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Water Resources- PART 1

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  1. Water Resources- PART 1 Chapter 13

  2. Core Case Study: Water Conflicts in the Middle East: A Preview of the Future • Water shortages in the Middle East: hydrological poverty • Nile River • Jordan Basin • Tigris and Euphrates Rivers • Peacefully solving the problems

  3. Three Major River Basins in the Middle East

  4. 13-1 Will We Have Enough Usable Water? • Concept 13-1A We are using available freshwater unsustainably by wasting it, polluting it, and charging too little for this irreplaceable natural resource. • Concept 13-1B One of every six people does not have sufficient access to clean water, and this situation will almost certainly get worse.

  5. Freshwater Is an Irreplaceable Resource That We Are Managing Poorly (1) • Why is water so important? • Earth as a watery world: 71% • Freshwater availability: 0.024% • Poorly managed resource • Hydrologic cycle • Water pollution

  6. Freshwater Is an Irreplaceable Resource That We Are Managing Poorly (2) • Access to water is • A global health issue • An economic issue • A women’s and children’s issue • A national and global security issue

  7. Girl Carrying Well Water over Dried Out Earth during a Severe Drought in India

  8. Most of the Earth’s Freshwater Is Not Available to Us • Hydrologic cycle • Movement of water in the seas, land, and air • Driven by solar energy and gravity • People divided into • Water haves • Water have-nots

  9. We Get Freshwater from Groundwater and Surface Water (1) • Ground water • Zone of saturation • Water table • Aquifers • Natural recharge • Lateral recharge

  10. We Get Freshwater from Groundwater and Surface Water (2) • Surface Water • Surface runoff • Watershed (drainage) basin • Reliable runoff • 1/3 of total

  11. Unconfined Aquifer Recharge Area Evaporation and transpiration Evaporation Precipitation Confined Recharge Area Runoff Flowing artesian well Well requiring a pump Stream Water table Infiltration Lake Infiltration Unconfined aquifer Less permeable material such as clay Confined aquifer Confining impermeable rock layer Fig. 13-3, p. 316

  12. We Use a Large and Growing Portion of the World’s Reliable Runoff • 2/3 of the surface runoff: lost by seasonal floods • 1/3 runoff usable • Domestic: 10% • Agriculture: 70% • Industrial use: 20% • Fred Pearce, author of When the Rivers Run Dry

  13. Case Study: Freshwater Resources in the United States • More than enough renewable freshwater, unevenly distributed • Effect of • Floods • Pollution • Drought • 2007: U.S. Geological Survey projection • Water hotspots

  14. Average annual precipitation (centimeters) Less than 41 81–122 41–81 More than 122 Fig. 13-4a, p. 317

  15. Fig. 13-4b, p. 317

  16. Washington North Dakota Montana Oregon South Dakota Idaho Wyoming Nevada Nebraska Utah Colorado Kansas California Oklahoma New Mexico Arizona Texas Highly likely conflict potential Substantial conflict potential Moderate conflict potential Unmet rural water needs Fig. 13-5, p. 318

  17. Water Shortages Will Grow (1) • Dry climate • Drought • Too many people using a normal supply of water

  18. Water Shortages Will Grow (2) • Wasteful use of water • China and urbanization • Hydrological poverty

  19. Asia Europe North America Africa South America Australia Stress High None Fig. 13-6, p. 319

  20. Long-Term Severe Drought Is Increasing • Causes • Extended period of below-normal rainfall • Diminished groundwater • Harmful environmental effects • Dries out soils • Reduces stream flows • Decreases tree growth and biomass • Lowers net primary productivity and crop yields • Shift in biomes

  21. In Water-Short Areas Farmers and Cities Compete for Water Resources • 2007: National Academy of Science study • Increased corn production in the U.S. to make ethanol as an alternative fuel • Decreasing water supplies • Aquifer depletion • Increase in pollution of streams and aquifers

  22. Who Should Own and Manage Freshwater Resources? (1) • Most water resources • Owned by governments • Managed as publicly owned resources • Veolia and Suez: French companies • Buy and manage water resources • Successful outcomes in many areas

  23. Who Should Own and Manage Freshwater Resources? (2) • Bechtel Corporation • Poor water management in Bolivia • A subsidiary of Bechtel Corporation • Poor water management in Ecuador • Potential problems with full privatization of water resources • Financial incentive to sell water; not conserve it • Poor will still be left out

  24. 13-2 Is Extracting Groundwater the Answer? • Concept 13-2 Groundwater that is used to supply cities and grow food is being pumped from aquifers in some areas faster than it is renewed by precipitation.

