Geography
Standard VIII
The Work Of Rivers
(The Journey Of a River)
RIVER PROFILE
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UPPER COURSE
MIDDLE COURSE
LOWER COURSE
Source
of the
River
Main Work:
Main Work:
TRANSPORTATION
DEPOSITION
Main Work:
DENUDATIONN
Mouth
of the
River
SEA
VERTICAL EROSION
Steep V-Sided Valley
VALLEY WIDENING
Open, gently sloped Valley
DEPOSITION OF
ALLUVIUM
Very gently sloped Valley
Q.1. Name the different courses of a river.
Ans.The course of a river from its source to its mouth is divided into three sections:
 The upper course (1st Stage)
 The middle course (2nd Stage)
 The lower course (3rd Stage)
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Q.2. What are the elements of a river in its 3 different courses?
Ans.
I.UPPER COURSE
II.MIDDLE COURSE
Characteristics:
Characteristics:
 The volume of  The volume of water has
water is small.
increased
as
the
 The source of the
catchment area (area
rivers is generally in
drained by single river
hilly
or
system) has increased.
mountainous area.
This is due to more
 The flow is very
tributaries joining the
swift as it flows
river.
through a steep  The middle course starts
gradient.
when the river leaves the
mountains & enters a
Main Work:
low lying/ plain region.
flow
becomes
 Denudation
or  The
relatively slow as the
Erosion.
volume & load has
 The young streams
increased.
are powerful agents
of erosion & rapidly Main Work:
erode a channel  To cope with the
increased volume of
vertically through
water, the river has to
the rocks.
widen its valley.
 Down cutting is
 Hence, lateral cutting
more evident.
tends to replace vertical
Features Formed:
cutting.
 The material eroded from
 Steep sided Vthe valley side is then
shaped valley called
transported along with
Gorge.
the river.
 Waterfalls, Rapids
Features Formed:
 Meanders, Ox-bow lakes
Uses:
 Flood plains
 The river is useful Uses:
for hydro-electricity  Flood
plains
are
in this stage as the
extremely fertile with
water falls through
layers of silt & best
a steep gradient.
suited for agriculture.
 For navigation
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III.LOWER COURSE
Characteristics:

In this stage the water
flows sluggishly as the
river is carrying lot of
load.
 The valley becomes broad
& shallow.
 The deposits are fine in
texture.
 River
branches
into
distributaries.
Main work:
 Deposition of the material
which
has
been
transported.
 The heaviest deposition of
silt occurs at the mouth of
the river where it meets
the sea.
Features Formed:
 Fan shaped alluvial tract
of land formed at the
mouth of the river – Delta
 Distributaries of the main
river.
Uses:
 Deltas are best suitable for
human settlement.
 Fishing
Q.3
(a) Identify the feature given in the above picture.
Ans. Meanders
(b) Where (which stage of the river) are they commonly formed?
Ans. Middle course (2nd stage)
(c) How are they formed?
Ans. As the river erodes laterally, it swings from side to side in wide, horseshoe like
loops called meanders. The name is derived from river Meander. The bank is worn
away on the outside bend where as solid material is deposited on the inside bend.
Q.4. Explain the formation of Ox-bow lakes?
An OX-BOW
LAKE
Ans. When a meandering river cuts across the narrow neck of land between the two stretches,
it leaves a backwater.
When silt is deposited at the entrance to this backwater, it forms an Ox-bow lake. Such lakes
are common in the banks of Mississippi.
Q.5.Answer the following:
(a) All rivers do not form deltas.
Ans. The following conditions do not allow the formation of deltas If the river is swift in its lower course
It carries little or no alluvium upto the sea
The sea near the coast is very deep.
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Presence of strong tidal currents near the mouth of the river.
If there are large lakes in the course of the river, much of the sediment is removed.
A Delta
(b) What is an Estuary? Mention its advantages.
Ans. Many of the rivers emptying into the sea have the shape of a gradually widening bay
cutting deep inland. Such a bay is called an Estuary.
Advantages – If the entrance of the estuary is not silted, it makes an excellent site for natural
river port. The funnel shape increases the height of the tide & so the river becomes navigable
some distance inland.
An Estuary
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