Methods
In this study, the models were built using Visual MODFLOW software, which is the most popular and internationally recognized professional standard visualization software system for 3D groundwater flow and solute transport simulation and evaluation. The system was developed by Waterloo Hydrogeology Canada based on the original MODFLOW software and has a powerful graphic visual interface function. The model area and the calculation unit can be circled directly on the computer, and the values for each unit and boundary condition can be assigned directly on the computer.
In this study, a quasi-ideal model is used to add the hydrogeological parameters of the actual area to the ideal model. The study area of the ideal model is a 10 km × 20 km rectangular area, with 10 km × 12 km of groundwater recharge area on the left side of the piedmont plain, 10 km × 8 km of wetland on the right side, and 4 km × 4 km of lake in the middle of the wetland.
In the ideal model, the western boundary is set as the flux boundary, the eastern boundary is the constant head boundary, the western boundary of the wetland completely cuts the phreatic aquifer, the direction of groundwater flow in the study area is from west to east, and the contour of the groundwater level is perpendicular to the north and south boundaries, which is set as the no-flux boundary. The generalized schematic diagram of the simulation area is shown in Figure 2.