HR: 1340h
AN: H23A-1109    [Abstracts]
TI: Quantifying Saturation-Dependent Anisotropy in Soil Hydraulic Conductivity
AU: * Zhang, Z F
EM: fred.zhang@pnl.gov
AF: Hydrology Group, Pacific Northwest Natl Lab, Battelle Boulevard, Richland, WA 99352
AU: Ward, A L
EM: andy.ward@pnl.gov
AF: Hydrology Group, Pacific Northwest Natl Lab, Battelle Boulevard, Richland, WA 99352
AU: Gee, G W
EM: glendon.gee@pnl.gov
AF: Hydrology Group, Pacific Northwest Natl Lab, Battelle Boulevard, Richland, WA 99352
AU: White, M D
EM: mark.white@pnl.gov
AF: Hydrology Group, Pacific Northwest Natl Lab, Battelle Boulevard, Richland, WA 99352
AU: Keller, J M
EM: jason.keller@pnl.gov
AF: Hydrology Group, Pacific Northwest Natl Lab, Battelle Boulevard, Richland, WA 99352
AB: The anisotropy in unsaturated hydraulic conductivity is saturation-dependent. Accurate characterization of soil anisotropy is very important in simulating flow and contaminants (e.g., radioactive nuclides in Hanford) transport. A recently proposed 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 results show that the anisotropy coefficient, A, is independent of soil water retention properties. At a certain saturation, A can be characterized by the ratio of the saturated hydraulic conductivities and the difference in the tortuosity-connectivity coefficients in orthogonal directions. The model was tested using directional measurements of unsaturated hydraulic conductivity of undisturbed soil cores. Results show that the TCT model can describe different types of soil anisotropy, previously ignored in other models. The TCT model can be used to describe either monotonic increases or decreases in A with saturation and allows the principal direction of hydraulic conductivity to rotate when saturation varies. The Pacific Northwest National Laboratory is operated for the U.S. Department of Energy by Battelle under Contract DE-AC06-76RL01830.
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting