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RIVERS
A river is a natural stream of water which
flows in a channel towards a
mouth
or lake or another river. Rivers have two banks (left and right
bank). They have a bed over which the water flows. Rivers
always have a
source,
from where they start. Rivers
always flow downwards.
River banks
Rivers have two
banks - the right bank
and the left
bank.
If you stand in a river and face the way the water is flowing, the
right bank will be on your right hand side and the left bank will be
on you left hand side.
 
River bed
The river bed is the bottom of
the river. It can be made of stones, pebbles, boulders, rock or mud.
The water flows over the river bed. You can see the water bed in
streams, and in the upper course of a river, because the water is
shallower. In the middle and lower courses of a river, you cannot
see the river bed because the water is much deeper.
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In the photo, the river bed can be seen between the boulders and
stones. The boulders and stones also form part of the river bed. |
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River channel
The river
channel is the course for the river water. It can either be a
straight channel like a
canal, or a
meandering
(zigzag) channel. The channel gives the river its shape.
Courses of rivers
River courses
have three parts.
The course
is
the journey the river makes to reach the sea. Rivers never have a
straight course from source to mouth. Their course is always bendy.
1. The upper
course
is found in the mountains and hills where the
river rises from its source. Often
waterfalls and
rapids are also found in this
course. The river is usually fast flowing in the upper course. There
are lots of stones and boulders for the water to flow over. The
river starts as a
stream and usually flows through
V-Shaped valleys
in the upper course.
2. The middle
course
is where the river starts to become wider and deeper. The land which
the river flows over becomes flatter. The river starts to
meander
or bend in the middle course.
3. The
lower course is where the river
becomes its widest and deepest. This course is found close to the
sea where the river has its
mouth. Sometimes a river can also have an
estuary or a
delta
as its mouth.
The flat area of
land by the river banks is known as a
floodplain.
Farmers grow crops there.
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Upper course |
Middle course |
Lower course |
Stages of rivers
Sometimes a
river is also described as having the following three stages of
life:
Stage 1
is a youthful river.
This is the river in its upper course where it is fast flowing and
is a stream.
Stage 2
is the mature river.
This is the river in its middle course where it meanders and flows
more slowly. Other rivers join it as
tributaries in its mature stage.
Stage 3
is the river in old age.
This is the river in its lower course, where it flows slowly towards
its mouth at the sea.
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Ten
Largest Rivers of the World |
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River |
Source |
Mouth |
Approx. length km |
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Nile |
Tributaries of Lake Victoria, Africa |
Mediterranean Sea |
6,700 |
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Amazon |
Glacier-fed lakes, Peru |
Atlantic Ocean |
6,300 |
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Mississippi-Missouri-
Red Rock |
Source of Red Rock, Montana |
Gulf of Mexico |
6,000 |
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Chang Jiang (Yangtze) |
Tibetan plateau, China |
China Sea |
5,800 |
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Ob |
Altai Mts., Russia |
Gulf of Ob |
5,600 |
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Huang Ho (Yellow) |
Eastern part of Kunlan Mts., West China |
Gulf of Chili |
4,700 |
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Yenisei |
Tannu-Ola Mts., western Tuva, Russia |
Arctic Ocean |
4,500 |
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Paraná |
Confluence of Paranaiba and Grande rivers |
Río de la Plata |
4,500 |
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Irtish |
Altai Mts., Russia |
Ob River |
4,500 |
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Zaire (Congo) |
Confluence of Lualab and Luapula rivers, Congo |
Atlantic Ocean |
4,400 |
Questions
1.
What is a river?
2.
From where does a
river begin?
3.
What is mouth of the
river?
4.
What is meant by river
bed?
5.
What are the banks of
the river called?
6.
What is a meandering
channel?
7.
What are the three
courses of a river?
8.
What is meant by
youthful river?
9.
Where is the mouth of
River Nile?
10.
What is the difference
between mature and old age river
stages? |
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