Drainage System of India — Updated 2025 (Easy Notes)
This chapter explains the Drainage System of India in an easy and exam-friendly format. It covers drainage patterns, Himalayan and Peninsular river systems, major tributaries, river origins, lakes, river basins, and the economic role of rivers.
The flow of water across the land through defined channels is called drainage. The network formed by these channels is called a drainage system.
The drainage pattern of a region depends on:
- Topography & slope
- Rock structure (hard/soft)
- Geological time period
- Amount & periodicity of water flow
Geomorphology
Study of landforms, their origin & evolution through physical and chemical processes.
Drainage Basin
Area drained by a single river system. A water divide separates two basins.
Dendritic
Like a tree branch. Common in Northern Plains.
Radial
Rivers flow outward from a hill/volcano. Example: Amarkantak highlands.
Trellis
Main rivers run parallel, tributaries join at right angles.
Centripetal
Rivers flow inward into a depression or lake.
Bay of Bengal Drainage
About 77% of India’s drainage — Ganga, Brahmaputra, Mahanadi, Godavari, Krishna etc.
Arabian Sea Drainage
About 23% — Indus, Narmada, Tapi, Mahi, Periyar.
The Himalayan rivers are perennial — fed by glaciers + rainfall. They are long, meandering and create depositional features.
The three major Himalayan river systems are:
- The Indus
- The Ganga
- The Brahmaputra
One of the world’s largest basins (1,165,000 sq km). Length: 2,880 km.
Origin: Bokhar Chu glacier, Kailash Range (Tibet) — called Singi Khamban.
It flows through Ladakh (India), enters Pakistan near Chilas.
Main Tributaries of Indus
Himalayan: Shyok, Gilgit, Zaskar, Hunza, Nubra, Shigar, Dras
Panjnad Rivers: Jhelum, Chenab, Ravi, Beas, Satluj
| Tributary | Origin & Key Notes |
|---|---|
| Chenab | Formed by Chandra + Bhaga at Tandi (HP). Length 1180 km. |
| Jhelum | Origin at Verinag spring (Kashmir). Passes through Wular Lake. |
| Ravi | Origin west of Rohtang Pass; flows through Chamba valley. |
| Satluj | Origin: Rakas Lake near Mansarovar. Enters India via Shipki La. |
Origin: Bhagirathi (Gangotri Glacier), joined by Alaknanda at Devprayag.
Total Length: 2,525 km. Basin area: 8.6 lakh sq km.
Flows through Uttarakhand → UP → Bihar → West Bengal; forms a large delta with Brahmaputra.
| Tributary | Type | Notes |
|---|---|---|
| Yamuna | Right bank | Origin: Yamunotri. Tributaries: Chambal, Sind, Betwa, Ken. |
| Ghaghara | Left bank | Origin: near Mansarovar; joins Ganga near Chhapra. |
| Gandak | Left bank | Origin: Nepal Himalaya; joins Ganga at Hajipur. |
| Kosi | Left bank | Known as “Sorrow of Bihar”; forms Sapt-Koshi region. |
| Son | Right bank | Origin: Amarkantak; joins near Danapur. |
Origin: Chemayungdung Glacier (near Mansarovar).
Called Tsangpo in Tibet. Travels 1200 km → cuts gorge at Namcha Barwa → enters India as Siang/Dihang.
Major tributaries: Dibang, Lohit, Subansiri.
Forms the world’s largest river island: Majuli.
Peninsular rivers are older, shorter and seasonal. Their main water divide is the Western Ghats.
Most flow eastward into the Bay of Bengal except the Narmada and Tapi which flow west.
Narmada
Origin: Amarkantak. Flows through rift valley. Famous for Marble Rocks & Dhuandhar Falls.
Tapi
Origin: Betul district (Satpura). Shorter; flows westwards parallel to Narmada.
| River | Origin | Length | Important Tributaries |
|---|---|---|---|
| Godavari | Nasik (Maharashtra) | 1500 km | Purna, Wardha, Pranhita, Manjra |
| Mahanadi | Chhattisgarh Highlands | 860 km | Hasdeo, Mand, Jonk |
| Krishna | Mahabaleshwar | 1400 km | Bhima, Tungabhadra, Musi |
| Kaveri | Brahmagiri Range | 760 km | Hemavati, Kabini, Bhavani |
India has freshwater, saltwater, glacial, lagoon and artificial lakes.
Largest freshwater lake in India: Wular (J&K)
Popular lakes: Dal, Nainital, Loktak, Barapani.
Artificial lakes: Govind Sagar, Rana Pratap Sagar.
Ox-Bow Lakes
Formed when meanders cut off. Seen in Ganga plains.
Lagoon Lakes
Separated by sand bars. Examples: Chilika, Pulicat, Kolleru.
Glacial Lakes
Formed by melting glaciers. Found in Himalayas.
| Name | Location |
|---|---|
| 8° Channel | Between Maldives & Minicoy |
| 9° Channel | Between Kavaratti & Minicoy |
| 10° Channel | Between Little Andaman & Car Nicobar |
| Grand Channel | Between Sumatra & Nicobar |
| Palk Strait | Between India & Sri Lanka |
| Duncan Pass | South Andaman & Little Andaman |
| Coco Strait | Between Coco Islands & North Andaman |
- Provide irrigation and drinking water
- Support navigation & transport
- Enable hydropower generation
- Fertile floodplains support agriculture
Rivers face pollution due to untreated sewage, industrial effluents, reduced water volume, and overuse. Government initiatives like the Ganga Action Plan and Namami Gange aim to restore river health.
Himalayan Rivers
Perennial, long, meandering, originate from glaciers.
Peninsular Rivers
Shorter, seasonal, originate from Western Ghats.
Drainage Direction
77% → Bay of Bengal; 23% → Arabian Sea.
Largest Basins
Ganga & Godavari.
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