CBSE 2026-27 | Book 2

NCERT Solutions for Class 11 Geography Chapter 3: Drainage System

📚 Class 11 CBSE 🌊 Geography – Book 2 ⚡ 5–7 Marks 🔵 Moderate

Trace the journey of India's mighty rivers from glaciers to the sea. This chapter covers drainage patterns, the Himalayan vs Peninsular river systems, the complete Ganga river system, Panch Prayag, and the Panchnad — with all NCERT solutions updated for CBSE Board Exams 2026-27.

📋Chapter at a Glance

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Chapter 3: Drainage System – Quick Reference

Chapter Name	Drainage System
Subject	Geography (Book 2: India: Physical Environment)
Board / Class	CBSE Class 11
Target Year	2026-27
Key Topics	Himalayan & Peninsular Rivers, River Basins, Drainage Patterns, Ganga System, Indus, Brahmaputra, Panchnad
Difficulty Level	Moderate
Exam Weightage	5–7 Marks (incl. map work)

📊Key Facts – Quick Numbers to Memorise

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Ganga Basin

Largest in India

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Godavari

Dakshin Ganga

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Panchnad

5 Rivers of Punjab

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Drainage Patterns

4 Main Types

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Mawsynram

Highest Rainfall

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Exam Weightage

5–7 Marks

🎯Learning Objectives

Understand the meaning of drainage, drainage basin, and watershed and how they differ.

Identify and describe different drainage patterns: dendritic, trellis, radial, and centripetal.

Differentiate between the Himalayan and Peninsular river systems in terms of origin, nature, and course.

Trace the complete course and major tributaries of the Ganga, Indus, and Brahmaputra rivers.

Describe the characteristics of major Peninsular rivers like Godavari, Krishna, Narmada, and Tapi.

Analyse the concept of river regimes and factors affecting them across different seasons.

💡Key Concepts & Definitions

Drainage

The flow of water through well-defined channels. The network of these channels is called a 'drainage system'.

Drainage Basin

The entire area drained by a single major river and its tributaries. Think of it as a giant bowl where all water flows to one point.

Watershed

A smaller area drained by a smaller river or rivulet. Watersheds are the building blocks of a larger drainage basin.

Dendritic Pattern

Tree branch-like drainage pattern that develops on uniform, non-resistant rock. Example: Rivers of the Northern Plains.

Most common pattern

Perennial Rivers

Flow throughout the year, fed by both glaciers AND rainfall. Examples: Ganga, Indus, Brahmaputra.

Himalayan Rivers

River Regime

The pattern of water flow (volume) in a river channel over a year, influenced by rainfall, glacier melt, and evaporation.

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4 Drainage Patterns — Quick Summary

1. Dendritic — Tree branches; uniform rock; Ganga plains
2. Trellis — Rectangular; folded mountains with alternating hard/soft rock; Singhbhum
3. Radial — Spokes of wheel; dome/peak; Amarkantak (Narmada, Son)
4. Centripetal — Converge inward to lake/depression; Loktak Lake, Manipur

❓NCERT Exercise MCQs – Practice & Self-Test

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How to Use

Click an option to check if it's correct or wrong. The explanation will appear instantly.

Difficulty: Easy

Q1. Which one of the following rivers has the largest river basin in India?

✅ Correct: (c) The Ganga — The Ganga basin is the largest in India, covering over 8.6 lakh sq. km. It is the most significant river system in terms of area and cultural importance.

Difficulty: Medium

Q2. Which one of the following rivers is NOT included in the 'Panchnad'?

✅ Correct: (c) The Indus — The 'Panchnad' includes the five rivers of Punjab: Satluj, Beas, Ravi, Chenab, and Jhelum. The Indus is the main river they all join — it is NOT one of the five.

Difficulty: Easy

Q3. Which one of the following rivers flows in a rift valley?

✅ Correct: (b) The Narmada — The Narmada river, along with the Tapi, flows westward through a rift valley (a block of land that dropped between two faults) towards the Arabian Sea.

