Rivers Key Terms Flashcards
Long profile
The rivers course from source to mouth.
Cross profile
The river from bank to bank at any given point
Upper course
Part of the river nearest the source characterised by V shaped, steep valleys
Middle course
Central part of a river where the valley widens and slope are gentler
Lower course
Last stage of a river before it reaches the sea, wide very flat valley floor.
Vertical erosion
Erosion that works downwards into the land creating a V-Shaped valley
Lateral erosion
Erosion that works sideways to widen the river channel.
Hydraulic action
The force of water hitting the bed and banks breaking it up.
Abrasion
The load carried by the river repeatedly hits the bed and banks dislodging particles into the flow of the river
Attrition
Stones carried by a river knock and bang into each other gradually making the stones smaller and more rounded
Solution (erosion)
When the rock is slowly dissolved in mildly acidic river water
Traction
When large particles are rolled along the river bed.
Saltation
When particles carried by the river are bounced along as they are too heavy to be carried in suspension.
Suspension
small sediments that are held within the river’s water
Solution (transportation)
the river carries the dissolved load.
Deposition
sediment is dropped by the river when the energy is reduced towards the mouth.
Waterfall
a step in the long profile of river over which water falls, usually when the river passes over a band of resistant rock.
Gorge
a vertically sided gash in the land formed when a wtaerfall retreats upstream
Interlocking spur
created as a river winds its way through the upper course.
Meander
a wide bend or curve in the river found mainly in the middle and lower sections of a river.
River cliff
cliff like feature created on the outside of a meander where flow is quickest and erosion at its greatest.
Slip off slope
a river beach created on the inside of a meander where flow is slower and deposition takes place
Ox-bow lake
curved lake created when the neck of a meander is cut off through constant erosion.
Flood plain
the wide flat area of land side of a river in the middle and lower course of a river
Levee (natural)
raised banks alongside the river created over years of flooding and deposition of sediment
Estuary
An estuary is the transitional zone between the river and coastal areas, they are affected by wave action and river processes
Hydrograph
A graph which plots river discahrge after a storm and includes the volume of rain that falls.
Rising limb
The part of the hydrograph which shows the increase in discharge
Falling limb
The part of the graph which shows the discharge of a river returning to normal
Peak discharge
When the amount of water in the river is at its highest
Lag time
The number of hours between the peak rainfall and the peak discharge
Infiltration
Water passes through the surface into the soil and underlying rock.
Surface runoff
Water flows over the surface into the river.
Interception
Waters route to the ground is slowed by trees and vegetation
Impermeable rock
Rock which does not allow water to pass through it.
Permeable rock
Rock which is porous and allows water to pass through it.
Relief of the land
The shape of the land, whether its is flat or hilly.
Hard engineering
Involves the use of man made structures to prevent or control natural processes taking place. E.g. dams and reservoirs
Soft engineering
Involves working with the natural river processes to manage flood risk e.g floodplain zoning
Dam/reservoir
When a rivers flow is blocked by a man made barrier, the flooded land behind the dam becomes a reservoir
Channel straightening
When the natural course of the river is straightened to increase the flow rate.
Embankments
Artificial banks built up on either side of the river to icrease the capacity of the river
Flood relief channel
Channels are built to take water away from the main river during times of flood to relieve the pressure on the main channel
Flood plain zoning
Restrictions placed on the developments allowed on the floodplain to reduce the damage caused when rivers flood
River restoration
Returning rivers that have been artificially altered to their natural course
