MDL Groundwater software: Laplace transforms and the De Hoog algorithm to solve contaminant transport equations

The Modeling with De Hoog and Laplace (MDL) Groundwater software is a contaminant transport-modeling program offering a suite of models suitable for simulating subsurface transport of contaminants (i.e., chromium and organics), biotracers, and microorganisms. The MDL Groundwater software provides solutions to a wide range of contaminant transport models that do not have closed-form analytical solutions. The models are solved in Laplace space and the De Hoog algorithm is used to numerically invert the frequency domain solutions. Each particular model is represented as a closed-form Laplace-space or frequency domain solution to a specific set of transport equation(s), boundary conditions, and initial conditions using Fortan dynamic link libraries in the MDL Groundwater software. The windows interface is used to simulate and visualize concentrations of tracer, contaminant, or microbial transport in the time-space domain. The program’s strength is that it readily provides solutions to numerous contaminant transport equations while being suitable for a wide audience. Several models within the program can be used to investigate the fate and transport of biotracers and microorganism associated with the reduction of chromium. While others can serve as instructional tools providing expanded understanding of various physical, biological, and chemical processes affecting the fate and transport of contaminants and microorganisms in one-, twoand three-dimensional systems. r 2004 Elsevier Ltd. All rights reserved.