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Water Use and Management


Water Use and Management Chapter 11 Section 2 Global Water Use The three major uses of water are residential, agricultural, and industrial Most fresh water worldwide ... – PowerPoint PPT presentation

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Title: Water Use and Management

Water Use and Management
  • Chapter 11 Section 2

Global Water Use
  • The three major uses of water are residential,
    agricultural, and industrial
  • Most fresh water worldwide is used to irrigate
  • Availability of fresh water, population size, and
    economic conditions affect how people use water

Residential Water Use
  • The average person in the U.S. uses about 300
    gallons of water every day--only half is used
    inside, the rest is used outside for watering,
    washing cars, etc.
  • In India, the average person uses 41 gallons of
    water every day

Water Treatment
  • Most water must be treated to make it potable
    (safe to drink)
  • Water treatment removes mercury, arsenic, and
    lead as well as pathogens (organisms that cause
    illness or disease)

Steps of Water Treatment
  • First filtration--the source of water supply is
    filtered to remove large organisms and trash
  • Coagulation--alum is mixed in to form sticky
    globs (flocs). Bacteria clings to the flocs which
    settle to the bottom
  • Second filtration--layers of sand, gravel, and
    coal filter remaining impurities
  • Chlorination--added to prevent bacteria from
  • Aeration--air is forced through to release
    unwanted gases reducing odor and improving taste
  • Additional treatment--some communities add
    fluoride for teeth, sodium or lime to soften
    water. Treated water is then pumped from storage
    tanks to homes and industry

Industrial Water Use
  • Industry accounts for 19 of water use worldwide
  • It is used to manufacture goods, dispose of
    waste, and generate power
  • 1,000 L of water is used to produce 1 kg of
    aluminum and 500,000 L of water is used to
    manufacture 1 automobile
  • Most is used to cool power plants

Agricultural Use of Water
  • It can take as much as 300 L of water or produce
    one ear of corn!
  • Agriculture accounts for 67 of water used
  • 80 of water used in agriculture evaporates and
    never reaches the plants roots

  • Fertile soil is sometimes found where there isn't
    much rainfall
  • Irrigation is a method of providing plants with
    water sources other than precipitation
  • Some crops are watered by shallow, water filled
    ditches. The U.S. uses high-pressure overhead
    sprinklers (this is very inefficient)

Water Management Projects
  • 2,000 years ago, Romans built aqueducts that
    brought water from the mountains to dry areas of
    France and Spain
  • People live in areas where the natural
    distribution of water is inadequate
  • Water management projects such as dams and water
    diversion canals are designed to meet people's
  • Goals of such projects can range from making a
    dry area habitable to creating a reservoir for

Water Diversion Projects
  • To supply dry regions with water, all or part of
    a river can be diverted into canals that carry
    water great distances
  • The Colorado River is diverted to meet the needs
    of 7 states
  • It is used for irrigation and drinking water in
    Arizona, Utah, and California
  • Many times the river is dry before reaching the
    Gulf of California

Dams and Reservoirs
  • When a river is dammed, an artificial lake
    (reservoir) is formed behind
  • Water from the reservoir can be used for flood
    control, drinking water, irrigation, recreation,
    and industry
  • Dam are also built to generate electrical
    power--20 of the world's power is produced by
    hydroelectric dams
  • When a dam is built, entire ecosystems can be

  • 50 million people worldwide have been displaced
    from dams being built
  • As the river enters the reservoir, it slows down
    and deposits sediment that it carries. This
    fertile sediment builds up behind the dam instead
    of enriching land farther down the river
  • Farmland below the dam becomes less productive
  • If the dam bursts, people living below the dam
    can be killed

Water Conservation
  • As water becomes depleted, water becomes more
    expensive because wells must be drilled deeper,
    polluted water must be cleaned before it can be
    used, etc.
  • Water conservation is one way to ensure everyone
    will have enough water at reasonable prices

Water Conservation in Agriculture
  • Most water loss in agriculture comes from
    evaporation, seepage, and runoff
  • Drip irrigation systems offer a promising step
    toward conservation
  • Drip irrigation systems deliver small amounts of
    water directly to plant roots using perforated

Water Conservation in Industry
  • Many industries have developed water conservation
  • Most involve the recycling of cooling water and
    waste water
  • Some cities, like Denver, CO, pay small
    businesses to conserve water

Water Conservation at Home
  • A few changes in residential water use will make
    a significant contribution to conservation
  • Low-flow toilets and showers
  • Water lawns at night to prevent as much
  • Xeriscaping involves designing landscaping that
    requires minimal watering

Solutions for the Future Desalination
  • Some coastal communities rely on the ocean to
    provide fresh water
  • Desalination is the process of removing salt from
    salt water
  • Most desalination plants heat salt water and
    collect the fresh water that evaporates

Transporting Water
  • Where fresh water resources are not adequate,
    water can be transported from other regions
  • This is being done in the Greek Isles because
    tourism is taxing the fresh water supply
  • It is being considered in the U.S. where almost
    half the fresh water is in Alaska
  • 77 of Earth's fresh water is in ice caps and

Copy now, answer later
  • Write a description of the evaporative method of
    desalination using terms from the water cycle.
  • Describe the drinking water treatment process in
    your own words.
  • Describe the benefits and costs of dams and water
    diversion projects.
  • List at least three things you can do to help
    conserve the world's water supply.
  • Describe three ways that communities can increase
    their freshwater resources.
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