1. The Flow of Fresh Water
Chapter 11

2. Rivers: Agents of Erosion
Many years ago there was a vast plain in the southwestern U.S.
Over the years the Colorado River cut out the Grand Canyon
This was done by erosion.

3. Grand Canyon

4. Grand Canyon

5. Grand Canyon

7. Erosion
The process by which soil and sediment are transported from one location to another.

8. Erosion can be caused by:
Wind
Rain
Ice
Snow

9. Wind

10. Rain

11. Ice

12. Snow

13. The Water Cycle
The continuous movement of water from the ocean, to the air, to the land, then back to the ocean.

15. Some Water Cycle Words to know:
Evaporation: When water from oceans, lakes, and other places on Earth’s surface turns in to water vapor and rises into the atmosphere.
Condensation: When water vapor cools and changes into water droplets that form clouds

16. More Words Precipitation: When rain, sleet or snow falls to the Earth.
Percolation: When water moves through pores in the earth’s surface into the ground
Runoff: Water that flows over land into lakes, seas, or oceans.
Water that flows over land into lakes, seas, or oceans.

17. Now you try! On the next slide, label all of the words below.
Evaporation
Condensation
Percolation
Runoff
Precipitation

19. River Systems
A tributary is a small stream that flows into a lake, or a larger stream.

20. Watershed
A watershed is an area of land that is drained by a water system.
The largest in the U.S. is the Mississippi Watershed.

21. Other Watersheds
Columbia
Rio Grande
Colorado

22. Divide
A divide is an area of higher ground that separates water sheds from each other.

23. How does this divide separate the U.S. and its watersheds?

24. Channel A channel is the path that a stream follows.
A new stream will have a narrow, steep channel.
An older stream will have a wider, and deeper channel.

25. The Ability to Erode
Gradient: Measure of change in elevation over a certain distance
Discharge: The amount of water a stream or river carries
Load: The material carried by a stream

26. Gradient
The steeper a stream is the more erosive energy it has

27. Discharge
The more water a river will discharge the more erosive power it will have.

28. Load Load is affected by speed. Fast = large particles
Slow = Smaller particles

29. Stages of a River Rivers go through a “life cycle.” Youthful Mature
Old

30. Youthful
Youthful rivers have a steep gradient, a steep and narrow channel, and many waterfalls. The channel will erode deeper, rather than wider.

31. Mature
Mature Rivers have a gradient that is not as steep as a youthful river. They have few falls and rapids. They will erode wider rather than deeper.

32. Old
Old rivers have a low gradient and little erosive energy. They deposit rather than erode.

33. Rejuvenated Rivers
Rejuvenated rivers are mature rivers that have a steeper gradient due to land rising because of tectonic activity.