(1) Background: Simulation of soil water infiltration process and analysis of its influencing factors are important for water resources management. (2) Methods: In this study, the relative contributions of the soil water retention characteristics (SWRC) estimation, initial water content, and constant pressure head at upper boundary to the cumulative infiltration under various soil conditions were quantified based on the 1-D Richards’ equation and 900 scenarios. Scenario simulations were performed for two SWRC estimation methods (Jensen method and Rosetta); three different initial water contents (0.15, 0.20, and 0.25 cm³/cm³); five different constant pressure heads (0.5, 1, 2, 4, and 8 cm); and thirty soil samples with varying texture and bulk density. (3) Results: Rosetta representing the drying branch of the SWRC yielded higher simulated cumulative infiltration compared with the Jensen method representing the wetting branch of the SWRC. However, the Jensen method–predicted cumulative infiltration fluxes matched well with the measured values with a low RMSE of 0.80 cm. (4) Conclusions: The relative contribution of the SWRC estimation method to cumulative infiltration (19.1–72.2%) was compared to that of constant pressure head (14.0–65.5%), and generally greater than that of initial water content (2.2–29.9%). Findings of this study have practical significance for investigating the transport of water, nutrients, and contaminants in the unsaturated zone.

中文翻译：

---

土壤入渗对保水特性，初始条件和边界条件的响应

（1）背景：模拟土壤水分入渗过程及其影响因素，对水资源管理具有重要意义。（2）方法：在本研究中，基于1-D定量分析了土壤保水特性（SWRC）估算，初始含水量和上边界恒压头对各种土壤条件下累积入渗的相对贡献。理查兹方程式和900个场景。对两种SWRC估计方法（Jensen方法和Rosetta）进行了方案模拟。三种不同的初始水分含量（0.15、0.20和0.25 cm ³ / cm ³）; 五个不同的恒压头（0.5、1、2、4和8厘米）；以及三十个质地和容重变化的土壤样品。（3）结果：与代表SWRC润湿分支的Jensen方法相比，代表SWRC干燥分支的Rosetta产生了更高的模拟累积入渗量。但是，Jensen方法预测的累积入渗通量与RMSE为0.80 cm的低测量值非常吻合。（4）结论：将SWRC估算方法对累计入渗的相对贡献（19.1–72.2％）与恒压水头的相对贡献（14.0–65.5％）进行了比较，并且通常大于初始含水量（2.2–29.9） ％）。这项研究的发现对于研究非饱和区水，养分和污染物的运输具有实际意义。