HYDRUS-1D has been extensively applied to the simulation of wettable soil infiltration, but very few studies have explored its applicability to the infiltration of water-repellent soil (WRS) at different depths. To this end, HYDRUS-1D was used to simulate water movement of layered soil with a surface repellent thickness of 10 cm. The parameters of the van Genuchten model were calibrated and validated using cumulative infiltration (CI), distance of the wetting front (Z_f) and volumetric water content (θ_v) through five respective treatments. Another 10 tilled scenarios were selected to simulate water movement of tilled WRS. RRMSE (relative root mean square error) and CRM (coefficient of residual mass) were adopted to evaluate simulation accuracy. For the calibration and validation, the RRMSE values ranged from 0.04 to 0.251 and 0.042 to 0.101, respectively, indicating that HYDRUS-1D could effectively simulate water movement of WRS. Furthermore, for layered treatments, the simulation accuracy of θ_v, CI and Z_f decreased with the increase of the degree of repellency and thickness. The treatments with the repellent thickness of 10 cm had higher simulation accuracy than that with repellent thickness of 5 cm when the top layer had the same WRS. The results revealed HYDRUS-1D was effective in the simulation of water movement in repellent clay loam with different degrees of repellency and depths.

中文翻译：

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HYDRUS-1D对不同深度拒水土壤入渗的适用性

HYDRUS-1D已广泛应用于可湿性土壤入渗的模拟，但很少有研究探讨其对不同深度防水土壤（WRS）入渗的适用性。为此，使用 HYDRUS-1D 模拟表面驱虫剂厚度为 10 cm 的层状土壤的水分运动。van Genuchten 模型的参数使用累积渗透 (CI)、润湿前沿距离 (Z _f ) 和体积含水量 (θ _v )进行校准和验证) 通过五个相应的处理。选择另外 10 个耕作场景来模拟耕作 WRS 的水运动。RRMSE（相对均方根误差）和CRM（残余质量系数）被用来评估模拟精度。对于校准和验证，RRMSE 值的范围分别为 0.04 至 0.251 和 0.042 至 0.101，表明 HYDRUS-1D 可以有效模拟 WRS 的水运动。此外，对于分层治疗，θ _v、CI 和 Z _f的模拟精度随着驱避度和厚度的增加而降低。当顶层具有相同的WRS时，驱虫剂厚度为10 cm的处理比驱虫剂厚度为5 cm的处理具有更高的模拟精度。结果表明，HYDRUS-1D 可以有效地模拟具有不同拒水性和深度的拒水性粘壤土中的水分运动。