Water geochemical markers allow estimation of the impact of climate change on the hydrological regime of an Alpine river (River Arve, France, Switzerland)

The impact of climate change upon the hydrological regimes of streams has become an issue of major concern that requires adapted tools to detect and follow the scale of possible changes. In this study, we use a geochemical approach that exclusively relies on measurements of chemical concentrations in order to investigate the effect of climate change on the hydrological regime of the River Arve, a Franco-Swiss river running from the Alps to the River Rhone. Our method relies on the use of a dimensionless parameter, the ratio of uranium and barium concentrations in river waters. This marker has the advantage of not needing the measurement of river discharges. Its application to 25 years of data collected in the River Arve by Canton Geneva, Switzerland, leads to the conclusion that the glacio-nival signature is appearing earlier in the year and lasts for longer periods.