Fresh Water. Water On Earth The positive hydrogen ends of one water molecule attract the negative oxygen ends of nearby water molecules. As a result,

Fresh WaterFresh Water

Water On EarthWater On Earth

The positive hydrogen ends of one water The positive hydrogen ends of one water molecule attract the negative oxygen molecule attract the negative oxygen ends of nearby water molecules. As a ends of nearby water molecules. As a result, the water molecules tend to stick result, the water molecules tend to stick together.together.

The Structure of WaterThe Structure of Water

Changing StateChanging State Ice is solid water, the familiar form of water Ice is solid water, the familiar form of water

is a liquid, and the water vapor in the air is a is a liquid, and the water vapor in the air is a gas.gas.

Changing State

Changing StateChanging State Water moves between the liquid and Water moves between the liquid and

gaseous states by evaporation and gaseous states by evaporation and condensation. Water moves between the condensation. Water moves between the liquid and solid states by freezing and liquid and solid states by freezing and melting.melting.

Water on EarthWater on Earth

Earth, has a surface covered mainly by Earth, has a surface covered mainly by water.water.

In fact, oceans cover about 70 percent In fact, oceans cover about 70 percent of our planet’s surface.of our planet’s surface.

That’s why Earth is often called the That’s why Earth is often called the “water planet.”“water planet.”

Water on EarthWater on Earth The Water CycleThe Water Cycle

– Earth’s water is naturally recycled Earth’s water is naturally recycled through the water cycle.through the water cycle.

– The water cycle is the continuous The water cycle is the continuous process by which water moves from process by which water moves from Earth’s surface to the atmosphere and Earth’s surface to the atmosphere and back.back.

– In the water cycle, water moves from In the water cycle, water moves from bodies of water, land, and living things on bodies of water, land, and living things on Earth’s surface to the atmosphere and Earth’s surface to the atmosphere and back to Earth’s surface.back to Earth’s surface.

The Water Cycle

Water on EarthWater on Earth

The water cycle has three major stepsThe water cycle has three major steps– EvaporationEvaporation– CondensationCondensation– PrecipitationPrecipitation

The cycle itself has no beginning or The cycle itself has no beginning or end. end.

But it is driven by an energy source – But it is driven by an energy source – the sun.the sun.

Water on EarthWater on Earth Water EvaporatesWater Evaporates

– In evaporation, liquid water changes to In evaporation, liquid water changes to a gas called water vapor.a gas called water vapor.

– Water is constantly evaporating from Water is constantly evaporating from the surfaces of lakes and oceans and the surfaces of lakes and oceans and even from the soil.even from the soil.

– Plants draw in water from the soil Plants draw in water from the soil through their roots and release it through their roots and release it through their leaves as water vapor.through their leaves as water vapor.

Water on EarthWater on Earth Condensation Forms CloudsCondensation Forms Clouds

– Warm air carries the water vapor Warm air carries the water vapor upward.upward.

– At higher altitudes, air tends to become At higher altitudes, air tends to become much colder. Cold air cannot hold as much colder. Cold air cannot hold as much water vapor as warm air can.much water vapor as warm air can.

– As a results, some of the water vapor As a results, some of the water vapor cools and condenses into liquid water. cools and condenses into liquid water. Condensed droplets of water clump Condensed droplets of water clump together around tiny dust particles in together around tiny dust particles in the air, forming clouds.the air, forming clouds.

Water on EarthWater on Earth PrecipitationPrecipitation

– As more water vapor condenses, the As more water vapor condenses, the drops of water in the cloud grow larger.drops of water in the cloud grow larger.

– The heavy drops fall back to Earth as The heavy drops fall back to Earth as precipitation – rain, snow, sleet, or hail.precipitation – rain, snow, sleet, or hail.

– Most falls back into the ocean or lakes.Most falls back into the ocean or lakes.– The precipitation that falls on land may The precipitation that falls on land may

soak into the soil and become soak into the soil and become groundwater.groundwater.

Distribution of Earth’s WaterDistribution of Earth’s Water

Most of Earth’s water–roughly 97 Most of Earth’s water–roughly 97 percent–is salt water found in oceans.percent–is salt water found in oceans.

