The Drainage System refers to the network of rivers, streams, and their tributaries that drain water from a particular region into a common outlet such as a sea, ocean, lake, or inland basin. The area drained by a river and its tributaries is known as a Drainage Basin, while the boundary separating two drainage basins is called a Watershed. India possesses one of the world’s largest and most diverse drainage systems, which plays a crucial role in agriculture, transportation, hydroelectric power generation, and ecosystem maintenance.
NDA & CDS 2 2026 Exam GK – Indian Geography – Drainage
Important Terms
1. Drainage Basin
The total area drained by a river and its tributaries.
2. Watershed
A highland or ridge separating two drainage basins.
3. River System
The main river along with all its tributaries.
4. Catchment Area
The geographical area from which a river collects its water.
Classification of Indian Drainage System
Indian rivers are broadly classified into:
- Himalayan Rivers
- Peninsular Rivers
- Coastal Rivers
- Inland Drainage Rivers
1. Himalayan River System
The Himalayan rivers originate from glaciers and snowfields of the Himalayas. These rivers are perennial, receiving water from both glaciers and rainfall throughout the year.
Characteristics
- Perennial in nature
- Long courses
- Large drainage basins
- Form meanders and oxbow lakes
- Carry heavy sediment loads
- Create extensive floodplains and deltas
Major Himalayan River Systems
A. Indus River System
- Origin: Near Lake Manasarovar, Tibet
- Flows through Ladakh and Pakistan
- Major Tributaries:
- Jhelum
- Chenab
- Ravi
- Beas
- Sutlej
B. Ganga River System
- Origin: Gangotri Glacier (Bhagirathi)
- Confluence of Bhagirathi and Alaknanda at Devprayag forms the Ganga.
- Major Tributaries:
- Yamuna
- Ghaghara
- Gandak
- Kosi
- Son
C. Brahmaputra River System
- Origin: Tibet (Yarlung Tsangpo)
- Enters India through Arunachal Pradesh as Siang/Dihang.
- Flows through Assam and Bangladesh.
- Major Tributaries:
- Dibang
- Lohit
- Subansiri
- Manas
2. Peninsular River System
Peninsular rivers are older than Himalayan rivers and mainly depend on monsoon rainfall. Most are seasonal and flow through hard crystalline rocks.
Characteristics
- Mostly seasonal
- Fixed river courses
- Less sediment load
- Broad and shallow valleys
- Fewer meanders
East-Flowing Rivers
These rivers drain into the Bay of Bengal and form large deltas.
Mahanadi
- Origin: Chhattisgarh Highlands
- Empties into Bay of Bengal
Godavari
- Origin: Trimbakeshwar, Maharashtra
- Longest Peninsular River
- Known as “Dakshin Ganga”
Krishna
- Origin: Mahabaleshwar, Maharashtra
- Tributaries: Bhima, Tungabhadra
Kaveri (Cauvery)
- Origin: Talakaveri, Karnataka
- Forms fertile delta in Tamil Nadu
West-Flowing Rivers
These rivers generally form estuaries instead of deltas.
Narmada
- Origin: Amarkantak Plateau
- Flows through a rift valley
- Empties into Arabian Sea
Tapi (Tapti)
- Origin: Satpura Range
- Flows parallel to Narmada
3. Coastal Rivers
These are short rivers flowing near coastal regions.
West Coast Rivers
- Periyar
- Sharavati
- Mandovi
- Zuari
East Coast Rivers
- Subarnarekha
- Vamsadhara
- Palar
Characteristics:
- Short length
- Small drainage basin
- Swift flow
4. Inland Drainage System
Some rivers do not reach the sea and disappear into lakes, marshes, or deserts.
Major Inland Drainage Rivers
Luni River
- Origin: Aravalli Range
- Drains into Rann of Kutch
- Largest inland drainage river of western India
Ghaggar-Hakra
- Seasonal river
- Disappears in Rajasthan desert
Major Drainage Patterns in India
1. Dendritic Pattern
- Tree-like branching pattern.
- Found in Peninsular Plateau.
2. Trellis Pattern
- Tributaries join the main river at right angles.
- Found in folded mountain regions.
3. Rectangular Pattern
- Develops along faulted and jointed rocks.
4. Radial Pattern
- Rivers flow outward from a central hill.
- Example: Amarkantak Plateau.
5. Centripetal Pattern
- Rivers flow towards a central depression.
- Found in inland drainage basins.
Difference Between Himalayan and Peninsular Rivers
| Feature | Himalayan Rivers | Peninsular Rivers |
|---|---|---|
| Origin | Himalayas | Peninsular Plateau |
| Nature | Perennial | Seasonal |
| Water Source | Snow and rainfall | Mainly rainfall |
| Valley | Deep and V-shaped | Broad and shallow |
| Course | Meandering | Fixed |
| Sediment Load | High | Low |
| Delta Formation | Extensive | Limited |
Important Facts for NDA & CDS Exams
- Godavari is the longest Peninsular River.
- Ganga is India’s most important river system.
- Narmada and Tapi flow westward.
- Kosi is called the “Sorrow of Bihar”.
- Brahmaputra enters India through Arunachal Pradesh.
- Luni is the largest inland drainage river of western India.
- Most Peninsular rivers flow from west to east.
- Western Ghats act as the major water divide in Peninsular India.
- About 77% of India’s drainage flows into the Bay of Bengal and about 23% into the Arabian Sea.
