基于HYDRUS-1D模拟的降雨入渗条件下VG模型参数敏感性分析

为了定量描述土壤水力参数变化对HYDRUS-1D模型输出变量10 cm层土壤水分动态分布、累积入渗量及湿润锋运移距离的影响,分别对HYDRUS-1D模型中的VG模型的5个土壤水力参数进行单因素扰动,采用修正的Morris筛选法分析降雨入渗条件下各土壤水力参数的敏感性。结果表明:模型参数的敏感性并不是一成不变的,针对不同的输出结果,参数敏感性随时间变化规律不同,根据研究需要确定参数敏感性区间对简化试验工作具有重要意义;边界条件也是影响模型参数敏感性的重要因素之一;对于不同的受影响研究对象,5个参数的敏感性不同。因此在应用模型模拟时,应该确保高敏感性参数的准确性及边界条件的真实性。

Sensitivity Analysis of VG Model Parameters under Rainfall Infiltration Using HYDRUS-1D Simulation

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.