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Ch. 13: Water Resources

Ch. 13: Water Resources. By Chris McCord and Weston Takata. How Can We Deal With Our Water Problems?. Will We Have Enough Usable Water?. We Are Misusing Our Freshwater. Earth’s surface is 71% saltwater Water is necessary for life, food, and shelter

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Ch. 13: Water Resources

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  1. Ch. 13: Water Resources By Chris McCord and Weston Takata

  2. How Can We Deal With Our Water Problems?

  3. Will We Have Enough Usable Water?

  4. We Are Misusing Our Freshwater • Earth’s surface is 71% saltwater • Water is necessary for life, food, and shelter • Global Health Issue – lack of water is single largest cause of illness • Economic Issue – vital for reducing poverty and producing food and energy • Environmental Issue – many environmental indicators related to water are worsening

  5. Availability of Freshwater • Only .024% of Earth’s water is readily available • Hydrologic cycle recycles Earth’s freshwater • Groundwater – collected water underground • Aquifers – underground caverns of rock through which water flows • Surface water – lakes, rivers, streams, etc. • Reliable surface runoff – the amount of surface runoff that we can generally count on as a source of freshwater • We are using a large and growing portion of the world’s reliable surface runoff

  6. Water Cycle

  7. Water Shortage • Drought – prolonged period in which precipitation is at least 70% lower and evaporation is higher than normal • Water shortages are growing • By 2025, 3 billion people could lack access to safe water • 30% of Earth’s land experiences severe drought • Who should own and manage freshwater resources?

  8. Is Extracting Groundwater the Answer?

  9. Withdrawing Groundwater Advantages Disadvantages • Useful for drinking and irrigation • Available year-round • Exists almost everywhere • Renewable if not overpumped or contaminated • No evaporation losses • Cheaper • Aquifer Depletion • Sinking of land – subsidence • Polluted aquifers • Saltwater intrusion near coast • Reduced water flows into surface waters • Increased cost and contamination

  10. Aquifer Depletion

  11. Is Building More Dams the Answer?

  12. Large Dams and Reservoirs • Dam – structure built across a river to control the river’s water flow • Reservoir – created behind dam • Increase reliable runoff • Generate electricity • Areas must be flooded to build the dam • Reservoirs can lose water due to evaporation

  13. Dams

  14. Will Transferring Water Solve Our Problems?

  15. California Water Project • Divert water from North to arid South • Major issue in CA • Analysts  improve irrigation efficiency

  16. Case Study: The Shrinking of the Aral Sea • 1960  Soviet Union creates large irrigation system • Salt desert left behind • Himalayas melting • Locals becoming ill • Hope for future

  17. China’s Water Transfer Project • Water arid North • Benefits outweigh risks & costs • Unfortunate ending for China?

  18. What about Converting Saltwater to Freshwater?

  19. Desalination • Distillation • Evaporate water & condense it • Requires lot of energy • Reverse Osmosis (Microfiltration) • Pressure pushes water through filter • Expensive

  20. How Can We Use Water Sustainably?

  21. Irrigation • Three types of Irrigation: • Gravity Flow  60% efficiency; 80% w/ surge valve • Center Pivot  80% efficiency; 90-95% w/ LEPA sprinkler • Drip Irrigation  90-95% efficiency

  22. Flood Irrigation Center Pivot Irrigation Drip Irrigation

  23. Domestic Water Use

  24. Solutions for Sustainable Water Use at Home and in Industry

  25. Floodplains • Flat land surrounding streams/rivers with potential for flooding • Humans have major impact on frequency & damage of flooding • We can reverse the current trend

  26. Case Study: Flooding in Bangladesh • Many people on small amount of land • Flat terrain at sea level • Annual monsoon flooding; 1 major every 50 yrs. • Due to human hand, major flood every 4 yrs. • Global warming a problem for future

  27. In Depth Look – Hoover Dam

  28. Hoover Dam • Border of Arizona and Nevada – Colorado River • Opened in 1936 • 726 feet high • Reservoir – Lake Mead – 167,800 sq miles • Generates 4.2 billion KWh annually • Provides power to Nevada, Arizona, and Southern California

  29. Environmental Impact • Decline of estuary at Colorado River Delta • Eliminated natural flooding of Colorado River – causing extinctions • Decreasing water levels due to evaporation

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