Only three percent of Earth’s water is Only three percent of Earth’s water is fresh waterfresh water..

3 percent, about three quarters is 3 percent, about three quarters is frozen in huge masses of ice near the frozen in huge masses of ice near the North and South poles.North and South poles.

Almost a quarter of the fresh water is Almost a quarter of the fresh water is underground.underground.



OceansOceans– A vast, salty ocean covers an area A vast, salty ocean covers an area

greater than all the land on Earth greater than all the land on Earth combined.combined.

– Pacific, Atlantic, Indian, and Arctic are Pacific, Atlantic, Indian, and Arctic are the names used for the different parts the names used for the different parts of the ocean.of the ocean.



IceIce– Most of Earth’s fresh water is locked in Most of Earth’s fresh water is locked in

thick sheets of ice that cover Antarctica, thick sheets of ice that cover Antarctica, near the South Pole, and Greenland, near the South Pole, and Greenland, near the North Pole.near the North Pole.

– Huge icebergs, floating chunks of ice Huge icebergs, floating chunks of ice made of fresh water, often break off the made of fresh water, often break off the ice sheets.ice sheets.

Distribution of Earth’s WaterDistribution of Earth’s Water Rivers and LakesRivers and Lakes

– Relatively little of Earth’s fresh water is Relatively little of Earth’s fresh water is found in rivers and lakes.found in rivers and lakes.

– But rivers and lakes are important But rivers and lakes are important sources of fresh water for the people sources of fresh water for the people who live near them.who live near them.

– North America’s five Great Lakes North America’s five Great Lakes contain nearly 20 percent of all the contain nearly 20 percent of all the water in the world’s freshwater lakes.water in the world’s freshwater lakes.

Distribution of Earth’s WaterDistribution of Earth’s Water GroundwaterGroundwater

– Water that fills the cracks and spaces in Water that fills the cracks and spaces in underground soil and rock layers.underground soil and rock layers.

– This water trickles down through This water trickles down through spaces between particles of soil and spaces between particles of soil and rock.rock.

– Far more fresh water is located Far more fresh water is located underground than in all of Earth’s rivers underground than in all of Earth’s rivers and lakes.and lakes.

Lecture QuizLecture Quiz1.1. What three major steps make up the What three major steps make up the

water cycle?water cycle?2.2. How does water enter Earth’s How does water enter Earth’s

atmosphere? Explain your answer.atmosphere? Explain your answer.3.3. Would cutting down trees affect the Would cutting down trees affect the

amount of evaporation in an area? amount of evaporation in an area? Explain.Explain.

4.4. What are Earth’s four main water What are Earth’s four main water sources contain salt water? Which sources contain salt water? Which contain fresh water?contain fresh water?

River SystemsRiver Systems A river and all of its tributaries make up a river A river and all of its tributaries make up a river

system.system.

Surface WaterSurface Water

River SystemsRiver Systems– Rivers often begin in mountains, where Rivers often begin in mountains, where

the runoff from melting snow forms the runoff from melting snow forms small streams.small streams.

– These streams would flow into a small These streams would flow into a small river.river.

– Eventually this path would lead to a Eventually this path would lead to a large river.large river.


TributariesTributaries– The streams and smaller rivers that The streams and smaller rivers that

feed into a main river.feed into a main river.– Flow downward toward the main river, Flow downward toward the main river,

pulled by the force of gravity.pulled by the force of gravity.– A river and all its tributaries together A river and all its tributaries together

make up a river system.make up a river system.


WatershedsWatersheds– The land area that supplies water to a The land area that supplies water to a

river system.river system.– Sometimes knows as drainage basins.Sometimes knows as drainage basins.– When rivers join another river system, When rivers join another river system,

the areas they drain become part of the the areas they drain become part of the largest river’s watershed.largest river’s watershed.


Surface WaterSurface Water DividesDivides

– A ridge of land that separate one A ridge of land that separate one watershed from another.watershed from another.

– Streams on each side of the divide flow Streams on each side of the divide flow in different directions.in different directions.

