Rivers Flashcards
What is traction?
Traction – large pebbles and boulders are rolled along the seafloor.
What is saltation?
Saltation – beach material is bounced along the seafloor.
What is suspension?
Suspension – beach material is suspended and carried by the waves.
What is solution?
Solution – material is dissolved and carried by the water.
What is the long profile of the river?
A Long profile shows the gradient of the river from its source to mouth.
Where is the steepest gradient in the long profile of a river?
The steepest gradient in the long profile of a river is found in the upper course near to the source.
Why in the upper course is the cross profile of a river valley narrow and steep sided?
It becomes narrow and steep sided in the upper course due to vertical erosion.
Why does the river channel become wider and deeper with distance downstream?
The river channel becomes deeper due to the increase in discharge and wider due to lateral erosion.
In the middle course of the river valley floor becomes wider why is this?
The increase in lateral erosion.
Why do discharge and velocity increase downstream?
Discharge increases downstream because of additional water from tributaries. Velocity increases due to the additional water from tributaries and less water is in contact with the bed and banks so there is less friction.
What is vertical erosion?
Vertical erosion involves the deepening of the river bed. This is mostly by hydraulic action. It is most common in the upper course of the river.
What is lateral erosion?
Lateral erosion erodes the banks of the river. This is more common in the middle and lower courses of a river.
Identify the four Processes of erosion that occur within a river.
Abrasion or corrasion, attrition, hydraulic action and solution or corrosion
What is hydraulic action?
Hydraulic action is when the force of fast-flowing water hits the bed and banks and forces water and air into cracks in the bedrock. The repeated changes in air pressure cause the river bed to weaken.
What is abrasion?
Abrasion, also known as corrasion, is when boulders and stones wear away the river banks and bed. Angular rocks that have entered the channel recently are useful tools of abrasion because they are more angular. Abrasion is responsible for both lateral and vertical erosion of the river channel
What is attrition?
Attrition is when sediment particles knock against the bed or each other and break, becoming more rounded and smaller as you move down the river.
What is the solution?
Solution (or corrosion) is when acidic water dissolves rocks such as chalk or limestone.
What happens to the shape and size of bed load as you move down the river?
It becomes more rounded and smaller.
What is the main process of erosion in the upper course of a river?
Hydraulic action.
Identify the four main processes of transportation in a river?
Solution, suspension, saltation and traction.
What is traction?
Large boulders and rocks are rolled along the river bed.
What is saltation?
Small pebbles and stones are bounced along the river bed.
