The soil hydraulic head is expressed by

(A) Potential energy per unit mass of soil water

(B) Potential energy per unit volume of soil water

(C) Potential energy per unit weight of soil water

(D) Height of standing water on the soil surface

Choose the correct answer from the options given below.

Correct option is D

Explanation of the Correct Option (d): (C) only
· Hydraulic head is defined as:
· The potential energy of water per unit weight
· It is expressed in terms of length (meters).
· Hydraulic head consists of:
· Pressure head
· Elevation (gravitational) head
· In soil physics, hydraulic head governs water movement in soil.
· Hence, potential energy per unit weight of soil water is the correct expression.
Explanation of Other Options
Option (A): Potential energy per unit mass of soil water
· Incorrect because:
· This represents water potential, not hydraulic head.
Option (B): Potential energy per unit volume of soil water
· Incorrect because:
· This represents energy density, not hydraulic head.
Option (D): Height of standing water on the soil surface
· Incorrect because:
· This refers only to surface water depth, not hydraulic head within soil.
Key Points Related to the Question
· Hydraulic head = Energy per unit weight
· Unit: meter (m)
· Governs direction and rate of soil water flow
· Important concept in Soil Physics, Irrigation, Hydrology