Extension and functional properties for TDR measurement application

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The purpose of the present study was to establish new applications of TDR measurement and to clarify their functional properties. In this report, three major research topics are included. (1) A multi TDR probe (MWP), having 8 probes in the electric board of 3-cm wide, was developed and properties of the MWP were investigated to measure water content profile near soil surface. The measurements of the profile conducted during evaporation process for sand and decomposed granite soil by using the MWP revealed clear difference of the profile between the soils. (2) Applicability of TDR technique to the monitoring of soil deposit level in water reservoir. A linear relationship between dielectric constant and the deposit level was found with minor impact of electrical conductivity of water. (3) The detection of boundary between fresh- and salt-water using TDR was examined. The analysis of TDR wave form made it possible to estimate the boundary level with high accuracy. With the measurement, we also found that the electrical conductivity of the fresh water can be also evaluated.