Explanation: Based on the size of the watershed, the drainage basins of India are grouped into three categories:

• Major river basins with more than 20,000 sq. km of catchment area. It includes 14 drainage basins such as the Ganga, the Brahmaputra, the Krishna, the Tapi, the Narmada, the Mahi, the Pennar, the Sabarmati, the Barak, etc.
• Medium river basins with catchment area between 2,000-20,000 sq. km incorporating 44 river basins such as the Kalindi, the Periyar, the Meghna, etc.
• Minor river basins with catchment area of less than 2,000 sq. km include a fairly good number of rivers flowing in the area of low rainfall.

Source: Class 11th NCERT