Improving soil hydrological simulation under freeze-thaw conditions by considering soil deformation and its impact on soil hydrothermal properties

Traditional agricultural or eco-hydrological models usually ignore soil deformation and its impact on hydro -thermal properties when simulating soil water, heat, and salt transport under freeze-thaw conditions. As a result, significant errors may occur when these models are used in areas with considerable frost heave, such as arid areas with shallow groundwater tables. In this study, the simultaneous heat and water model (SHAW model) was modified with considering soil deformation and its impact on hydrothermal properties during the freeze-thaw period. The modified SHAW model was then validated using the experimental data collected at the Hetao Irri-gation District, in the upper Yellow River basin. Comparison between the simulated and observed data showed that the modified SHAW model performed well and obviously better than the original SHAW model in simulating the soil water, heat, and salt transport. As compared with the SHAW model, the modified SHAW model averagely decreased the RMSE value by 37.5% and 23% for soil water content and soil temperature, respectively. The modified model can be used as a decision tool for water management and salinity control of farmland in cold areas with significant frost heave.