Y10 Geography - River profiles + fluvial processes (27)

What is a river profile?

How a river’s characteristics and processes change from source to mouth.

What is a long profile?

A side view showing how a river’s height changes from source to mouth.

What is the typical shape of a river’s long profile?

Steep near the source, becoming progressively gentler downstream in a concave curve.

What is a cross profile?

The shape of a river valley and channel when viewed across the river.

Describe the upper

course valley and channel.

Describe the middle

course valley and channel.

Describe the lower

course valley and channel.

How do erosion processes change downstream?

Vertical erosion dominates upstream it decreases downstream while lateral erosion becomes more important.

What are the three main fluvial processes?

Erosion, transportation and deposition.

What is hydraulic action?

The force of water hits the bed and banks, water and compressed air in cracks can break rock apart.

What is abrasion (corrasion)?

Sediment carried by the river scrapes and grinds against the bed and banks.

What is attrition?

Rocks carried by the river collide with each other, becoming smaller, smoother and rounder.

What is solution (corrosion) as an erosion process?

Soluble rock is dissolved by the river water.

What factors increase river erosion?

A steeper gradient, higher discharge, faster velocity and a larger/heavier load.

What is transportation?

The movement of a river’s load downstream.

What are the four processes of river transportation?

Traction, saltation, suspension and solution.

What is traction?

Large rocks and boulders are rolled or pushed along the river bed.

What is saltation?

Small pebbles bounce or hop along the river bed.

What is suspension?

Fine particles such as silt and clay are carried within the water.

What is solution as a transport process?

Dissolved minerals are carried within the water.

How does river load usually change downstream?

It generally becomes smaller, smoother and rounder due to attrition.

Why can rivers usually transport more material downstream?

Discharge generally increases downstream, allowing more load to be carried.

What is deposition?

The dropping of sediment when a river loses energy and can no longer carry as much load.

Why does a river lose energy?

Velocity or discharge may decrease, the gradient may become gentler, friction may increase, or the river may enter still water.

Which material is deposited first?

The largest and heaviest material, because it requires the most energy to transport