Simulation of solute transport in a heterogeneous vadose zone describing the hydraulic properties using a multistep stochastic approach
Simulation of solute transport in a heterogeneous vadose zone describing the hydraulic properties using a multistep stochastic approach
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DOI：
10.1029/2005wr004580
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发表时间：
2006-05
影响因子：
5.4
通讯作者：
L. I. Oliveira;A. Demond;L. Abriola;P. Goovaerts
中科院分区：
文献类型：
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作者：
L. I. Oliveira;A. Demond;L. Abriola;P. Goovaerts
非均质非饱和土壤中保守溶质运移的模拟依赖于对土壤水化学性质空间变异性的描述。从拉斯克鲁塞斯海沟网站的数据被用来探讨的影响，替代方法来描述水力特性的变化。三种不同的方法被认为是：米勒和米勒缩放，Leverett缩放，和一个多步骤的方法，涉及分类的保水曲线。有条件的顺序地质统计模拟用于产生同样可能实现的土壤性质的每种方法，这些实现，然后被用来作为输入到一个数值模拟器来量化溶质运移预测的不确定性。模拟结果表明，缩放技术似乎过于简化的描述非均质性在拉斯克鲁塞斯海沟，导致非常狭窄的空间的不确定性。由于多步方法允许再现土壤类别的现有连续性模式和田间水力特性的对比值，因此它导致溶质羽流分裂成几个优先路径，这些路径在基于缩放方法的模拟中没有观察到，这增加了标准偏差溶质羽流时刻。结果表明，需要收集的水分保持曲线和饱和导水率的测量更现实，保守的研究在非均质非饱和土壤中的流动。
The simulation of conservative solute transport in a heterogeneous unsaturated soil depends on the description of spatial variability of soil hydraulic and chemical properties. The data from the Las Cruces Trench Site were used to explore the impact of alternative ways of describing the variability of hydraulic properties. Three different approaches were considered: Miller and Miller scaling, Leverett scaling, and a multistep approach involving categorization of water retention curves. Conditional sequential geostatistical simulation was used to generate equally probable realizations of soil properties for each approach, and these realizations were then used as input to a numerical simulator to quantify the resultant uncertainty in solute transport predictions. Simulation results show that the scaling techniques seem to oversimplify the description of heterogeneity in the Las Cruces Trench, leading to very narrow spaces of uncertainty. Because the multistep approach allows the reproduction of existing patterns of continuity of soil classes and of contrasting values of hydraulic properties in the field, it led to solute plumes that split into several preferential pathways that were not observed in the simulations based on the scaling approaches, which increased the standard deviation of the solute plume's moments. The results indicate that measurements of both water retention curves and saturated hydraulic conductivity need to be collected for more realistic, conservative studies of flow in heterogeneous unsaturated soils.