Evaluation of the Multistep Outflow Method for the Determination of Unsaturated Hydraulic Properties of Soils
Evaluation of the Multistep Outflow Method for the Determination of Unsaturated Hydraulic Properties of Soils
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DOI：
10.1097/00010694-199709000-00003
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发表时间：
1997-09
期刊：
影响因子：
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通讯作者：
H. Vereecken;R. Kaiser;M. Dust;T. Pütz
中科院分区：
文献类型：
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作者：
H. Vereecken;R. Kaiser;M. Dust;T. Pütz
采用多步出流法测定了57个土样的持水特性h(θ)和导水率曲线K(θ)。利用Mualem-van Genuchten h(θ)和K(θ)模型，分析了4种不同参数向量对水力功能估计的影响。这些参数向量的固定参数数量在2到4之间不同，对应于关于参数值的不同假设和/或可用信息。为了将饱和导水率(Ks)的估计值与同一样本的实测值进行比较，提出了一种改进的多步流出法。分析了目标函数中包含的附加含水率对参数估计的影响。对数据进行了地统计学分析，以确定观测到的参数分布的变异来源。对四个不同参数向量的分析表明，表征孔径相互作用的参数Ks和L应作为拟合参数。从流出实验中直接获得的其他保湿特性数据点提供了更好的保湿特性估计。从四参数情况下获得的保湿特性的参数估计不能很好地描述h(θ)。
The moisture retention characteristic h(θ) and the hydraulic conductivity curve K(θ) of 57 soil samples were determined using the Multistep Outflow method. Using the Mualem-van Genuchten h(θ) and K(θ) models, the effect of four different parameter vectors on the estimation of the hydraulic functions was analyzed. These parameter vectors differed in the number of fixed parameters between two and four, corresponding to different assumptions and/or available information concerning the value of the parameters. To compare estimated saturated hydraulic conductivity values (Ks) with measured values from the same sample, a modified Multistep Outflow method was developed. The effect on the estimation of parameters using additional moisture content values, which were included in the objective function, was analyzed. A geostatistical analysis of the data was performed to identify the source of variation in the observed parameter distributions. Analysis of the four different parameter vectors showed that Ks and l, a parameter characterizing pore size interaction, should be regarded as fitting parameters. Additional data points of the moisture retention characteristic, which were obtained directly from the outflow experiment, provided better estimates of the moisture retention characteristic. Parameter estimates of the moisture retention characteristic obtained from the four-parameter case did not provide a good description of h(θ).