A river basin or drainage basin is an area of land drained by a river and its tributaries. The edge of the drainage basin is known as the watershed. This can be compared to a sink or basin, which catches the water falling into it. The water travels towards the centre and leaves the sink through a plug hole. In a similar way, the water flowing through the river will eventually leave the river basin through its mouth and enter the sea or a lake.
The interactive diagram shows a simple version of a drainage basin. Can you label it correctly?