For the calculation of the groundwater isolines of the main aquifer, the irregularly distributed groundwater measurement data (base points) were transformed into an equidistant grid with the aid of a program for the calculation and graphic representation of surfaces (Surfers 7.0, by Golden Software). This was accomplished by interpolation according to the Kriging method. The 400-meter grid size produced a network of 14,241 nodes. The groundwater isolines were represented on the basis of this grid, after smoothing.