– The Continental Divide, the longest The Continental Divide, the longest divide in North America, follows the line divide in North America, follows the line of the Rocky Mountains.of the Rocky Mountains.


PondsPonds– Bodies of fresh water.Bodies of fresh water.– In general, however, ponds are smaller In general, however, ponds are smaller

and shallower than lakes. Sunlight and shallower than lakes. Sunlight usually reaches to the bottom of all usually reaches to the bottom of all parts of a pond.parts of a pond.

Surface WaterSurface Water How Ponds FormHow Ponds Form

– Form when water collects in hollows Form when water collects in hollows and low-lying areas of land.and low-lying areas of land.

– Ponds are supplied by rainfall, melting Ponds are supplied by rainfall, melting snow and ice, and runoff.snow and ice, and runoff.

– Others are fed by rivers or Others are fed by rivers or groundwater.groundwater.

Surface WaterSurface Water Exploring a PondExploring a Pond

– The muddy bottom is often covered The muddy bottom is often covered with weeds.with weeds.

– A quiet pond is actually a thriving A quiet pond is actually a thriving habitat, supporting a wide diversity of habitat, supporting a wide diversity of living things.living things.

– An organism’s habitat is the place An organism’s habitat is the place where it lives and obtains all the things where it lives and obtains all the things it needs to survive.it needs to survive.

Surface WaterSurface Water LakesLakes

– Lakes are generally deeper and bigger Lakes are generally deeper and bigger than ponds.than ponds.

– In addition, sunlight does not reach the In addition, sunlight does not reach the bottom in a deep lake, as it does in a bottom in a deep lake, as it does in a pond.pond.

– A lake bottom may consist of sand, A lake bottom may consist of sand, pebble, or rock, whereas the bottom of pebble, or rock, whereas the bottom of a pond is usually covered with mud and a pond is usually covered with mud and algae.algae.

Surface WaterSurface Water How Lakes FormHow Lakes Form

– Some lakes may form through the Some lakes may form through the same processes that form ponds.same processes that form ponds.

– Other lakes, especially larger ones, are Other lakes, especially larger ones, are the result of powerful forces that shape the result of powerful forces that shape Earth’s surface.Earth’s surface.

– Some natural lakes, such as the Great Some natural lakes, such as the Great Lakes, formed in depressions created Lakes, formed in depressions created by ice sheets that melted at the end of by ice sheets that melted at the end of the Ice Age.the Ice Age.

Surface WaterSurface Water– Other lakes were created by Other lakes were created by

movements of Earth’s crust.movements of Earth’s crust.– Other lakes are the result of volcanoes.Other lakes are the result of volcanoes.– Some lakes form in the empty craters Some lakes form in the empty craters

of volcanoes.of volcanoes.– People can also create a lake by People can also create a lake by

building a dam across a river.building a dam across a river.– A lake that stores water for human is A lake that stores water for human is

called a reservoir.called a reservoir.

Surface Water


WetlandsWetlands– A land area that is covered with water A land area that is covered with water

during part or all the year.during part or all the year.– Help control floods and provide habitats Help control floods and provide habitats

for many species.for many species.– Form where water is trapped in low Form where water is trapped in low

areas or where groundwater seeps to areas or where groundwater seeps to the surface.the surface.

– Fill up during spring rains, but dry up Fill up during spring rains, but dry up during summer.during summer.


Types of WetlandsTypes of Wetlands– The three common types of freshwater The three common types of freshwater

wetlands are:wetlands are:MarshesMarshesSwampsSwampsBogsBogs

Surface WaterSurface Water Marshes are usually grassy areas Marshes are usually grassy areas

covered by shallow water or a stream.covered by shallow water or a stream. They teem with cattails and other tall, They teem with cattails and other tall,

grass like plants.grass like plants. Swamps look more like flooded forests, Swamps look more like flooded forests,

with trees and shrubs sprouting from the with trees and shrubs sprouting from the water.water.

Many swamps are located in warm, Many swamps are located in warm, humid climates, where trees grow quickly.humid climates, where trees grow quickly.


Bogs are more common in cooler Bogs are more common in cooler northern areas.northern areas.

