The Drainage Basin - Key Terms

Tributary

A small steam that joins the main river

Permeable

Allowing liquid to mass through

Drainage Basin

An area of land drained by a river and its tributaries

Watershed

An invisible line that determines the edge of the drainage basin (high land)

Impermeable

Not allowing liquid to mass through

Source

Start of the river (highest point)

Drainage Density

Stream length / Drainage basin area

Drainage Pattern

The ways is which land is drained by a river. They are determined by shape, height and geology of the land

High Drainage Density

Water drains more quickly to a river. This is because the ground is impermeable, so water drains by surface run off, This leads to many tributaries and a danger of floods

Low Drainage Density

Water drains more slowly to a river. This is because the ground is permeable, so water drains by infiltration and so through flow, base flow and ground water flow. This leads to less tributaries and a smaller danger of floods

Confluence

Where 2 rivers meet

River Channel

Where the river flows

Mouth

Where the river meets the sea/lake