HR: 1340h
AN: H13I-1422    [Abstracts]
TI: The effect of mineral precipitation and dissolution on the predicted van Genuchten parameters of variably saturated media.
AU: Wheatcraft, S
EM: wheatcraft@unr.edu
AF: Univ Nevada Reno, Dept Geological Sci/172, Reno, NV 89557
AU: * Fenstemaker, T
EM: tomf@unr.edu
AF: Univ Nevada Reno, Grad Prog Hdro Sci/175, Reno, NV 89557
AU: Tyler, S
EM: tylers@unr.edu
AF: Univ Nevada Reno, Grad Prog Hdro Sci/175, Reno, NV 89557
AB: This research presents methodologies to determine a set of functions that alter the van Genuchten parameters (α, n and m) to describe the evolution of unsaturated hydraulic characteristics of geologic material as minerals dissolve and/or precipitate. Mualem (1976) proposed a method to predict soil hydraulic properties given a statistical distribution of pore sizes. Mualem's model describes a relationship between volumetric moisture content (θ), matric moisture potential (Ψ) and unsaturated hydraulic conductivity K(θ). Mualem's model states that as volumetric moisture content decreases the remaining water is retained in the smaller pore spaces by capillary forces. A capillary rise equation can be used to establish a relationship between moisture content and the maximum pore size that could retain water for that moisture content. These relationships suggest that a moisture retention curve for any sample can be correlated to a statistical distribution of pore sizes contained in that sample. Van Genuchten (1980) introduced a parameterized equation to describe any moisture retention curve predicted by Mualem's model. The three parameters (α, n and m) can be adjusted to fit many moisture retention curve with a reasonable degree of accuracy. In this research, the effect that geochemical changes have on the statistical distribution of pore sizes is investigated. As geochemical changes alter the pore size distribution, the moisture retention characteristics will also be altered thereby resulting in a change in the unsaturated hydraulic characteristics of geologic material. As a result of geochemical changes, the van Genuchten parameters (α, n and m) that best describe the altered moisture retention characteristics will also be affected. This research focuses on the methodologies needed to establish a quantitative relationship between the changes in a statistical distribution of pore sizes and the corresponding changes in the van Genuchten parameters (α, n and m) describing the unsaturated hydraulic characteristics of that pore size distribution.
DE: 1800 HYDROLOGY
SC: Hydrology [H]
MN: Fall Meeting 2005