RIVERS DEFINITIONS

Drainage basin

The whole area of land drained by a river and its tributaries

Source

The place where a river begins to flow.

Mouth

The point at which a river flows into the sea.

Floodplain

An area of flat land close to a river, which is covered with water when the river floods.

Sediment

Material that is carried or deposited by a river (e.g. boulders, pebbles, sand, mud)

Traction

Larger stones and rocks are rolled along the river bed.

Solution

Dissolved load is carried along as a solution. You cannot see it.

Erosion

The process that wears away the river bed and banks, or also particles which are being carried downstream in a river.

Saltation

Sand grains and small stones bounce along the river bed.

Suspension

Small particles of rock and soil are carried along in the water. They make it look muddy.

Abrasion

Sand and stones in the river scrape the bed and banks and wear them away.

Attrition

Rocks and stones knock together and wear each other away.

Solution

Water also dissolves soluble minerals from the bed and banks. This helps to break them up.

Hydraulic action

In a fast-flowing river, water is forced into cracks in the bank. Over time, it breaks up the bank.

Deposition

When material that has been carried by a river is dropped.

Transportation

The different processes by which the river carries sediment downstream.

Surface runoff

If the ground is hard, or very wet (saturated), the rainwater just runs along it.

Through flow

When water below ground flows sideways through the soil

Evaporation

The sun warms oceans, lakes and seas, turning water into a water vapour, a gas.

Condensation

The water vapour cools in the sky and turns back into water liquid.

Transpiration

When vegetation lose water

Precipitation

Any form of moisture falling from the sky e.g. rain, hail, sleet or snow

Watershed

An imaginary line through areas of high land. It separates the areas of land that are drained by two neighbouring river systems

Tributary

A smaller river that feeds into a larger river

Confluence

The place where a tributary joins the main river.

Gravitational potential energy

The energy that an object has due to its height above sea level.

Lateral erosion

Erosion which is taking place sideways

Vertical erosion

Erosion which is taking place downwards

Meander

A bend in a river