Influence of heterogeneity on unsaturated hydraulic properties (2) – percentage and shape of heterogeneity |
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| Authors: | Cheng‐Mau Wu Pen‐Yuan Chen Chu‐Hui Chen Nien‐Sheng Hsu Jet‐Chau Wen |
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| Institution: | 1. National Yunlin University of Science & Technology, Research Center for Soil & Water Resources and Natural Disaster Prevention, , Douliou, Yunlin County, Taiwan;2. National Chiayi University, Department of Landscape Architecture, , Chiayi, Taiwan;3. China University of Technology, Department of Civil Engineering, , Taipei, Taiwan;4. National Taiwan University, Department of Civil Engineering and Hydrotech Research Institute, , Taipei, Taiwan;5. National Yunlin University of Science & Technology, Department and Graduate School of Safety Health and Environmental Engineering, , Douliou, Yunlin County, Taiwan |
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| Abstract: | In subsurface porous media, the soil water retention curve (WRC) and unsaturated hydraulic conductivity curve (UHC) are two important soil hydraulic property curves. Spatial heterogeneity is ubiquitous in nature, which may significantly affect soil hydraulic property curves. The main theme of this paper is to investigate how spatial heterogeneities, including their arrangements and amounts in soil flumes, affect soil hydraulic property curves. This paper uses a two‐dimensional variably saturated flow and solute transport finite element model to simulate variations of pressure and moisture content in soil flumes under a constant head boundary condition. To investigate the behavior of soil hydraulic property curves owing to variations of heterogeneities and their arrangements as well, cases with different proportions of heterogeneities are carried out. A quantitative evaluation of parameter variations in the van Genuchten model (VG model) resulting from heterogeneity is presented. Results show that the soil hydraulic properties are strongly affected by variations of heterogeneities and their arrangements. If the pressure head remains at a specific value, the soil moisture increases when heterogeneities increase in the soil flumes. On the other hand, the unsaturated hydraulic conductivity decreases when heterogeneities increase in the soil flumes under a constant pressure head. Moreover, results reveal that parameters estimated from both WRC and UHC also are affected by shapes of heterogeneity; this indicates that the parameters obtained from the WRC are not suitable for predicting the UHC of different shapes in heterogeneous media. Copyright © 2011 John Wiley & Sons, Ltd. |
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| Keywords: | heterogeneity hydraulic property curve UHC WRC van Genuchten model VSAFT2 |
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