3.7. (9/9) CREEP - Hillslope transport Flashcards
How do we move clastic sediments out of a sediment factory and down a hillslope?
- creep
- landslide
- debris flow
what is the vadose zone?
undersaturated area
what is the phreatic zone?
fully saturated area, below-ground water table
What is infiltration?
goes into the soil
what is runoff?
water that flows across the surface
What is through flow?
water that moves through soil
How does water go back up?
evaporation and transpiration
What are the parts of the water budget?
infiltration, precipitation, evaporation, transpiration, runoff, through flow
If water gets into the vadose zone and freezes, how does it expand?
normal to slope
How does the frozen water particle move when it melts?
gravity pulls it down
How do particles move down a slope in the vadose zone?
expansion/contraction of water/clay
What is bioturbation?
living organisms affecting soil
- trees with roots (stir up) and squirrels by digging
Angle of repose
30-35 degrees
the shape left after all other sediments have moved
What does the ratio of gain to loss determine?
whether a cell inflates or goes down
What if a cell gains more than it looses?
slope goes up
What if a cell loses more than it gains?
slope goes down
What is rule number one in a model of a physical process?
Conservation of Mass:
ΔQ/ΔX = -ρs (ΔZ/Δτ)
change in sediment flux with respect to x is balanced by change in elevation of cell with respect to time
amount of sediment moving from cell to cell (X) must be balanced by the time rate of change of a cell’s elevation
q- sediment flux
ρs- density of sediment
What is rule number two in a model of a physical process?
Q = ρsK(Δz/ΔX)
- the amount of sediment moving is proportional to the slope’s shape (fast where steep, slow where gentle)
- movement against a gradient
K- diffusivity
What is the equilibrium condition?
diffusion on a hillslope, convex slope, satisfies both rules
what is diffusivity?
a characteristic of particles
higher when wet (sticky)