Difficulty: Medium

Q4. Which one of the following is the place of confluence of the Alaknanda and the Bhagirathi?

✅ Correct: (d) Dev Prayag — At Dev Prayag in Uttarakhand, the Bhagirathi meets the Alaknanda. From this point onwards, the combined river is known as the Ganga.

Difficulty: Easy

Q5. Which one of the following is the longest river of Peninsular India?

✅ Correct: (b) Godavari — With a length of about 1,465 km, the Godavari is the longest Peninsular river, often referred to as the 'Dakshin Ganga' (Ganga of the South).

Extra Practice MCQs

Difficulty: Easy

Q6. The river Brahmaputra is known as Tsangpo in Tibet and __________ in Bangladesh.

✅ Correct: (c) Jamuna — Brahmaputra is called Tsangpo (Tibet) → Dihang (Arunachal Pradesh) → Brahmaputra (Assam) → Jamuna (Bangladesh).

Difficulty: Medium

Q7. The Amarkantak Plateau is the source of which two major rivers flowing in opposite directions?

✅ Correct: (b) Narmada and Son — Narmada flows west, and Son (tributary of Ganga) flows north from Amarkantak Plateau — a perfect example of radial drainage pattern.

📝Full NCERT Solutions – All Exercise Questions

📌 Exercise 2 – State the Differences

3 Marks Distinguish between River Basin and Watershed. ▼

✅ Model Answer

Basis	River Basin	Watershed
Size	Large area drained by a major river and its tributaries	Smaller area drained by a smaller stream or river
Unit	Macro-level planning unit	Micro or meso-level planning unit
Example	The Ganga Basin, The Amazon Basin	Watershed of a small local stream or 'nala'
Relationship	Composed of many smaller watersheds	Part of a larger river basin

3 Marks Distinguish between Dendritic and Trellis drainage patterns. ▼

✅ Model Answer

Basis	Dendritic Pattern	Trellis Pattern
Appearance	Resembles the branches of a tree	Rectangular pattern, like a garden trellis
Formation	Uniform, non-resistant rock terrain	Folded mountains with alternating hard and soft rocks
Tributaries	Join main river at acute angles	Parallel; join main river at right angles
Example	Ganga river system in northern plains	Rivers in Singhbhum region, Chotanagpur

3 Marks Distinguish between Radial and Centripetal drainage patterns. ▼

✅ Model Answer

Basis	Radial Pattern	Centripetal Pattern
Flow Direction	From central high point outward in all directions	From all directions inward to a central depression
Appearance	Like spokes of a wheel	Rivers converging to a single point
Topography	Dome-shaped hill or volcanic cone	Basin or depression with no outlet to the sea
Example	Rivers from Amarkantak Plateau (Narmada, Son)	Streams into Loktak Lake, Manipur

📌 Exercise 3 – Short Answer Questions (~30 words)

3 Marks What are the socio-economic advantages of inter-linking of rivers in India? ▼

✅ Model Answer

Water Scarcity Management: Transfers water from surplus basins (Ganga) to deficit basins (Peninsular India).
Irrigation: Expands net irrigated area, boosts agricultural production and food security.
Flood & Drought Control: Mitigates simultaneous floods in one region and drought in another.
Navigation & Hydropower: Creates navigable waterway network and generates hydroelectric power.

2 Marks Write three characteristics of the Peninsular river system. ▼

✅ Model Answer

Origin: Peninsular Plateau and central highlands.
Water Source: Seasonal / non-perennial — depend on monsoon rainfall only.
Course: Shorter, shallower, with well-developed graded valleys compared to Himalayan rivers.

📌 Exercise 4 – Long Answer Questions (~125 words)

5 Marks What are the useful and harmful effects of floods? How can they be controlled? ▼

✅ Model Answer

Useful Effects:

Fertile Silt: Floods deposit fine, fertile khadar soil over plains — excellent for agriculture.
Recharge Groundwater: Floodwaters seep into the ground, raising the water table.
Clean Riverbeds: High-velocity floodwater flushes pollutants and sediments from the riverbed.

