Chapter 2: Fresh Water

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Chapter 2 Fresh Water

• To create your title page preview
• Section 1 Streams and Rivers (42)
• Section 3 Wetland Environments (59)
• Section 5 Water Underground (68)

https//www.youtube.com/watch?vuAsV5-Hv-7U
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Section 1 Streams and Rivers

• Page 42

https//www.youtube.com/watch?vuAsV5-Hv-7U
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How do rivers begin?

• Rivers begin when trickles of water run over the
  ground and join together in larger streams. The
  water follows the slope of the land.

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What happens to rain that falls to Earth?

1. some evaporates immediately
2. some soaks into the soil
3. the remaining water flows over the ground surface
   (runoff)

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Runoff

• Runoff is water that flows over the ground
  surface rather than soaking into the ground.
• Runoff can come from rain or melting ice and
  snow.

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3 factors that influence water soaking in or
becoming runoff

• One nature of the ground surface
• The amount of space between the particles that
  make up the ground cover.
• soil vs. pavement?
• plants vs. bare soil?

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3 factors that influence water soaking in or
becoming runoff

• Two rate of rainfall
• The ground can only absorb so much rain during a
  heavy downpour. What cant soak into the ground
  becomes runoff.

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3 factors that influence water soaking in or
becoming runoff

• Three slope of the land flat or hilly
• Force of gravity pulls water downhill.
• Water flows faster down a steep slope than over
  flat ground.
• Fast water runs off instead of soaking in this
  is how a river begins.

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River Systems

• Define the following words using pages 44-45 in
  your text
• tributary
• river system
• watershed
• divide
• Add these words to your WWK list on page 55.

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How do rivers shape the land?

• Rivers wear away landforms through erosion and
  build new landforms through deposition.
• With erosion, sediment is carried away.
• Soil and rock are left behind with deposition.

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Sediment

• The particles of rock and soil that are picked up
  and moved by erosion and deposition are called
  sediments.
• Add these words to your list on page 55
• erosion
• deposition
• sediment

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How fast is that river?

• https//www.youtube.com/watch?vy4xQnLEskbM
• A rivers speed affects its ability to wear away,
  or erode, the land.
• Faster water flow has more energy.

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Profile of a River

• We are going to take a journey down a river from
  its headwaters to its mouth. As we travel, the
  speed and volume of the water will change and
  also the shape of the river. Each part of the
  river forms a different habitat for living
  things.

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Profile of a River

• Our trip starts in the mountains.
• The many small streams that come together at the
  source of the river are the headwaters.
• Water is moving fast and picking up sediment as
  it flows. Erosion continues and the channel gets
  wider and deeper.

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Profile of a River

• We are starting to move downriver.
• Some smaller streams have joined our river,
  increasing the volume of water.
• It is less steep and smoother but we are
  continuing to move swiftly (less friction).

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Profile of a River

• Next, the river meanders through the middle of
  its flood plain. In the flat land of the flood
  plain, the rivers speed is determined by its
  volume.
• The broad, flat valley through which the river
  flows is called the flood plain.

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Profile of a River

• Do you see the crescent shaped lakes?
• Small obstacles can create a slight bend in the
  river causing erosion and deposition to occur.
  This process gradually forms looping curves in
  the river called meanders.

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Profile of a River

• Back to the lakes, see them?
• After the river has meandered for many years, the
  river may eventually break through the ends of
  the meander forming a new channel.
• The crescent-shaped, cutoff body of water that
  remains is an oxbow lake.
• https//www.youtube.com/watch?v4qKS_Nk7UmY
• https//www.youtube.com/watch?v8a3r-cG8Wic

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Profile of a River

• Our trip is nearly over as we approach the mouth.
  At its mouth, the river slows down and deposits
  the sediments it carries.
• The mouth is the point where a river flows into
  another body of water a larger river, a lake,
  or an ocean.

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Profile of a River

• As the river is slowing down, it deposits most of
  its sediments.
• These deposits at the rivers mouth build up,
  forming an area called a delta.
• The sediments are rich in nutrients and minerals.
  A great place to farm!

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Words Worth Knowing

• Add these words to page 55
• Headwaters
• Flood plain
• Meanders
• Oxbow lake
• Mouth
• Delta

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When does a flood occur?

• A flood occurs when the volume of water in a
  river increases so much that the river overflows
  its channel.
• https//www.youtube.com/watch?vRNde3bnXaVM

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Fear or welcome a flood?

• Yippee flood!
• Deposition leaves a layer of nutrient rich
  sediment behind.

• Boo flood!
• Destroy farms and crops
• Destroy homes
• Loss of electricity, transportation, clean water
• Injury or death of people and livestock

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How can we control floods?

• Build a dam a barrier across a river that may
  redirect the flow of a river to other channels OR
  store the water in an artificial lake.
  https//www.youtube.com/watch?voD4QHkN57FM
• Levees can be natural or people made. People
  can build up a natural levee with sandbags.
• Add to your list on 55 dam and levee