[Applicability of HYDRUS-1D model in simulating the soil moisture in deep profiles on the Weibei rainfed highland, China].

Soil water balance has been greatly changed with the implementation of ecological restoration in the Loess Plateau. Some hydrological variables, such as deep drainage, can be hardly determined by traditional monitoring methods, and thus need to be analyzed by models. We simulated vertical distribution and time variation of soil moisture within 10 m profiles under a farmland and apple orchard by HYDRUS-1D model, and further evaluated model applicability. Based on observation from September 2011 to October 2013, the spatial and temporal discretization of soil water was simulated with calibrated soil hydraulic parameters. For the calibration and validation periods, HYDRUS-1D performed well with coefficient of determination of 0.65-0.85, model efficiency coefficients of 0.55-0.83, and root mean square errors from 0.01 to 0.02 cm·cm. The simulated soil water contents had similar vertical distribution and temporal variation as the observation, implying that HYDRUS-1D was suitable for simulation of soil hydrology in deep profiles on the Weibei rainfed highland.