Russo, D.

Zaidel, J.

Laufer, A.

Zaidel, J.

Laufer, A.

The applicability of results of Lagrangian‐stochastic analyses of vadosezone transport [Russo, 1993a, b] to realistic situations is investigated using results of detailed numerical simulations of transport in a hypothetical, yet realistic heterogeneous, partially saturated soil, obtained in the first companion paper (Russo et al., this issue) for both quasi steady state and transient, nonmonotonic flows. For both flow regimes, lower mean water saturation and longer travel time are shown to increase solute spreading, while lower water saturation and smaller travel distance are shown to increase the skewing of mean solute breakthrough curves. Solute plumes associated with the latter flow regimes, however, exhibit less spreading in the longitudinal direction and more spreading in the transverse direction, while the respective breakthrough curves are less skewed and less erratic, as compared with solute spreading and breakthrough associated with the former flow regimes. Components of the time‐dependent displacement covariance tensor, X and expected solute flux through a given horizontal control plane 〈s〉, based on the Lagrangian‐stochastic analyses, compared favorably with estimates of X and 〈s〉 obtained from the simulated transport under quasi steady state, essentially unidirectional flows, but failed to predict estimates of X and 〈s〉 obtained from the simulated transport under transient, nonmonotonic, multidirectional flows. The latter can be predicted by a particle‐tracking method [Rubin, 1990] that allows for deviation of the solute particles from their mean path, provided that the pertinent flow regime is quantifiable in terms of an appropriate velocity covariance function. Copyright 1994 by the American Geophysical Union.

Stochastic analysis of solute transport in partially saturated heterogeneous soil: 2. Prediction of solute spreading and breakthrough

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Russo, D.

Zaidel, J.

Laufer, A.

Zaidel, J.

Laufer, A.

Stochastic analysis of solute transport in partially saturated heterogeneous soil: 2. Prediction of solute spreading and breakthrough

The applicability of results of Lagrangian‐stochastic analyses of vadosezone transport [Russo, 1993a, b] to realistic situations is investigated using results of detailed numerical simulations of transport in a hypothetical, yet realistic heterogeneous, partially saturated soil, obtained in the first companion paper (Russo et al., this issue) for both quasi steady state and transient, nonmonotonic flows. For both flow regimes, lower mean water saturation and longer travel time are shown to increase solute spreading, while lower water saturation and smaller travel distance are shown to increase the skewing of mean solute breakthrough curves. Solute plumes associated with the latter flow regimes, however, exhibit less spreading in the longitudinal direction and more spreading in the transverse direction, while the respective breakthrough curves are less skewed and less erratic, as compared with solute spreading and breakthrough associated with the former flow regimes. Components of the time‐dependent displacement covariance tensor, X and expected solute flux through a given horizontal control plane 〈s〉, based on the Lagrangian‐stochastic analyses, compared favorably with estimates of X and 〈s〉 obtained from the simulated transport under quasi steady state, essentially unidirectional flows, but failed to predict estimates of X and 〈s〉 obtained from the simulated transport under transient, nonmonotonic, multidirectional flows. The latter can be predicted by a particle‐tracking method [Rubin, 1990] that allows for deviation of the solute particles from their mean path, provided that the pertinent flow regime is quantifiable in terms of an appropriate velocity covariance function. Copyright 1994 by the American Geophysical Union.

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