The Drainage System of India


  • The drainage system is an integrated system of tributaries and a trunk stream which collects and funnels surface water to the sea, lake or some other body of water.
  • The total area that contributes water to a single drainage system is known as a ‘drainage basin’. This is basic spatial geomorphic unit of a river system, distinguished from a neighbouring basin by ridges and highlands that form divides.
  • Thus, river basin is natural units of land. They are regarded as the fundamental geomorphic as well as hydrological units for a systematic study of the river basins.

Himalayan River System

  • The Himalayan drainage system comprises all the international river of India, i.e., the Indus, the Ganga, and the Brahmaputra. Most of these rivers and the major tributaries are perennial in character, obtaining their water from the glaciers and rains.
  • These rivers are in their youthful stage carving out a number of erosional landforms like waterfalls, cataracts, rapids, gorges, steep slopes, and river terraces.
  • The Himalayan Rivers are not only eroding agents, but are also depositing agents in the plains and the deltas.
  • They are antecedent, and drain not only the southern slopes of the Himalayas but to a large extent, the northern Tibetan slopes as well. Several rivers of the Himalayan Rivers are older than to the Himalayas. Such rivers are known as Antecedent Rivers.

The rivers originating from the Himalayan and Trans-Himalayan regions consist of three river systems, namely:

  1. The Indus System
  2. The Ganga System
  3. The Brahmaputra System

The Indus System

  • It is one of the largest river basins of the world.
  • It is also known as the Sindhu and is the westernmost of the Himalayan Rivers in India.
  • It originates from a glacier near Bokhar Chu in the Tibetan region in the Kailash Mountain range.
  • In Tibet, it is known as ‘Singi Khamban’; or Lion’s mouth.
  • It has a large number of tributaries in both India and Pakistan and has a total length of about 2897 km from the source to the point near Karachi where it falls into the Arabian Sea out of which approx 700km lies in India.
  • The major tributaries of the Indus River in India are Jhelum, Ravi, Chenab, Beas, and Sutlej.

The Ganga System

  • With a length of 2510km and a basin area of 80833.44, the Ganga basin is the most important and the largest basin in India. It is an international river as it passes through Bangladesh before merging into the Bay of Bengal.
  • The Ganga originates as Bhagirathi from Gaumukh (Gangotri Glacier) in Uttar Kashi district of Uttarakhand at an elevation of about 7010 m.
  • Alaknanda, originating from the Satopanth Glacier, Joins the Bhagirathi at Devprayag. Before making a confluence at Devprayag Alaknanda and its tributaries make five confluences known as Panch Prayag.

Five Confluences in the upper reaches of Ganga

Alaknanda(Satopanth Glacier)Vishnu Prayag
Dhauli Ganga(Mana Glacier)Vishnu Prayag
Alaknanda and Nandakni (Trishul Glacier)Nand Prayag
Alaknanda and Pindari (Pindari Glacier)Karan Prayag
Alaknanda and Mandakini or Kali Ganga (Chorabari Glacier)Rudra Prayag
Alaknanda and Bhagirathi (Gaumukh)Dev Prayag
  • After the confluence of the Bhagirathi and Alaknanda, the river is known as Ganga. Ganga flows through the states of Uttarakhand, Uttar Pradesh, Bihar and West Bengal.
  • Son is the major right bank tributary and the important left bank tributaries are Ramganga, Gomati, Ghaghara, Gandak, Kosi and Mahananda.
  • Yamuna is the western most and the longest tributary of the Ganga and has its source in the Yamunotri glacier.
  • Ganga flows into the Bay of Bengal near the Sagar Island.

The Brahmaputra System

  • Originating from the Angsi glaciers lying to the south-east of Kailash Mountain and ManSarovar Lake, at an elevation of 5150 m, The Brahmaputra is known as the Tsangpo in Tibet.
  • It pierces the Greater Himalayas (7755m) near Namcha Barwa. It passes the Dihang –Gorge in Arunachal Pradesh. At Sadiya, the river comes down to 135m above sea level.
  • In India, the river is known as Brahmaputra.
  • The river flows to the west in Assam upto Dhubri (28m), and further below, it takes a sharp southward bend to enter into Bangladesh.
  • The catchment areas of the Brahmaputra receive heavy rainfall.
  • Consequesntly, it has numerous tributaries on both of its banks in 750km long Assam Valley.
  • Most of the tributaries are large and pour large quantity of water and sediments into the Brahmaputra River. During the rainy season, the river oscillates from one bank to other for a width of 10km, and being turbulent with heavy loads of silt, the channel is heavily braided.
  • There is a constant silt movement resulting in the instability of the river regime, channel shifting and formation of sandy shoals.
  • Majuli, the largest river island in Asia, lies in this river which is bounded by lakhimpur district in the north and the jorhat district in the south.

In Bangladesh, it merges with the river Padma, which falls in the Bay of Bengal

Peninsular River System

  • The Peninsular drainage system is older than the Himalayan one. This is evident from the broad, largely-graded shallow valleys, and the maturity of the rivers.
  •  The Western Ghats running close to the western coast act as the water divide between the major Peninsular Rivers, discharging their water in the Bay of Bengal and as small rivulets joining the Arabian Sea.
  • Most of the major Peninsular Rivers except Narmada and Tapi flow from west to east. The Chambal, the Sind, the Betwa, the Ken, the Son, originating in the northern part of the Peninsula belong to the Ganga river system.
  • The other major river systems of the peninsular drainage are – the Mahanadi the Godavari, the Krishna and the Kaveri.
  • Peninsular rivers are characterised by fixed course, absence of meanders and non-perennial flow of water.
  • The Narmada and the Tapi which flow through the rift valley are, however, exceptions.
  • The major river systems of the peninsular drainage are – the Mahanadi, the
  • Godavari, the Krishna and the Kaveri, the Narmada, the Tapi and the Luni.
RiverSourceLength in Km
GodavariTrimbak plateau Near Nasik(Maharashtra)1465
KrishnaNear Mahabaleshwar (Maharashtra)1400
NarmadaAmarkantak (Madhya Pradesh)1310
MahanadiDandakaranya Plateau near Raipur857
KaveriTaal Kaveri (Karnataka)800
TapiMultai in Betul district(Madhya Pradesh)730

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