Abstract
In order to investigate the simultaneous movement of salt and water in unsaturated soil, or in order to determine the dispersion coefficient associated with soil solution, we need the sensor that can monitor quickly the salinity of the soil solution and its changes with time. In this paper, we developed a method to determine the changes in NaCl concentrations (C) and water contents (θ)in a laboratory soil column, in which bulk soil electrical conductivities (ECa) were measured by the fou卜electrodes and matric suction by tensiometers simultaneously. We get a calibration equation for a sandy soil without clay particles that gives the bulk soil electrical conductivity (ECa) from volumetric water content (θ)and soil water electrical conductivity (ECw): ECa= a • ECw •θ2+ b•θ
where a and b are experimental coefficients. Examples of applying this method for monitoring simultaneous movement of water and salt in the unsaturated sand during infiltration and evaporation process were shown.
