Chapter 8 of 20

40%

CBSE Class 9 Social Studies★ 5–6 marks · CBSE Class 9 Board (Book 2: Contemporary India — I — Geography)

Drainage

India's rivers are the lifelines of its civilisations. Class 9 Geography Book — Drainage covers the Himalayan and Peninsular river systems, the Ganga and its tributaries, the Indus river system, the Brahmaputra, the Godavari, Krishna, Mahanadi, Narmada, Tapi, and Kaveri — with major lakes, water pollution, and 20+ exam-style problems.

⏱ 35 min readMedium difficulty✓ Free · NCERT-aligned

Ask AI about this

By the end of this chapter you'll be able to…

1Distinguish Himalayan rivers (perennial) from Peninsular rivers (seasonal)
2Name and trace the three major Himalayan river systems: Indus, Ganga, Brahmaputra
3Identify the Five Rivers (Panchanad) of the Indus system: Jhelum, Chenab, Ravi, Beas, Sutlej
4Recall the Indus Water Treaty (1960) and its provisions
5Trace the Ganga from Gangotri to its delta; identify major tributaries (Yamuna, Ghaghara, Gandak, Kosi, Son, Damodar)
6Describe the Brahmaputra's course (Tibet → Arunachal → Assam → Bangladesh) and characteristics (braided, flood-prone)
7Name major Peninsular rivers: Mahanadi, Godavari, Krishna, Kaveri (east-flowing) + Narmada, Tapi (west-flowing)
8Identify major Indian lakes — Chilika (brackish, largest in Asia), Wular (largest freshwater), Sambhar (largest salt)
9Discuss water pollution and conservation efforts (Namami Gange programme)

💡

Why this chapter matters

India's rivers underpin agriculture, water supply, hydroelectricity, transport, religion, and ecology. Inter-state water disputes and pollution are recurring national issues. Understanding the drainage system is foundational for any later study of Indian agriculture, industry, environment.

Before you start — revise these

A 5-minute refresher here will save you 30 minutes of confusion below.

🔗

Physical Features of India (Ch7)

Knowing the Himalayas and Peninsular Plateau is essential for understanding river systems.

Drainage — Class 9 (CBSE)

The Indus, the Ganga, the Brahmaputra, the Godavari, the Krishna, the Kaveri — these names form the geography of Indian civilisation. India's rivers have shaped where cities are built, what crops are grown, who lives where, and what religious practices are followed. This chapter is the map of India's water — and how rivers, watersheds, and lakes connect the entire subcontinent.

1. The story — why drainage matters

A drainage system is a network of rivers, streams, and lakes draining a particular area. India has one of the most complex drainage systems in the world — shaped by the mountains, plateaus, and coastal plains we studied in Chapter 7.

India's drainage is divided into TWO MAIN SYSTEMS:

Himalayan rivers — perennial (flowing year-round), fed by snowmelt + monsoon.
Peninsular rivers — seasonal, fed mainly by rainwater.

Each system has its own characteristics, supports different agricultures, and has shaped different cultures.

2. Himalayan rivers — perennial flow

These rivers start in the Himalayas and flow into the plains. They're characterised by:

Perennial flow (year-round).
Vast catchment areas.
Heavy sediment loads (carrying eroded Himalayan rock).
Long courses.
Form deep valleys, gorges, and floodplains.

Three major Himalayan river systems

(a) The Indus river system

Source: A glacier near Mansarovar Lake in Tibet.

Course: Flows through Tibet, then enters India in Jammu & Kashmir (Ladakh), continues into Pakistan, and empties into the Arabian Sea.

Total length: 2,900 km.

Tributaries (memorise these — collectively called the "Five Rivers" or Panchanad):

Jhelum — flows through Kashmir Valley.
Chenab — formed by joining of Chandra and Bhaga rivers.
Ravi — flows through Punjab.
Beas — flows through Punjab and Himachal Pradesh.
Sutlej — longest tributary; originates in Tibet.

Indus Water Treaty (1960) between India and Pakistan:

India gets full use of Ravi, Beas, Sutlej.
Pakistan gets full use of Indus, Jhelum, Chenab.

(b) The Ganga river system

Source: Gangotri glacier in Uttarakhand. The headstream is called the Bhagirathi.

Course:

Bhagirathi + Alaknanda meet at Devprayag to form the Ganga.
The Ganga then flows ~ 2,510 km through Uttarakhand, UP, Bihar, West Bengal.
Splits into two distributaries at the delta — the main Ganga (→ Bangladesh) and the Hooghly (→ Kolkata).

Major tributaries:

Yamuna (right bank) — flows from Yamunotri glacier; joins Ganga at Allahabad/Prayagraj (the Sangam).
Ghaghara, Gandak, Kosi (left bank) — Himalayan, perennial.
Son, Damodar, Mahananda (right bank) — Peninsular tributaries.

Special features:

The Sundarbans (largest delta in the world, in Bangladesh + India) is formed by the Ganga + Brahmaputra.
The Ganga is sacred to Hindus.
Highly polluted in many stretches.

(c) The Brahmaputra river system

Source: Mansarovar Lake region in Tibet (called Tsang Po in Tibet).

Course:

Flows EAST through Tibet for ~ 1,200 km.
Turns SOUTH and enters India in Arunachal Pradesh as the Dihang.
Flows through Arunachal Pradesh and Assam as the Brahmaputra.
Enters Bangladesh and joins the Ganga.

Special features:

Highly braided (multiple channels in the plain).
Heavy flooding — Assam floods almost every year.
Forms the largest delta with the Ganga (Sundarbans).
Carries enormous sediment.

3. Peninsular rivers — seasonal flow

These rivers flow across the Peninsular Plateau. Characterised by:

Seasonal flow (mainly during monsoon).
Smaller catchment areas.
Less sediment than Himalayan rivers.
Mostly flow east into the Bay of Bengal (the plateau slopes east).
Few flow west into the Arabian Sea (Narmada and Tapi — flowing through rift valleys).

