The drainage system of an area refers to the pattern of flow of rivers and streams over the land surface. India has a well-developed drainage system that can be broadly classified on the basis of drainage patterns and river systems. The nature of drainage depends on factors such as relief, geological structure, slope, and climate.
Drainage Patterns
India exhibits various drainage patterns based on the terrain and structure of rocks:
- Dendritic Pattern
- Resembles the branches of a tree
- Develops on uniform rock structure
- Trellis Pattern
- Tributaries join the main river at right angles
- Found in areas of alternating hard and soft rocks
- Radial Pattern
- Rivers originate from a central dome or peak and flow outward
- Example: Rivers originating from the Amarkantak Plateau
- Centripetal Pattern
- Rivers drain water into a central lake or depression
Indian River System
The rivers of India are broadly divided into:
- Himalayan Rivers
- Peninsular Rivers
Himalayan Rivers
- Perennial rivers (water throughout the year)
- Originate from glaciers
- Have long courses from source to sea
- Major river systems:
- Indus
- Ganga
- Brahmaputra
- Some rivers are antecedent, meaning they maintain their original course despite changes in topography
- Examples: Indus, Satluj, Kosi
Peninsular Rivers
- Mostly ephemeral (seasonal rivers)
- Reduced flow during dry season
- Shorter and shallower courses
- Most rivers originate in the Western Ghats and flow towards the Bay of Bengal
- Examples: Narmada, Tapi, Godavari
The Indus River System
- Source: Bokhar Chu Glacier near Lake Mansarovar
- Total length: 2880 km (1114 km in India)
- Flows through China, India, and Pakistan
- Drains into the Arabian Sea
- Known as Singi Khamban (Lion’s Mouth) in Tibet
- National river of Pakistan
Doabs of Indus System
- Indus + Jhelum → Sindh Sagar Doab
- Jhelum + Chenab → Jech Doab
- Chenab + Ravi → Rechna Doab
- Ravi + Beas → Bari Doab
- Beas + Sutlej → Bist Doab
Major Tributaries (Panchnad)
- Jhelum, Chenab, Ravi, Beas, Sutlej
Ganga River System
- Total length: 2525 km
- Longest river of India
- Declared National River of India in 2008
- Passes through Uttarakhand, Uttar Pradesh (longest stretch), Bihar, Jharkhand (shortest), West Bengal
- In Bangladesh, Ganga is known as Padma
- Water stored in a bottle remains fresh due to bacteriophage viruses
Yamuna River
- Length: 1370 km
- Longest tributary of Ganga
- Tributaries: Chambal, Sindh, Betwa, Ken, Tons
Son River
- Origin: Amarkantak Plateau
- Tributaries: Koel, Rihand
- Punpun River joins Ganga near Fatuha (Patna)
Important Cities on Ganga (West → East)
- Prayagraj
- Kanpur (largest)
- Varanasi
- Patna
Brahmaputra River System
- Total length: 2900 km
- Length in India: 916 km
- Names:
- Yarlung Tsangpo – Tibet
- Siang/Dihang – Arunachal Pradesh
- Brahmaputra – Assam
- Jamuna – Bangladesh
- Takes a U-turn at Namcha Barwa
- Turns south at Dhubri (Assam)
- Majuli Island – World’s largest riverine island
- Origin: Chemayungdung / Angsi Glacier
Tributaries
- Left Bank: Lohit, Dhansiri
- Right Bank: Dibang, Kameng, Manas, Teesta, Subansiri
- Padma + Jamuna = Meghna
- Sundarbans Delta – World’s largest delta (Sundari trees)
Indus Water Treaty (1960)
- Signed at Karachi
- Between Jawaharlal Nehru and Ayub Khan
- Mediated by the World Bank
Water Sharing
- Indus, Jhelum, Chenab
- 80% Pakistan | 20% India
- Ravi, Beas, Sutlej
- 80% India | 20% Pakistan
Conclusion
The drainage system of India reflects the country’s diverse relief and geological structure. Himalayan rivers ensure perennial water supply, while Peninsular rivers are seasonal but vital for regional development. A thorough understanding of river origins, courses, tributaries, and drainage patterns is essential for geography-related competitive examinations.