Laboratory characterization of sandy soil water content during drying process using electrical resistivity/resistance me
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ORIGINAL PAPER
Laboratory characterization of sandy soil water content during drying process using electrical resistivity/resistance method (ERM) Ni An 1,2 & Chao-Sheng Tang 1 & Qing Cheng 1 & De-Yin Wang 1 & Bin Shi 1 Received: 16 August 2019 / Accepted: 8 April 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract 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. Keywords Soil water evaporation . Soil water content . Electrical resistivity/resistance method (ERM) . Evaporation front . Temperature effect
* Chao-Sheng Tang [email protected] Ni An [email protected] Qing Cheng [email protected] De-Yin Wang [email protected] Bin Shi [email protected] 1
School of Earth Sciences and Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, China
2
Geoenvironmental Research Centre, Cardiff School of Engineering, Cardiff University, Newport Road, Cardiff CF24 3AA, UK
Introduction Evaporation is of great importance in water and energy transfer between soil and atmosphere interaction. The drying process may lead to soil cracking, salinization, degradation, and other problems in arid and semi-arid areas (Shimojima et al. 1996; Tang et
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