Class 9, Ncert Cbse Social Science (Geography)
Chapter 3, Contemporary India - I
Drainage
NCERT Solutions (Important Exercise Questions)
Question.2:
Answer the following questions briefly,
(i) What is meant by a water divide? Give an
example.
(ii)
Which is the largest river basin in India?
(iii)
Where do the rivers Indus and Ganga have their origin?
(iv)
Name the two head-streams of the Ganga. Where do they meet to form Ganga?
(v) Why
does the Brahmaputra in its Tibetan part have less silt, despite a longer
course?
(vi)
Which two peninsular rivers flow through trough?
(vii) State
some economic benefits of rivers and lakes.
Solution:
(i) Any upland or a mountain separating
two adjoining drainage basins is known as water divide. Though the Indus, the
Sutlej and the Brahmaputra rivers rise very close to each other near the
Mansarovar Lake but because of the water divides they flow in different
directions.
(ii) The Ganga basin is the largest
river basin in India.
(iii) The Indus river has its origin in
Tibet near the Mansarovar Lake while the Ganga River has its origin in Gangotri
Glacier in Uttaranchal.
(iv) Alaknanda and Bhagirathi are the
two headstreams of the Ganga. They meet at Devaprayag.
(v) The Brahmaputra river, which is
known as Tsangpo in Tibet, receives very little volume of water in Tibet so; it
has very little silt there. On the other hand, this river when enters India it
passes through such a region which receives heavy rainfall. As such in India,
in India it carries a large volume of water and larger amount of silt.
(vi) Narmada and Tapi are two peninsular
rivers which flow through trough.
(vii) Refer to answer to the question
no.6 below.
Question.3: Below are given names of a few lakes of India. Group
those under two categories - natural (N) and created by human beings (HB).
(a) Wular (b) Dal (c) Nainital (d) Bhimtal (e) Govind Sagar (f)
Loktak (g) Barapani (h) Chilika (i) Sambhar (j) Rana Pratap Sagar (k) Nizam
Sagar (l) Pulicat (m) Nagarjuna Sagar (n) Hirakund.
Solution: (a) N (b) N (c) N (d) N
(e) HB (f) N (g) N (h) N (i) N (j) HB (k) HB (l) N (m) HB (n) HB.
Question.4: Discuss the significant difference between the
Himalayan and the Peninsular Rivers.
Solution: The following table
differentiates between the Himalayan and the Peninsular Rivers -
The Himalayan Rivers
|
The Peninsular Rivers
|
1. The Himalayan rivers rise in the snow-covered
mountains are perennial type.
2. They flow in leveled Northern Plains and are highly useful
for irrigation, cultivation and also navigation purpose.
3. The Himalayan Rivers bring with them fertile
alluvium which they deposit in the Indo-Gangetic plains.
4. Canals have been dug to use the water of these
rivers for irrigation.
5. Many important towns and centers of trade are
situated on the banks of these rivers.
6. The porous soil of Northern Plain absorbs the water
which is later on used as ground water by digging wells and tube wells.
|
1. The mountains in which the Peninsular Rivers rise
not snow covered. Hence they dry up during summer.
2. The Peninsular Rivers flow on rocky surface and so,
they are neither navigable nor useful for irrigation.
3. They do not bring with them any alluvium. Due to
their swift current the depositional activity are negligible.
4. as the terrains are rocky and the banks of these
rivers are high so, canals can not be dug. However, dams are built to store
the flood water for irrigation with the help of small channels.
5. Very few important towns and centers of trade are
situated on the banks of these rivers.
6. The underlying soil being rocky does not absorb any
water. Hence, no wells can be dug.
|
Question.5: Compare the east flowing and the west flowing rivers
of the Peninsular plateau.
Solution: The following table gives a comparison between the
east flowing and the west flowing rivers of the Peninsular plateau:
East flowing Rivers
|
West flowing Rivers
|
1. The Mahanadi, the
Godavari, the Krishna, the Cauvery are the main east flowing rivers of
Peninsular India.
2. These rivers drain in
the Bay of Bengal.
3. These rivers make
deltas at their mouth.
4. These rivers have a
developed, large tributary system.
5. These river flow not
through very deep canals.
|
1. The Narmada and the
Tapi are the main west flowing rivers of Peninsular India.
2. These rivers drain in the Arabian sea.
3. These rivers enter the
sea through estuaries.
4. These rivers are devoid
of a developed tributary system. Their tributaries are quite small in size.
5. These rivers flow in
troughs.
|
Question.6: Why are rivers important for the country’s economy?
Solution:
Rivers are highly important for the country’s economy. Following are some of
the points which indicate the importance of rivers for the country’s economy:
=> The rivers contain natural fresh
(sweet) water which is required for the survival of most of the animals
including man.
=> They provide water for irrigation and
cultivation.
=> They make soil rich and arable which
can be easily brought under cultivation without much labour.
=> Used for navigation and transport thus,
important for commercial activities.
=> Estuaries near the sea-shores, where
the sweet water mixes freely with the salty water of the oceans, have proved
one of the most biologically productive areas of the world.
=> The rivers are being harnessed for
generating hydro-electric power.
=> Some lakes are also important tourist
spots e.g. Dal Lake, Nainital etc.
Also Read
very useful
ReplyDeletethanqz
answers are good but except the 4th question is very big so it would be better if you make it small.
ReplyDelete