SPECIFICATION TARGET: know the meaning of the following drainage basin terms: watershed, confluence, tributary, source and mouth.

The drainage basin

• All rivers receive a water supply and the area of land this comes from is known as a drainage basin.

• The boundaries of the basin are known as the watershed and will usually be marked by areas of high land.

River drainage basins• Rivers begin in upland areas and flow downhill, becoming

deeper and wider until they reach the sea. • A drainage basin is part of the water cycle where water is

transferred in a continuous cycle between the sea, atmosphere and the land.

• As the river flows downstream its characteristics change through the three main sections of

The Upper CourseThe Middle CourseThe Lower Course

Drainage basin diagram:

• River basins are an open system with inputs and outputs of water

Any rain falling here will flow within this basin

Main channel

Amazon drainage basin