Gravitational Potential (yg)

• The gravitational potential is determined by height of water above reference point which results in downward movement of water in response to gravity.
• This is always positive because it increases the free energy of water. Water in macro pores moves under the force of gravity.
• Water in micropores is also influenced by gravitational potential but matric potential is dominant for this.
• In saturated conditions, gravitational potential is most important for water flow.

The gravitational potential of soil water may be expressed mathematically as,

yg = gh

Where, g = acceleration due to gravity, h = height of soil water above the reference elevation.