Indian Drainage System Classification

A drainage system is the pattern formed by the streams, rivers, and lakes in a particular drainage basin. A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point or where the waters join another water body, such as a river, lake, reservoir, estuary, wetland, sea, or ocean.

The basin can be closed basin or open Basin. In open basin, the water body is hydro-logically toward the sea. The rivers which drain to oceans and seas have open basins.

In closed drainage basins the water converges to a single point inside the basin, known as a sink, which may be a permanent lake, dry lake, or a point where surface water is lost underground.

The drainage basin includes both the streams and rivers that convey the water as well as the land surfaces from which water drains into those channels, and is separated from adjacent basins by a drainage divide. The other words used for basin are catchment, catchment area, catchment basin, drainage area, river basin, water basin and watershed.

The river basins are controlled by the topography of the land such as rock types, gradient, soil type etc. The stream in a basin can be runoff, through flow or underground flow. The topographic barriers make watersheds. A watershed would represent all the stream tributaries that flow to some distance along the main stream. Almost all of India’s rivers are of open basin as more than 90% of total surface water runoff would go to Bay of Bengal. Rest goes to Arabian Sea.  There is just a small area in parts of Ladakh, northern parts of the Aravalli range and the arid parts of the Thar Desert, that have inland drainage.