Chapter 14 – water resources

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  • 1. Chapter 14 – Water Resources Where does your drinking water come from?
  • 2.
    • I. Earth’s Water Supply
      • A. Where is Earth’s water?
        • 1. 97.2% - oceans
        • 2. 2.2% - icecaps and glaciers
        • 3. 0.6% - surface or groundwater
  • 3.
    • B. Earth’s supply of fresh water is continuously being renewed through the water cycle
      • 1. Definition – the movement of water from the oceans and freshwater sources to the air and land and finally back to the oceans
  • 4.  
  • 5.
    • 2. Processes:
      • a. evaporation – from surface water, soil and organisms
      • b. condensation – air containing water vapor cools and forms clouds
      • c. precipitation – rain, sleet, snow, or hail
          • i. may run-off into surface water
          • ii. may infiltrate into groundwater
  • 6. Review Questions
    • 1. What percentage of Earth’s water is available to us as fresh water?
    .6%
  • 7. 2. Draw a simple diagram of the water cycle and label the 3 main processes.
  • 8. II. Surface Water
    • A. Running Water
      • 1. Includes rivers and streams
      • 2. May enter through surface run-off from the surrounding watershed (the land area from which surface run-off drains into a system of rivers and streams)
  • 9.  
  • 10.
    • B. Standing Water
      • 1. Includes lakes, ponds, wetlands (ie. swamps and marshes), and reservoirs
      • 2. Form when run-off gets caught in low places , or by artificial means
  • 11.
    • III. Groundwater
      • A. Water continues to move downward after it hits the ground, through permeable layers of soil and rock, then stops moving when it reaches an impermeable layer of rock
  • 12.  
  • 13.  
  • 14.
    • B. Water table – the level below which the ground is saturated with water
      • 1. May be high in some areas (ie. near the sea, or in low-lying forests), and deep in others (ie. deserts)
      • 2. Depth may change with precipitation, drought, or overuse of wells
  • 15.  
  • 16.
    • C. Aquifers – layers of rock or sediment that allow groundwater to pass freely; sources of groundwater
      • 1. Rate of movement varies with amount of precipitation, porosity of the rock, and slope of the aquifer
  • 17.  
  • 18. 2. Groundwater may leave the aquifer and become surface water at the “ zone of discharge ”, may pump out on its own (when under pressure) through an “ artesian well ”, or may be accessed by drilling wells
  • 19. Artesian Well
  • 20.  
  • 21. Review Questions 1. What is a watershed? How does water get from a watershed to a river? The land area from which water drains into rivers and streams.
  • 22. 2. Describe how groundwater forms. Water moves down through the ground through permeable layers of rock until it hits an impermeable layer.
  • 23. 3. What causes the differences in the depth of the water table? Precipitation Drought Overuse
  • 24. 4. Name 2 ways that we may obtain water from an aquifer. Drilling wells or artesian wells.
  • 25. IV. Uses of Water
    • A. Residential use
      • 1. The average person in the U.S. uses about 300 L of water each day
      • 2. Uses include personal hygiene, cleaning, flushing toilets, gardening/landscaping, car washing, and recreational activities
  • 26.
    • B. Industrial use
      • 1. About 44% of all fresh water is used by industry
      • 2. Uses include transporting goods, disposal of waste, generating power, cooling machinery, mining and refining natural resources, manufacturing raw materials , and producing synthetic materials
  • 27.
    • C. Agricultural use
      • 1. The single largest user of water in the U.S. (almost ½ of all freshwater use)
      • 2. Irrigation – the process of bringing water to an area for use in growing crops
  • 28.  
  • 29. Review Questions
    • 1. Compare your daily residential use of water to that of a person in a developing country (like Kenya). What ways do you use water that they probably do not?
    -daily shower -wash cars
  • 30. 2. Make a list of all of the ways that you have used water so far today. Don’t forget to include industrial and agricultural uses!
  • 31.
    • V. Water Resource Problems
      • A. Overdraft
    • 1. Occurs when a body of water is drained faster than it is filled ; may occur in surface water or groundwater Ex. The Ogallala aquifer is the largest aquifer in the world and supplies water to 8 midwestern states; the water in this aquifer is expected to last only 40 more years
  • 32. Ogallalla Aquifer
  • 33.
    • 2. Other problems with overdraft–
      • a. intrusion of salt water into freshwater aquifers
      • b. subsidence , or sinking, of bedrock
  • 34.  
  • 35.
    • B. Habitat degradation or destruction
      • 1. Includes water diversion (changing stream courses), building dams and reservoirs , and draining wetlands
  • 36. Extinct woodpecker because of habitat loss
  • 37. 2. Damages or destroys habitat of aquatic organisms such as fish, amphibians, and invertebrates, as well as migratory birds
  • 38.  
  • 39. Review Questions
    • 1. What is overdraft? What causes overdraft?
    Overdraft occurs when a body of water is drained faster than it is replenished.
  • 40. 2. Why do humans change stream courses, build dams and reservoirs, and drain wetlands? The main reason is to develop the land.
  • 41. 3. What do humans need to do in order to solve some of our water resource problems? Make water conservation a priority.
  • 42. VI. Water Treatment
    • A. Removing Salts
      • 1. The process by which salts are removed from the water is called desalination
  • 43.
    • 2. Methods:
      • a. Distillation – water is heated to boiling so water evaporated but salt remains; water vapor is cooled and fresh water collected
      • b. Reverse Osmosis - salt water is forced through a strainer that traps the salt and lets the fresh water pass
  • 44. Distillation
  • 45. c. Freezing – salt water is frozen and separates, forming an ice and brine slush; ice can be melted to obtain fresh water
  • 46. B. Water Purification
    • Water Purification
      • 1. This process removes harmful chemicals and microorganisms that make the water unpotable , or unfit to drink
      • 2. Process:
        • a. Screening – traps and removes large debris from water
  • 47.
    • b. Sedimentation –
      • i. water passes to large settling tanks where particles suspended in the water settle to the bottom as sediment
      • ii. chemicals called coagulants may be added to cause the particles to clump together and aid in settling
  • 48. c. Filtration – water is passed through a filtering material such as fine sand to remove smaller particles
  • 49.
    • d. Aeration –
      • i. water is exposed to air and sunlight by allowing it to spray into the air or flow as a waterfall
  • 50. ii. bacteria enter the water and break down organic matter and oxygen is mixed in; this process improves the smell and taste of the water
  • 51. e. Sterilization – water is exposed to extreme heat or chemicals such as chlorine in order to remove harmful bacteria and microorganisms
  • 52.  
  • 53. Review Questions
    • 1. If the ocean was your only source of water, what process could remove the salt so it would be drinkable? Describe how this might be done.
    Distillation or reverse osmosis
  • 54. 2. What does “unpotable” mean? It means that it is unsafe to drink.
  • 55. 3. Name the 5 steps of the water treatment process.
    • Screening
    • Sedimentation
    • Filtration
    • Aeration
    • Sterilization
  • 56.