Topic 1: Water on the Land - Features of a river basin

A river basin or drainage basin is an area of land where surface water converges to a single point, usually the exit of the basin, where the waters join another water body such as the ocean, a lake or a reservoir. Sometimes, drainage basins drain into other drainage basins, with smaller basins combining into larger ones.

This diagram shows some of the key features of river basins -

Watershed: The watershed is the edge of the drainage basin, and usually the top of a hill, any water that falls inside the watershed will flow down into the basin and any that falls on the other side will enter a different drainage basin.

Source: The source of the river is the point furthest from the river's estuary or confluence with another river.

Tributary: A tributary is a stream or river that flows into another parent river, rather than directly into the sea.

Main river channel: This is the main part of the river, which flows to the sea, and to which other tributaries connect.

Confluence: A confluence is where two bodies of water meet one another, either in a tributary meeting a river, or two rivers joining to form another river of a new name.

River mouth: This is where the river enters the sea or a lake.