Transcript Fresh Water Chapter 11

Fresh Water
Chapter 11
Unit Essential Question: What would
the world be like without water?
Water on Earth – Section 1
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97% salt water
3% fresh water
Of the 3% of fresh water
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Ice 76%
Water vapor 0.037%
Lakes and rivers 0.34%
Deep groundwater 11%
Shallow groundwater 12%
Less than 1% of water on Earth is available for
human use
The Water Cycle
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Water cycle – continuous process by which
water moves through the living and non-living
parts of the environment
In the water cycle, water moves from bodies of
water, land, and living things on Earth’s surface
to the atmosphere and back to Earth’s surface.
The process of the water cycle
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Evaporation – the process by which molecules at the
surface of a liquid absorb enough energy to change to
the gaseous state.
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Name three places that water evaporates from.
1.
2.
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Transpiration – the process of water being given off
through leaves as water vapor.
Water Cycle continued
Clouds form – condensed droplets of water clump
together around tiny dust particles in the air, forming
clouds.
Precipitation – The water vapor in the clouds
becomes so heavy that they fall back to Earth.
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1.
2.
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Name the 4 types of precipitation.
How do we use water?
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Agriculture – growing plants
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Irrigation – the process of supplying water to areas
of land to make them suitable for growing crops.
Industry – industries use water in many
different ways
Transportation – oceans and rivers are used
fore transportation
Recreation – swimming, boating, skiing,
snowboarding, skating
How do we use water?
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2.
List an agricultural use, and industrial use, and
a household use of water that you relied on
today.
Water and living things
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Water makes up nearly 2/3 of your body
Water is necessary to keep your body
functioning
Water is essential for living things to grow,
reproduce, and carry out other important
processes.
Photosynthesis – plants use water, plus carbon
dioxide and energy from the sun, to make food
Questions
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What is the water cycle?
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Where is most of the fresh water on Earth
found?
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How does the water cycle renew Earth’s
supply of fresh water?
Water on the Surface – Section 2
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River system – a river and all of its tributaries
together make up a river system
Tributary – smaller streams and rivers that feed
into a main river
Watershed – the land area that supplies water to
a river system. Watersheds are also called
drainage basins.
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A river can flow into another larger river. When
rivers join another river system, the areas they drain
become part of the largest river’s watershed.
River systems
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Divides – One watershed is separated from
another by a ridge of land called a divide.
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Streams on each side of the divide flow in different
directions.
What is the longest divide in North America?
Rivers and Floods
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Floods occur when the volume of water in a
river increases so much that the river overflows
it’s channel.
Can floods be controlled?
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Building dams is one method of flood control.
Dam – a barrier across a river that may redirect
the flow of a river to other channels or store
water in an artificial lake.
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Name a large artificial lake around here that was
created when a dam was built.
Levees
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Sediment deposits can build a natural defense
against floods. As a river overflows onto its
flood plain, it slows down and deposits heavier
sediment alongside the channel. Over time these
deposits build up into long ridges called levees.
Bodies of Fresh Water
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Water in streams and rivers is always on the
move
Water in lakes and ponds is still, or standing
water
Ponds are smaller and shallower than lakes
Sunlight usually reaches to the bottom of all
parts of a pond.
Most lakes have parts were the water is too
deep for sunlight to reach the bottom
Ponds and Lakes
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Ponds and lakes form when water collects in
hollows and low-lying areas of land.
Both are supplied by melting snow and ice and
runoff
Some are fed by rivers or ground water
Some ponds only appear in the spring and are
created by runoff
Why can plants grow throughout a pond?
Ponds and Lakes
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The bottom of a pond is usually covered with
mud and algae
The bottom of a lake consists of sand, pebbles
or rock
Lakes
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Lakes are created by
A cutoff river meander – oxbow lake
 Ice sheets that melted at the end of the Ice Age
 Movement of Earth’s crust
 Erupting volcano
 Building a dam
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Reservoir – a lake that stores water for human
use
Changes in a Lake
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As the water heats and cools the layers of water mix, as
the water mixes, minerals, plant matter, and other
nutrients rise from the lake bottom to the surface. This
lake turnover refreshes the supply of nutrients
throughout the lake.
Eutrophication occurs when the nutrients build up in
the lake and cause more algae to grow. This causes
thick green scum on the surface of the water. As the
algae gets thicker and blocks out more sunlight, the
animals in the lake can not survive. The Lake will
eventually dry up and be only plants.
Glaciers and Icebergs
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Glacier – any large mass of ice that moves
slowly over land, 76% of fresh water on Earth
Iceberg – When a glacier reaches the seacoast,
icebergs form
Icebergs break into chunks as big as houses as they
drift south
 They begin to melt in warmer water
 90% of an iceberg lies below the surface of the
water. Only 10% is visible
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Questions
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What bodies of water make up a river system?
Explain how ponds and lakes form.
Where do icebergs form