A three-dimensional numerical model for variably saturated groundwater flow using meshless weak-strong form method

Meshless numerical models have attracted much attention due to the circumvention of troublesome mesh generation. Current meshless numerical groundwater (GW) models either focus on only pumping in fully saturated zone or merely simulate variably saturated GW flow without pumping. However, these two components are both essential for a GW model to represent practical real-world conditions. This gap is bridged in this study by developing a three-dimensional model, CCHE3D-GW-Meshless, using the meshless weak-strong form method. The new model code was verified with three representative cases, and good agreement was found with the analytical/numerical solutions in all cases. CCHE3D-GW-Meshless was then applied to a field case of a pumping well near a meandering river located at Shellmound, Mississippi, USA. The hydrological properties of the site were obtained through calibration which yielded a generally good match with observed data considering the incompletely known heterogeneity in aquifer properties, indicating the applicability of the model. •A meshless groundwater model using weak-strong form method is developed.•This meshless model can simulate pumping in variably saturated groundwater flow.•This model has been successfully applied to a pumping well near a meandering river.