Classification of river basins by size
Topic: Drainage System of India: Rivers, Basins and Patterns · NCERT: Class 11, Ch 3 "Drainage System"
Meaning
India's river basins are sorted into three classes by the size of their catchment (the land that collects their water).
- Major basins are larger than 20,000 sq km. There are 14 of them.
- Medium basins are 2,000 to 20,000 sq km. There are 44 of them.
- Minor basins are smaller than 2,000 sq km. There are many, mostly in low-rainfall areas.
This grouping helps planners match the scale of a project to the size of the basin. NCERT uses this older CWC data. The CWC–NRSC River Basin Atlas (2012) instead divides India into 20 basins.
Example
The Ganga, Brahmaputra, Krishna, Narmada, Tapi, Mahi, Pennar, Sabarmati and Barak are major basins. The Periyar in Kerala, the Kalindi and the Meghna are medium basins.
Don't confuse with
- Classification by origin: this sorts rivers into Himalayan and Peninsular by where they start, not by basin size.