River Key Terms

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Drainage Basin

An area of land drained by a river and its tributaries.

Source

The start of a river.

Mouth

Where a river meets the sea.

Tributary

A stream or small river that joins a larger river.WatershedThe boundary

of a river basin. Usually highland.

Confluen

The point where two rivers meet.

Surface Runoff

Rainwater that runs along the ground

Infiltration

Water that soaks into the ground

Throughflow

Water than runs down the slope to the river (after it has infiltrated)

Groundwater

Water that is stored in the cracks and pores in the rock.

Width

How far it is from one bank of the river to the other.

Depth

The distance between the top and bottom of the water in the river.

Velocity

The speed that the water in the river is moving at.

Discharge

The amount of water passing a specific point at a given time. The volume (amount of water in the river) x the velocity of the river.

Gradient

The slope that the river is moving down.

Mechanical weathering

When water gets into cracks in rocks, freezes when the temperature drops below 0ᵒC, and expands. This results in the cracks getting bigger. Eventually the rock breaks.

Chemical weathering

Rain water contains weak acid. This acid reacts with certain rock types, such as Limestone. The rock is slowly dissolved and disintegrates.

Biological weathering

Seeds fall into cracks of rocks. Roots grow when moisture is present. The roots widen the cracks and weaken the rock. Burrowing animals weaken the rocks further, and they break up.

Hydraulic action

This is an erosion process. It is the sheer force of the water against the beds and banks of the river. It involves water being forced into the cracks in the river bank.

Attrition

This is an erosion process. The rocks and pebbles that the river is carrying bump into each other, becoming smaller and smoother.

Abrasion

This is an erosion process. The material that the river is carrying rubs against the beds and the banks of the river like sandpaper, wearing them away.

Solution/

corrosion

This is an erosion process. The acids in the water dissolve material from the beds and the banks.

Traction

This is a transportation process. Large boulders are rolled along the river bed.

Saltation

This is a transportation process. Smaller pebbles and stones are bounced along the river bed.

Suspension

This is a transportation process. Fine sand and silt particles are carried along in the flow giving the river its brown appearance.

Solution

This is a transportation process. Some minerals such as chalk are dissolved in the water and carried along in the flow, although they cannot be seen.

Deposition

When a river drops the material it is carrying. It does this when it has less energy.