They often form in depressions left by They often form in depressions left by melting ice sheets thousands of years melting ice sheets thousands of years ago.ago.

The water in bogs tends to be acidic, and The water in bogs tends to be acidic, and mosses thrive in these conditions.mosses thrive in these conditions.

Surface WaterSurface Water Wetlands along coasts usually contain Wetlands along coasts usually contain

both fresh and salt water.both fresh and salt water. Coastal wetlands include salt marshes Coastal wetlands include salt marshes

and mangrove forests.and mangrove forests. Tall, strong grasses grow in the rich, Tall, strong grasses grow in the rich,

muddy bottoms of salt marshes.muddy bottoms of salt marshes. Mangrove forests are found along the Mangrove forests are found along the

southeastern coast of the United States.southeastern coast of the United States. In these forests, the mangrove trees are In these forests, the mangrove trees are

short and have thick, tangled roots.short and have thick, tangled roots.


The Everglades: A WetlandThe Everglades: A Wetland– Water is the key to the Everglades, a Water is the key to the Everglades, a

vast marsh in south Florida.vast marsh in south Florida.– Tall, sharp-edged blades of saw grass Tall, sharp-edged blades of saw grass

grow in the water.grow in the water.– The thick growth of saw grass gave this The thick growth of saw grass gave this

region its Native American name, region its Native American name, Pa-Pa-hay-okeehay-okee, which means “river of grass.”, which means “river of grass.”



– The Everglades are home to many The Everglades are home to many kinds of wildlife – alligators, fishes, kinds of wildlife – alligators, fishes, snakes, and wading birds.snakes, and wading birds.

– The Everglade provide habitats for The Everglade provide habitats for many rare or endangered species, such many rare or endangered species, such as the Florida panther and the as the Florida panther and the manatee.manatee.


Importance of WetlandsImportance of Wetlands– Water in a wetland is shallow, and plant Water in a wetland is shallow, and plant

animal material add natural fertilizers to animal material add natural fertilizers to the water and soil.the water and soil.

– Because of their sheltered waters and Because of their sheltered waters and rich supply of nutrients, wetlands rich supply of nutrients, wetlands provide habitats for many living things.provide habitats for many living things.

Surface WaterSurface Water– Wetlands are important to people.Wetlands are important to people.– They help with pollution control and flood They help with pollution control and flood

control.control.– In these ways, wetlands act as natural In these ways, wetlands act as natural

water filters. water filters. – They also help control floods by absorbing They also help control floods by absorbing

extra runoff from heavy rains.extra runoff from heavy rains.– Wetlands are like giant sponges, storing Wetlands are like giant sponges, storing

rainwater until it gradually drains or rainwater until it gradually drains or evaporates.evaporates.

Water UndergroundWater Underground

How Water Moves UndergroundHow Water Moves Underground– Water underground trickles down Water underground trickles down

between particles of soil and through between particles of soil and through cracks and spaces in layers of rock.cracks and spaces in layers of rock.

Water UndergroundWater Underground Effects of Different MaterialsEffects of Different Materials

– The size and pores determines how easily The size and pores determines how easily water moves through rock and soil.water moves through rock and soil.

– If the pores are connected, this too affects If the pores are connected, this too affects water movement.water movement.

– Because they have large and connected Because they have large and connected pores, materials such as sand and gravel pores, materials such as sand and gravel allow water to pass through, or permeate.allow water to pass through, or permeate.

– They are thus known as permeable They are thus known as permeable materials.materials.

Water UndergroundWater Underground– As water soaks down through As water soaks down through

permeable rock and soil, it eventually permeable rock and soil, it eventually reaches layers of material that it cannot reaches layers of material that it cannot pass through.pass through.

– These materials have few or no pores These materials have few or no pores or cracks.or cracks.

– The examples are clay and granite.The examples are clay and granite.– Clay and granite are impermeable, Clay and granite are impermeable,

meaning that water cannot pass meaning that water cannot pass through easily.through easily.


Water ZonesWater Zones– Once water reaches an impermeable Once water reaches an impermeable

layer, it is trapped.layer, it is trapped.– The areas of permeable rock or soil The areas of permeable rock or soil

that is totally filled, or saturated, with that is totally filled, or saturated, with water is called the saturated zone.water is called the saturated zone.

