Which device is used to measure hydraulic conductivity in soil?

Which device is used to measure hydraulic conductivity in soil?

• A. Hydrometer
• B. Penetrometer
• C. Odometer
• D. Tube permeameter

Answer: (D)

Hydraulic conductivity is a measure of how easily water can move through saturated soil when there is a driving gradient. To determine it in the lab, you use a device that drives water through a soil specimen and relates the flow rate to the hydraulic gradient, by Darcy’s law. A tube permeameter specifically fits this purpose: soil is placed inside a tube, water is passed through, and you measure the discharge rate and the head difference across the specimen (with known length and cross-sectional area). From those measurements, you compute K using K = Q L / (A Δh) for a constant-head test (or the appropriate form for a falling-head test). This setup directly yields the saturated hydraulic conductivity, whereas other devices measure something else: a hydrometer analyzes grain-size distribution, a penetrometer gauges resistance to penetration (soil strength), and an oedometer assesses compression and consolidation behavior. The tube permeameter is the straightforward choice for permeability, though finer clays can pose practical challenges due to clogging and saturation requirements.

Hydraulic conductivity is a measure of how easily water can move through saturated soil when there is a driving gradient. To determine it in the lab, you use a device that drives water through a soil specimen and relates the flow rate to the hydraulic gradient, by Darcy’s law. A tube permeameter specifically fits this purpose: soil is placed inside a tube, water is passed through, and you measure the discharge rate and the head difference across the specimen (with known length and cross-sectional area). From those measurements, you compute K using K = Q L / (A Δh) for a constant-head test (or the appropriate form for a falling-head test). This setup directly yields the saturated hydraulic conductivity, whereas other devices measure something else: a hydrometer analyzes grain-size distribution, a penetrometer gauges resistance to penetration (soil strength), and an oedometer assesses compression and consolidation behavior. The tube permeameter is the straightforward choice for permeability, though finer clays can pose practical challenges due to clogging and saturation requirements.