Abstract: The aim of this study is to quantify the influence of hydraulic parameters of soil on three output variables of HYDRUS-1D. The three parameters include:dynamic distribution of soil moisture in 10 cm layer, cumulative infiltration capacity, and migration distance of wetting front. By individually perturbing the five hydraulic parameters, namely, θ_r, θ_s, K_s, α, and n in the HYDRUS-1D VG model, we examined the sensitivities of these five parameters under rainfall infiltration by using the modified Morris screening method. Results manifested the importance of determining the intervals of parameter sensitivity to simplifying tests process. The sensitivities of model parameters changed with time depending on different output results. Boundary condition is also a crucial factor that affects the model parameter sensitivity. In addition, the sensitivity of each of the five parameters differs with various research objects. In conclusion, the accuracy of highly sensitive parameters and the authenticity of boundary conditions should be ensured.

Key words: hydraulic parameters of soil, rainfall infiltration, sensitivity analysis, migration distance of wetting front, HYDRUS-1D, numerical simulation, single-factor perturbation