Abstract—

Hysteresis of soil water retention curve (SWRC hysteresis) is widely used for modeling water flux in an unsaturated soil during infiltration and irrigation processes. The aim of the work was to predict soil moisture of a wetting curve from the main drying branch based on an effective degree of saturation for the drying branch by suggesting pedotransfer functions (PTFs). Furthermore, the efficiency of the proposed PTFs (M-1) was estimated by comparing it with a model having the same purpose such as a model of Mualem (1977) (M-77). The drying and wetting branches were measured using capillary meter at soil water pressure heads lower than –1000 mbar. The effective degree of saturation for drying \(S_{d}^{e}\left( h \right)\) and wetting \(~S_{w}^{e}\left( h \right)\) curves was estimated at different values of soil water pressure heads. The proposed PTFs (M-1) \(S_{w}^{e}\left( h \right)~\) = \(\frac{{\sqrt 3 }}{2}\) \(S_{d}^{e}\left( h \right)\) was derived by dividing the mean values of \(S_{w}^{e}\left( h \right)\) to the mean values of \(S_{d}^{e}\left( h \right)\). The results show that the estimation error for the proposed PTFs (M-1) and the Mualem model (M-77) was less for estimating soil moisture of a wetting curve at the higher values of soil water pressure heads as –500, –700 and –900 mbar than their values calculated at the lower values of soil water pressure heads as –50, –150, and –300 mbar and near of saturation. While the proposed PTFs (M-1) was more accurate than the Mualem model (M-77) for calculating soil moisture of a wetting branch at a saturation point and at the lower values of soil water pressure heads as –50, –150, and –300 mbar. The proposed PTFs (M-1) \(S_{w}^{e}\left( h \right)~\) = \(\frac{{\sqrt 3 }}{2}\)\(S_{d}^{e}\left( h \right)\) can be used for simulating soil moisture of wetting branch during infiltration and irrigation processes at soil water pressure heads lower than ‒1000 mbar and a near of saturation for agrosoddy-podzolic soil of silt loam and silty clay loam textures.

中文翻译：

---

基于有效饱和度的Pedo传递函数优化预测湿润曲线的土壤湿度

摘要-

土壤保水曲线的滞后性（SWRC滞后性）被广泛用于模拟非饱和土壤在渗透和灌溉过程中的水通量。这项工作的目的是根据干燥支路的有效饱和度，通过建议脚踏传递函数（PTF）来预测主要干燥支路的湿润曲线的土壤湿度。此外，通过与具有相同目的的模型（例如Mualem（1977）（M-77））进行比较，估算了拟议的PTF（M-1）的效率。使用毛细管流量计在低于–1000 mbar的土壤水压头下测量干燥和湿润分支。干燥\（S_ {d} ^ {e} \ left（h \ right）\）和润湿\（〜S_ {w} ^ {e} \ left（h \ right）\）的有效饱和度在不同的土壤水压头值下估算曲线。拟议的PTF（M-1）\（S_ {w} ^ {e} \ left（h \ right）〜\） = \（\ frac {{\ sqrt 3}} {2} \） \（S_ {d } ^ {e} \ left（h \ right）\）是通过将\（S_ {w} ^ {e} \ left（h \ right）\）的平均值除以\（S_ { d} ^ {e} \ left（h \ right）\）。结果表明，在较高的土壤水压头值为–500，–700的情况下，拟议的PTF（M-1）和Mualem模型（M-77）的估计误差在估计湿润曲线的土壤水分时较小。和–900 mbar的值，而不是在–50，–150和–300 mbar且接近饱和的较低土壤水压头下计算得到的值。尽管拟议的PTF（M-1）比Mualem模型（M-77）更精确，但它在饱和点和较低的土壤水压头值为–50，–150时，计算湿润分支的土壤湿度，和–300 mbar。拟议的PTF（M-1）\（S_ {w} ^ {e} \ left（h \ right）〜\） = \（\ frac {{\ sqrt 3}} {2} \）\（S_ {d } ^ {e} \ left（h \ right）\） 可以用于模拟渗水和灌溉过程中水压头低于‒1000 mbar的湿润分支的土壤水分，并且对于粉质壤土和粉质粘土质壤土的土壤农业土壤而言，其饱和度接近饱和。