Representation of the influence of soil structure on hydraulic conductivity prediction
Yunquan Wang, Rui Ma, Gaofeng Zhu
Abstract
The significant impact of soil structure on soil hydraulic properties and then on the associated water and solute transport is well recognized. However, existing soil hydraulic models that account for the effect of soil structure often at the cost of overparameterization, preventing further application in simulation of water and solute transport on large scales. In this study, we developed a new model that considers the effects of soil structure near saturation in prediction of hydraulic conductivity while introducing no new free parameters. Testing with 52 soil samples that include different soil types showed that the new model considerably improved the prediction of hydraulic conductivity compared to an earlier version of the model that did not take into account the effects of soil structure. The reported root-mean-square error (RMSE) of the new model is 0.78 cm d−1, much lower than the 0.90 cm d−1 when the earlier version of model is used. When the new model was used for fitting observations, it performed very well, with an RMSE of only 0.23 cm d−1 remained for 52 soil samples. This new soil hydraulic model provides a simple and practical way to incorporate the influence of soil structure near saturation in water and solute transport simulations.