A large natural watercourse flowing in a channel to the sea, a lake, or another river is called a river. The entire area where river and its tributaries flow is known as a drainage basin. Drainage is the natural or artificial removal of excess surface and sub-surface water from an area. The drainage basin is the area of land drained by a single river and its tributaries.
A drainage system is the pattern formed by the streams, rivers and lakes in a particular drainage basin. It is governed by the topography and the gradient of a land.
All drainage systems are made of an interconnected network of rivers and streams, which form drainage patterns.
Major drainage patterns are dendriatic, rectangular, radial and trellis patterns.
On the basis of origin, nature and characteristics, rivers of India are classified as:
The Himalayan Rivers and
The Peninsular Rivers
Himalayan rivers are perennial, as these carry water throughout the year. These rivers receive water from the molten snow and rainfall. These rivers form large basins. Himalayan rivers follow a long course from the source they originate to the sea.
The major Himalayan Rivers are the Indus, the Ganga and the Brahmaputra.
Peninsular rivers are seasonal in nature as their flow is dependent on rainfall. Most of the Peninsular Rivers originate in the Western Ghats and flow into the Bay of Bengal. Some originate in the highlands and flow westwards. Their course is shorter and shallower as compared to the Himalayan rivers. The Peninsular rivers can be classified as eastward flowing rivers, and westward flowing rivers.
The major Peninsular Rivers are the Narmada, Tapi, Godavari, Mahanadi, Krishna and Kaveri.
Rivers play an important role in the economy of India as they are used in almost all the sectors like agriculture, irrigation, transportation and recreation.
River, which is such an important resource, is getting polluted these days. The pollution is generally because of the growing demand in domestic sector, municipal sector, industrial sector, agricultural sector, etc.
Various measures need to be taken to conserve rivers of India.