With a land area of 3,287,263 km2 (1,269,219 sq mi) consisting of diverse ecosystems, India has many rivers systems and perennial streams.[1] The rivers of India can be classified into four groups – Himalayan, Deccan, Coastal, and Inland drainage. The Himalayan rivers, mainly fed by glaciers and snow melt, arise from theHimalayas. The Deccan rivers system consists of rivers inPeninsular India, that drain into theBay of Bengal and theArabian Sea. There are numerous short coastal rivers, predominantly on theWest coast. There are few inland rivers, which do not drain into sea.[2][3]
Most of the rivers in India originate from the four majorwatersheds in India. The Himalayan watershed is the source of majority of the major river systems in India including the three longest rivers–theGanges, theBrahmaputra and theIndus.[3][4] These three river systems are fed by more than 5000 glaciers.[5] TheAravalli range in the north-west serves the origin of few of the rivers such as theChambal, theBanas and theLuni rivers.[4]
TheNarmada andTapti rivers originate from theVindhya andSatpura ranges inCentral India.[4] In the peninsular India, majority of the rivers originate from theWestern Ghats and flow towards the Bay of Bengal, while only a few rivers flow from east to west from theEastern Ghats to the Arabian sea. This is because of the difference in elevation of the Deccan plateau, which slopes gently from the west to the east.[6] The largest of the peninsular rivers include theGodavari, theKrishna, theMahanadi and theKaveri.[3][4]
As per the classification ofFood and Agriculture Organization, the rivers systems are combined into 20 river units, which includes 14 major rivers systems and 99 smaller river basins grouped into six river units. The Ganges-Brahmaputra-Meghna basin is the largest, which covers 34% of the land area and contributes to nearly 59% of the available water resources.[2]
| River unit | Region | Draining into | Catchment area (% of land area) | Average annual runoff (km3) | Surface water (km3) |
|---|---|---|---|---|---|
| Ganges-Brahmaputra-Meghna | North-east | Bangladesh | 34.0 | 610.62 | 294.0 |
| Other North-east rivers | Bangladesh,Myanmar | 1.1 | 31.0 | ||
| Subarnarekha | Bay of Bengal | 0.9 | 12.4 | ||
| Brahmani-Baitarani | 1.6 | 28.5 | 6.8 | ||
| Mahanadi | Central-east | 4.4 | 66.9 | 18.3 | |
| East flowing rivers betweenMahanadi andPennar | 2.7 | 22.5 | 19.0 | ||
| Godavari | Central | 9.7 | 110.5 | 50 | |
| Krishna | 8.0 | 78.1 | 76.3 | ||
| Pennar | South-east | 1.7 | 6.3 | 58.0 | |
| East flowing rivers betweenPennar andKanyakumari | 3.1 | 16.5 | 13.1 | ||
| Kaveri | South | 2.5 | 21.4 | 6.9 | |
| West flowing rivers betweenTadri andKanyakumari | South-west | Arabian Sea | 1.7 | 113.5 | 16.7 |
| West flowing rivers betweenTapti andTadri | Southwest | 1.7 | 87.4 | 24.3 | |
| Tapti | Central-west | 2.0 | 14.9 | 11.9 | |
| Narmada | 3.1 | 45.6 | 14.5 | ||
| Mahi | North-west | 1.1 | 11.0 | 34.5 | |
| Sabarmati | 0.7 | 3.8 | 3.1 | ||
| West flowing rivers betweenKutch andSaurashtra | 10.0 | 15.1 | 1.9 | ||
| Rajasthan inland basin | North-east | None | Negligible | Negligible | 15.0 |
| Indus tributaries | North-west | Pakistan | 10 | 73.3 | 46.0 |
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