Soil water retention curve (SWRC) is key hydraulic property for vadose zone hydrology. Selected 22 SWRC models with different structures were divided into four types: traditional, single‐segment, two‐segment, and three‐segment models. According to the accuracy and model selection criterion, these models were compared and evaluated using water retention data from saturation to oven dryness of 94 soil samples covering almost all soil types. Among the models, the EG model (exponential model combined with the Groenevelt–Grant model) shows the best performance, but the BC (Brooks–Corey) and VG (van Genuchten) models performed the worst. The relationship between model performance and complexity showed that traditional models with residual water content performed worse than segmental models from saturation to oven dryness, and the segmental models performed worse with an increase in the segment number. In general, models with more parameters perform better, but when the parameter number is greater than five, the model performance gradually worsens due to the equifinality of different parameters. The correlation analysis between soil properties on model performance showed that soil texture has a more significant effect on model performance than bulk density and organic matter content, because the models are primarily affected by their mathematical forms rather than the physical significance of the parameters. Each model picks its limitations and may apply to only one or particular group(s) of soil(s). Therefore, the complementarities of different models may be a great choice to improve SWRC fitting and simulation in arid soil.

中文翻译：

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比较22种描述从饱和到干燥的土壤保水曲线的模型的性能

土壤水分保持曲线（SWRC）是渗流带水文学的关键水力特性。选择的22种结构不同的SWRC模型分为四种类型：传统模型，单段模型，两段模型和三段模型。根据准确性和模型选择标准，使用涵盖几乎所有土壤类型的94个土壤样品从饱和到干燥的保水数据对这些模型进行了比较和评估。在这些模型中，EG模型（指数模型与Groenevelt-Grant模型结合使用）表现出最佳性能，而BC（布鲁克斯-科里）模型和VG（van Genuchten）模型表现最差。模型性能与复杂性之间的关系表明，从饱和到烤箱干燥，具有残留水分的传统模型的性能要比分段模型差，细分模型的效果则随着细分数量的增加而变差。通常，具有更多参数的模型性能更好，但是当参数数量大于五个时，由于不同参数的均等性，模型性能会逐渐变差。土壤特性与模型性能之间的相关性分析表明，土壤质地对模型性能的影响比体积密度和有机质含量更为重要，因为模型主要受其数学形式的影响，而不是参数的物理意义。每种模型都有其局限性，并且可能仅适用于一个或一组特定的土壤。因此，不同模型的互补性可能是改善干旱土壤SWRC拟合和模拟的一个很好的选择。