Drought-induced evaporation can reduce soil water content and significantly alter soil hydro-mechanical behavior. Understanding the temporal and spatial distribution characteristics of soil water content during evaporation is of great significance for evaluating the encountered geotechnical and geo-environmental problems in arid or semi-arid regions. In this study, an electrical resistivity/resistance method (ERM) with a high spatial resolution of centimeter-level was developed for a small-scale laboratory test and applied to quantitatively characterize the evaporation-induced water content variations along a depth gradient. A total of 8 groups of initially saturated sandy soil columns (84 mm in diameter and 290 mm in height) were prepared, and eight pairs of mini electrodes (3.5 mm in diameter) were installed in each soil sample with a vertical distance of 30 mm. The soil columns were subjected to continuous drying. The changes in soil electrical resistance at different depths were monitored by the electrode couples. The gravimetric water contents at different depths were also measured at the end of drying. It is found that soil water content decreases exponentially with increasing electrical resistance. Based on the obtained data, a calibration relationship between soil gravimetric water content and corrected electrical resistance was well established with consideration of temperature effect. This relationship was validated successfully by the experimental results, indicating the feasibility of the developed ERM to characterize the soil water content dynamics during the drying process. Besides, the drying process with the movement of the evaporation front was discussed. The results of this study demonstrate the good performance of ERM in the estimation of temporal and spatial variations of soil water content and its potential application in arid or semi-arid regions with frequent droughts.

干旱引起的蒸发可以减少土壤中的水分，并显着改变土壤的水力力学行为。了解蒸发过程中土壤水分的时空分布特征对于评估干旱或半干旱地区遇到的岩土和地球环境问题具有重要意义。在这项研究中，开发了一种具有厘米级高空间分辨率的电阻率/电阻方法（ERM），用于小型实验室测试，并用于定量表征蒸发引起的水含量沿深度梯度的变化。总共准备了8组初始饱和的沙土柱（直径为84 mm，高度为290 mm），以及八对微型电极（3个）。直径5毫米）以30毫米的垂直距离安装在每个土壤样品中。使土壤柱连续干燥。通过电极对监测不同深度土壤电阻的变化。在干燥结束时还测量了不同深度的重量含水量。发现土壤含水量随电阻的增加呈指数下降。根据获得的数据，考虑到温度效应，可以很好地建立土壤重量水含量与校正电阻之间的校准关系。实验结果成功验证了这种关系，表明开发的ERM在干燥过程中表征土壤水分动态的可行性。除了，讨论了干燥过程中蒸发前沿的运动。这项研究的结果表明，ERM在估算土壤含水量的时空变化方面具有良好的性能，并且在干旱频繁的干旱或半干旱地区具有潜在的应用价值。