Measurement of soil water content in a hyper-arid environment using time-domain reflectometry sensors

Abstract

Time-domain reflectometry (TDR) sensors have been widely used in many fields for measurement of soil water content. However, few TDR sensors have been used in a hyper-arid environment (e.g. less than 0·05 m3 m-3), and such sensor applicability is not yet confirmed. In this study we examine θ - t and θ - ε bulk relations and temperature dependency for natural sand and glass beads in a laboratory using commercially available TDR sensors. As a result, this study clarifies that TDR sensors are applicable even in a hyper-arid environment when calibration was properly made. We also focus on a specific range of soil water content, which leads to a highly precise calibration equation. Copyright © 2005 John Wiley & Sons, Ltd.