| dc.description.abstract | Time Domain reflectometry (TDR) evaluates the apparent dielectric constant, εa, of soil by measuring the travel time of an electromagnetic pulse through a sensor. Correlations between the apparent dielectric constant, εa, and the volumetric water content (θ) of soils can be established by regression.
A TDR probe is capable of measuring the dielectric constant and electrical conductivity (EC) of soil simultaneously. Overestimate of the water content can occur to soils with high fines content and/or salinity, which exhibit high conductivity level that affects the estimate of moisture by TDR. Further, the electrical conductivity is a main factor affecting the apparent dielectric constant determined by TDR. This influence is investigated theoretically and experimentally.
There are two points for attention of measuring content water. First, the reflection of TDR becomes much reduced in soils with high fines content and high pore water conductivity, thus affects the precision in moisture determination. Therefore, a detailed evaluation of the EC on TDR measurements is required, in order to exploit the full potential of the promising TDR technique. By using soils with varying fines contents and pore water with varying concentrations in electrolyte, this study presents information in these regards.
In application aspect, utilizing the electrical responses of the TDR to monitor the groundwater level and saline water intrusion will benefit the development of the monitoring system at waste disposal sites. | en_US |