WaterWater

Environmental ScienceEnvironmental Science

Spring 2010Spring 2010

Water ResourcesWater Resources

Two kinds of water found on Earth:Two kinds of water found on Earth:• Fresh water, the water that people can Fresh water, the water that people can

drink, contains little salt.drink, contains little salt.• Salt water, the water in oceans, Salt water, the water in oceans,

contains a higher concentration of contains a higher concentration of dissolved salts. dissolved salts.

Most human uses for water, such as Most human uses for water, such as drinking and agriculture, require drinking and agriculture, require fresh water.fresh water.

Global Water Global Water DistributionDistribution

Only a small Only a small percentage of the percentage of the water on Earth is water on Earth is liquid fresh water liquid fresh water that humans can use.that humans can use.

The fresh water we The fresh water we use comes mainly use comes mainly from lakes and rivers from lakes and rivers and from a relatively and from a relatively narrow zone beneath narrow zone beneath the Earththe Earth’’s surface.s surface.

Name a conflict Name a conflict people have had people have had

over water.over water.

Water Use and Water Use and ManagementManagement

When a water supply is polluted or overused, When a water supply is polluted or overused, everyone living downstream can be affected.everyone living downstream can be affected.

A shortage of clean, fresh water is one of the A shortage of clean, fresh water is one of the worldworld’’s most pressing environmental s most pressing environmental problems.problems.

According to the World Health Organization, According to the World Health Organization, more than 1 billion people lack access to a more than 1 billion people lack access to a clean, reliable source of fresh water.clean, reliable source of fresh water.

Residential Water UseResidential Water Use The average person in the The average person in the

United States uses about United States uses about 300 L of water a day. But 300 L of water a day. But in India, the average in India, the average person uses only 41 L of person uses only 41 L of water everyday.water everyday.

In the U.S., only about half In the U.S., only about half of residential water use is of residential water use is for activities inside the for activities inside the home, such as drinking home, such as drinking and cooking. and cooking. The remainder of the water The remainder of the water

is used for activities outside is used for activities outside the home such as watering the home such as watering lawns.lawns.

What are the top 2 What are the top 2 ways your family ways your family

uses water in your uses water in your home?home?

Water TreatmentWater Treatment

Most water must first be made potable.Most water must first be made potable. PotablePotable means suitable for drinking. means suitable for drinking.

Water treatment removes elements such as Water treatment removes elements such as mercury, arsenic, and lead, which are mercury, arsenic, and lead, which are poisonous to humans even in low poisonous to humans even in low concentrations.concentrations.

These elements are found in polluted These elements are found in polluted water, but they can also occur naturally in water, but they can also occur naturally in groundwater.groundwater.

A A pathogenpathogen is a virus, microorganism, or is a virus, microorganism, or other substance that causes disease.other substance that causes disease.

Pathogens are found in water Pathogens are found in water contaminated by sewage or animal feces, contaminated by sewage or animal feces, but can be removed with water treatment.but can be removed with water treatment.

There are several methods of treating There are several methods of treating water to make it potable. A common water to make it potable. A common method includes both physical and method includes both physical and chemical treatment.chemical treatment.

What kind of What kind of diseases are caused diseases are caused

by water born by water born pathogens?pathogens?

Agricultural UsesAgricultural Uses Agriculture accounts for 67 percent of the Agriculture accounts for 67 percent of the

water used in the world.water used in the world.

IrrigationIrrigation is a method of providing plants is a method of providing plants with water from sources other than direct with water from sources other than direct precipitation.precipitation.

In the U.S., high-pressured overhead In the U.S., high-pressured overhead sprinklers are the most common form of sprinklers are the most common form of irrigation. However, this method is inefficient irrigation. However, this method is inefficient because nearly half the water evaporates and because nearly half the water evaporates and never reaches the plant roots. never reaches the plant roots.

Industrial UsesIndustrial Uses

Most of the water that is used in Most of the water that is used in industry is used to cool power industry is used to cool power plants.plants.

The water that is returned is usually The water that is returned is usually warmer than the source, but is warmer than the source, but is generally clean and can be used generally clean and can be used againagain

What industries do What industries do you think use large you think use large amounts of water?amounts of water?

Water Management Water Management ProjectsProjects

People often prefer to live in areas where People often prefer to live in areas where the natural distribution of surface water is the natural distribution of surface water is inadequate.inadequate.

Water management projects can have Water management projects can have various goals, such as brining in water to various goals, such as brining in water to make a dry area habitable, creating a make a dry area habitable, creating a reservoir for drinking water, or generating reservoir for drinking water, or generating electric power, which then allows people electric power, which then allows people to live and grow crops in desert areas.to live and grow crops in desert areas.

Dams and ReservoirsDams and Reservoirs

A A damdam is a structure that is built is a structure that is built across a river to control a river’s flow.across a river to control a river’s flow.

A A reservoirreservoir is an artificial body of is an artificial body of water that usually forms behind a water that usually forms behind a dam. Water from a reservoir can be dam. Water from a reservoir can be used for flood control, drinking water, used for flood control, drinking water, irrigation, recreation, and industry.irrigation, recreation, and industry.

Name a water Name a water management management

projects in Georgia?projects in Georgia?