33 terms

AQA Geography- River Terms

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dynamic system
A system that is characterised by constant change - A River.
Fluvial Processes
Processes related to a river.
Erosion
Wearing away of the land by moving forces.
Hydraulic action
Where the sheer force of the water erodes the stones, bed and banks of the river.
Abrasion
Where stones in transport bash against the beds and the banks of the river, eroding them.
Corrosion
Where weak acids in the water react with the rocks, bed and banks of the river.
Attrition
Where stones in transport are thrown into one another.
Transport
The movement or material, in this case by the river water.
Solution
Where material is dissolved within the water.
Suspension
Where small particles are held up or suspended in the water.
Saltation
The bouncing motion of larger particles along the river bed.
Traction
The rolling motion of sediment along the bed, normally much larger sediment.
When will larger sediment be moved?
During periods of high river flow.
Deposition
The laying down of sediment in the river channel or on floodplains.
How does deposition occur?
Occurs when river velocities slow within the channel. It slows due to the river widening and becoming shallower, increasing the friction between the water and the river bed. When rivers enter the sea they tend to spread out and counter currents from the tidal motion of the sea slows river water and encourage sediment to be dropped.
Source
Where a river begins.
Drainage Basin
The area of land drained by a river system.
Mouth
Where the river meets the sea.
Cross Profile
The side to side cross section of the river channel and/or valley.
Lateral erosion
Sideways erosion by a river on the outside of the meander channel. It eventually leads to the widening of the valley and contributes to the formation of the flood plain.
Long profile
The gradient of a river, from its source to its mouth.
Vertical erosion
Downward erosion of a river bed.
Precipitation
Water in any forms that comes from clouds (rain, sleet, snow...).
Interception
This is where plants, trees, or buildings that collect the precipitation.
Transpiration
The loss of water from a plant.
Through fall
Where the precipitation is not intercepted but falls straight to the ground.
Infiltration
Where the water filters through the ground and tiny pores in the soil.
Percolation
Where the water moves downwards through the soil.
over land flow
This happens when either the soil is impermeable or saturated and the water flows over the top of it.
ground water flow
This is the movement of water sideways through the soil.
Underground flow
Slow movement of water through the ground.
Evaporation
Where the water evaporated straight from the ground or from the sea.
evapo-transpiration
The water vapour consists of both evaporated and transpired water.