Water Use and Management

Environmental ScienceSpring 2011

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

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

Three major uses for water: residential, agriculture, industrial

Agriculture > industrial > residential Amounts used

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

Cooking and Drinking 10

Other 5

Water treatment Potable: safe to drink

Most water must be treated to make it potable Removes elements such as mercury, arsenic,

lead (found in polluted water and occur naturally)

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

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

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

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

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

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 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

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

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

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 may become less productive Dam failure!

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

In Industry Recycling of cooling water and waste water Instead of discharging water into river,

businesses often recycle water

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

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

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

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

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