Chapter: Water Table 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 Water 3

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.

Earth’s Water Reservoirs Recycling Water 3 Of the world’s total water supply, 97 percent is located in the oceans and is salt water , leaving only about three percent that is freshwater .

Of the world’s total water supply, 97 percent is located in the oceans and is salt water , leaving only

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. Recycling Water 3

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.

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. Recycling Water 3 Unfortunately, removing salt from ocean water usually isn’t practical and is only done in a few arid regions.

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.

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. Recycling Water 3

Ice sheets and glaciers are common in Earth’s polar regions .

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

Ice Recycling Water 3 Ice accounts for just more than two percent of the total water on Earth, but that’s 77 percent of the planet’s freshwater supply.

Ice accounts for just more than two percent of the total water

Groundwater Where does the water that lands on the ground go? Some of it runs off and flows into streams , and some evaporates . Recycling Water 3 A large amount soaks into the ground. Water that is held underground in layers of rock and sediment is called groundwater .

Where does the water that lands on the ground go?

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

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 . Recycling Water 3 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.

The part of the groundwater that is held within openings in the soil is called soil water .

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. Recycling Water 3 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.

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

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. Recycling Water 3

Sometimes aquifers are used to supply water to towns and farms.

Aquifers The water is pumped to Earth’s surface through a well. Recycling Water 3 Sometimes Earth’s surface dips below the level where groundwater would be. This is where natural lakes and rivers are located.

The water is pumped to Earth’s surface through a well.

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

Recycling Water 3 Lakes, 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.

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 Recycling Water 3 Earth’s atmosphere can consist of anywhere from near zero to about four percent water vapor by volume.

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

Water in the Atmosphere Recycling Water 3 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.

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. Recycling Water 3 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.

Heat is given off when water vapor condenses to form the water droplets in clouds.

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. Recycling Water 3

The water on Earth constantly is recycled through the water cycle.

The Water Cycle Recycling Water 3

A Valuable Resource Humans are lucky that water circulates, but this doesn’t mean that it doesn’t need to be cared for. Recycling Water 3 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.

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

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 Check 3 Question 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

Section Check 3 Answer The correct answer is D. Freshwater that is available for humans is found in lakes, streams, rivers, and as ground water. NC: 3.02

Section Check 3 Question 2 Explain how water from a lake or stream can be recycled into the water cycle . NC: 3.02

Section Check 3 Answer 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

Section Check 3 Question 3 What is groundwater? Answer Groundwater is water that is held underground in layers of rock and sediment. NC: 3.02

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