Water Use and Management

1
Water Use and Management

• Chapter 11 Section 2

2
Global Water Use

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

3
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

4
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)

5
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
  growing
• 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

6
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

7
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
  worldwide
• 80 of water used in agriculture evaporates and
  never reaches the plants roots

8
Irrigation

• 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)

9
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
  needs
• Goals of such projects can range from making a
  dry area habitable to creating a reservoir for
  recreation

10
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

11
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
  destroyed

12

• 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

13
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

14
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
  tubing

15
Water Conservation in Industry

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

16
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
  evaporation
• Xeriscaping involves designing landscaping that
  requires minimal watering

17
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

18
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
  icebergs

19
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.