Water Movement in Soil (Guest Lecture)

Question 1

How does water move in soil?

Movement into, across, and throught the soil

Answer 1

Infiltration: Movement (entry) into the soil

Runoff: Movement across the soil

Percolation/subsurface water flow: Movement through the soil profile

Question 2

Where does water flow based on potential energy?

Answer 2

Water flows from higher (like from positive or less negative, wetter) to lower potential energy (more negative, drier)

Question 3

Infiltration

Answer 3

A process by which water enters the soil pore spaces and becomes soil water

Rate decreases over time as macropores fill with water

The larger the macropores, the faster a soil drains.
Infiltration is proportional to the (radius of pores)^4

Question 4

Saturated hydraulic conductivity

Answer 4

When infiltration rate becomes constant due to saturation

Question 5

Runoff

Answer 5

Water that runs off of soil surface (instead of infiltration)

As soil becomes more saturated, more runoff happens

Question 6

Surface crusting

Answer 6

Surface layer denser than soil below

Question 7

Reduction in porosity

Answer 7

Lower percentage of pores and smaller proportion of large pores

Question 8

Water flow through saturated soil is dependant on what two components?

Answer 8

The driving force: the gradient in water potential
The ease of flow: the hydraulic conductivity