Evapotranspiration is the major component of the water cycle excluding precipitation. Evapotranspiration sub-processes represent important paths of water which have been poorly investigated and may play an important role in the water cycle. Two of these sub-processes are root water uptake (RWU) and root hydraulic redistribution (RHR), which were modelled and numerically explored in this study. Both RWU and RHR were evaluated using the source/sink term in Richards' equation coupled to a vegetation-atmosphere system. This coupling composes a model of water transfer in which the interplay between evapotranspiration and three different root density distributions (exponential, linear and constant scenarios) was simulated to understand, mainly, the influence of rooting systems on RWU and RHR. The results showed that the model consistently described the water dynamics and accurately estimated water fluxes, with evapotranspiration and RWU greater under the constant scenario. RHR contributed, from simulations, up to 21% of the evapotranspiration on a daily basis. Precipitation events may invert the direction of RHR from upward (hydraulic lift) to downward. The last process tends to conserve soil moisture in the root zone. The root systems modified the dynamics of the drainage, being the exponential scenario the greatest contributor to free drainage.

蒸散是除降水以外水循环的主要组成部分。蒸发蒸腾的子过程代表了重要的水路径，但尚未对此进行深入研究，并且可能在水循环中发挥重要作用。这些子过程中的两个子过程是根系吸水量（RWU）和根系水力再分配（RHR），在本研究中已对其进行了建模和数值研究。RWU和RHR均使用Richards方程中的源/汇项与植被-大气系统耦合进行了评估。这种耦合构成了一个输水模型，在该模型中，模拟了蒸散量与三种不同根系密度分布（指数，线性和恒定情景）之间的相互作用，从而主要了解了生根系统对RWU和RHR的影响。结果表明，该模型始终如一地描述了水的动力学过程并准确地估计了水通量，在恒定的情况下，蒸散量和RWU更大。通过模拟，RHR每天贡献了高达21％的蒸散量。降水事件可能会使RHR的方向从向上（液压升力）转向向下。最后一个过程倾向于在根部保存土壤水分。根系改变了排水的动力，是指数情景中自由排水的最大贡献者。降水事件可能会使RHR的方向从向上（液压升力）转向向下。最后一个过程倾向于在根部保存土壤水分。根系改变了排水的动力，是指数情景中自由排水的最大贡献者。降水事件可能会使RHR的方向从向上（液压升力）转向向下。最后一个过程倾向于在根部保存土壤水分。根系改变了排水的动力，是指数情景中自由排水的最大贡献者。