Time domain reflectometry as a field method for measuring water content and soil water electrical conductivity at a continuous permafrost site

Time domain reflectometry (TDR) is evaluated as a field technique for measuring volumetric water content theta and bulk electrical conductivity sigma(b) in Arctic soils. Calibration measurements of theta and sigma(b) were carried out on three different slopes at a field site in Siberia (74 degrees 32'N; 98 degrees 35'E). Comparison of theta calculated from TDR using two different approaches and gravimetrically determined water contents shows a close correlation. TDR determined sigma(b), applying theoretical relationships and a simple regression model, are compared with the electrical conductivity sigma(w) of soil solutions obtained with suction cups. Best results for sigma(w) are obtained using the regression model, with highest precision when probe specific calibration is carried out. In this permafrost setting, TDR can be applied to obtain quantitative estimates of theta and sigma(w) in the active layer. The application of the regression model in different permafrost soils to infer sigma(w) requires additional calibration. (C) 1997 John Wiley & Sons, Ltd.