Class IX - Dainage

Class IX - Drainage

Questions Within The Lesson

Q.1. Find out which river has the largest basin in India.

Ans. The Ganga river.

Q.2. Find out the name of the biggest waterfall in India.

Ans. The Jog Falls in Karnataka.

Questions in the Exercise

Q.1. Choose the right answer from the four alternatives given below:

(i) Which one of the following describes the drainage patterns resembling the branches of a tree?

(a) Radial (b) Dendritic (c) Centrifugal (d) Trellis

Ans. Dendritic

(ii) In which of the following States is the Wular Lake located?

(a) Rajasthan (b) Uttar Pradesh (c) Punjab (d) Jammu and Kashmir

Ans. Jammu and Kashmir

(iii)The river Narmada has its source at:

(a) Satpura (b) Brahmagir (c) Amarkantak (d) Slopes of the Western Ghats

Ans. Amarkantak

(iv)Which one of the following lakes is a salt water lake? (CBSE 2010)

(a) Sambhar (b) Dal (c) Wular (d) Gobind Sagar

Ans. Sambhar

(v) Which one of the following is the longest river of the Peninsular India?

(a) Narmada (b) Krishna (c) Godavari      (d) Mahanadi

Ans. Godavari

(vi)Which among the following rivers flows through a rift valley? (CBSE 2010)

(a) Damodar (b) Tungabhadra (c) Krishna (d) Tapi

Ans. Tapi

Q.2. Answer the following questions briefly.

(i) What is meant by a water divide? Give an example.

Ans. Any elevated area such as a mountain or an upland that separates two drainage basins is called

a water divide. An example of water divide is the Western Ghats.

(ii) Which is the largest river basin in India?

Ans. The Ganga river basin is the largest river basin in India.

(iii) Where do the rivers Indus and Ganga have their origin?

Ans. Indus rises in Tibet near Lake Mansarovar.

Ganga has Bhagirathi as the head water which is fed by the Gangotri glacier.

(iv) Name two headstreams of the Ganga. Where do they to form the Ganga?

 Ans. The two headstreams of the Ganga are the Alaknanda and the Bhagirathi and they both meet

to form the Ganga at Devprayag.

(v) Why does Brahmaputra in the Tibetan part have less silt despite a longer course?

Ans. Called river Tsangpo in Tibet, Brahmaputra has very little volume of water. So it obviously

carries little silt. But once it enters India, Brahmaputra is fed by heavy rains, and it carries lot

of water and silt.

(vi) Which two peninsular rivers flow through troughs? What features do they form

while entering the sea?

Ans. The two rivers that flow through troughs  are Narmada and Tapi. They form estuaries while

entering the sea.

(vii) Give five economic benefits of rivers and lakes.

Ans. Role of rivers in the economy :

(a) Rivers create alluvial soils.

(b) River irrigation is the backbone of agriculture in areas that have insufficient rainfall.

(c) Many industrial processes depend on river water as a coolant and for generation of hydro-

electricity.

(d) Rivers provide inland channels for transport.

(e) Rivers provide fisheries, scope for developing adventure sports like rafting and

entertainment joints.

Lakes like the Sambhar Lake provide edible salt. They also help develop tourism and

provide recreation.

Q.3. Below are given names of a few lakes of India. Group those under two categories —

natural and created by human beings.

(a) Wular (b) Dal (c) Nainital (d) Bhimtal

(e) Gobind Sagar (f) Loktak (g) Barapani (h) Chilika

(i) Sambhar (j) Rana Pratap Sagar (k) Nizam Sagar

(l) Pulicat (m) Nagarjuna Sagar (n) Hirakud

Ans. Natural Lakes :  Wular, Dal, Nainital, Bhimtal, Chilika, Pulicat, Sambhar, Barapani, Loktak

Created by human beings : Gobind Sagar, Hirakud, Rana Pratap Sagar, Nagarjuna Sagar,

Nizam Sagar

Q.4. Discuss the significant differences between the Himalayan and the Peninsular rivers.

Ans. The drainage system of the Indian subcontinent are mainly controlled by the broad relief

features. The Indian rivers are divided into two major groups : (a) The Himalayan rivers and

(b) The Peninsular rivers.

Points of difference : (a) The Himalayan rivers mostly originate in the Himalayan ranges

whereas the Peninsular rivers mostly originate in the Western Ghats (b) The Himalayan rivers

are perennial whereas the Peninsular rivers are seasonal (c) The Peninsular rivers have shorter

and shallower courses in comparison to the Himalayan rivers.

Q.5. Compare the east-flowing and the west-flowing rivers of the Peninsular Plateau.

(CBSE 2010)

OR

Why are the rivers of Penisula seasonal ? Give two differences between the west-flowing

and east-flowing rivers of Peninsular Plateau. (CBSE 2010)

Ans. The Peninsular Plateau of India is marked by a large number of east-flowing rivers and a few

west-flowing rivers.

Most of the major rivers of Peninsular India such as the Mahanadi, the Godavari, the Krishna and the Kaveri and their tributaries flow eastwards. They rise from the Western Ghats, the highlands of the Deccan Plateau, flow towards east and drain into the Bay of Bengal. Only two big rivers, the Narmada and the Tapi, with long courses flow westwards in Peninsular Plateau region. They rise from the Satpura range and Amarkantak hills, flow westwards through faults and drain into the Arabian Sea. The coastal plains between Western Ghats and the Arabian Sea are very narrow. Hence, the west-flowing coastal rivers are short and swift flowing. The Sabarmati, Mahi, Bharathpuzha and Periyar are the west-flowing rivers. The Sabarmati and the Mahi originate in the Central highlands and flow into the Arabian Sea. The Western Ghats form the main water divide in Peninsular India. The east-flowing rivers have wide basins. They have dendritic drainage pattern with many tributaries joining them. They form large deltas at their mouths. The west-flowing rivers flow between highlands and have elongated courses. They have trellis and rectangular drainage pattern. They flow through rift valleys and are fault guided rivers. They form estuaries at their mouths. The west-flowing rivers do not form deltas.

Q.6. Why are rivers important for the country’s economy?

Ans. Rivers are the lifelines of a nation. Rivers have been of fundamental importance in the

settlement and progress of man throughout the human history.

The rivers form broad, fertile alluvial plains that have been the cradle of human civilisation.

Water from the river is a basic natural resource, essential for various human activities. They

provide water for domestic use. Rivers provide water for irrigation that helps to develop

agriculture in the surrounding area.

The fertile soil of the riverine plain, abundant supply of water and the flat land provides

opportunities for the development of agriculture. In an agricultural country like India, rivers

play a major role in shaping the country’s economy.

Rivers supply water for industrial use. Rivers provide for a cheap mode of transportation,

inland navigation.

Hydro-electricity harnessed from river water supplies power to our industries, to our homes

and to our agricultural fields. Integrated water management of rivers through River Valley

Projects by building dams provide hydro-electricity, water for irrigation, inland navigation,

fishing, recreation etc.

Hence, rivers are of prime importance in the flourishing of a country’s economy.