Transcript Chapter 11 Section 2

Water Use and Management
CHAPTER 11 SECTION 2
Environmental Science
Spring 2011
OBJECTIVES
Identify patterns of global water use
 Explain how water is treated so that it can be
used for drinking
 Identify how water is used in homes, in
industry, and in agriculture
 Describe how dams and water diversion
projects are used to manage freshwater
resources
 Identify 5 ways that water can be conserved

CLEAN, FRESH WATER
A shortage of clean, fresh water is one of the
world’s most pressing environmental problems
 According to World Health Organization, more
than 1 billion people lack access to a clean,
reliable source of fresh water

GLOBAL WATER USE
Three major uses for water: residential,
agriculture, industrial
 Agriculture > industrial > residential

 Amounts
used
RESIDENTIAL WATER USE
Average person in US uses about 300L of water
every day
 Average person in India uses about 41L of
water every day

Daily Water Use in the United States (per person)
Use
Water (L)
Lawn Watering and Pools
95
Toilet Flushing
90
Bathing
70
Brushing Teeth
10
Cleaning (inside and
outside)
20
RESIDENTIAL WATER USE

Water treatment
 Potable:
 Most
safe to drink
water must be treated to make it potable
 Removes elements such as mercury, arsenic, lead (found
in polluted water and occur naturally)
RESIDENTIAL WATER USE

Water treatment
 Pathogens:
organisms that cause illness or disease
 Water
treatment removes these
 Ex. Bacteria, viruses, protozoa, parasitic worms
 Often found in water contaminated by sewage or animal
feces

Water treatment methods usually include
physical and chemical treatments
INDUSTRIAL WATER USE
Accounts for 19% of water used in world
 Used to manufacture goods, dispose of waste,
and to generate power
 Most of water used is to cool power plants

 Pump
from river or lake, carry to cooling tower,
return to source
 Returned water is usually warmer but clean and
can be reused
AGRICULTURAL WATER USE
Accounts for 67% of water used in the world
 Plants require a lot of water to grow, and as
much as 80% of water used in agriculture
evaporates before reaching plant roots

AGRICULTURAL WATER USE

Irrigation: method of providing plants with water
from sources other than direct precipitation
 In
areas where rainfall is inadequate, extra water is
supplied by irrigation
 Cotton is irrigated by shallow water filled ditches
 High pressure overhead sprinklers are common
form of irrigation in US
 Inefficient
because nearly half of water evaporates
WATER MANAGEMENT PROJECTS
Humans have altered streams and rivers to
make them more useful
 Aqueducts: Romans built these huge canals
that brought water from mountains to dry areas
of France and Spain

WATER MANAGEMENT PROJECTS
Dams and water diversion canals, are designed
to meet needs of those that live in areas of
inadequate surface water distribution
 Water management projects have various
goals: bringing in water to make dry area
habitable, creating a reservoir for recreation or
drinking water, or generating electric power

WATER MANAGEMENT PROJECTS

Water Diversion Projects
 To
supply dry regions with water, all or part of a
river can be diverted into canals that carry water
across great distances
 Owen River in California
 Colorado River meets needs of western states
WATER MANAGEMENT PROJECTS

Dams and Reservoirs
 Dam:
structure built across a river to control rivers
flow
 Reservoir: when a river is dammed, artificial lake or
reservoir, is formed behind the dam
WATER MANAGEMENT PROJECTS

Dams and Reservoirs
 Water
from reservoir can be used for flood control,
drinking water, irrigation, recreation, and industry
 Dams are also built to generate electric energy
 Hydroelectric dams use power of flowing water to
turn turbine that generates electricity
WATER MANAGEMENT PROJECTS

Dams and Reservoirs
 Interrupting
river’s flow can have far-reaching
consequences
 People are often displaced and entire ecosystems
can be destroyed
 Also effect land below dam, sediments will build up
behind dam instead of below and farther down river
 Farmland
 Dam
may become less productive
failure!
WATER CONSERVATION

In Agriculture
 Technologies
that reduce problems of water loss
(evaporation, seepage, runoff) help to conserve
water
 Drip irrigation systems: deliver small amounts of
water directly to plant roots by using perforated
tubing
 Water
is released as needed and at a controlled rate
WATER CONSERVATION

In Industry
 Recycling
of cooling water and waste water
 Instead of discharging water into river, businesses
often recycle water
WATER CONSERVATION

At Home
 People
can conserve water by changing a few
habits and using water only when needed
 Low flow toilets and showerheads
 Water lawns at night
 Xeriscaping: designing a landscape that requires
minimal water use
WATER CONSERVATION
What You Can Do To Save Water
Take shorter showers, and avoid taking baths unless you keep the water level
low
Install a low-flow shower head in shower
Install inexpensive, low-flow aerators in your water faucets at home
Purchase a modern, low-flowing toilet, install a water-saving device in toilet, or
simply place a water filled bottle inside your toilet tank to reduce the water
used for each flush
Do not let the water run when you brush your teeth
Fill up the sink basin, rather than letting water run when you are shaving,
washing your hands or face, or washing dishes
Wash only full loads in your dishwasher and washing machine
Water your lawn sparingly
SOLUTIONS FOR THE FUTURE

In some places conservation alone will not be
enough to prevent water shortages
 As
populations grow other sources of fresh water
need to be developed
 Two possible solutions are desalination and
transporting fresh water
SOLUTIONS FOR THE FUTURE

Desalination: process of removing salt from salt
water
 Costal
communities
 Middle east, built desalination plants to provide
fresh water
 Heat salt water and collect fresh water that
evaporates
 Process consumes a lot of energy, often too
expensive
SOLUTIONS FOR THE FUTURE

Transporting Water
 Islands
of Greece have fresh water brought in by
boat
 May be used in US where half of fresh water is in
Alaska
 Icebergs are another potential source