CBSE Class 9 Social Science: Drainage NCERT Solutions

Reviewed by NCERT Help Editorial Team · Updated on 29 Jul 2026

NCERT Solutions PDF Class 9 PDF

This chapter, "Drainage" from CBSE Class 9 Social Science (Contemporary India - I), delves into India's intricate river systems and water bodies. The NCERT Solutions provide clear explanations and answers to key questions about drainage patterns, major river basins like the Indus and Ganga, the origins of prominent rivers such as Narmada and Brahmaputra, and the formation of lakes, including both freshwater and saltwater types. It also touches upon the significance of water divides and the economic benefits derived from rivers and lakes. These solutions are designed to help students grasp the geographical concepts related to drainage and prepare effectively for their examinations by offering detailed, step-by-step answers.

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Board	CBSE
Class	Class 9
Subject	Social Science
Session	2026
Language	English
Type	NCERT Solutions
Chapter	Geography (Contemporary India – I) - Drainage

Chapter summary

This chapter focuses on India's drainage system, covering various drainage patterns, the major river basins (Indus, Ganga, Brahmaputra), and peninsular rivers. It explains concepts like water divides, the formation and types of lakes (freshwater and saltwater), and the origins of key rivers. The solutions also highlight the economic importance of rivers and lakes, providing students with a thorough understanding of the geographical features of India's water resources.

Learning outcomes

Understand the concept of a water divide and its significance.
Identify and differentiate various drainage patterns in India.
Locate and describe the major river systems and their basins.
Explain the origin and course of important Indian rivers.
Recognize different types of lakes and their geographical locations.
Appreciate the economic benefits of rivers and lakes.

Topics covered

Paper topics

Drainage System
Drainage Patterns
Water Divide
River Basins
Indus River System
Ganga River System
Brahmaputra River System
Peninsular Rivers
Narmada River
Tapi River
Lakes (Freshwater and Saltwater)
Economic Benefits of Rivers and Lakes

Important topics

Major River Systems of India (Indus, Ganga, Brahmaputra)
Drainage Patterns
Peninsular Rivers Flowing Through Rift Valleys
Types and Locations of Lakes
Concept of Water Divide

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Questions and Solutions

Question 1

Choose the right answer from the four alternatives given below.

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

Radial
Centrifugal
Dendritic
Trellis

Solution: The correct option is (c) Dendritic. The Dendritic drainage pattern is characterized by its resemblance to the branches of a tree, where the tributaries join the main river at acute angles, forming a tree-like structure. This pattern typically develops in areas where the river erodes softer rocks more easily than harder ones.

Question 1 (ii)

In which of the following states is the Wular lake located?

Rajasthan
Punjab
Uttar Pradesh
Jammu and Kashmir

Solution: The correct option is (d) Jammu and Kashmir. The Wular lake is one of the largest freshwater lakes in India and is situated in the Bandipora district of the Union Territory of Jammu and Kashmir. It is fed by the Jhelum River.

Question 1 (iii)

The river Narmada has its source at

Satpura
Amarkantak
Brahmagiri
Slopes of the Western Ghats

Solution: The correct option is (b) Amarkantak. The river Narmada originates from the Amarkantak Plateau in Madhya Pradesh, which is part of the Vindhya Range. It flows westwards through a rift valley and drains into the Arabian Sea.

Question 1 (iv)

Which one of the following lakes is a salt water lake?

Sambhar
Wular
Dal
Gobind Sagar

Solution: The correct option is (a) Sambhar. The Sambhar lake, located in Rajasthan, is India's largest inland salt lake. It is a shallow lake that dries up significantly during the dry season, leaving behind salt deposits. Wular and Dal are freshwater lakes, and Gobind Sagar is a man-made reservoir.

Question 1 (v)

Which one of the following is the longest river of the Peninsular India?

(a) Narmada

(b) Godavari

(d) Mahanadi

Solution: The correct option is (b) Godavari. The Godavari River is the longest river in Peninsular India, flowing through Maharashtra, Telangana, Andhra Pradesh, and emptying into the Bay of Bengal. It is often referred to as the 'Dakshin Ganga' or the 'Ganga of the South'.

Question 1 (vi)

Which one amongst the following rivers flows through a trough?

(a) Mahanadi

(b) Krishna

(d) Tapi

Solution: The correct option is (d) Tapi. The Tapi River, like the Narmada, flows through a rift valley or trough. This geological feature is formed by the down-faulting of land between two parallel faults. The Tapi originates in the Satpura Range and flows westwards into the Arabian Sea.