  25. Water Tables Fall When Groundwater Is Withdrawn Faster Than It Is Replenished • India, China, and the United States • Three largest grain producers • Overpumping aquifers for irrigation of crops • India and China • Small farmers drilling tubewells • Effect on water table • Saudi Arabia • Aquifer depletion and irrigation

  26. 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. 13-7, p. 321

  27. Natural Capital Degradation: Irrigation in Saudi Arabia Using an Aquifer

  28. Case Study: Aquifer Depletion in the United States • Ogallala aquifer: largest known aquifer • Irrigates the Great Plains • Water table lowered more than 30m • Cost of high pumping has eliminated some of the farmers • Government subsidies to continue farming deplete the aquifer further • Biodiversity threatened in some areas • California Central Valley: serious water depletion

  29. Groundwater Overdrafts: High Moderate Minor or none Fig. 13-9, p. 322

  30. SOUTH DAKOTA WYOMING NEBRASKA COLORADO KANSAS OKLAHOMA NEW MEXICO Miles TEXAS 0 100 160 0 Kilometers Saturated thickness of Ogallala Aquifer Less than 61 meters (200 ft.) 61–183 meters (200–600 ft.) More than 183 meters (600 ft.) (as much as 370 meters or 1,200 ft. in places) Fig. 13-10, p. 323

  31. Groundwater Overpumping Has Other Harmful Effects (1) • Limits future food production • Bigger gap between the rich and the poor • Land subsidence • Mexico City • Sinkholes

  32. Groundwater Overpumping Has Other Harmful Effects (2) • Groundwater overdrafts near coastal regions • Contamination of the groundwater with saltwater • Undrinkable and unusable for irrigation

  33. SOLUTIONS Groundwater Depletion Prevention Control Waste less water Raise price of water to discourage waste Subsidize water conservation Tax water pumped from wells near surface waters Limit number of wells Set and enforce minimum stream flow levels Do not grow water-intensive crops in dry areas Divert surface water in wet years to recharge aquifers Fig. 13-11, p. 324

  34. Science Focus: Are Deep Aquifers the Answer? • Locate the deep aquifers; determine if they contain freshwater or saline water • Major concerns • Geological and ecological impact of pumping water from them • Flow beneath more than one country • Who has rights to it?

  35. Active Figure: Threats to aquifers

  36. 13-3 Is Building More Dams the Answer? • Concept 13-3 Building dam and reservoir systems has greatly increased water supplies in some areas, but it has disrupted ecosystems and displaced people.

  37. Large Dams and Reservoirs Have Advantages and Disadvantages (1) • Main goals of a dam and reservoir system • Capture and store runoff • Release runoff as needed to control: • Floods • Generate electricity • Supply irrigation water • Recreation (reservoirs)

  38. Large Dams and Reservoirs Have Advantages and Disadvantages (2) • Advantages • Increase the reliable runoff available • Reduce flooding • Grow crops in arid regions

  39. Large Dams and Reservoirs Have Advantages and Disadvantages (3) • Disadvantages • Displaces people • Flooded regions • Impaired ecological services of rivers • Loss of plant and animal species • Fill up with sediment within 50 years

  40. Advantages and Disadvantages of Large Dams and Reservoirs

  41. The Ataturk Dam Project in Eastern Turkey

  42. Some Rivers Are Running Dry and Some Lakes Are Shrinking • Dams disrupt the hydrologic cycle • Major rivers running dry part of the year • Colorado and Rio Grande, U.S. • Yangtze and Yellow, China • Indus, India • Danube, Europe • Nile River-Lake Victoria, Egypt • Lake Chad Africa: disappearing

  43. Case Study: The Colorado River Basin— An Overtapped Resource (1) • 2,300 km through 7 U.S. states • 14 Dams and reservoirs • Located in a desert area within the rain shadow of the Rocky Mountains • Water supplied mostly from snowmelt of the Rocky Mountains

  44. Case Study: The Colorado River Basin— An Overtapped Resource (2) • Supplies water and electricity for more than 25 million people • Irrigation of crops • Recreation

  45. Case Study: The Colorado River Basin— An Overtapped Resource (3) • Four Major problems • Colorado River basin has very dry lands • Modest flow of water for its size • Legal pacts allocated more water for human use than it can supply • Amount of water flowing to the mouth of the river has dropped

  46. Case Study: The Colorado River Basin— An Overtapped Resource (4) • What will happen if some of the reservoirs empty out? • Economic and ecological catastrophe • Political and legal battles over water

  47. The Colorado River Basin

  48. Aerial View of Glen Canyon Dam Across the Colorado River and Lake Powell

  49. 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. 13-16, p. 328

  50. Case Study: China’s Three Gorges Dam (1) • World’s largest hydroelectric dam and reservoir • 2 km long across the Yangtze River • Benefits • Electricity-producing potential is huge • Holds back the Yangtze River floodwaters • Allows cargo-carrying ships