Catchment Area, Drainage basin, Watershed and River basin

A river drains the water collected from a specific area, which is called its ‘catchment area’.

An area drained by a river and its tributaries is called a drainage basin. The boundary line separating one drainage basin from the other is known as the watershed.

The catchments of large rivers are called river basins while those of small rivulets and rills are often referred to as watersheds.

There is, however, a slight difference between a river basin and a watershed. Watersheds are small in area while the basins cover larger areas. River basins and watersheds are marked by unity. What happens in one part of the basin or watershed directly affects the other parts and the unit as a whole. That is why, they are accepted as the most appropriate micro, meso or macro planning regions.