The rivers of India may be classified as follows: (a) The Himalayan rivers, (b) the Deccan river, (c) the Coastal rivers and (d) the rivers of the inland drainage basin. The Himalayan rivers are generally snowled and have, therefore continuous flow throughout the year. During the monsoon months the Himalayas receive very heavy precipitation everywhere and the rivers discharge the maximum amount of water during this season, causing frequent floods.
The Deccan River are generally rain-fed and, therefore, flucluate very much in volume. A large number of streams are non-perennial. The coastal stroms, specially of the west coast, are short in length and have limited catchment areas. Most of them also are non-perennial. The streams in the inland drainage basin of western Rajsthan are few and for between. Most of the are of an ephemeral character. They drain towards the individual basins or salt lakes like the Sambhar or are lost in the sands, having no outlet to the sea. Only the river Luni drains into the Rann of Kutchh.
The Ganga basin, which is receiving waters from an area of about one-quarter of the total area of the India, is the largest. Its boundaries are defined by the Himalayas in the north and the Vindhya Mountains in the south. The Ganga has former rising from the Gangotri glacier at Gaumukh and the latter from a glacial spout of the Alkopuri glacier. A number of Himalayan rivers including the Yamuna, Ghagra, Gomiti, Gandak and Kosi join Ganga. Yamuna which rises from the Yamnatri glacier and joins the Ganga at Allahabad, is the western most river of the Ganga system. Of the rivers flowing north from central India into the Yamuna or the Ganga, mention may be made of the Chambal, the Betwa and the Sone.
The Godavari river basin is the second largest in India. It convers an area of about 10 percent of the total area of India. The brahamputra basin in the east and the Indus basin in the west are about the some size. The Krishna basin is second largest in the Peninsula. The Mahanandi flows through the third largest basin in the peninsula. The basins of the Narmada in the uplands of the Deccan flowing into the Arabian Sea and of the Cauvery in the for south flowing into the Bay of Bengal are of about the same size, though of different character and shape.
The two other river systems, though small but nevertheless agriculturally very important, are those of the Tapti in the north and the Pennar in the South.