Eastern-flowing rivers (into Bay of Bengal)

(a) Mahanadi

Length: 858 km.
Source: Chhattisgarh.
Major dam: Hirakud (one of the world's longest earthen dams).

(b) Godavari (Vridha Ganga or "Old Ganga")

Length: 1,465 km (largest Peninsular river).
Source: Western Ghats in Maharashtra.
Major tributaries: Penganga, Wardha, Wainganga (right bank); Indravati, Sabari (left bank).

(c) Krishna

Length: 1,400 km.
Source: Western Ghats (Mahabaleshwar).
Major tributaries: Bhima, Tungabhadra.
Major dams: Nagarjuna Sagar.

(d) Kaveri (or Cauvery)

Length: 800 km.
Source: Talakaveri (Brahmagiri Range, Karnataka).
Flows through Karnataka and Tamil Nadu.
Major dams: Krishnaraja Sagar (KRS), Mettur.
Long-standing Karnataka-Tamil Nadu water-sharing dispute.

Western-flowing rivers (into Arabian Sea)

(a) Narmada

Length: 1,312 km.
Source: Amarkantak (Madhya Pradesh).
Flows WESTWARD through a rift valley between the Vindhyas and Satpuras.
Forms beautiful waterfalls (Dhuandhar, near Jabalpur).
Sardar Sarovar Dam — controversial mega-project.

(b) Tapi (or Tapti)

Length: 724 km.
Source: Satpura Range.
Flows WESTWARD parallel to Narmada.

These two are exceptional — most Peninsular rivers flow EAST. Narmada and Tapi flow west because the Indian Plate's tilt creates a slight downward slope to the west in this region.

4. Major Indian lakes

Many types — natural (tectonic, oxbow, glacial) and artificial (reservoirs).

Salt-water lakes (the most famous in India)

Chilika Lake (Odisha) — largest brackish-water lake in Asia.
Sambhar Lake (Rajasthan) — largest inland salt-water lake in India.
Pulicat Lake (Andhra-Tamil Nadu border) — second-largest brackish lake.

Fresh-water lakes

Wular Lake (J&K) — largest fresh-water lake in India.
Dal Lake (Srinagar, Kashmir) — famous houseboats.
Loktak Lake (Manipur) — famous for floating biomass.
Vembanad Lake (Kerala) — connected to Arabian Sea via canals.

Tectonic lakes

Wular Lake is a tectonic lake.
Kashmir lakes (Anchar, Manasbal) are tectonic in origin.

Glacial lakes

Tsomgo Lake (Sikkim).
Pangong Tso (Ladakh — border with China).

Man-made (reservoirs)

Hirakud Reservoir (Mahanadi, Odisha) — longest earthen dam in India.
Indira Sagar (Narmada, MP).
Govind Ballabh Pant Sagar (Sonbhadra, UP).

5. Why drainage matters

Agriculture

Indian agriculture depends heavily on river water:

Rice cultivation requires water from rivers.
Wheat cultivation uses irrigation from rivers/groundwater.
60-70% of India's cropland is irrigated.

Water supply

Most major Indian cities are on rivers:

Delhi on the Yamuna.
Kolkata on the Hooghly (Ganga).
Mumbai on Mithi.
Varanasi on the Ganga.
Patna on the Ganga.
Chennai partly on the Cooum.
Hyderabad on Musi.

Hydroelectricity

Major hydroelectric projects on rivers:

Bhakra-Nangal (Sutlej).
Tehri (Bhagirathi).
Sardar Sarovar (Narmada).
Hirakud (Mahanadi).
Nagarjunasagar (Krishna).

Transportation

The Ganga, Hooghly, Brahmaputra were important historical transport routes.
National Waterway 1 (Allahabad-Haldia) is being developed on the Ganga.

Culture and religion

Ganga is sacred to Hindus.
Many cities are pilgrimage sites at river junctions or banks.
Festivals (Kumbh Mela, Chhath Puja) are held on rivers.

6. Water pollution and conservation

India's rivers are under severe pressure:

Major problems

Sewage: Most Indian cities discharge untreated sewage into rivers.
Industrial waste: Tanneries, paper mills, dyeing factories release toxic chemicals.
Agricultural runoff: Fertilisers and pesticides reach rivers.
Garbage: Plastic and waste dumped into rivers.
Religious offerings: Flowers, ash, idol immersion contribute pollution.

Notable polluted stretches

Yamuna in Delhi — among the world's most polluted rivers.
Ganga in Kanpur, Varanasi, Patna — heavily polluted.
Sabarmati in Ahmedabad.
Kaveri in some stretches.

Government action

Namami Gange programme (launched 2014) — multi-billion rupee effort to clean the Ganga.
National Mission for Clean Ganga (NMCG) — coordinates clean-up.
National River Conservation Plan.
Various state-level river clean-up programmes.

Results have been mixed. Pollution levels remain high despite significant investment.

Other water challenges

Groundwater depletion: Especially Punjab, Haryana, parts of South India.
Inter-state water disputes: Kaveri (Karnataka-Tamil Nadu), Krishna (Maharashtra-Karnataka-Andhra-Telangana), Mahanadi (Odisha-Chhattisgarh).
International water disputes: Indus (with Pakistan), Ganga (with Bangladesh), Brahmaputra (with China).
Climate change: glacial retreat threatens long-term water supply.

7. Closing thought

Rivers are India's most important resource — more than land, more than minerals. Without rivers, Indian civilisation would not exist.

The Himalayan rivers (perennial, sediment-rich, flood-prone, sacred) and the Peninsular rivers (seasonal, smaller, more controllable) together support 1.4 billion people, the world's largest agricultural workforce, and one of the world's most ancient civilisations.

But India's rivers are increasingly threatened — by pollution, by climate change, by competing demands. Managing India's water is one of the central challenges of the 21st century. Every later chapter (Population, agriculture, industry, climate) connects back to the rivers studied here.

