Home | Session 4 | Rivers Pg 1, 2, 3, 4, 5, 6
Rivers
Presented
by Ellen Metzger
San Jose State University and BAESI
- River Systems
A. A river and its tributaries form a system.
B. The land drained by a river system is known as a watershed. No matter where you live, you live in a watershed.
On-line resource from the Environmental Protection Agency: "Surf Your Watershed". Locate your watershed and read about the quality of its water.
1. Watersheds can be small or large.
a. The Mississippi River watershed drains nearly half of the continental United States.
b. One watershed is separated from another by a ridge of land called a divide. The Continental Divide, located in the Rocky Mountains, separates streams that flow westward into the Great Basin or Pacific Ocean from those that flow towards the Gulf of Mexico.
- The Course of a River
How does a river change from its source or headwaters (which is often, but not always in a mountainous region) to its mouth (where it flows into another body of water such as a bay, lake, or ocean)?
A. Longitudinal profile or sideways view of a river channel.
Note that the gradient becomes less steep downriver.
- Headwaters: steep slope. Waterfalls and rapids, narrow valley. Dominant process: downward erosion of channel towards base level (the lowest elevation to which a stream can cut downward; ultimate base level is the sea).
- Downriver: slopes less steep; lateral erosion increases.
Wide flood plains with meanders (bends).
- Mouth: river slows down and deposits sediment to form beaches/deltas.
updated March 4, 2002
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