Simulación numérica de las fluctuaciones inducidas por marea en acuíferos libres

Abstract

Coastal zones represent one of the most complex hydrogeological scenarios, as the aquifers in these areas are in direct hydraulic contact with freshwater or saltwater bodies. Hydraulic characterization of flow in these aquifers is crucial to optimize production and prevent contamination. Since traditional pumping tests can be costly and prohibitively expensive, alternative non-invasive methods have been implemented, such as the induced tidal method, which was studied through both the development of analytical solutions and numerical methods. However, analytical solutions are valid for very limited cases and are generally not applicable to unbound aquifers. The objective of this work is to use a numerical method to solve the flow equation in an unbound aquifer subject to tidal fluctuations, using an algorithm based on the Finite Element Method. Using this tool, different hypothetical scenarios were studied to analyze the effect of the various hydraulic and geometric parameters that affect the induced tidal response in unbound aquifers. In addition, the hydraulic response was analyzed using a tide gauge signal measured off the coast of the Rio de la Plata during a Sudestada event as a boundary condition. Finally, numerical simulation was used to estimate hydraulic conductivity by fitting signals recorded in two wells near the Rio de la Plata. The resulting fits were compared with previous estimates, validating the usefulness of the proposed numerical tool for this particular case.