Lecture #2 Flashcards
What does alluvial do to its own channel?
Makes its own channel by flowing over its own deposits
What kind of river is the Mississippi?
Towards the lower end of the river, its flowing over exposed bedrock
What happens when boulders are all in the same general area within the river?
This imposes some structure on the sediments itself
-creates: Step Pool Channels
What is a Plane Bed?
No obvious depositional features, its the same thing all the way down the river
What is a Wide Braided Channel?
They form islands int he middle of the channel, vegetation can form on these islands
What are the 2 main developments that can occur?
Vertical- plane bed and step pool
Lateral- Pool riffle or meandering
What can affect vertical and lateral developments, and intern change the river channel?
- Watershed
- Climatic characteristic
What are signs of a well developed alluvial channel?
- Well developed flood plane
- Sediment banks
What is an Anastomosed Channel?
Separate threads of the river that aren’t connected to the active part of the river , they are just to the side
What is a Wandering Channel?
Isolated chunk of island or flood plane between the 2 channels
Whats the downfall of a braided channel?
- Very unstable
- Change from day to day
- vegetation doesn’t grow on the islands due to too much erosion
What does Processes –>
The river has the characteristics it does because of certain processes create it
- if we know one (process or morphology) we can predict the other
How are dunes formed within rivers?
Dunes are formed in high flow area
How are ripple formed within rivers?
Formed when there is low flow in the river
What are Tongee banks??
They are underwater made from sand and can be sen from an aerial view
-they are migrating/ being pushed down the river
What can happen to Astomose’s individual branches?
They can either braid or meander
What happens when river channels don’t fit textbook classifications?
Usually the case is that they were engineered, aka man made
What controls what river types we are going to see?
- Landscape
- Quantity of water
What are the 3 zones of river channels?
- Mountain portion
- channel itself
- Watershed
What happens to discharge as you go down the system?
It increases
Why is discharge important in the making of the actual channel?
Discharge supplies the energy to do the work in making the actual channel
What happens to the size of material as you go down the system?
size of material decreases
Why at a particular location does the river have that characteristic?
it has the characteristic it does because of the valley and the supply of water and sediment that came from the upstream watershed and the characteristics of the watershed
Can lower parts of the river change the upper parts?
no, indépendant variables cant be changed so they are the ones that change the lower parts of the river
