Application of a model for simulating transport of reactive multispecies components to the study of the hydrochemistry of salt water intrusions

A model for simulating transport of reactive multispecies components has been applied to simulate the chemical changes occurring during salt water intrusion in a confined aquifer. One-dimensional reactive flow in permeable media is simulated by means of a numerical method which assumes local thermodynamic equilibrium. The method uses a set of partial differential equations, based on the conservation of mass, applied to each one of the chemical elements of the system (instead of applying them to the chemical species). In this way, the solution of the problem is simpler since the term which takes into account the addition or loss of mass by reaction is eliminated. The differential equations have been solved together with the proposed equilibrium equations, and the material and charge balances between the different chemical species and elements. The model has been applied to predict and analyze the laboratory experimental data of C.A.J. Appelo and coworkers which had not been represented exactly using existing models. The model presented predicts and explains these experimental data perfectly.