Question

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.

Hint:

Hydraulic head can be measured in terms of energy or actual water height — all are valid representations.

Answer 1

The Correct Option is C

Step 1: Hydraulic head must have units of length (m or cm), since it is measured in the field as a column height.
Step 2: Check each option's unit: energy/mass gives \( \text{m}^2/\text{s}^2 \); energy/volume gives Pascal (pressure); energy/weight gives \( \text{m} \).
Step 3: Only energy per unit weight reduces to a length unit, matching hydraulic head.
Step 4: The correct option is potential energy per unit weight of soil water.