Harmful Effects:

Loss of Life & Property: Houses, roads, bridges, crops destroyed — huge economic losses.
Diseases: Stagnant water breeds mosquitoes and bacteria — cholera, malaria, dengue outbreaks.
Disruption: Transport, communication, and power supply disrupted; communities isolated.

Flood Control Methods:

Structural: Dams & Reservoirs (store excess water); Embankments & Levees (contain rivers within banks); Channel Improvement (deepening/widening).

Non-Structural: Afforestation (reduces runoff); Floodplain Zoning (no construction in flood-prone areas); Flood Forecasting (timely warnings and evacuation).

5 Marks Differentiate between the Himalayan and Peninsular river systems. ▼

✅ Model Answer

Feature	Himalayan Rivers	Peninsular Rivers
Origin	Himalayan mountains covered with glaciers	Peninsular Plateau and central highlands
Nature of Flow	Perennial — fed by glaciers + rainfall	Seasonal — dependent on monsoon only
Drainage Type	Antecedent and consequent; dendritic in plains	Superimposed and rejuvenated; trellis, radial, rectangular
Course Length	Long; rugged mountains, intense erosion	Shorter; well-defined graded profile; shallower valleys
Catchment Area	Very large basins	Relatively smaller basins
Age	Young, active; often shift course	Old rivers with a stable course
Deltas/Estuaries	Form large deltas (e.g., Sundarban Delta)	West-flowing → estuaries (Narmada, Tapi); East-flowing → deltas (Godavari, Krishna)
Examples	Ganga, Indus, Brahmaputra	Godavari, Krishna, Kaveri, Narmada, Tapi

🚀Extra Board Exam Questions (2026-27)

📌 Long Answer Questions

5 Marks Describe the course of the Ganga River from its source to its mouth, mentioning its important tributaries. ▼

✅ Model Answer

Source: Originates as the Bhagirathi from Gangotri glacier. Joins Alaknanda at Devprayag → becomes the Ganga.
Upper Course: Flows through narrow Himalayan valleys. Emerges onto the plains at Haridwar.
Middle Course: Flows across the vast North Indian Plains.
- Right-bank tributaries: Yamuna (joins at Prayagraj/Allahabad), Son, Damodar.
- Left-bank tributaries: Ramganga, Ghaghara, Gandak, Kosi.
Lower Course: In West Bengal, it bifurcates — Hooghly (distributary) flows south through Kolkata to Bay of Bengal. Main branch (Padma) flows into Bangladesh, joins Jamuna (Brahmaputra) and Meghna → forms the world's largest delta, the Sundarban Delta.

3 Marks Name the five Prayags (Panch Prayag) of the Alaknanda river in their correct order. ▼

✅ Model Answer

Vishnuprayag — Alaknanda meets DhauliGanga
Nandaprayag — Alaknanda meets Nandakini
Karnaprayag — Alaknanda meets Pindar
Rudraprayag — Alaknanda meets Mandakini
Devprayag — Alaknanda meets Bhagirathi → becomes the Ganga

💡 Memory: V-N-K-R-D — Vishnu, Nanda, Karna, Rudra, Dev (upstream to downstream)

5 Marks Explain the major drainage patterns with suitable examples. ▼

✅ Model Answer

Dendritic Pattern: Resembles tree branches. Develops where the river follows slope with uniform, non-resistant rock. Example: Rivers of the Northern Plains (Ganga system).
Trellis Pattern: Develops in folded topography with alternating hard and soft rocks. Primary tributaries are parallel, shorter secondary tributaries join at right angles. Example: Rivers in Singhbhum region of Chotanagpur.
Radial Pattern: Streams flow from a central peak outward like spokes of a wheel. Example: Narmada, Son, and Mahanadi originating from Amarkantak Plateau.
Centripetal Pattern: Rivers flow from all directions into a central lake or depression. Example: Streams flowing into Loktak Lake in Manipur.

