future Chapter 7

Environmental Sciences: Towards a Sustainable Future Chapter 7. Water: Hydrologic Cycle and Human Use. The Water Cycle Exists to Purify Water. There are three principal loops in the water cycle. Human have managed to pollute or compromise the function of each loop.

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Environmental Sciences: Towards a Sustainable Future Chapter 7

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  1. Environmental Sciences: Towards a Sustainable Future Chapter 7 Water: Hydrologic Cycle and Human Use

  2. The Water Cycle Exists to Purify Water • There are three principal loops in the water cycle. • Human have managed to pollute or compromise the function of each loop. • We are running out of water in terms of quantity and quality. • Water conservation and stewardship are imperative actions.

  3. Earth’s Water

  4. Water Cycle Processes • Evaporation: water molecules move from liquid to gaseous state; e.g. steam • Condensation: water molecules move from gaseous to liquid or frozen state; e.g. water droplets on cold beverage container • Purification: occurs as a result of evaporation and condensation; impurities are left behind

  5. Condensation

  6. Precipitation • Adiabatic cooling: warm air rises, expands and cools • 100% relative humidity + cooling = clouds • Increasing condensation = water droplets

  7. Global Precipitation • Global precipitation distribution depends on patterns of rising and falling air currents • Two main factors: • global convection currents • rain shadow effect

  8. Rain Shadow Effect

  9. The Water Cycle

  10. Water Cycle Filters Evapotranspiration Loop F D G Surface Runoff Loop B E Ground Water Loop A C

  11. B Water Cycle A D C E F H G

  12. Human Impacts on the Water Cycle • Changing the earth’s surface • Pollution • Withdrawal for use

  13. Changing Earth’s Surface Through Urbanization • Decreased infiltration • Increased runoff

  14. Water Pollution

  15. Water Use

  16. Consequences of Overdrawing Water Supplies • Surface waters: • shortages • ecological effects

  17. Water Use

  18. Vanishing Wetlands

  19. Chemical and Biological Values of Wetlands: Hydrological Cycle • Purify waters • Control floods • Protect shorelines • Recharge groundwater

  20. Chemical and Biological Values of Wetlands: Chemical Cycles • Nitrogen cycle • Sulfur cycle • Carbon cycle

  21. Chemical and Biological Values of Wetlands: Increase Biodiversity • Terrestrial ecosystems • Aquatic ecosystems

  22. Wetland Values - Economic • Pelt and skin harvesting (alligator) • Waterfowl hunting • Sport and commercial fishing • Timber harvesting (hardwood and cypress swamps) • Energy source • Food source

  23. Wetland Values - Intrinsic • Bird watching and wildlife photography • Recreation (hiking, boating) • Biological laboratory for students of all ages

  24. Consequences of Overdrawing • Groundwater: • Falling water tables • Diminishing surface waters (wetlands) • Land subsidence • Saltwater intrusion

  25. Aquifer Exploitation

  26. Sinkholes: YIKES!

  27. Saltwater Anyone?

  28. Using Less Water • Irrigation • Surge flow • Drip irrigation $$$$ • Municipal uses • Incentives and regulations limiting water use • Gray water

  29. Desalting Seawater • Reverse osmosis • Distillation

  30. Storm Water Mismanagement

  31. Other Consequences of Storm Water Mismanagement • Stream bank erosion • Increased pollution • Fertilizers • Pesticides • Pet fecal matter • Road salts and chemicals • Oil

  32. Channelization: Solution or Problem? • Stream bed was straightened and lined with rock or concrete • Passed the problem of flooding downstream to your neighbors

  33. Water Stewardship Working Together • Louisiana Wetlands Conservation and Restoration Trust Fund • $1.5 billion to restore LA wetlands

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