Key formulas & results

Everything you need to memorise, in one card. Screenshot this for revision.

Two main river systems

Himalayan (perennial, snow + monsoon fed) + Peninsular (seasonal, rain fed)

Most fundamental classification.

Three Himalayan river systems

Indus (NW) + Ganga (N) + Brahmaputra (NE)

Memorise their courses and tributaries.

Five Rivers of Punjab (Panchanad)

Jhelum + Chenab + Ravi + Beas + Sutlej

All tributaries of the Indus.

Indus Water Treaty

India: Ravi + Beas + Sutlej · Pakistan: Indus + Jhelum + Chenab · Signed 1960 (Nehru-Ayub Khan)

Major bilateral water agreement.

Ganga origin

Bhagirathi (Gangotri Glacier) + Alaknanda meet at Devprayag → Ganga

Don't confuse with Yamuna (separate origin at Yamunotri).

Brahmaputra course

Tibet (Tsang Po) → Arunachal Pradesh (Dihang) → Assam (Brahmaputra) → Bangladesh (Jamuna)

Four names in four regions for the same river.

East vs West-flowing Peninsular rivers

EAST (Bay of Bengal): Mahanadi, Godavari, Krishna, Kaveri · WEST (Arabian Sea): Narmada, Tapi

Narmada and Tapi flow through rift valleys.

Largest lakes

Chilika (largest brackish, Asia) · Wular (largest freshwater, India) · Sambhar (largest salt)

Common 1-mark MCQs.

⚠️

Common mistakes & fixes

These are the exact errors that cost students marks in board exams. Read them once, save yourself the trouble.

WATCH OUT

✗ Saying the Ganga starts in Gangotri Glacier

✓ The Bhagirathi starts at Gangotri Glacier. The Ganga is FORMED when the Bhagirathi joins the Alaknanda at Devprayag. So technically the Ganga starts at Devprayag, not Gangotri.

WATCH OUT

✗ Calling the Narmada an east-flowing river

✓ The Narmada flows WEST into the Arabian Sea. It's one of only TWO major Peninsular rivers (the other being the Tapi) that flow west. All others flow east into the Bay of Bengal.

WATCH OUT

✗ Saying the Brahmaputra is shorter than the Ganga in length

✓ The Brahmaputra (~2,900 km total from source) is actually LONGER than the Ganga (~2,510 km in India). The Brahmaputra carries MORE water than the Ganga.

WATCH OUT

✗ Confusing Yamuna with Bhagirathi

✓ Two different rivers with different origins. Yamuna starts at Yamunotri glacier and flows separately. Bhagirathi starts at Gangotri glacier and (combined with Alaknanda) becomes the Ganga. The Yamuna joins the Ganga at Allahabad (Sangam), much further downstream.

WATCH OUT

✗ Saying Chilika Lake is freshwater

✓ Chilika is BRACKISH (mixed fresh + salt water), connecting to the Bay of Bengal. It's the largest brackish-water lake in Asia. Wular Lake (J&K) is the largest FRESHWATER lake in India.

WATCH OUT

✗ Forgetting the Indus Water Treaty provisions

✓ INDIA gets full use of Ravi, Beas, Sutlej (eastern rivers). PAKISTAN gets full use of Indus, Jhelum, Chenab (western rivers). Memorise which country gets which three rivers.

WATCH OUT

✗ Saying Sundarbans is in India only

✓ The Sundarbans is shared between India and Bangladesh. Most of it (62%) is in Bangladesh; ~38% in India (West Bengal). Don't claim it's wholly Indian.

NCERT exercises (with solutions)

Every NCERT exercise from this chapter — what it covers and how many questions to expect.

Section I (NCERT)

Drainage systems of India — Himalayan vs Peninsular

Questions

Section II (NCERT)

Himalayan rivers: Indus, Ganga, Brahmaputra in detail

Questions

Section III (NCERT)

Peninsular rivers: Mahanadi, Godavari, Krishna, Kaveri, Narmada, Tapi

Role of rivers in the economy + pollution + conservation

Questions

End-of-chapter (Ex s)

End-of-chapter (Exercises)

Long-form + map work

Questions

Practice problems

Try each one yourself before tapping "Show solution". Active recall > rereading.

Q1EASY· Distinguish

Distinguish between Himalayan and Peninsular rivers.

▶ Show solution

Step 1 — Flow regime.
  Himalayan: PERENNIAL (year-round) due to snowmelt + monsoon.
  Peninsular: SEASONAL (mainly during monsoon).

Step 2 — Catchment.
  Himalayan: VAST catchment areas.
  Peninsular: SMALLER catchment areas.

Step 3 — Sediment.
  Himalayan: HEAVY sediment (eroding Himalayas).
  Peninsular: LESS sediment (older, more stable terrain).

Step 4 — Course.
  Himalayan: LONG, winding (cross plains for hundreds of km).
  Peninsular: SHORTER, more direct.

Step 5 — Examples.
  Himalayan: Indus, Ganga, Brahmaputra.
  Peninsular: Godavari, Krishna, Kaveri, Narmada, Tapi, Mahanadi.

✦ Answer: Himalayan rivers are perennial (snowmelt + monsoon), with vast catchments, heavy sediment, long courses. Peninsular rivers are seasonal (rainfall only), with smaller catchments, less sediment, shorter courses. Examples: Ganga/Brahmaputra (Himalayan); Godavari/Krishna (Peninsular).

Q2EASY· Identify

Name the source and the longest tributary of the Indus river.

▶ Show solution

Step 1 — Source.
  The Indus originates near Mansarovar Lake in Tibet (Manasarovar region).

Step 2 — Longest tributary.
  Sutlej — flows from Tibet, joins the Indus in Pakistan. Approximately 1,400 km long.

✦ Answer: Source: near Mansarovar Lake in Tibet. Longest tributary: Sutlej.

