NCERT Solutions Class 9 Social Science Chapter 3 Drainage

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

Answer: (b) Dendritic

(ii) In which of the following states is the Wular lake located?

(a) Rajasthan

(b) Uttar Pradesh

(c) Punjab

Answer: (d) Jammu and Kashmir

(iii) The river Narmada has its source at

(a) Satpura

(b) Brahmagiri

(c) Amarkantak

(d) Slopes of the Western Ghats

Answer: (c) Amarkantak

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

(a) Sambhar

(b) Dal

(c) Wular

(d) Gobind Sagar

Answer: (a) Sambhar

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

(a) Narmada

(b) Krishna

(vi) Which one amongst the following rivers flows through a rift valley?

(a) Mahanadi

(b) Tungabhadra

(c) Krishna

(d) Tapi

Answer: (d) Tapi

2. Answer the following questions briefly.

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

Answer: Any elevated area, such as a mountain or an upland, separates two drainage basins. Such an upland is known as a water divide. Western Ghats is best example of water divide.

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

Answer: The Ganga river basin is the largest river basin in India.

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

Answer: The Indus river has its origin in Tibet near the Mansarovar Lake while the Ganga River has its origin in Gangotri Glacier in Uttarakhand.

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

Answer: Alaknanda and Bhagirathi are the two headstreams of the river Ganga. They both meet to form the Ganga at Devprayag.

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

Answer: The Brahmaputra river in Tibet receives very heavy rains, and it carries lot of water and silt. little volume of water in so it carries little silt there. However, 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 trough?

Answer: The two rivers that flow through troughs are Narmada and Tapi. These are the west flowing rivers, which form estuaries while entering the Arabian Sea.

(vii) State some economic benefits of rivers and lakes.

Answer: Some economic benefits of rivers and lakes are:

a. Lakes and rivers are used to produce hydroelectricity.

b. They are useful for navigation.

c. They are beneficial for fisheries. d. They are useful for irrigation.

e. Many ancient human settlements are established near the lakes and rivers. For example: Bhopal in India is a lake city while Indo-Gangetic Plains are known for their ancient civilisation.

f. They are also tourist destinations. 

3. Below are given names of a few lakes of India. Group them 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) Hirakund

Answer:

4. Discuss the significant difference between the Himalayan and the Peninsular Rivers.

5. Compare the east flowing and the west flowing rivers of the Peninsular plateau.

Answer:

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

Answer: The rivers are important in country's economy because of the following reasons:

       Most of the ancient the human civilizations originated, flourished and developed in the river valleys.

       They carry water containing sediments and minerals, which are very useful for agriculture.

       They provide water for various human activities like, domestic, agricultural, and industrial purposes.

       Rivers provide cheap and efficient inland transport for trade and commerce.

       They are in generating hydroelectricity.

       They also provide water to reservoirs, which are used for fishing and recreational activities.