Long-term soil-water tension measurements in semi-arid environments: A method for automated tensiometer refilling

Vadose Zone Journal
By:  and 

Links

Abstract

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.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Long-term soil-water tension measurements in semi-arid environments: A method for automated tensiometer refilling
Series title Vadose Zone Journal
DOI 10.2136/vzj2018.04.0070
Volume 17
Issue 1
Year Published 2019
Language English
Publisher Soil Science Society of America, Inc
Contributing office(s) Geologic Hazards Science Center
Description 180070; 5 p.