Numerical evaluation of groundwater flows: MODFLOW vs. FE models

Abstract

[Abstract] In this contribution, a finite-element model (FLUMP) that numerically assesses the groundwater flow through porous media is compared with the MODFLOW standard software. FLUMP constitutes a nonlinear MATLAB code developed by the present authors in 2018 that evaluates the flow in unconfined saturated heterogeneous and anisotropic porous media. The model also incorporates a tool for evaluating the free surface flow through the conservation of mass. The present contribution illustrates the benefits of this code through its comparison with the broadly used finite-difference software MODFLOW, highlighting the main benefits of both approaches in the assessment of flow in porous media. In order to do so, Wang's benchmark problem of the lowering reservoir has been used for checking and comparison purposes, after which FLUMP and MODFLOW have been compared in the assessment of the Barces Watershed, a practical case deeply monitored and modeled by the present research team in the last decade. The so-developed code does not claim to take the place of a powerful and broadly employed tool such as MODFLOW, a de facto standard for the international hydrogeologic community, but it just humbly emphasizes the benefits and drawbacks of finite-difference models versus finite-element ones in the resolution of the flow through porous media, and in particular of these two approaches here being considered.