Q3EASY· Identify

Name the largest Peninsular river of India.

▶ Show solution

Step 1 — Recall.
  The GODAVARI is the largest Peninsular river of India.

Step 2 — Details.
  Length: 1,465 km. Source: Western Ghats in Maharashtra. Drains into Bay of Bengal in Andhra Pradesh.
  Nicknamed 'Vridha Ganga' or 'Old Ganga' for its size and significance.

✦ Answer: Godavari (1,465 km). Also called Vridha Ganga / Old Ganga.

Q4EASY· Lakes

Which is the largest freshwater lake in India? Where is it located?

▶ Show solution

Step 1 — Recall.
  Wular Lake is the largest natural freshwater lake in India.

Step 2 — Location.
  Jammu & Kashmir. Located in the Kashmir Valley, north of Srinagar.

Step 3 — Origin.
  Tectonic origin — formed by Himalayan plate movements.

✦ Answer: Wular Lake (Jammu & Kashmir). Largest natural freshwater lake in India. Tectonic origin.

Q5EASY· Indus Treaty

What is the Indus Water Treaty (1960) and what does it specify?

▶ Show solution

Step 1 — Date and parties.
  Signed in 1960 between India (Prime Minister Nehru) and Pakistan (Field Marshal Ayub Khan). Mediated by the World Bank.

Step 2 — Provisions.
  • INDIA gets full use of the EASTERN rivers: Ravi, Beas, Sutlej.
  • PAKISTAN gets full use of the WESTERN rivers: Indus, Jhelum, Chenab.
  • Both can use the other's rivers for limited non-consumptive purposes (hydroelectricity).

Step 3 — Significance.
  Despite multiple wars between India and Pakistan (1965, 1971, 1999), the Indus Water Treaty has continued to function. It's considered one of the most successful international water-sharing agreements in the world.

Step 4 — Modern concerns.
  Climate change and political tensions are creating new challenges. India has periodically threatened to revisit the treaty.

✦ Answer: The Indus Water Treaty (1960) between India and Pakistan, mediated by the World Bank, gave India full use of Ravi, Beas, Sutlej (eastern rivers) and Pakistan full use of Indus, Jhelum, Chenab (western rivers). It has functioned despite multiple wars — a notable success.

Q6MEDIUM· Ganga system

Describe the Ganga river system from source to mouth.

▶ Show solution

Step 1 — Origin.
  Source: Gangotri Glacier in Uttarakhand, where it emerges as the BHAGIRATHI river.

Step 2 — Junction at Devprayag.
  At Devprayag (Uttarakhand), the Bhagirathi joins another stream — the ALAKNANDA (originating from another glacier). The combined river is called the GANGA from this point on.

Step 3 — Course through plains.
  The Ganga flows EAST through:
  • Uttarakhand → Uttar Pradesh → Bihar → Jharkhand → West Bengal.
  • Major cities along the Ganga: Haridwar, Allahabad/Prayagraj (junction with Yamuna), Varanasi, Patna, Kolkata.

Step 4 — Tributaries.
  Right bank (Peninsular): YAMUNA, Son, Damodar, Mahananda.
  Left bank (Himalayan): Ghaghara, Gandak, Kosi.
  All major tributaries are perennial.

Step 5 — Delta.
  Near Bangladesh border, the Ganga splits into two distributaries:
  • The MAIN GANGA flows into Bangladesh (where it's called the Padma).
  • The HOOGHLY (Bhagirathi-Hooghly) continues through West Bengal — past Kolkata — to the Bay of Bengal.
  Together with the Brahmaputra in Bangladesh, they form the SUNDARBANS DELTA — the largest delta in the world.

Step 6 — Length.
  ~2,510 km from Devprayag to mouth.

✦ Answer: Source: Bhagirathi from Gangotri Glacier (Uttarakhand) + Alaknanda meet at Devprayag → Ganga. Flows through UP, Bihar, West Bengal. Tributaries: Yamuna, Ghaghara, Gandak, Kosi, Son, Damodar. Splits at delta into Hooghly (to Kolkata) and main Ganga (to Bangladesh). Forms Sundarbans Delta — world's largest.

Q7MEDIUM· Brahmaputra

Why does the Brahmaputra have a different name in each region it flows through?

▶ Show solution

Step 1 — Name changes across regions.
  • In TIBET, the river is called the TSANG PO.
  • In ARUNACHAL PRADESH (where it enters India), it's the DIHANG.
  • In ASSAM (where it widens into the plains), it's the BRAHMAPUTRA.
  • In BANGLADESH (where it joins the Ganga), it's the JAMUNA.

Step 2 — Why so many names.
  Each region's local language and culture had its own name for the river before modern atlases standardised things. The names reflect the river's:
  • Origin (Tsang Po = 'cleanser' or 'purifier' in Tibetan).
  • Course transition (Dihang refers to the Arunachal stretch).
  • Cultural significance (Brahmaputra means 'son of Brahma' — the Hindu creator god).
  • Different identity in Bangladesh (Jamuna is the name in Bengal).

Step 3 — Single river, many cultures.
  The Brahmaputra/Tsang Po/Dihang/Jamuna crosses three countries (China, India, Bangladesh) and many cultural-linguistic regions. Each names it differently — reflecting the river's significance to each culture.

✦ Answer: The Brahmaputra has different names in each region — Tsang Po (Tibet), Dihang (Arunachal), Brahmaputra (Assam), Jamuna (Bangladesh) — because each culture had its own local name before modern atlases standardised geography. Single river, many cultural identities.

Q8MEDIUM· Pen rivers

Why do most Peninsular rivers flow eastward, while the Narmada and Tapi flow westward?

▶ Show solution

Step 1 — General slope.
  The Peninsular Plateau slopes from west to east. The Western Ghats are higher (~ 1,000-2,500 m); the Eastern coast is at sea level. So MOST rivers naturally flow east — following the slope toward the Bay of Bengal.
  Examples: Mahanadi, Godavari, Krishna, Kaveri all flow east.

