Lecture 9 Flashcards
What controls the diversity of channel shape
Bed load, slope, stream power, bank strength
How does clay and silt change river shape
More suspension, therefore fewer bar form, more cohesive structures less bank erosion
If everything is moving as suspended load what channel will form
Straight, low sinuosity
What will increasing discharge lead to
Increasing stream power
Why can’t we think of stream power seperatly
Works in relation with other factors
What factor is said to be largely erroneous
Discharge regularity
How does slope effect river shape
Links with shear stress, can create more erosion
What is required for gravel bar formation
Higher shear stress, more strean power
What can be said about braided river channels
They are in continuum
What might one river system have
Multiple channel systems
How can river channels change temporally
They can evolve and move across time going through different channel phases
What is a river called where there is more than 1 channel belt
Anabranching rivers
What is a anastamosed channel
Multiple belts but fixed, not wandering
What defines a wandering river system
Weaker banks, still anabrancjmhing but avulsion and channel movement takes place
Where will we get highly braided channels
High stream power and smallish grains
Which channel features can be found across all types of channel
Ripples, dunes, antidunes ect
What determines bar form size
Length proportional to local channel width and height proportion to channel depth
What is the difference in bars between braided and meander
Meander are attached to the bank, point bar
What is river sinuosity
Valley distance and river distance, channel length divided by valley length
Above what value gives us a braided river
1.5
Where does the unit bar come from
An amalgamation of dune forms
Which part of the uni bar is highest
The end, build up of sediment
Where does erosion occur in a bar system
On the banks if banks are erodable
Where is deposition in meander unibars
Over lower slower flow inside of the bend
