A river basin is the part of land through which a main river and all its tributaries flows. It is the basic hydrological unit for planning and development of water resources of a country. In India, there are various river basins classified by different organizations – India WRIS (Water Resource Information System) Basin, NCIWRDP (National Commission for Integrated Water Resources Development Plan) Basin, AISLUS (All India Soil and Land Use Survey) Basin, CGWB (Central Ground Water Board) Basin and CWC (Central Water Commission) Basin. CWC has classified 22 river basins in India (Fig.1).
The 10 largest river basins (area wise) in order of highest to lowest, classified by CWC are as follows:
It is the largest basin in India with area about 861452 sq. km. It originates from the Gangotri glacier in Himalaya and traverses about 2,525 km across the states of Uttarakhand, Uttar Pradesh, Bihar, Jharkhand and West Bengal before falling into the Bay of Bengal. Its principal tributaries are Yamuna, Chambal, Banas, Kali Sindh, Parbati, Sind, Betwa, Dhasan, Keri, Gomti, Sarda, Ghaghara, Gandak, Son, Damodar, and Hooghly, Ramganga, and Mahananda.
River Basins of West Flowing Rivers of Kutch and Saurashtra including Luni
This basin with an area of 321851 sq. km, has many independent rivers – Luni, Shetrunji, Bhadar, Machhu, Rupen, Saraswati and Banas of which Luni constitutes the major river system of the basin. Luni originates from western slopes of the Aravalli ranges, in the Ajmer district of Rajasthan and travels 511 km before falling into the Arabian Sea. Luni’s principal tributaries are Lilri, Guhiya, Bandi, Sukri, Jawai, Khari Bandi, Sukri Bandi, Sagi and Jojri.
Indus Basin Up to the Indo-Pak border
This basin has an area of 321289 sq. km. Indus originates around Mansarovar Lake in the Himalaya and travels a total length of 2880 km before entering into the Arabian Sea. In India it flows through the state of Jammu and Kashmir and covers a length of 1114 km. Its principal tributaries are Shyok, Jhelum, Chenab, Ravi, Beas, Satluj and Ghagghar.
Godavari a 1465 km long river that originates from Trimbakeshwar in the Nashik district of Maharashtra. It receives all its water through a basin of area about 312812 sq. km. Godavari flows through Maharashtra, Telangana and Andhra Pradesh and finally falls into Bay of Bengal. Principal tributaries are Pravara, Manjra, Purna, Penganga, Wardha, Wainganga, Indravati and Kolab.
It has an area of about 258948 sq. km. Main River Krishna originates from Jor village of Satara district of Maharashtra. It has length of 1400 km and flows through states of Maharashtra, Karnataka, Telangana and Andhra Pradesh and falls into Bay of Bengal. Its principal tributaries are Ghatprabha, Malprabha, Tungabhadra, Bhima, Musi and Munneru.
This basin has area of about 194413 sq. km. Brahmaputra has total length of about 2900 km out of which it travels only 916 km in India through the states of Assam and Arunachal Pradesh. It originates from north of Kailash ranges just south of the lake called Konggyu Tsho and has many principal tributarie Lohit, Dibang, Subansiri, Jiabharali, Dhansiri, Manas, Torsa, Sankosh, Teesta, Burhidihing, Desang, Dikhow, Dhansiri, and Kopili.
The total area of the basin is 141589 sq. km which spreads over five States Chhattisgarh, Odisha, Madhya Pradesh, Jharkhand and Maharashtra of which most of the area lies in Chhattisgarh and Odisha. Manandi originates near Farsiya village of Dhamtari district of Chhattisgarhand traverse 851 km in the states of Chhattisgarh and Odisha and falls in Bay of Bengal. Its principal tributaries are Seonath, Hasdeo, Mand, Ib, Ong, Tel and Jonk.
River Basins of East Flowing Rivers between Pennar and Kanyakumari
This has two river systems: River system between Pennar and Cauvery and between Cauvery and Kanyakumari rivers having total area of about 100139 sq. km and constitutes many independent rivers such as Kandleru, Swarnamukhi, Arani, Korttalaiyar, Cooum, Adyar, Palar, Gingee, Ponnaiyar, Vellar, Varshalei, Vaigai, Gundar, Vaippar and Tambraparni. All rivers fall into Bay of Bengal.
This basin covers area of about 98796 sq. km in states of Madhya Pradesh, Gujarat, Maharashtra and Chhattisgarh. Narmada River (length1312 km) originates from Maikala range near Amarkantak in Anuppur district of Madhya Pradesh and flows through states of Madhya Pradesh, Maharashtra and Gujarat. Its principal tributaries are Burhner, Banjar, Sher, Shakkar, Dudhi, Tawa, Ganjal, Kundi, Goi, Karjan, Tendoni, Barna, Kolar, Man, Uri, Hatni and Orsang.
River Basins of East Flowing Rivers between Mahanadi and Pennar
This has three river systems: the river systems between Mahanadi and Godavari; river systems between Krishna and Pennar; and, a small area between Godavari and Krishna drained mainly by the small stream of Palleru. Total area of basin is 86643 sq. km and has many independent rivers such as Rushikulya, Bahuda, Vamsadhara, Nagavali, Sarada, Varaha, Tandava, Eluru, Gundlakamma, Musi, Paleru and Manneru. All rivers fall into Bay of Bengal.
Many other smaller but significant river basins, with large number of people depending on it for their livelihood, have not been mentioned here. The remaining CWC classified basins are Cauvery, Tapi, West Flowing Rivers from Tadri to Kanyakumari, West Flowing Rivers from Tapi to Tadri, Pennar, Brahmani-Baitarni, Barak and other minor rivers basins.