Step 2 — Exception: Narmada and Tapi.
  These two rivers flow WESTWARD through what are called RIFT VALLEYS — long, narrow troughs created by geological faulting (subsidence between parallel faults).
  • The Narmada flows between the Vindhyas (north) and Satpuras (south).
  • The Tapi flows just south of the Satpuras.

Step 3 — Why the rift valleys go west.
  During Earth's geological history, faulting in the Peninsular Plateau created these grabens (sunken blocks between fault lines). The faulting tilted the floor of these valleys WESTWARD, so rivers within them flow toward the Arabian Sea.

Step 4 — Implications.
  Narmada and Tapi:
  • Flow through narrow valleys with steep walls.
  • Don't form large deltas (because they flow into the Arabian Sea with no shallow continental shelf).
  • Their valleys are major north-south transport corridors.

Step 5 — Summary.
  General slope of the Peninsular Plateau → most rivers flow east. Geological faulting creates west-flowing exceptions (Narmada, Tapi).

✦ Answer: Most Peninsular rivers flow east because the Peninsular Plateau slopes from west (higher) to east (lower). The Narmada and Tapi are exceptions — they flow west through RIFT VALLEYS (subsiding blocks between geological faults) that tilt westward. Geological faulting creates these exceptional river courses.

Q9MEDIUM· Pollution

Why is the Ganga heavily polluted, and what is being done about it?

▶ Show solution

Step 1 — Sources of Ganga pollution.

  (a) SEWAGE: Most major cities along the Ganga (Kanpur, Allahabad, Varanasi, Patna, Kolkata) discharge largely untreated sewage. ~80% of pollution comes from domestic sewage.

  (b) INDUSTRIAL EFFLUENTS: Kanpur leather tanneries (chromium pollution), paper mills, distilleries, chemical factories all discharge waste.

  (c) AGRICULTURAL RUNOFF: Fertilisers and pesticides from intensive agriculture in the Ganga plains.

  (d) RELIGIOUS OFFERINGS: Flowers, ash, plastic items, idol immersion (especially during Durga Puja) contribute to pollution.

  (e) SOLID WASTE: Plastic, dead animals, garbage dumped into the river.

Step 2 — Current state.
  Several stretches of the Ganga have:
  • Bacterial contamination far exceeding safe levels (faecal coliform).
  • Dissolved oxygen too low for most aquatic life.
  • Heavy metal contamination (especially Kanpur stretch).
  • Visible garbage and plastic.

Step 3 — Government response.

  (a) NAMAMI GANGE programme (2014 onwards):
  • Multi-billion rupee mission to clean the Ganga.
  • Sewage treatment plant (STP) construction.
  • Industrial pollution control.
  • Public awareness campaigns.
  • Solid waste management.

  (b) National Mission for Clean Ganga (NMCG):
  • Coordinates all Ganga clean-up.
  • Special legal status to the Ganga (under the Environment Protection Act).

  (c) Earlier programmes:
  • Ganga Action Plan (1985 — Rajiv Gandhi).
  • Ganga Action Plan Phase 2 (1993).
  • National River Conservation Plan (NRCP).

Step 4 — Results.
  Mixed. Some stretches have improved (Allahabad area). Others (Kanpur, Varanasi) remain heavily polluted. Coordinated multi-state effort is difficult; political will varies; population pressure continues to grow.

Step 5 — What needs more work.
  • Universal sewage treatment.
  • Industrial pollution enforcement.
  • Behavioural change (religious practices).
  • Long-term governance.

✦ Answer: The Ganga is polluted by sewage (80%), industrial effluents (tanneries, paper mills, chemicals), agricultural runoff, religious offerings, and solid waste. The Namami Gange programme (2014) is a multi-billion rupee national effort to clean the river — including sewage treatment plants, industrial pollution control, and awareness campaigns. Results have been mixed; some stretches have improved while others remain heavily polluted.

Q10MEDIUM· Lakes

Compare Wular Lake, Chilika Lake, and Sambhar Lake.

▶ Show solution

Step 1 — Wular Lake.
  • Location: J&K, north of Srinagar.
  • Type: FRESHWATER, TECTONIC origin (formed by Himalayan plate movements).
  • Status: Largest natural freshwater lake in India.
  • Use: Fishing, water supply for Srinagar.

Step 2 — Chilika Lake.
  • Location: Odisha (eastern coast).
  • Type: BRACKISH (mixed freshwater + saltwater) — connected to Bay of Bengal.
  • Status: Largest brackish-water lake in ASIA.
  • Use: Major fishing area; bird sanctuary; Ramsar wetland site.
  • Famous for: dolphins, migratory birds (flamingos, pelicans).

Step 3 — Sambhar Lake.
  • Location: Rajasthan (north India, near Jaipur).
  • Type: SALT-WATER (inland salt lake).
  • Status: Largest inland salt-water lake in India.
  • Use: Salt production (~ 196,000 tonnes per year).
  • Endorheic basin: water has no outlet to the sea, so salt accumulates.

Step 4 — Comparison summary.

  | Lake | Type | Status | Use |
  |------|------|--------|-----|
  | Wular | Freshwater (tectonic) | Largest freshwater in India | Fishing, water |
  | Chilika | Brackish | Largest in Asia (brackish) | Fishing, bird sanctuary |
  | Sambhar | Saltwater (inland) | Largest inland salt | Salt production |

✦ Answer: Wular Lake (J&K) is the largest natural freshwater lake in India, of tectonic origin. Chilika Lake (Odisha) is the largest brackish-water lake in Asia, connected to the Bay of Bengal. Sambhar Lake (Rajasthan) is the largest inland salt-water lake in India, used for salt production.

Q11HARD· Long-form

Describe the role of rivers in the Indian economy and culture.

