A three-dimensional model of the effect of stemflow on soil water dynamics around a tree on a hillslope.
A three-dimensional model of the effect of stemflow on soil water dynamics around a tree on a hillslope.
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DOI：
10.1016/j.jhydrol.2008.12.009
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发表时间：
2009-03
影响因子：
6.4
通讯作者：
W. Liang;K. Kosugi;T. Mizuyama
中科院分区：
文献类型：
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作者：
W. Liang;K. Kosugi;T. Mizuyama
在林分中，降水被冠层截留，并被分成透雨和茎流，分别作为漫射输入和点输入。因此，到达森林地面的水在空间上是不均匀的。虽然有许多模拟降水再分配过程的数值模式，但通常忽略了茎流集中的雨水。在这项研究中，我们对风暴期间的土壤水动力学进行了详细的观测，并建立了一个三维模型，用于描述森林山坡上树木周围茎流对土壤水动力学的影响。在茎流入渗过程中，水在较深的土层中快速流动，造成土壤垂直含水量的不规则变化。这一过程与垂直降雨入渗过程有很大的不同，在垂直降雨入渗过程中，湿润锋从上层向深层缓慢扩展。因此，使用传统净降水输入假设的模拟结果可能包含很大的误差。该模型考虑了茎流和参数化茎流作为土层源通量源的点输入特征，表现出充分的土壤水动力学时空变化特征，与观测结果吻合较好。将理查兹方程中的变源项应用于茎流是一种新的方法，它可以表示生长在山坡上的树木周围的根诱导旁通流入渗过程。
In forested stands, precipitation is intercepted by the canopy and partitioned into throughfall and stemflow as diffuse input and point input, respectively. Therefore, the water reaching the forest floor is not spatially uniform. Although there are many numerical models that simulate precipitation redistribution processes, the rainwater concentrated by stemflow is usually disregarded. In this study, we performed detailed observations of soil water dynamics during a storm event and developed a three-dimensional model of the effect of stemflow on soil water dynamics around a tree on a forested hillslope. In the stemflow infiltration process, water flowed rapidly through a deep layer, causing irregular changes in the vertical soil water content. This process is very different from the vertical rainfall infiltration process, in which the wetting front expands slowly from the upper layer to the deeper layer. Thus, simulations using the conventional net precipitation input assumption are likely to contain large errors as a result. The model proposed in this study, which considered the point input characteristic of stemflow and parameterized stemflow as a source flux spring in the soil layers, showed adequate spatial and temporal variations in soil water dynamics and closely agreed with observations. Applying the variable source term in the Richards equation to stemflow is a new approach and makes it possible to represent the root-induced bypass flow infiltration process around a tree growing on a hillslope.