– The top of the saturated zone is the The top of the saturated zone is the water table.water table.


– Soil and rock layers above the water Soil and rock layers above the water table contain some moisture, too.table contain some moisture, too.

– But here the pores contain air as well But here the pores contain air as well as water. as water.

– They are not saturated.They are not saturated.– Therefore, the layer of rocks and soil Therefore, the layer of rocks and soil

above the water table is called the above the water table is called the unsaturated zone.unsaturated zone.

Water Underground


Bringing Up GroundwaterBringing Up Groundwater– Springs can form as groundwater Springs can form as groundwater

bubbles or flows out of cracks in the bubbles or flows out of cracks in the rock.rock.

– A short distance away, the water table A short distance away, the water table may be deep underground.may be deep underground.


AquifersAquifers– Any underground layer of rock or sediment Any underground layer of rock or sediment

that holds water.that holds water.– Can range in size from a small underground Can range in size from a small underground

patch of permeable material to an area the patch of permeable material to an area the size of several states.size of several states.

– The huge Ogallala aquifer lies beneath the The huge Ogallala aquifer lies beneath the plains of the Midwest, from South Dakota to plains of the Midwest, from South Dakota to Texas,.Texas,.


http://upload.wikimedia.org/wikipedia/commons/f/f7/Ogallala_changes_in_feet_1980-1995_USGS.gif


– Millions of people obtain drinking water Millions of people obtain drinking water from aquifers.from aquifers.

– The aquifer also provides water for The aquifer also provides water for crops and livestock.crops and livestock.

– The water is moving, seeping through The water is moving, seeping through layers of rock.layers of rock.


WellsWells– Since ancient times, people have Since ancient times, people have

brought groundwater to the surface for brought groundwater to the surface for drinking and other everyday uses.drinking and other everyday uses.

– People can obtain groundwater from an People can obtain groundwater from an aquifer by drilling a well below the aquifer by drilling a well below the water table.water table.

Water Underground


Using PumpsUsing Pumps– Pumping water out of an aquifer lowers Pumping water out of an aquifer lowers

the water level near the well.the water level near the well.– If too much water is pumped out too If too much water is pumped out too

fast, a well may run dry.fast, a well may run dry.– New water that enters the aquifer from New water that enters the aquifer from

the surface is called recharge.the surface is called recharge.


Relying on PressureRelying on Pressure– In an artesian well, water rises because In an artesian well, water rises because

of pressure within an aquifer.of pressure within an aquifer.– If the top layer of rock is punctured, the If the top layer of rock is punctured, the

pressure sends water spurting up pressure sends water spurting up through the hold.through the hold.

– No pump is necessary – in an artesian No pump is necessary – in an artesian well, pressure does the job.well, pressure does the job.


Springs and GeysersSprings and Geysers– Most springs contain water at normal Most springs contain water at normal

temperatures.temperatures.– Others, contain water that is warmed by Others, contain water that is warmed by

the hot rocks deep below the surface. the hot rocks deep below the surface. – The heated water bubbles to the The heated water bubbles to the

surface in hot springs.surface in hot springs.


– In some areas, you might see a In some areas, you might see a fountain of boiling hot water and white fountain of boiling hot water and white steam burst into the air. steam burst into the air.

– This is a geyser, a type of hot spring This is a geyser, a type of hot spring from which the water periodically from which the water periodically erupts.erupts.

– The word The word geysergeyser comes from an comes from an Icelandic word, Icelandic word, geysirgeysir, which means , which means “gusher.”“gusher.”


– A geyser forms A geyser forms when very hot when very hot water that has water that has been circulating been circulating deep underground deep underground begins to rise begins to rise through narrow through narrow passages in the passages in the rock.rock.

http://en.wikipedia.org/wiki/Image:GeysirEruptionNear.jpg

Using Freshwater ResourcesUsing Freshwater Resources

People use water for household People use water for household purposes, industry, transportation, purposes, industry, transportation, agriculture, and recreation.agriculture, and recreation.

Water is constantly recycled in the Water is constantly recycled in the water cycle.water cycle.

