3.7. (9/9) CREEP - Hillslope transport

Question 1

How do we move clastic sediments out of a sediment factory and down a hillslope?

Answer 1

1. creep
2. landslide
3. debris flow

Question 2

what is the vadose zone?

Answer 2

undersaturated area

Question 3

what is the phreatic zone?

Answer 3

fully saturated area, below-ground water table

Question 4

What is infiltration?

Answer 4

goes into the soil

Question 5

what is runoff?

Answer 5

water that flows across the surface

Question 6

What is through flow?

Answer 6

water that moves through soil

Question 7

How does water go back up?

Answer 7

evaporation and transpiration

Question 8

What are the parts of the water budget?

Answer 8

infiltration, precipitation, evaporation, transpiration, runoff, through flow

Question 9

If water gets into the vadose zone and freezes, how does it expand?

Answer 9

normal to slope

Question 10

How does the frozen water particle move when it melts?

Answer 10

gravity pulls it down

Question 11

How do particles move down a slope in the vadose zone?

Answer 11

expansion/contraction of water/clay

Question 12

What is bioturbation?

Answer 12

living organisms affecting soil
- trees with roots (stir up) and squirrels by digging

Question 13

Angle of repose

Answer 13

30-35 degrees
the shape left after all other sediments have moved

Question 14

What does the ratio of gain to loss determine?

Answer 14

whether a cell inflates or goes down

Question 15

What if a cell gains more than it looses?

Answer 15

slope goes up

Question 16

What if a cell loses more than it gains?

Answer 16

slope goes down

Question 17

What is rule number one in a model of a physical process?

Answer 17

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

Question 18

What is rule number two in a model of a physical process?

Answer 18

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

Question 19

What is the equilibrium condition?

Answer 19

diffusion on a hillslope, convex slope, satisfies both rules

Question 20

what is diffusivity?

Answer 20

a characteristic of particles
higher when wet (sticky)