Dual-porosity models have been shown to improve models of soil–water movement and enhance the water balance of structured soils. In this study we introduce novel, continuous, closed-form, bimodal, lognormal functions for soil–water retention, θ(ψ), and unsaturated hydraulic conductivity, K(ψ), enhancing traditional models and significantly improving predictions, particularly for pumice soils. These functions incorporate the thresholds for (a) water pressure, (b) soil water content, and (c) unsaturated conductivity, which accurately differentiates macropores from matrix pores. Validation using 313 observation points from laboratory data shows an increase in the Nash–Sutcliffe efficiency coefficient of θ(ψ) from 0.94 to 0.97, and for K(ψ) from 0.83 to 0.95. The model also requires six constant, semi-empirical tortuosity parameters and provides a physically constrained approach for the hydraulic parameters that reduces non-uniqueness risks. The derived functions yield improved predictions and enable the computation of macropore soil water content and flow contributions, with potential applications for the advancement of preferential flow modelling.

中文翻译：

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改善基质和大孔流之间的分配：浮石和非浮石土壤中保水性和导水率的新型双峰对数正态函数


双孔隙率模型已被证明可以改进土壤-水运动模型并增强结构土壤的水平衡。在这项研究中，我们引入了新颖的、连续的、闭合形式的、双峰的、对数正态的土壤保水函数 θ(ψ) 和不饱和导水率 K(ψ)，增强了传统模型并显着改进了预测，特别是对于浮石土。这些函数包含 (a) 水压、(b) 土壤含水量和 (c) 不饱和电导率的阈值，可准确区分大孔隙和基质孔隙。使用实验室数据中的 313 个观察点进行的验证显示，θ(ψ) 的纳什-萨特克利夫效率系数从 0.94 增加到 0.97，K(ψ) 从 0.83 增加到 0.95。该模型还需要六个恒定的半经验弯曲度参数，并为水力参数提供物理约束方法，以减少非唯一性风险。导出的函数产生改进的预测，并能够计算大孔隙土壤含水量和流量贡献，具有促进优先流建模的潜在应用。