Question 2

Answer the following questions briefly:

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

Solution: A water divide refers to any elevated landform, such as an upland or a mountain, that separates two adjacent drainage basins. This separation causes rivers flowing from these basins to move in different directions. For instance, the Indus, the Sutlej, and the Brahmaputra rivers originate very close to each other near the Mansarovar Lake, but due to the presence of water divides in the region, they flow in distinct directions, forming separate river systems.

Question 2 (ii)

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

Solution: The Ganga basin is recognized as the largest river basin in India. It encompasses a vast area, supporting a large population and diverse ecosystems as it flows through the northern plains of the country.

Question 2 (iii)

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

Solution: The Indus River originates in the northern part of Tibet, near the Mansarovar Lake. The Ganga River has its origin in the Gangotri Glacier, located in the Garhwal Himalayas of Uttarakhand.

Question 2 (iv)

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

Solution: The two principal head-streams of the Ganga are the Bhagirathi and the Alaknanda. The Bhagirathi originates from the Gangotri Glacier, and the Alaknanda originates from the Satopanth Glacier. These two rivers meet at Devprayag in Uttarakhand, after which they are known as the Ganga River.

Question 2 (v)

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

Solution: In its upper course in Tibet, the Brahmaputra River flows through a cold, arid region. The limited rainfall and vegetation in this area mean that the river erodes less material from its banks and bed. Consequently, it carries a significantly smaller amount of silt compared to its lower course in India, where it flows through a region with heavier rainfall and more erodible land.

Question 2 (vi)

(vi) Which two peninsular rivers flow through trough?

Solution: The two major peninsular rivers that flow through troughs or rift valleys are the Narmada and the Tapi. These rivers originate in central India and flow westwards, carving their paths through the geological depressions before emptying into the Arabian Sea.

Question 2 (vii)

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

Solution: Rivers and lakes offer numerous economic benefits. They are vital sources of water for irrigation, which is crucial for agriculture, and also supply water for domestic consumption and industrial processes. Rivers are extensively used for generating hydroelectricity, providing a renewable energy source. Furthermore, they support fisheries, facilitate inland navigation and transportation, and are important for tourism and recreational activities, contributing to local economies. Lakes also play a role in regulating water supply and supporting biodiversity.

Common mistakes

Confusing drainage patterns (e.g., Dendritic vs. Radial).
Incorrectly identifying the origin or course of major rivers.
Misplacing the location of specific lakes or river basins.
Not clearly defining or providing examples for concepts like 'water divide'.

Revision tips

Draw a map of India and mark the major rivers, their tributaries, and basins.
Create flashcards for key terms like 'drainage pattern', 'water divide', and 'river basin'.
Practice identifying the correct river or lake based on its description or origin.
Review the economic uses of rivers and lakes to understand their importance.

Practice MCQs

Q1. Which drainage pattern resembles the branches of a tree?

Q2. The Wular lake, a prominent freshwater lake, is located in which Indian state?

Q3. From where does the river Narmada originate?

Q4. Which of the following is identified as a saltwater lake in India?

Q5. Which is the longest river of Peninsular India?

Q6. Which peninsular river flows through a rift valley?

Frequently asked questions

What is a water divide?

A water divide is an upland or a mountain that separates two adjoining drainage basins, directing rivers to flow in different directions. An example is the area separating the Indus, Sutlej, and Brahmaputra river systems near Mansarovar Lake.

Which is the largest river basin in India?

The Ganga basin is the largest river basin in India, covering a significant portion of the northern plains.

Where do the Indus and Ganga rivers originate?

The Indus River originates in Tibet near the Mansarovar Lake, and the Ganga River originates from the Gangotri Glacier in Uttarakhand.

What are the two main headstreams of the Ganga?

The two main headstreams of the Ganga are the Bhagirathi and the Alaknanda. They meet at Devprayag to form the Ganga River.

Why does the Brahmaputra have less silt in Tibet?

In its Tibetan part, the Brahmaputra flows through a drier, colder region with a shorter course, resulting in less erosion and thus carrying less silt compared to its course in India.

Which peninsular rivers flow through a trough or rift valley?

The Narmada and the Tapi are the two major peninsular rivers that flow through rift valleys.

What are some economic benefits of rivers and lakes?

Rivers and lakes provide water for irrigation, domestic use, and industries. They are also crucial for generating hydroelectricity, supporting fisheries, facilitating navigation, and promoting tourism and recreation.

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