Semi-analytical Reactive Contaminant Transport Modeling in a Fractured Groundwater System

Understanding the contaminant transport phenomena in the fractured groundwater systems is of a great important in evaluating the safety degree of deep landfills to dispose of dangerous wastes. In this study, a semi-analytical solution to a reactive contaminant transport in a five-layer fracture-matrix groundwater system characterized by a thin rock matrix between the fractures. The governing equation in the fracture (not matrix) incorporates terms accounting for advection and longitudinal dispersion. Only one-dimensional vertical molecular diffusion is considered for rock matrix transport. The problem is solved under conditions of steady-state flow using the Laplace transform. The solutions in the real time domain are obtained by numerically inverting the solutions in the Laplace domain using the De Hoog algorithm. This study reveals that the parameters such as the mobile/immobile porosity ratio and the thickness of adjacent rock matrix layers may have a significant influence on contaminant mechanism through the system