▶ Show solution

Step 1 — Agriculture.
  Rivers underpin ~70% of India's agriculture:
  • Direct irrigation from rivers and canals.
  • Groundwater recharge — about 90% of irrigated land uses groundwater that's recharged by rivers and rainfall.
  • Riverine alluvial soils (Northern Plains, deltas) are India's most fertile.
  • Rice cultivation: heavily dependent on river water (Ganga Plain, eastern coast deltas).
  • Wheat cultivation: irrigated by canals from rivers (Punjab, Haryana).
  • Cotton: relies on Krishna, Godavari, Tapi systems.

Step 2 — Water supply.
  Major cities are on rivers:
  • Delhi on the Yamuna.
  • Mumbai on Mithi and other minor rivers.
  • Kolkata on the Hooghly.
  • Chennai partly on the Cooum.
  • Hyderabad on the Musi.
  • Bangalore on the Vrishabhavathi.
  Rivers provide drinking water, industrial water, and municipal supply.

Step 3 — Hydroelectricity.
  Major hydroelectric projects:
  • Bhakra-Nangal (Sutlej, 1948-63): India's largest concrete gravity dam.
  • Tehri (Bhagirathi, 2006): one of world's tallest dams.
  • Sardar Sarovar (Narmada, 1980-2017): controversial mega-dam.
  • Hirakud (Mahanadi, 1957): one of world's longest dams.
  • Nagarjuna Sagar (Krishna).
  • Idukki (Periyar): Kerala's major hydro project.
  Hydroelectricity is ~12% of India's installed capacity but provides peaking power.

Step 4 — Industry.
  Heavy industry concentrated where water + minerals + power are available:
  • Iron and steel: Jamshedpur (Subarnarekha), Durgapur (Damodar).
  • Paper mills: along the Cauvery, Krishna.
  • Textile mills: depend on water for processing.
  Water-intensive industries are often located near rivers.

Step 5 — Transportation.
  Historically major:
  • The Ganga, Hooghly, Brahmaputra were the highways of pre-colonial trade.
  • Modern: National Waterway 1 (Allahabad-Haldia) on the Ganga.
  • Other waterways being developed for cargo transport.
  • Less important now than road and rail, but expanding.

Step 6 — Tourism.
  Religious pilgrimage:
  • Haridwar, Rishikesh on the Ganga.
  • Varanasi on the Ganga.
  • Pushkar on Pushkar Lake.
  • Allahabad/Prayagraj at the Sangam (Ganga + Yamuna + mythical Saraswati).
  Heritage tourism along the rivers.
  Adventure tourism: rafting in Himalayan rivers (Ganges, Indus, Zanskar).

Step 7 — Culture and religion.
  • Ganga is considered SACRED by Hindus — bathing in it cleanses sins. Death rituals (ashes scattered in Ganga) believed to bring moksha.
  • Yamuna also sacred — associated with Lord Krishna.
  • Kaveri sacred to many Tamilians.
  • Kumbh Mela: largest religious gathering in the world (held at Allahabad/Prayagraj, Haridwar, Nashik, Ujjain on a 12-year cycle).
  • Chhath Puja: major festival for Surya Worship, held on rivers (especially Bihar, UP).
  • Diwali, Durga Puja: idol immersion in rivers.

Step 8 — Cultural identity.
  Many Indian languages, cultures, and identities are tied to rivers:
  • Bengali culture closely tied to the Ganga and the Hooghly.
  • Punjabi culture: 'land of five rivers' (Pancha + Aap = five waters).
  • Telugu culture: along the Godavari and Krishna.
  • Tamil culture: along the Kaveri.

Step 9 — Modern challenges.
  • Pollution threatens all these uses.
  • Inter-state disputes (Kaveri, Krishna, Mahanadi, Periyar).
  • Climate change (glacial retreat, monsoon variability).
  • Groundwater depletion.
  • Damming controversies (Sardar Sarovar protests).

✦ Answer: India's rivers are economic infrastructure (agriculture, water supply, hydroelectricity, industry, transport, tourism) AND cultural-religious infrastructure (sacred Ganga, Yamuna, Kaveri; pilgrimages, festivals, identity). The economy and culture both depend on rivers — making their pollution, depletion, and inter-state disputes major national issues. India's water future is one of its central 21st-century challenges.

5-minute revision

The whole chapter, distilled. Read this the night before the exam.

•Two main river systems: Himalayan (perennial, snow+monsoon-fed) and Peninsular (seasonal, rain-fed).
•Three major Himalayan systems: Indus, Ganga, Brahmaputra.
•Indus tributaries (Five Rivers / Panchanad): Jhelum, Chenab, Ravi, Beas, Sutlej. Indus Water Treaty 1960: India gets E (Ravi, Beas, Sutlej); Pakistan gets W (Indus, Jhelum, Chenab).
•Ganga formation: Bhagirathi (from Gangotri Glacier) + Alaknanda → meet at Devprayag → Ganga. Major tributaries: Yamuna (right), Ghaghara/Gandak/Kosi (left, Himalayan), Son/Damodar (right, Peninsular).
•Brahmaputra: Tsang Po (Tibet) → Dihang (Arunachal) → Brahmaputra (Assam) → Jamuna (Bangladesh). Highly braided, flood-prone. Forms Sundarbans Delta with Ganga.
•Major east-flowing Peninsular rivers: Mahanadi, Godavari (largest Peninsular), Krishna, Kaveri. Drain into Bay of Bengal.
•West-flowing Peninsular exceptions: Narmada, Tapi — flow through rift valleys into Arabian Sea.
•Largest lakes: Chilika (largest brackish in Asia, Odisha), Wular (largest freshwater in India, J&K), Sambhar (largest inland salt, Rajasthan).
•Sundarbans = world's largest delta, formed by Ganga + Brahmaputra. Shared by India + Bangladesh.
•Pollution: heavy in Ganga (sewage, industrial, religious). Namami Gange programme (2014) — multi-billion rupee clean-up. Mixed results.
•Inter-state disputes: Kaveri (Karnataka-TN), Krishna (Maharashtra-Karnataka-AP-Telangana), Mahanadi (Odisha-Chhattisgarh).