A water shortage occurs when there is A water shortage occurs when there is too little water or too great a demand in too little water or too great a demand in an area – or both.an area – or both.


In the HomeIn the Home

–BathingBathing

–Brushing teethBrushing teeth

–Flushing the toilet.Flushing the toilet.

–CookingCooking

–CleaningCleaning


Industry and TransportationIndustry and Transportation

–Industries use water in other ways, Industries use water in other ways, too.too.Power plantsPower plantsSteel millsSteel mills

–Water has been used to transport Water has been used to transport people and goods.people and goods.

Using Freshwater ResourcesUsing Freshwater Resources AgricultureAgriculture

– Growing fruits and vegetables requires water.Growing fruits and vegetables requires water.

– On a large farm, a constant supply of fresh On a large farm, a constant supply of fresh water is essential.water is essential.

– Irrigation is the process of supplying water to Irrigation is the process of supplying water to areas of land to make them suitable for areas of land to make them suitable for growing crops.growing crops.

– In the US, more water is used for irrigation In the US, more water is used for irrigation than for any other single purpose.than for any other single purpose.


RecreationRecreation

–SwimmingSwimming

–FishingFishing


Conserving WaterConserving Water

–Conservation is the practice of using Conservation is the practice of using less of a resource so that it will not less of a resource so that it will not be used up.be used up.

–Reducing water use, recycling water, Reducing water use, recycling water, and reusing water are three ways to and reusing water are three ways to conserve water.conserve water.


In the HomeIn the Home–Take shorter showers. If you take Take shorter showers. If you take

baths, fill the tub only halfway.baths, fill the tub only halfway.–Keep drinking water in the Keep drinking water in the

refrigerator instead of running the refrigerator instead of running the water until it gets cold.water until it gets cold.

–Scrub vegetables in a basin of water, Scrub vegetables in a basin of water, not under running water.not under running water.


–Turn off the faucet instead of letting Turn off the faucet instead of letting the water run while you brush your the water run while you brush your teeth.teeth.

– If you have a lawn, water it early in If you have a lawn, water it early in the morning or late in the afternoon the morning or late in the afternoon so the sun won’t evaporate the water.so the sun won’t evaporate the water.

–Only run the washing machine when Only run the washing machine when you have a full load.you have a full load.


In IndustryIn Industry–New water-saving techniques help New water-saving techniques help

industries save money in water costs industries save money in water costs and meet the requirements of and meet the requirements of environmental laws.environmental laws.

–These techniques conserve water These techniques conserve water while also reducing the amount of while also reducing the amount of wastewater that plants release.wastewater that plants release.


In AgricultureIn Agriculture

–Accounts for the highest Accounts for the highest consumption of water in the US.consumption of water in the US.

–Using pipes to carry water reduces Using pipes to carry water reduces the water loss.the water loss.

–Sprinkler irrigation and drip irrigation Sprinkler irrigation and drip irrigation both use pipes to conserve water.both use pipes to conserve water.


–Sprinkler irrigation sprays water onto Sprinkler irrigation sprays water onto crops from overhead pipes.crops from overhead pipes.

–Drip irrigation distributes water Drip irrigation distributes water through pipes with tiny holes that lie through pipes with tiny holes that lie close to the ground.close to the ground.


What Is Pollution?What Is Pollution?

–Water pollution is the addition of any Water pollution is the addition of any substance that has a negative effect substance that has a negative effect on water or the living things that on water or the living things that depend on the water.depend on the water.

–The substances that cause water The substances that cause water pollution are called pollutants.pollution are called pollutants.


–Scientists classify sources of Scientists classify sources of pollution, in part, by how they enter a pollution, in part, by how they enter a body of water.body of water.

–A point source is a specific source of A point source is a specific source of pollution that can be identified.pollution that can be identified.

–Nonpoint source is a widely spread Nonpoint source is a widely spread source of pollution that can’t be to a source of pollution that can’t be to a specific point of origin.specific point of origin.

Documents

Fresh Water. Water On Earth The positive hydrogen ends of one water molecule attract the negative oxygen ends of nearby water molecules. As a result,