River Processes Flashcards
Define a Drainage Basin
The area of land around the river that is drained by the river and its tributaries
Define a tributary
A small river or stream that joins a larger river
Define a mouth
Where a river meets the sea
Define a source
Where a river begins
Define confluence
The point at which two rivers meet
Define a channel
Where the river flows
Define a watershed
The area of high land forming the edge of a river basin
What is a long profile of a river?
A long profile shows how the river changes over its course to its mouth
What is an upper course of a river?
Where the river starts and is usually an upland area. The river’s load is large in the upper course, as it hasn’t been broken down by erosion yet.
What is the lower course of a river?
The final course of the river is where the land is a lot flatter. The river’s load is fine sediment, as erosion has broken down the rocks.
What is a cross profile?
A view of the valley from one side to another.
What happens when the river flows downhill?
There is an increase in vertical erosion, the channel is shallow and narrow because there is not a lot of water in the channel.
What happens when the river flows into the middle course?
There is some vertical erosion but more lateral erosion, the channel is wider and deeper as a result.
What happens in the lower course of a river?
There is a lot less erosion and greater influence of deposition, with only some lateral erosion. The channel is at its widest and deepest.
What are the four types of erosion?
Hydraulic action, abrasion, attrition and solution
Define hydraulic action
This is the sheer power of the water as it smashes against the river banks. Air becomes trapped in the cracks in the rock of the river bank and bed, and causes the rock to break apart.
Define abrasion
When pebbles are picked up by the flowing water and smash against the river bank and bed, wearing it away.
Define attrition
When rocks that the river is carrying knock against each other. They break apart to become smaller and more rounded.
Define solution
When the water dissolves certain types of rock, eg limestone.
What are the four types of transportation?
Traction, saltation, suspension and solution.
Define traction
Large, heavy pebbles are rolled along the river bed.
Define saltation
Pebbles are bounced along the river bed, most commonly near the source.
Define suspension
Lighter sediment is suspended within the water, most commonly near the mouth of the river.
Define solution
The transport of dissolved chemicals. This varies along the river depending on the presence of soluble rocks.
