The major extraperinsular rivers are the Indus, Ganges (Ganga River) and the Brahmaputra and their tributaries

The major extraperinsular rivers are the Indus, Ganges (Ganga River) and the Brahmaputra and their tributaries.

These rivers are perennial as they are fed by glaciers from the Himalayas. The major peninsular rivers are westerly flowing (Narmada and the Tapti) and South Easterly flowing (Mahanadi, Godavari, Krishna and Cauvery).

The Mahanadi is the longest river of Orissa followed by the Brahmani, Baitarani, Subarnarekha, Bansdhara and the Rushikulya etc. The Tel River is a large tributary of Mahanadi; similarly, the Indravati is a large tributary of Godavari.

The Satkoshia gorge is typical of its kind in the Mahanadi River. The river Mahanadi forms a large delta with numerous, branching distributaries like Kathjori, Kuakhai, Daya, Bharati, Kushabhadra, Devi, Luna, Chittrotpala, Birupa etc.

This, delta looks like a bird’s foot (this name is brought from B.F.D. of U.S.A.) from the aerial view. Naraj is at the head of the Mahanadi delta, east of which the alluvial plain extends upto the Bay of Bengal. The deltas of the Mahanadi, Brahmani and the Baitarani join and coalesce to form one delta, although, in detail, they are three and can be termed as Tri-delta.