### Model of the initial state

The 3D model was set up to determine the potential values (piezometric levels) and a free surface level with a sealing wall but without any pumping. The determined piezometric levels at the bottom of the aquifer are depicted by means of contours of potential. The flow of groundwater is uniform at the aquifer’s bottom and the field of velocity is therefore homogeneous. The picture shows the contours of potential at the free surface level. It seems from the picture that the barrier effect of the sealing wall at this level has already shown itself by curving the equipotentials and by changing the character of the velocity field.