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

When working on wetlands, or other surface and subsurface water systems wit h multiple water sources, it is not always easy to identify the mixing betw een the different waters. Here, we have tried to adapt an easy technique, i .e., conductivity, but regularly standardised against stable natural isotop e O-18, to immediately give a glimpse on the field site of the percentage t he two kinds of water. In certain cases, this method is also valid to discr iminate a third source of water. The first experimental site to be describe d is in a meander of the Garonne river in south-west France, where there ex ists an interesting case of active paleo-channels. The second site is locat ed in North India, in the Himalayas mountains, Garhwal, at the source of th e Ganges river. Here, the samples were taken to discriminate between snow a nd glacier melt. (C) 2000 Elsevier Science B.V. All rights reserved.