Correlation of conductivity and stable isotope 18O for the assessment of water origin in river system

When working on wetlands, or other surface and subsurface water systems with multiple water sources, it is not always easy to identify the mixing between the different waters. Here, we have tried to adapt an easy technique, i.e., conductivity, but regularly standardised against stable natural isotope 18O, to immediately give a glimpse on the field site of the percentage the two kinds of water. In certain cases, this method is also valid to discriminate a third source of water. The first experimental site to be described is in a meander of the Garonne river in south-west France, where there exists an interesting case of active paleo-channels. The second site is located in North India, in the Himalayas mountains, Garhwal, at the source of the Ganges river. Here, the samples were taken to discriminate between snow and glacier melt.