Ch 13 – Streams & Rivers
pgs 280 – 292
Almost half of the water that falls to the Earth’s surface eventually ends up in a
stream or river (runoff) where it travels overland to the oceans. Streams and Rivers
are an essential part in the water cycle and account for most of the erosion on Earth.
A tributary is a stream that runs into a larger stream. The main river
will eventually drain into the ocean. A river and all of its tributaries
is called a river system.
The watershed or drainage basin, of a river includes all the land that
drains into the river either directly or through its tributaries. The
largest drainage basin in the U.S. is the Mississippi River.
The high land that separates one drainage basin from another is called a divide.
The major divide in the U.S. is called the
Continental Divide. Rain falling east of the divide
will flow into the Atlantic Ocean and rain falling
west of the divide will flow into the Pacific Ocean.
Parts of a River System
Label Me!
The beginning of a river is known as the source.
When the mouth of a river finally reaches its
destination, the water slows down & deposits its
sediment, forming a delta.
An alluvial fan is similar to a delta, but forms on
land where a river emerges from a mountainous
area and flows out onto a more gently sloping plain.
River Development
The three stages in the development of a river are youthful, mature & old.
Most rivers begin in the highlands or mountains. There, water sources such as
melting snow and ice feed fast moving, young rivers.
As the young rivers feed into larger rivers over flatter land they may take on
characteristics of mature rivers.
As the river approaches the ocean it slows and becomes wider taking on the
characteristics of an old river.
1. A young river has a steep slope, fast-moving water, V-shaped valleys, and many
rapids and waterfalls.
Rapids & Waterfalls – caused by differential erosion
2. A mature river has a shallower slope, is slow moving, and winds back and forth
in broad curves called meanders
3. An old river moves very slowly, has a nearly flat slope, and has oxbow lakes.
Elevated ridges along stream banks are called natural levees.
Meander & Oxbow Lake Formation:
Inside curve = deposition / Outside curve: erosion
A river wants to find the shortest, straightest way
to the ocean, so it will change paths along the
floodplain cutting off wide loops leaving behind a
curved body of water called an oxbow lake.
Floods: Rivers may overflow its banks as a flood. The floodwater may cover part
or the entire valley floor where the river runs eroding and depositing sediments.
This part of the valley floor is called the flood plain.
Floods can erode or deposit.
Ch 13 – Streams & Rivers
pgs 280 – 292
Basic Drainage Patterns
Use the following words to label the parts of a rivers system shown in the diagram.
Young, mature, old, tributary, source, delta, rapids, waterfalls, oxbow lake, meander
A – youthful river
B – rapids
C – source
D – waterfall
E – tributary
F – old river
G – delta
H – meander
I – oxbow lake
J – mature river