Streams and Rivers
Dana Desonie, Ph.D.
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Printed: October 14, 2014
AUTHOR
Dana Desonie, Ph.D.
www.ck12.org
C HAPTER
Chapter 1. Streams and Rivers
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Streams and Rivers
• Define stream and describe its parts.
• Define divide.
What makes this river so much fun to raft?
Whitewater rafting is a popular recreational activity. The river is fast because its in the mountains traveling downhill.
There is a lot of water from snow melt higher up. Sometimes water is added from springs. Did you ever go
whitewater rafting? It’s fun!
What Are Streams and Rivers?
A stream is a body of freshwater that flows downhill in a channel. The channel of a stream has a bottom, or bed,
and sides called banks. Any size body of flowing water can be called a stream. Usually, though, a large stream is
called a river.
Features of Streams and Rivers
All streams and rivers have several features in common ( Figure 1.2). The place where a stream or river starts is
its source. The source might be a spring, where water flows out of the ground. Or the source might be water from
melting snow on a mountain top, like the stream pictured below ( Figure 1.1). A single stream may have multiple
sources.
A stream or river probably ends when it flows into a body of water, such as a lake or an ocean. A stream ends at
its mouth. As the water flows into the body of water, it slows down and drops the sediment it was carrying. The
sediment may build up to form a delta.
Several other features of streams and rivers are also shown above ( Figure 1.2).
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FIGURE 1.1
A stream flows fast and steep where it
originates in the mountains. This stream,
in Glacier National Park in Montana, is
coming from snow melt.
FIGURE 1.2
Water in a stream flows along the ground
from higher to lower elevation. What force
causes the water to keep flowing?
• Small streams often flow into bigger streams or rivers. The small streams are called tributaries. A river and
all its tributaries make up a river system.
• At certain times of year, a stream or river may overflow its banks. The area of land that is flooded is called the
floodplain. The floodplain may be very wide where the river flows over a nearly flat surface.
• A river flowing over a floodplain may wear away broad curves. These curves are called meanders. Pictured
below is an example of this ( Figure 1.3).
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Chapter 1. Streams and Rivers
FIGURE 1.3
A river meanders across an estuary in
Florida.
River Basins and Divides
All of the land drained by a river system is called its basin, or watershed. One river system’s basin is separated from
another river system’s basin by a divide. The divide is created by the highest points between the two river basins.
Precipitation that falls within a river basin always flows toward that river. Precipitation that falls on the other side of
the divide flows toward a different river. A continental divide separates rivers that flow into different oceans.
Pictured below are the major river basins in the U.S. ( Figure 1.4).
FIGURE 1.4
River basins in the U.S.
Vocabulary
• continental divide: Divide that separates water that goes to different oceans.
• divide: Ridge that separates one water basin from another.
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•
•
•
•
•
•
•
•
floodplain: Region near a stream where water overflows during floods.
headwaters: Location where a stream forms, often high in the mountains.
meander: Bend in a stream channel.
mouth: Where a stream enters a larger body of water such as a lake or an ocean.
source: Where a stream begins; usually in mountains.
stream: Body of moving water, contained within a bank (sides) and bed (bottom).
tributary: Smaller of two streams that join together to make a larger stream.
watershed: All of the land area that is drained by a river and its tributaries.
Summary
• A moving body of water of any size is a stream. A river is a large stream.
• A tributary begins at its headwaters on one side of a divide. Two tributaries come together at a confluence.
• A river ends at an estuary. If the river drops sediment, it may create a delta.
Explore More
Use the resources below to answer the questions that follow.
https://www.youtube.com/watch?v=UPLt9fQ-owo Start at 0:49
1. What is the tributary system? What does that mean in simple English?
2. What does a tributary flow into?
3. What do the tributaries in the Rocky Mountains near Woodland Park feed into? What does that flow into?
And what does that flow into? And finally what does that flow into?
4. At what point does a tributary meet a river?
5. What is the biggest trunk river in the U.S.?
6. What is the end of the Mississippi River in the Gulf of Mexico?
7. What is a delta?
8. What is found in a delta?
9. How did a delta get its name?
Review
1. Describe the features of a river from where it begins to where it ends.
2. What happens to two drops of water that fall on opposite sides of a divide?
3. Why does a tributary not cross over a divide?
References
1. Miles Orchinik. Rapid stream in Glacier National Park. CC BY-NC 3.0
2. Hana Zavadska. Diagram of the features of a river. CC BY-NC 3.0
3. South Florida Water Management District (Flickr:JaxStrong). A river meanders across an estuary in Florida.
CC BY 2.0
4. Courtesy of the National Weather Service. The river basins in the United States. Public Domain
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