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Title: Relationship between Anisotropy in Soil Hydraulic Conductivity and Saturation

Anisotropy in unsaturated hydraulic conductivity is saturation-dependent. Accurate characterization of soil anisotropy is very important in simulating flow and contaminant (e.g., radioactive nuclides in Hanford) transport. A recently developed tensorial connectivity-tortuosity (TCT) concept describes the hydraulic conductivity tensor of the unsaturated anisotropic soils as the product of a scalar variable, the symmetric connectivity tortuosity tensor, and the hydraulic conductivity tensor at saturation. In this study, the TCT model is used to quantify soil anisotropy in unsaturated hydraulic conductivity. The TCT model can describe different types of soil anisotropy; e.g., the anisotropy coefficient, C, can be monotonically increase or decrease with saturation and can vary from greater than unity to less than unity and vice versa. Soil anisotropy is independent of soil water retention properties and can be characterized by the ratio of the saturated hydraulic conductivities and the difference of the tortuosity-connectivity coefficients in two directions. ln(C) is linearly proportional to ln(Se) with Se being the effective saturation. The log-linear relationship between C and Se allows the saturation-dependent anisotropy to be determined using linear regression with the measurements of the directional hydraulic conductivities at a minimum of two water content levels, of which one may be at full saturation. Themore » model was tested using measurements of directional hydraulic conductivities.« less
Authors:
Publication Date:
OSTI Identifier:
1136611
Report Number(s):
PNNL-SA--98575
Journal ID: ISSN 1539-1663; TRN: US1400379
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Vadose Zone Journal; Journal Volume: 13; Journal Issue: 6
Publisher:
Soil Science Society of America
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES Vadose Zone; Soil Physics; Flow