A method for estimating soil water characteristic curve with limited experimental data

Abstract Because of the difficulty to reach high suction at the residual state of unsaturated soils, the saturation-suction experimental data for soil water characteristic curve (SWCC) is often limited and incomplete, which will lead to unreliable estimation of mechanical and hydraulic conductivity of unsaturated soils. However, no study has been published on how to obtain a reliable SWCC for unsaturated soils with limited experimental data. In response to this situation, an innovative method was proposed based on the analysis of shape characteristics of SWCC with three identified critical points in it. 78 experimental datasets from existing literature were compiled to identify the mathematical relationship among three critical points in the SWCC. The proposed method was evaluated by experimental datasets from this study and existing literature and proved to have a satisfying performance in predicting a complete SWCC for a wide range of soils, from the coarse-grained to the fine-grained. Overall, the research results present an effective and capable method for estimating a more reliable SWCC when experimental data is limited.