Core Ideas We provide details of an automated tensiometer refilling system. The systems monitors soil water tension in a rugged, steep, and arid post-fire debris flow source area. Vadose zone processes are looked at through remote data acquisition and SCADA applications. Tensiometer-equipped data acquisition systems measure and record positive and negative soil-water pressures. These data contribute to studies in hillslope hydrology, including analyses of rainfall runoff, near-surface hydrologic response, and slope stability. However, the unique ability of a tensiometer to rapidly and accurately measure pre- and post-saturation subsurface pressures requires maintenance techniques that have precluded their application to unattended sensor networks in semiarid regions. Under suction, the de-aired water in the tensiometer is drawn from a porous cup. Under positive pressure, dissolved gases from pore water infiltrates the cup. Over time, both contribute to unreliable readings and/or poor signal response through cavitation. To address this problem, we used commercially available equipment to develop a simple system of solenoid valves and a water reservoir that enable automated in situ tensiometer refilling. We tested the system at two post-wildfire hydrologic monitoring sites in the Angeles National Forest, southern California. We present example results from 3 mo of monitoring and show how the tensiometers can be refilled by a remote trigger. By remotely refilling the tensiometer, we were able to continuously monitor quasi-saturated soil pore-water pressures without making repeated and costly maintenance visits.
CITATION STYLE
Smith, J. B., & Kean, J. W. (2018). Long‐Term Soil‐Water Tension Measurements in Semiarid Environments: A Method for Automated Tensiometer Refilling. Vadose Zone Journal, 17(1), 1–5. https://doi.org/10.2136/vzj2018.04.0070
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