Description:
<jats:p>The need exists for a measurement technique to accurately determine the depth of surface runoff on natural soil surfaces. The objective of this note was to determine the sensitivity to the immersion depth of commercially available frequency‐domain probes. Within the range of 0 to 25 mm, measurement accuracies better than 0.5 mm were reached. Interestingly, soiling of the rods or droplets did not influence the results significantly. The influence of the electrical conductivity of the water or internal characteristics of different probes did not lead to a bias of more than 1 mm. A field test with grid‐like mounted frequency‐domain probes showed a stable output signal and a high sensitivity to hydrograph changes. We concluded that frequency‐domain probes were well suited for tracking shallow depths of surface runoff in field studies and allow high spatial and time resolution. They provide higher accuracy than alternative systems in the water‐level range <5 mm. However, when the measurement precision must be higher than 0.5 mm, an individual calibration of the probes is necessary as well as a correction for salinity.</jats:p>