Estimations of unsaturated hydraulic parameters in 1D soil column by using self-potential observations

• Main Authors: Chen-Chieh Chen, 陳鎮傑
• Other Authors: Chuen-Fa Ni
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/46425824264345336423

碩士 === 國立中央大學 === 應用地質研究所 === 104 === The hydraulic properties in unsaturated soils control the movement of gas, water and solute in shallow aquifer systems. It is crucial to obtain such hydraulic parameters for accurate predictions of flow and contaminant transport in unsaturated soils. This study aims to obtain the relationship of streaming potential and water content dring an infiltration process and uses the self-potential observations to assess the estimations of unsaturated hydraulic parameters for soils. A one-dimensional sand column with #30 & #60 sand was used to conduct constant head infiltration tests. The variation of water content in the column was measured by TDR (Time Domain Reflectometry) during the infiltration test. The observations of the infiltration test in a vertical sand column are then used in HYDRUS-1D model to obtain parameters of the Van Genuchten formula. The results show that the migration of the wetting front in the sand column can be detected in real-time by the self-potential observations. However, the measured signals might be influenced by the grain sizes、TDR signals and saturation conditions. The results of self-potential observations and water content are different in #30 and #60 sand cases. The results of estimated water content in #30 sand case show better estimation of Van Genuchten formula as compared with the results of pressure plate estimations.