CBSE marks blueprint

Where the marks come from in this chapter — so you can plan your prep.

Typical chapter weightage: 5-6 marks per board paper (1-2 short + 1 long question)

Question type	Marks each	Typical count	What it tests
MCQ / Very Short	1	1-2	Indus tributaries; longest Peninsular river; largest lakes
Short Answer	3	1	Indus Water Treaty; Himalayan vs Peninsular rivers
Long Answer	5	0-1	Course of Ganga; Brahmaputra system; role of rivers
Map-based	5	0-1	Locate major rivers, tributaries, lakes, dams

Prep strategy

FIVE RIVERS of Indus (Panchanad): Jhelum, Chenab, Ravi, Beas, Sutlej
Indus Water Treaty 1960: India gets Ravi/Beas/Sutlej; Pakistan gets Indus/Jhelum/Chenab
Brahmaputra's FOUR names: Tsang Po, Dihang, Brahmaputra, Jamuna
THREE major lakes: Wular (largest freshwater, J&K), Chilika (largest brackish, Odisha), Sambhar (salt, Rajasthan)
Distinguish HIMALAYAN (perennial, sediment-rich) from PENINSULAR (seasonal, smaller)

Where this shows up in the real world

This chapter isn't just an exam topic — it lives in the world around you.

Namami Gange programme

₹20,000+ crore Indian government effort to clean the Ganga. Includes sewage treatment plants, industrial pollution control, awareness campaigns. Launched 2014; ongoing.

Sardar Sarovar Dam

Massive multi-state dam on the Narmada River. Controversial — displaced 250,000+ people. Provides irrigation to Gujarat, Rajasthan; hydroelectricity to MP, Maharashtra. Symbol of India's development-displacement dilemma.

Bhakra-Nangal Dam

Built 1948-63 on the Sutlej. Foundation of Punjab's Green Revolution. Provides irrigation to Punjab, Haryana, Rajasthan. Major hydroelectric source.

Inter-State Water Disputes

Multiple Tribunals: Cauvery Tribunal (1990), Krishna Tribunal, Godavari Tribunal. Many disputes still unresolved decades later. Constitution Article 262 gives mechanism but slow.

Yamuna Action Plan

Effort to clean the heavily polluted Yamuna, especially through Delhi. Started 1993; results have been disappointing. Despite multiple programs, Yamuna remains among India's most polluted rivers.

Climate change and rivers

Glacial retreat in Himalayas threatens future flow of Indus, Ganga, Brahmaputra. India is a major stakeholder in international climate negotiations affecting these glaciers.

Exam strategy

Battle-tested tips from teachers and toppers for this chapter.

Memorise the FIVE RIVERS (Panchanad) of the Indus: Jhelum, Chenab, Ravi, Beas, Sutlej. And the Indus Water Treaty (1960) distribution.
Memorise the GANGA's tributaries in order — Yamuna (right), Ghaghara/Gandak/Kosi (left, Himalayan), Son/Damodar (right, Peninsular).
Memorise the BRAHMAPUTRA's four names: Tsang Po (Tibet) → Dihang (Arunachal) → Brahmaputra (Assam) → Jamuna (Bangladesh).
Memorise the PENINSULAR east-flowing rivers in order from north to south: Mahanadi → Godavari → Krishna → Kaveri.
Memorise the PENINSULAR west-flowing rivers: Narmada and Tapi (only major exceptions to east-flow rule). Flow through RIFT VALLEYS.
Memorise THREE major lakes: Wular (largest freshwater, J&K), Chilika (largest brackish in Asia, Odisha), Sambhar (largest inland salt, Rajasthan).
Map work: practice locating rivers, dams, lakes on a blank India map. Common 5-mark question.
For 'difference between' questions, use a comparison table. CBSE prefers structured answers.

Going beyond the textbook

For olympiad aspirants and curious learners — topics that build on this chapter.

Hydrology and river morphology: how rivers shape landscapes (V-shaped valleys, oxbow lakes, meanders, deltas). Earth surface processes.
International water law: the Helsinki Rules (1966), UN Watercourses Convention (1997). How countries share rivers like the Ganga-Brahmaputra.
Glacial hydrology: how the Himalayas store water as ice, the role of monsoon, and climate change implications.
River engineering: dams, barrages, embankments. The economics, ecology, and politics of dam construction (Sardar Sarovar protests, Three Gorges in China).

Where else this chapter is tested

CBSE board isn't the only one — other exams test this chapter too.

NTSE / NMMSHigh — major rivers and tributaries are routine MCQs

Olympiad (Social Studies)High — river systems and inter-state issues

UPSC FoundationVery high — Indian Geography is core

CLAT / Legal FoundationMedium — Inter-State Water Disputes (Article 262)

AI helpers for this chapter

Generate more practice on the fly, or have the chapter explained at a different level.

⚡

Generate 5 more questions

Fresh MCQs + short-answer items based on this chapter, plus answer keys.

🧠

Explain at a different level

Re-explain the chapter at the level you actually want.

📝 My notes

Saved on this device — sign in to sync · how this works

0/600

Questions students ask

The real ones — pulled from the Q&A community and tutor sessions.

Multiple reasons: (i) The Brahmaputra has a steeper gradient through the Himalayas, carrying more water and sediment; (ii) it widens dramatically in Assam, where sediment deposits and channel braiding cause overbank flow; (iii) heavy monsoon rains in the Bramhaputra catchment (Assam, Bhutan, China); (iv) the channel is unstable due to high sediment load; (v) infrastructure in floodplains is less developed than along the Ganga.

Mixed picture. Glacial melt from climate change is INCREASING summer flow in Himalayan rivers initially — but as glaciers shrink, future flow will DECREASE. Groundwater levels are dropping rapidly in northern India (Punjab, Haryana especially). Pollution is making available water less usable. Climate change is making monsoon patterns more variable. So overall: water STRESS is increasing even if rivers aren't technically 'drying up.'

