India is blessed with many rivers. Twelve of them are classifled as major rivers whose total catchment area is 252.8 million heactare (M.Ha). Of the major rivers, the Ganga - Brahmaputra Meghana system is the biggest with catchment area of about 110 M.Ha which is more than 43 percent of the catchment area of all the major rivers in the country. The other major rivers with catchment area more than 10 M.Ha are Indus (32.1 M.Ha.), Godavari (31.3 M.Ha.), Krishna, (25.9 M.Ha.) and Mahanadi (14.2 M.Ha). The catchment area of medium rivers is about 25 M.Ha and Subernarekha with 1.9 M.Ha. catchment area is the largest river among the medium rivers in the country.