Modeling Water Potentials and Flows in the Soil–Plant System Comparing Hydraulic Resistances and Transpiration Reduction Functions
Modeling Water Potentials and Flows in the Soil–Plant System Comparing Hydraulic Resistances and Transpiration Reduction Functions
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DOI：
10.2136/vzj2013.02.0039
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发表时间：
2013-08
影响因子：
2.8
通讯作者：
Q. Jong Van Lier;J. Dam;Angelica Durigon;Marcos A. Santos;K. Metselaar
中科院分区：
文献类型：
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作者：
Q. Jong Van Lier;J. Dam;Angelica Durigon;Marcos A. Santos;K. Metselaar
在水文模拟中，常使用蒸腾折减函数来估算实际蒸腾量与土壤水分状况的关系。由于机械模型的数据需求和计算要求更高，经验简化函数是最常用的。然而，经验模型缺乏对物理机制的描述，其参数需要广泛的校准。我们推导出一个基于过程的约简函数，预测系统电位、电阻和水流。给出了布鲁克斯和科里土的一种特殊情况的解析解。在土壤-水-大气-植物（SWAP）水文模型中实现了货车土壤的还原函数的数值版本，允许预测分层土壤剖面和根长密度随深度的变化。该模型的分析和数值版本允许越来越多的定量洞察根系吸水的机制，如最大根系吸水速率作为土壤水分状况，土壤水力特性，根长密度和根半径的函数的存在，根系吸水量对径向根导和轴向根导的敏感性随根长的增加而降低密度增加。该方法可用于经验约简函数的阈值估计。
Transpiration reduction functions are often used in hydrological modeling to estimate actual transpiration as a function of soil water status. Empirical reduction functions are most frequently used due to the higher data needs and computational requirements of mechanistic models. Empirical models, however, lack a description of physical mechanisms and their parameters require extensive calibration. We derive a process‐based reduction function predicting system potentials, resistances, and water flows. An analytical solution for a special case of Brooks and Corey soils is presented. A numerical version of the reduction function for van Genuchten soils was implemented in the Soil–Water–Atmosphere–Plant (SWAP) hydrological model, allowing predictions for layered soil profiles and root length density variations over depth. The analytical and numerical versions of the model allow an increasingly quantitative insight into the mechanism of root water uptake, such as the existence of a maximum root water uptake rate as a function of soil water status, soil hydraulic properties, root length density, and root radius, in addition to the fact that sensitivity of simulated root water uptake to the radial root conductivity and axial conductance decrease when root length density increases. The approach can be used for the estimation of threshold values for empirical reduction functions.