Rivers Flashcards
Factors that effect the amount of discharge
Rainfall - type and amount Temperature - hot or cold Previous weather - wet or dry Relief - steep or gentle Rock type - permeable or impermeable Land use - rural or urban
Velocity
Speed of the river measured in meters per second (m/s). Increases from the source to the mouth because the discharge increases meaning there’s less friction from the bed and banks. Water is able to flow faster even though the gradient becomes gentler.
River erosion - hydraulic action
the sheer force of the flowing water on the bed and banks
River erosion - abrasion
Stones carried by the river wear away the channel (sandpaper effect)
River erosion - attrition
Stones collide, wearing them away, becoming smaller and rounder
River erosion - corrosion
Slightly acidic river water dissolves rocks made of calcium carbonate
Transportation - traction
Stones rolled long the river bed by the force of flowing water
Transportation - saltation
Stones bounce along the river bed
Transportation - suspension
Partials of slit and coat float in the water, making the river look cloudy
Transportation - solution
Minerals dissolve in the water
Upper course
Steep v-shaped valley and bedload is angular boulders and cobbles
Middle course
Erodes laterally and has gently sloping valleys. Bedload is round cobbles and pebbles
Lower course
Deposits to form a wide valley with a flat valley floor. Bedload is sand, slit and clay
Watershed
An area of higher land separating two drainage basins
Source
Where the river begins
Tributary
Smaller river joining a larger river
Confluence
The place where two rivers join
Mouth
The place where the river enters a lake or the sea
Flood plains
An area of flat land formed on wither side of a river.
Formed in the lower course of the river due to combination of erosion and depositation
Levees
Raised banks of deposited sediment formed either sided of a river channel.
Formed during many years of river flooding, when the largest material is deposited next to the river
Discharge
The amount of water in a river measured in cubic meters per second (m3/sec). It increases from the source to mouth. As this increases so does the width and depth.
Flood management - hard engineering
The use of structures and machinery to control natural processes (e.g dams and creating a reservoir)
Flood management - soft engineering
Working with the environment to modify and/or prepare for natural processes (e.g. floodplain zoning and flood warnings)
