The river systems of India can be classified into four groups viz. Himalayan, Deccan, Coastal streams, and streams of inland drainage basin of western Rajasthan.
The Himalayan rivers are formed by melting snow and glaciers and therefore, continuously flow throughout the year. The main Himalayan river systems are those of the Indus and the Ganga-Brahmaputra-Meghna system. The Deccan rivers on the other hand are rainfed and therefore fluctuate in volume. Many of these are non-perennial. In the Deccan region, the major east flowing rivers are Godavari, Krishna, Cauvery and Mahanadi. Narmada and Tapti are major west flowing rivers. The Coastal streams, especially on the west coast are short in length and have limited catchment areas. Most of them are non-perennial. The streams of inland drainage basin of western Rajasthan are few and far apart. Most of them are of an ephemeral character.
The Godavari in the southern Peninsula has the second largest river basin covering 10 percent of the area of India.
Table of Contents
Major River Basins
The entire country has been divided into 20 river basins/group of river basins comprising 12 major basins and eight composite river basins. The 12 major river basins are : (1) Indus, (2) Ganga-Brahmaputra-Meghna, (3) Godavari, (4) Krishna, (5) Cauvery, (6) Mahanadi, (7) Pennar, (8) Brahmani-Baitarani, (9) Sabarmati, (10) Mahi, (11) Narmada and (12) Tapti. Each of these basins has a drainage area exceeding 20,000 sq. km.
Composite River Basins
The eight composite river basins combining suitably together all the other remaining medium (drainage area of 2,000 to 20,000 sq. km) and small river systems (drainage area less than 2000 sq. km) for the purpose of planning and management are:
- Subarnarekha—combining Subarnarekha and other small rivers between Subarnarekha and Baitarani;
- East flowing rivers between Mahanadi and Pennar;
- East flowing rivers between Pennar and Kanyakumari;
- Area of Inland drainage in Rajasthan desert;
- West flowing rivers of Kutch and Saurashtra including Luni;
- West flowing rivers from Tapi to Tadri;
- West flowing rivers from Tadri to Kanyakumari and
- Minor rivers draining into Myanmar (Burma) and Bangladesh.