Question

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 headstreams of the Ganga. Where do they meet to form the 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.

Class 9 - Social science - Drainage Page 24

Answer 1

1. a water divide is an upland that separates two drainage basin. for eg Western Ghats
2. the Indus river has the largest river basin in India
3. the Indus has its origin in Tibet near mansarovar lake while gang a river has its origin in gangotri glacier in uttaracnhal.
4. alaknanda and bhagirathi are the two head streams of the ganga. they both meet to form the ganga at devprayag.
5. it carries less amount of silt b'coz it is a cold and a dry area.
6. the two rivers that flow through troughs are narmada and tapi.
7. # river is very beneficial for agricultural purpose and generating hydro- electricity.
# it provides fisheries, inland channels for transport.
# lakes like the sambar lake provide edible salt.
# they also help develop tourism and provide recreation.

Answer 2

i)
A raised area separating the headstreams of two different river system is called a watershed or water divide.
In India the Ganga River system flows eastwards and drains into the Bay of Bengal while the Indus River system flows westward and drain into the Arabian Sea.
The area near Ambala with the height of 283 M is a water divide between the Ganga and the Indus. It separates two drainage basins.

ii)
The Ganga Brahmaputra river basin is the largest in India. The Ganga river is 2525 km long and the Brahmaputra river is 2900 km long. The two rivers join together to form the largest delta of the world.

iii)
River Indus and Ganga are Himalayan rivers.
a)
River Indus rises in Kailash range in western Tibet near Lake Mansarovar.

b)
River Ganga Rises from the Gangotri Glacier.

iv)
The headwaters of the Ganga called the Bhagirathi is fed by the Gangotri Glacier and is joined by the Alaknanda at Devprayag in Uttarakhand. The two join to form the Ganga river .

V)
Most of the course the Brahmaputra lies in Tibet. It enters India in Arunachal Pradesh. The river is called Tsangpo in Tibet. In tibet , the volume of water (due to less rainfall) of the river is less and has less silt as it is a cold and dry area.

But in India the river has large volume of water(due to heavy rainfall) and silt. The river has a braided channel in Assam.

vi)
The Narmada and the Tapi river flow through the trough. These rivers form estuaries before falling into the river.


vii)
Economically, rivers are very beneficial for a nation's economy.
Some few points are given below:


i) They are helpful for irrigation.
ii) During heavy rainfall these prevent flooding and during the dry season these help to maintain an even flow of water.
iii) they are used for boating and fishing.
iv) they add to the beauty of the nature.
v) they are a source of attraction for the tourist.
vi) salt water lakes are used in preparing salt.
vii) they can be used to produce electricity.
viii) river transport has helped in the industrial development.

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Hope this will help you.....