S-Cool Revision Summary

S-Cool Revision Summary

Attrition Boulders collide with one another as they move down the river, and can break into smaller pieces. Over time rocks become more rounded in appearance.


Water moving slowly through the ground.

Base level

The lowest point to which erosion by running water can occur.

Bedload Can be either exogenetic or endogenetic, and moves by sliding, saltating, or rolling.
Climatic change Glaciations and changes in rainfall.
Corrasion When a river picks up material and then rubs it against its bed and banks. Erosion occurs by the process of abrasion. Most effective during times of flood. Main method of both vertical and horizontal erosion.


River sediment deposited as a river enters lake, lagoon or ocean.


Volume of water flowing in a river at a particular point, during a particular period of time.

Dissolved load Held in solution and can come from erosion, pollution, mineral springs and chemical weathering.

Drainage basin

Area of land that is drained by a river.

Drainage density

Found by dividing total length of all streams in a basin (L) by its area (A).


Drowned lower part of a river, as it enters the sea.


Water lost from vegetation via both evaporation and transpiration.


Water held in the ground.

Hydraulic action Force of water that hits river banks, and then pushes water into cracks. Air becomes compressed, pressure increased and the riverbank may, in time collapse.


This is when plants prevent some rainfall from directly reaching the ground, for example, water on leaves.


Where water slowly soaks into the soil from the ground.

Lag time

Length of time between peak rainfall and peak discharge.

Overland flow

Water flowing overland, often as a result of land being saturated.


Water in the soil does not remain there but moves down slowly into the lower layers of soil and rock.

Potential evapotranspiration

The amount of water that could be lost by evapotranspiration.


Changes in the flow of a river throughout that occur with different seasons.

Saltation Pebbles, sand and gravel are lifted up by the current and bounced along the bed.
Solution/corrosion A continual process, which is as a result of the chemical composition of the water.
Storm hydrograph Graphs that show how a drainage basin responds to a period of rainfall.

Suspended sediment load

Carried with the body of the current.

Suspension Very small particles of clay and silt are carried in suspension.
Tectonic change Where land is uplifted after plate movement or volcanic activity.
Traction Larger boulders rolling or sliding along the riverbed. Only experienced in times of great flood.


Loss of water from plants.


Where water moves downwards through layers of soil.


Dividing line between drainage basins (usually higher ground).