Influence of heterogeneity on subsurface contaminant transport is one of the most important and challenging tasks in contaminant hydrogeology, and it often requires a stochastic approach that is found to be difficult to apply in real-world problems. This thesis adopts a simple analytical approach to investigate the influence of heterogeneity structure on contaminant transport in a one-dimensional setting. Compared with numerical models, analytical treatment is more commonly used for this issue, since it is straightforward to apply and is free from numerical problems such as numerical dispersion and artificial oscillation. This thesis assumes that Fickian dispersion is valid and uses the advection-dispersion equation (ADE) as the governing equation for studying one-dimensional contaminant transport in a heterogeneous system consisting of two zones with different transport properties, first-order reaction and linear sorption. The governing equation is solved in Laplace domain and the solution is obtained in real-time domain using a numerical inverse Laplace transform program named the de Hoog algorithm. A MATLAB program is created to facilitate the computation. Through analyzing several conceptual cases, the results of this research reflect that: (1) The order of heterogeneity will affect the contaminant transport in the two-zone porous media; (2) The difference of transport properties will affect the contaminant transport results when the order of heterogeneity reverses; (3) The accuracy of parameter homogenization will decrease with the increasing difference between parameters of the two zones. The homogenized parameter values will depend on the order of heterogeneity; (4) Dispersivity has the greatest influence on the results of BTCs, and it is also the most difficult one to be homogenized. The accuracy of homogenization of dispersivity is scale-dependency; and (5) When there are multiple parameters to be homogenized simultaneously, the homogenized solutions may be out of the range bonded by the parameter of two zones. This research is expected to fill the gap of subsurface heterogeneity structure influence on solute migration in two-zone porous media.
ETD Chair
Zhan, Hongbin Holder of Endowed Dudley J. Hughes '51 Chair in Geology and Geophysics