4 Marks Case-Based: The Peninsular drainage system — answer questions from the passage. ▼

✅ Model Answer

"The Western Ghats act as the water divide between major Peninsular rivers. Most major Peninsular rivers, except Narmada and Tapi, flow from west to east."

Why Peninsular rivers are 'mature': They flow through stable, graded, broad valleys. They have completed most of their erosional work and have a fixed course.
Water divide in Peninsular India: The Western Ghats.
Why most Peninsular rivers flow west to east: The general slope of the Peninsular Plateau is from the west (higher elevation) to the east (lower elevation).

⚠Common Mistakes to Avoid

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Confusing Tributaries

Mixing up left and right-bank tributaries of the Ganga is very common. Draw a flow chart to remember them (Right: Yamuna, Son; Left: Kosi, Gandak).

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Himalayan vs Peninsular

Confusing their characteristics is a major error. Create the comparison table above and revise it multiple times before the exam.

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Ignoring Map Work

Drainage is a map-heavy chapter. Students who don't trace rivers on a blank map regularly lose easy marks. Practice daily for 10 minutes.

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West vs East Flowing

Narmada and Tapi flow West (through rift valleys to Arabian Sea). Mahanadi, Godavari, Krishna, Kaveri flow East to Bay of Bengal.

📚Exam Preparation Tips for 2026-27

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Master the Comparison

Himalayan vs Peninsular rivers is the most frequently asked long answer. Master all 8 points of the comparison table.

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Ganga System Map

Draw and label the Ganga river system — all tributaries (right-bank: Yamuna, Son; left-bank: Kosi, Gandak), Panch Prayag, and the Sundarban Delta.

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Map Practice Daily

Mark all major rivers, lakes (Chilika, Wular), water divides (Western Ghats, Ambala ridge) on a blank map of India.

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Flowcharts

Create a simple flowchart for the Indus and Brahmaputra systems showing the river's journey and where tributaries join it.

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Last-Minute Revision

Before the exam, quickly revise: key definitions, Panchnad (5 rivers of Punjab), Panch Prayag order, and the drainage comparison table.

🅾Frequently Asked Questions (FAQs)

What is the difference between a delta and an estuary?▼

A delta is a triangular, fertile landform created at the mouth of a river by deposition of sediment. East-flowing rivers like Ganga and Godavari form deltas. An estuary is a deep, funnel-shaped valley at the river's mouth where fresh water meets salt water. West-flowing rivers like Narmada and Tapi form estuaries.

Why is the Godavari river called the 'Dakshin Ganga'?▼

The Godavari is called the 'Dakshin Ganga' (Ganga of the South) because it is the longest and largest river system in Peninsular India, with similar significance, religious importance, and cultural reverence as the Ganga has in North India.

What is an inland drainage system?▼

Inland drainage is a system where rivers do not reach the sea but drain into an inland lake or get lost in the sand. The Luni river in the Thar Desert of Rajasthan is a prime example of an inland drainage system.

Which are the two main west-flowing rivers of Peninsular India?▼

The two main west-flowing rivers of Peninsular India are the Narmada and the Tapi. They are unique because they flow through rift valleys (formed by faulting of the earth's crust) towards the Arabian Sea, forming estuaries — not deltas.

What is the 'Panchnad'?▼

'Panchnad' refers to the land of five rivers in Punjab. The five rivers are the Satluj, Beas, Ravi, Chenab, and Jhelum — all tributaries of the Indus River. The word 'Punjab' itself means 'land of five rivers' (Panj = five, Aab = water).

Master the Drainage System 🌊

Mastering the Drainage System chapter is all about understanding the story of India's rivers. It's a fascinating and high-scoring topic with rich map work. Keep revising comparison tables and practicing river maps. For best results, solve Previous Year Questions (PYQs) to understand the exam pattern.

⚡ Practice Chapter 3 MCQs Free

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