A piezometer is placed in groundwater to measure hydraulic head. What is hydraulic head a measure of?

• A. Temperature
• B. Pressure and elevation
• C. pH level
• D. Turbidity

Answer: (B)

The main idea is that hydraulic head represents the total energy per unit weight of groundwater, combining both pressure energy and elevation energy. A piezometer shows how high a column of water would rise at that point, which reflects the pressure in the water (pressure head) plus the height of the point above a reference datum (elevation head). Together they form hydraulic head: pressure head plus elevation head. This is what the piezometer reading conveys about the groundwater system. It’s not about water quality properties like temperature, pH, or turbidity, which describe the water itself rather than its energy state. The hydraulic head tells you where water would tend to flow—from higher head to lower head—driving the groundwater gradient.