Chapter: 3

What are Drainage ?

  • Drainage describes the river system of an area.
  • The area drained by a single river is called river basin.
  • The Indian drainage is divided in two parts

Indian Drainage

The Himalayan Rivers

  • Most of the Himalayan rivers are perennial (flow all year).
  • These river receive water from rain as well as from melted snow from the lofty mountains.
  • The major Himlayan rivers are: The Indus, The Ganga and The Brahmaputra.

The Peninsular Rivers

  • A large number of peninsular rivers are seasonal as there flow  depends on rainfall.
  • The major Peninsular rivers are: The Mahanadi, The Krishna and The Kaveri flow eastwards and The Narmada and The Tapi flow westwards.

The Himalayan Rivers

  • The Ganga River System The headwaters of the Ganga, called the ‘Bhagirathi’ is fed by the Gangotri Glacier and joined by the Alaknanda at Devaprayag in Uttarakhand. At Haridwar, the Ganga emerges from the mountains on to the plains.
  • The Brahmaputra River System rises in Tibet east of Mansarowar lake very close to the sources of the Indus and the Satluj. It is slightly longer than the Indus, and most of its course lie outside India.

The Peninsular Rivers

  • The Narmada Basin – The Narmada rises in the Amarkantak hills in Madhya Pradesh. It flows towards the west in a rift valley formed due to faulting. On its way to the sea, the Narmada creates many picturesque locations.
  • The Tapi Basin – The Tapi rises in the Satpura ranges, in the Betul district of Madhya Pradesh. It also flows in a rift valley parallel to the Narmada but it is much  shorter in length. Its basin covers parts of Madhya Pradesh, Gujarat and Maharashtra.
  • The Godavari Basin – The Godavari is the largest Peninsular river. It rises from the slopes of the Western Ghats in the Nasik district of Maharashtra. Its length is about 1500 km. It drains into the Bay of Bengal. Its drainage basin is also the largest among the peninsular rivers.

Lakes: India has many lakes which differ from each other in the size and other characteristics. Most of the lakes are permanent while some contain water only during the rainy season.

Artificial lake is formed by damming of rivers for the generation of hydro power.

Importance of lakes: Helps to regulate flow of the river, used for developing hydro power, maintaining ecosystem and moderate the climate of surroundings.

Example: The Wular lake in Jammu & Kashmir and Guru Gobind Sagar (Artificial Lake) in Himachal Pradesh.

Roles Of Rivers In The Economy

  • Water from rivers is a basic natural resource, essential for various human activities. Therefore, riverbanks have attracted settlers from ancient times. These settlements have now become big cities.
  • River water is used for irrigation, navigation, hydro-power generation.

River Pollution

  • The demand for water from river is increasing to meet growing domestic, municipal, industrial and agricultural need which naturally affects the quality of water.
  • More and more water is being drained out of the rives reducing their volume.
  • Heavy load of untreated sewage and industrial effluents are emptied into the rivers which affects not only the quality of water but also the self-cleansing capacity of water.