Simulation of soil water transport considering the effects of soil structure and adsorption forces

ObjectiveTraditional soil hydraulic models based on capillarity theory, poorly characterize soil structure (e.g., soil macropores) and adsorption forces, which limits their ability to accurately describe soil hydraulic properties under near-saturation and low soil water content conditions. Consequently, these models struggle to accurately simulate soil water movement. MethodsIn this study, we evaluated the performance of different soil hydraulic characteristic models using continuous field-measured soil moisture data from seven FLUXNET sites. We employed the FXW-M3 model, which accounts for soil structure, adsorption, and capillary forces, and the VGM model, which considers only capillary forces. Using the improved HYDRUS-1D software, we simulated and analyzed site-specific soil moisture data. ResultsThe results indicated that the FXW-M3 model significantly improved the accuracy of soil water movement simulation. The average root mean square error (RMSE) for the FXW-M3 model was 0.0048 cm3/cm3, which was lower than the 0.0113 cm3/cm3 for the VGM model. The average R for the FXW-M3 model was 0.80, which was higher than 0.75 for the VGM model. ConclusionThese results highlighted the significant impact of soil structure and adsorption forces on soil water movement.