Estimating vertical soil water fluxes with tracers and time domain reflectometry (tdr) in a sand column under controlled labo
Authors: S.A. Kreba And C.P. Maule
Description: There are a number of methods that have been developedand used for determination of soil water flux. Soil water flux determination is a complex measurement, requiring measurementof various components over a period of time. The objectives of this study are to show that time domain reflectrometry (TDR)can be a useful tool for estimation of soil water fluxes using tracer methods and to evaluate the accuracy of a tracer methodin estimating soil water flow under mostly saturated conditions. A TDR system within a sand column with a KCl tracer was used.The TDR was used to simultaneously determine tracer concentration and moisture content. Two methods of flow determination were used: peak migration and soil water balance. Both methods were used for upward and downward flow directions. The peak migration method is based upon change in peaklocation with time and utilized TDR measurements. The water balance method is based upon changes in soil moisture contentand the rate water is added to or taken from the system. The peak migration method provided similar average upward anddownward water fluxes as compared to the soil water balance method. The average estimated upward soil water fluxes by thepeak migration and the soil water balance methods were 10.2 and 11.3 mm d-1, respectively, and were 91.9 and 90.2 mm d-1,respectively for the downward fluxes. An advantage of the peak migration method is that it shows greater spatial and temporal resolution.
Keywords: soil water flux, time domain reflectometry, tracer method, soil column