Simulation of soil moisture dynamics in croplands using SHAW model in the semi-arid region of the Loess Plateau

In the semiarid region of the Loess Plateau, soil evaporation strongly depletes soil water. It is crucial for soil water management in dryland farming to know the dynamics of soil moisture and soil evaporation. In this study, the Simultaneous Heat and Water(SHAW) model, a one-dimensional canopy-residue-soil system with physical processes, was applied to simulate dynamics of soil moisture and soil evaporation in Chabagou basin of Zizhou County and Liudaogou basin of Shenmu County, Shaanxi province. The differences between simulated and measured values for surface soil moisture were larger than deep soil during 1964～1967 and 2006. For soil moisture simulation, the RMAE(Relatively mean absolutely error) was ranged from 5.2％ to 11.4％ during the same period. Average relative error between measured and simulated soil evaporation for approximately 200 days in 1964～1967 was ranged from 0.8％ to 6.1％. The above results showed that SHAW model could accurately estimate the dynamics of soil moisture in cropland in semiarid region of the Loess Plateau.