资源环境科技发展态势分析平台

Predicting specific yield for a given aquifer remains a great challenge due to its dynamic characteristics, especially under periodic (e.g., seasonal and diurnal) groundwater level fluctuations. In this study, a dimensionless period of groundwater level fluctuations, which depends on the saturated hydraulic conductivity, the length of the groundwater level fluctuation period, and the soil water retention properties, is first introduced. Then, the relationship between the predicted specific yield and the dimensionless period of groundwater level fluctuations is defined based on the theory of variably saturated flow. The proposed approximate formula is tested by series of simulations of variably saturated flow within homogeneous and isotropic porous media with the Hydrus-1D program. The results of numerical experiments demonstrate an invariant relationship between the predicted specific yield and the dimensionless period for a wide range of changes in the dimensionless period of groundwater level oscillations. Furthermore, the sensitivity analysis of the dependence of the predicted specific yield on the van Genuchten parameters indicates the applicability of estimating the specific yield via van Genuchten parameters, which can be predicted by the soil texture classes for a given length of the oscillation period and a known saturated hydraulic conductivity in the zone of groundwater level fluctuations. The proposed model can be used for predicting the dynamics of the specific yield under seasonal or diurnal groundwater level fluctuations.