The statistical evaluation of isotope measurements in precipitation shows that Deuterium values of precipitation and natural waters of meteoric origin are linearly correlated with those of O-18, forming the so-called global waterline, or global meteoric waterline.
For water subjected to evaporation, the linear correlation between the Deuterium and O-18 values still holds, but a slope of evaporation line is less senses slope of the mean of the meteoric water line. And the meteoric water line is therefore a kind of reference line against which any measuring point can be compared. The result of the comparison provide a fingerprint of this sample and indicate whether the sample represents surface water, like here, ground water recharged by rain mainly along the meteoric line, ground water containing irrigation, when it can lay on this, when it is situated along this line, or a mixture between fresh ground water and lake water. Proportions of the mixing components can be calculated.