Measurement of solution electrical conductivity in porous medium using TDR method
2002
"Haraguchi, T. (Kyushu Univ., Fukuoka (Japan)) | Hirota, O. | Nakano, Y. | Funakoshi, T. "
"As the fundamental study for the measurement of electrical conductivity, EC, or solute concentration of soil water using TDR method, the calibration experiment of the relationship between EC of soil water, EC sub(w), volumetric water content, th, and bulk soil EC, s , was conducted on glass beads. The characteristics of the four functions for calculating s were evaluated and the accuracy of the eye analysis of TDR waveform was examined through the calibration experiment. Furthermore the measurement of EC sub(w) using TDR method was done on sand to check the precision of the measuring procedure. The results of the calibration experiment on glass beads showed that the apparent dielectric constant, e sub(a), of samples, to which NaCl solution applied, were smaller than that of samples, to which distilled water applied, on the same condition of volumetric water content. The underestimation of esub(a) on the solution-applied samples might occur because of the unbecoming analysis technique, and the cause of this has not been solved yet. While the comparisons of the s using esub(a) of solution-applied sample and that using esub(a) of distilled water applied sample showed that the influence of the differences of ea on estimating s was negligible. The bulk soil EC was calculated by using four functions in various conditions of th and EC sub(w). The values of s evaluated by these models were compared each other, and the models were examined whether they were suitable for this measuring system. Then the Topp model was selected for the measuring system in consideration of the facts such that the TDR instrument would be operated manually."
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