Rivers cross state boundaries; states have competing demands. Specific disputes: Kaveri (Karnataka vs TN — TN downstream demands more water; Karnataka upstream wants to retain it). Krishna (Maharashtra, Karnataka, AP, Telangana). Sutlej-Yamuna Link (Punjab, Haryana, Rajasthan). The Constitution provides for Inter-State Water Disputes Tribunals (Articles 262), but disputes drag on for decades. Climate change is increasing pressure.

Difficult. The Sundarbans is the largest mangrove forest in the world but also one of the most threatened. Sea-level rise is encroaching; salinity is destroying mangroves and crops; cyclones are getting more intense. India and Bangladesh are jointly working on conservation. But complete preservation may not be feasible — some adaptation (managed retreat) is likely necessary.

TRIBUTARY: a smaller river that JOINS a larger one. The Yamuna is a tributary of the Ganga. DISTRIBUTARY: a smaller channel that BRANCHES OFF from a larger river. The Hooghly is a distributary of the Ganga. Tributaries flow IN; distributaries flow OUT. Deltas typically have many distributaries.

Yes — within India, the Ganga is the longest (2,510 km in India). The Brahmaputra is longer in total (2,900 km from source) but only 916 km of it is in India. The Indus is also longer in total (2,900 km from source) but the major portion is in Pakistan. So depending on how you measure (total length vs length in India), the answer differs.

Practice more, ask doubts, find a tutor

CBSE Class 9 mock tests

CBSE Class 9 PYQs

Ask in Q&A

Social Studies flashcards

Related chapters

Students who read Drainage usually read these next.

The French Revolution

In 1789, the people of France overthrew their king, abolished feudal privileges, and inspired democratic movements worldwide. Class 9 History Book — The French Revolution covers the causes (Estates System, economic crisis, Enlightenment ideas), the storming of the Bastille, the Declaration of Rights, the Reign of Terror, Napoleon's rise, and 20+ exam-style problems with full step-by-step explanations.

Socialism in Europe and the Russian Revolution

In 1917, Russian workers and peasants overthrew the Tsar and tried to build the world's first socialist society. Class 9 History Book — Socialism in Europe and the Russian Revolution covers industrial inequality, the rise of socialism, Karl Marx, the 1905 Revolution, February & October 1917, Lenin and the Bolsheviks, civil war, Stalin's collectivisation, and 20+ exam-style problems with full step-by-step explanations.

Nazism and the Rise of Hitler

How did a small fringe party become the ruler of Europe's most cultured nation — and start the worst war in human history? Class 9 History Book — Nazism and the Rise of Hitler covers Germany after WWI, the failure of the Weimar Republic, the Great Depression, Hitler's rise, Nazi ideology, the Holocaust, WWII, and 20+ exam-style problems.

Forest Society and Colonialism

For thousands of years, forests had been home to millions across India, Indonesia, and the world. British and Dutch colonialism turned forests from communal homes into commercial commodities. Class 9 History Book — Forest Society and Colonialism covers commercial forestry, scientific forestry, the impact on forest dwellers, rebellions, and the Bastar Rebellion with 20+ exam-style problems.

Verified by the tuition.in editorial team

Last reviewed on 18 May 2026. Written and reviewed by subject-matter experts — read about our process.

Editorial process →

Take the next step

Stuck on Drainage? Get a tutor

Pair self-study with a tutor, a live course or a coaching centre.

1-on-1 help

🧑‍🏫

Find a verified tutor

School, college and competitive — online or at home.

Find tutors

Live cohorts

Join a live course

Test series and recorded lessons from top creators.

Browse courses

Classroom

Browse coaching centres

Verified institutes near you for every exam.

Find centres

Drainage

By the end of this chapter you'll be able to…

Before you start — revise these

Drainage — Class 9 (CBSE)

1. The story — why drainage matters

2. Himalayan rivers — perennial flow

Three major Himalayan river systems

(a) The Indus river system

(b) The Ganga river system

(c) The Brahmaputra river system

3. Peninsular rivers — seasonal flow

Eastern-flowing rivers (into Bay of Bengal)

(a) Mahanadi

(b) Godavari (Vridha Ganga or "Old Ganga")

(c) Krishna

(d) Kaveri (or Cauvery)

Western-flowing rivers (into Arabian Sea)

(a) Narmada

(b) Tapi (or Tapti)

4. Major Indian lakes

Salt-water lakes (the most famous in India)

Fresh-water lakes

Tectonic lakes

Glacial lakes

Man-made (reservoirs)

5. Why drainage matters

Agriculture

Water supply

Hydroelectricity

Transportation

Culture and religion

6. Water pollution and conservation

Major problems

Notable polluted stretches

Government action

Other water challenges

7. Closing thought

Key formulas & results

Common mistakes & fixes

NCERT exercises (with solutions)

Practice problems

5-minute revision

CBSE marks blueprint

Where this shows up in the real world

Exam strategy

Going beyond the textbook

Where else this chapter is tested

AI helpers for this chapter

Generate 5 more questions

Explain at a different level

📝 My notes

Questions students ask

Why does the Brahmaputra flood so much more than the Ganga?

Are India's rivers drying up?

Why are inter-state water disputes so common in India?

Can the Sundarbans Delta be saved from sea-level rise?

What's the difference between a tributary and a distributary?

Is the Ganga the longest river in India?

Practice more, ask doubts, find a tutor

Related chapters

The French Revolution

Socialism in Europe and the Russian Revolution

Nazism and the Rise of Hitler

Forest Society and Colonialism

Stuck on Drainage? Get a tutor

Find a verified tutor

Join a live course

Browse coaching centres

About

Categories

Support

Documentation

Get Study Tips & Updates

Download Our App

Download for iOS

Download for Android

Popular Cities