Chapter 5: S3- Recycling Water

Chapter: Water

Table of ContentsTable of Contents

Section 3: Recycling Water

Section 1: The Nature of Water

Section 2: Why is water necessary?

Earth’s Water Reservoirs• Many people call Earth the “water planet”

because about 70 percent of Earth is covered by water.

• But, only a small portion is available for human use.

Recycling WaterRecycling Water

33

Earth’s Water Reservoirs


33

• Of the world’s total water supply, 97 percent is located in the oceans and is salt water, leaving onlyabout three percent that is freshwater.

Earth’s Water Reservoirs• More than three-

quarters of freshwater is frozen in glaciers.

• Of the less than one percent of Earth’s total water supply available for human use, much of it lies underneath Earth’s surface.


33

Oceans• Ocean water is plentiful on Earth, but it’s

salty and therefore not readily available for human use.

• You would have to remove the salt (desalination) if you wanted to use ocean water for drinking, bathing, or irrigating crops.


33

• Unfortunately, removing salt from ocean water usually isn’t practical and is only done in a few arid regions.

Ice • Ice sheets and glaciers are common in

Earth’s polar regions.

• These ice sheets lock up a large percentage of Earth’s freshwater.


33

Ice


33

• Ice accounts for just more than two percent of the total wateron Earth, but that’s 77 percent of the planet’s freshwater supply.

Groundwater

• Where does the water that lands on the ground go?

• Some of it runs off and flows into streams, and some evaporates.


33

• A large amount soaks into the ground.

• Water that is held underground in layers of rock and sediment is called groundwater.

Groundwater • The part of the groundwater that is held

within openings in the soil is called soil water.


33

• It keeps plants and crops alive. • Groundwater also includes underground

streams. • People in houses that get their water from

wells are drinking groundwater. • The water is purified as it slowly permeates

through layers of sediment and rock.

Aquifers

• An aquifer is a layer of rock or sediment that has enough well-connected openings to allow groundwater to flow through it.


33

• Water collects in the open spaces between rock particles.

• This water flows slowly from one open space to another at rates of a few meters per year.

Aquifers• Sometimes aquifers are used to supply water

to towns and farms.


33

Aquifers• The water is pumped to

Earth’s surface through a well.


33

• Sometimes Earth’s surface dips below the level where groundwater would be. This is where natural lakes and rivers are located.


33Lakes, Rivers, and Ponds

• The water at Earth’s surface is called surface water. It is found in streams, rivers, ponds, lakes, and reservoirs. This is the water you easily can see and use.

Water in the Atmosphere


33

• Earth’s atmosphere can consist of anywhere from near zero to about four percent water vapor byvolume.

Water in the Atmosphere


33

• Clouds need it to form; therefore, water vapor is the source of rain, sleet, and snow.

• Water vapor in Earth’s atmosphere has several important roles.

Water in the Atmosphere• Heat is given off when water vapor condenses

to form the water droplets in clouds.


33

• But, heat is absorbed when water evaporates to water vapor.

• The atmosphere uses these heating and cooling properties to move energy around.

• It can brew up wind, storms, and even hurricanes.

• Water vapor also absorbs heat and acts as a blanket to help keep Earth warm and hospitable to life.

The Water Cycle• The water on Earth constantly is recycled

through the water cycle.


33

The Water Cycle


33

A Valuable Resource

• Humans are lucky that water circulates, but this doesn’t mean that it doesn’t need to be cared for.


33

• Now that you have learned how important water is to Earth, you can understand why it is crucial that it be protected.

• Water is truly a valuable resource.

Section CheckSection Check

33Question 1

How much of Earth’s water is available for human consumption?

A. 97%B. 70%C. 3%D. less than 1%

NC: 3.02


33Answer

The correct answer is D. Freshwater that is available for humans is found in lakes, streams, rivers, and as ground water.

NC: 3.02


33Question 2

Explain how water from a lake or stream can be recycled into the water cycle.

NC: 3.02


33Answer

Water in a lake or stream evaporates when the Sun’s energy changes it into water vapor. Water vapor condenses in the atmosphere and falls back to Earth as precipitation. The precipitation soaks through Earth’s surface or forms runoff and eventually returns to the lake, stream, or ocean.

NC: 3.02


33Question 3

What is groundwater?

Answer

Groundwater is water that is held underground in layers of rock and sediment.

NC: 3.02

To advance to the next item or next page click on any of the following keys: mouse, space bar, enter, down or forward arrow.

Click on this icon to return to the table of contents

Click on this icon to return to the previous slide

Click on this icon to move to the next slide

Click on this icon to open the resources file.

HelpHelp

Click on this icon to go to the end of the presentation.

End of Chapter Summary File

Education

Chapter 5: S3- Recycling Water