A reduced-order framework for three-dimensional-equivalent confined groundwater modeling with emphasis on well-boundary implementation

Groundwater management frameworks rely on budget-friendly mathematical groundwater flow models for identifying sustainable policies. Such models should be capable of modeling well-flow hydraulics and aquifer dynamics simultaneously. A robust well-flow model considers the finite well radius to estimate the hydraulic head distribution in and around a pumping well, considering the effects of partial well penetration, well-bore storage, and well-bore skin. This paper introduces the concept of well-boundary to develop a three-dimensional (3D)-equivalent 2D confined groundwater flow modeling framework for monitoring natural aquifer systems. The developed OpenFOAM ® -based model— modFlowFOAM —implements the analytical solution of the well-hydraulics problem for confined aquifer systems as a Dirichlet boundary condition on the well boundary to account for the vertical flow in the neighborhood of the pumping well. To minimize the computational burden (CPU time and usage) involved in modeling large-scale confined aquifer systems, a reduced-order modeling solver for the modFlowFOAM library has also been developed. The numerical results of modFlowFOAM depict excellent correspondence with the MODFLOW results and other numerical results presented in the literature for various well-hydraulics and confined-aquifer flow problems involving regional and synthetic aquifer systems. The accuracy and efficiency of modFlowFOAM ensure its potential applicability to characterize the dynamics of confined aquifer systems.