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Prediction of hydrodynamic dispersion coefficient of saturated soil
Abstract
Prediction of hydrodynamic coefficient in saturated porous explored prediction of dispersion coefficient from average pore water velocity assuming either diffusion like model, namely convective-dispersion equation, or assuming single or multiple capillaries. Pore water velocity distribution utilizing capillary bundle model was not successful in prediction dispersion in soils. Previous approaches have taken different directions. They approached the problem assuming a geometric model which either used average pore water velocity or pore water velocity distribution inferred from water retention data. Both of those approaches were not sufficient to describe pore water velocity distribution. An interaction term in the model to account for the mixing of adjacent flow path was needed to describe dispersion more appropriately. In this work, pore water velocity distribution was described using basic soil property of unsaturated hydraulic conductivity function. The approach does not assume any specific pore geometry. The unsaturated hydraulic conductivity function was computed form soil water diffusivity measured by the one-step outflow method. A model with interaction term was considered to predict dispersion coefficient a priori. The interaction term was determined through the calibration of the model. The dependance of dispersion coefficient on average pore water velocity is also of prime importance. The dependance provides an approach to predict dispersion coefficient from average pore water velocity. The relationship was close to linear form with uncertainty as the factors involved in interaction between velocity, diffusion and geometrical configuration in determining dispersion coefficient. In this work, the relationship between dispersion coefficient and average pore water velocity was examined. The dependance of interaction on average pore water velocity was also examined.
Subject Area
Agronomy|Hydrology
Recommended Citation
Hussain, Samir K, "Prediction of hydrodynamic dispersion coefficient of saturated soil" (1990). ETD collection for University of Nebraska-Lincoln. AAI9030127.
https://digitalcommons.unl.edu/dissertations/AAI9030127