An Alternative Simplified Evaporation Method for Measuring the Hydraulic Conductivity Function of the Unsaturated Soils

The simplified evaporation method (SEM) is frequently used for the determination of the hydraulic conductivity function (HCF) of the unsaturated soil. Usually, the mass of soil samples during evaporation is often monitored to calculate the flux. However, the balance is sensitive to the external conditions, such as the tensiometers connected by the cables to transmit data, and the cable will have a disturbing effect on the balance. In this study, a series of laboratory tests were conducted to obtain the hydraulic conductivity function of six kinds of soils, which texture ranged from sand to silty clay by using the alternative simplified evaporation method (ASEM) that reduces the sensitivity of the external environment brought by the balance. The volumetric water content near the centre depth was monitored by the soil moisture sensor, and the change of flux during evaporation was calculated by the volumetric water content. At the same time, for comparison, the mass was monitored during the evaporation process, and the mass of evaporated water was used to calculate the flux (SEM). The HCF obtained by the ASEM was consistent with that obtained by the SEM.