In the next step, a model calculation is carried out with the geometrically correct overall mesh. In order to obtain comparable results, it is important to ensure that the same programme/parameter combination is used when calculating the partial model and the overall model.

The plausibility check is carried out by comparing the groundwater equations of the calculated free groundwater surface of the integrated overall model with those calculated with the old overall model and the partial model.

As expected, differences will occur in a zone around the model boundary of the sub-area. As the recalibration of a partial model is not usually limited to the inside of the model, this results in changes in the flow situation that also have an influence on the model boundary.

The boundary flow determined from the old overall model and kept constant in the partial model as a boundary condition also leads to changes in the groundwater levels in the boundary area during the adjustments made in the course of the partial model calibration. When calculating with the integrated overall model, the constraint due to the specified boundary condition is now eliminated and the model can create a balance between the situation in the overall area and the new situation in the improved partial model area.

A balancing comparison of the boundary flows of the partial model specified as boundary conditions with the rates that flow over this area in the integrated overall model can also be carried out.

Notes and recommendations