Macroscopic Representation of the Interface between Flow Domains in Structured Soil
Macroscopic Representation of the Interface between Flow Domains in Structured Soil
复制标题
结构土中流域界面的宏观表示
DOI：
10.2136/vzj2011.0125
复制
发表时间：
2012
影响因子：
2.8
通讯作者：
H. Gerke
中科院分区：
文献类型：
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作者：
H. Gerke
本研究试图量化宏观双孔渗流和输运模型中流动区域之间的界面。对于结构性土壤，这种界面可能与作为优先流动路径的土壤团聚体和生物孔的表面有关。通过该界面与土壤基质区域的质量交换需要包括各种结构形状和大小的组合效应，这一点还没有得到适当的定义。其目的是测试一种通过使用两个具有不同结构的土样基于表面积/体积比来表征区域界面来测试独立土壤结构量化的方法。对医用扫描仪采集的原状土样的X射线CT数据进行了分析。对于一定范围的密度阈值，表面积是以体素为基础进行识别的。结果发现，对于具有圆柱形针孔的底土样品和聚集的表土样品，所得到的函数是特有的。结果表明，域间界面面积可用于计算质量交换系数和与目测土体结构有关的宏观特性。该方法代表了单个结构特征向宏观尺度的提升，通过找到一种方法，从土壤协议中给出的定性土壤结构信息获得相对简单的几何系数估计，可以提高双域模型的适用性。虽然这种分析不能确定多孔域之间明确定义的界面，但它能够缩小物理上合理区域内的可能值的范围。在其他特征中，还需要更多的努力来识别特定类型的结构表面。
This study attempts to quantify the interface between flow domains in macroscopic dual‐porosity flow and transport models. For a structured soil, this interface could be related to the surfaces of soil aggregates and biopores that may serve as preferential flow paths. Mass exchange with the soil matrix domain across this interface requires including the combined effect of various structural shapes and sizes, which has not yet been properly defined. The objective was to test an approach for independent soil structure quantification by characterizing domain interfaces based on surface area/volume ratios using two soil samples with contrasting structures. X‐ray computed tomography data from undisturbed soil cores from a medical scanner were analyzed. For a range of density threshold values, surface areas were identified on a voxel basis. The resulting functions were found to be characteristic for the subsoil sample with cylindrical pinhole pores as well as for the aggregated topsoil sample. The results suggest that the interdomain interface area could be used for deriving mass exchange coefficients and a macroscopic characteristic related to visual inspection of the soil structure. The approach, representing an upscaling of individual structural features to the macroscopic scale, may improve the applicability of two‐domain models by finding a way to obtain relatively simple estimates of the geometry coefficient from qualitative soil structure information given in soil protocols. Although this analysis did not allow determination of a well‐defined interface between porous domains, it enabled narrowing of the range of possible values in a physically plausible region. Still more effort is required to identify specific types of structural surfaces among other features.