Seasonal discharge response to temperature-driven changes in evaporation and snow processes

Abstract. This study analyses how temperature-driven changes in evaporation and snow processes influence the discharge in large river basins. Using a distributed efficient hydrological model at high spatio-temporal resolution, we investigate the relative contribution of snow and evaporation. Comparing two 10-year periods (1980s and 2010s) in the Rhine allowed to determine the contribution of changes in snow, evaporation and precipitation to the discharge. Around half of the observed changes could be explained by the changes induced by snow (11 %), evaporation (19 %) and precipitation (18 %), while 52 % was driven by a combination of these variables. Increased temperature scenarios show that seasonal changes in snow-dynamics could offset a fairly constant negative change in relative runoff induced by evaporation, but not during the melt season. This study shows how the combined effect of temperature-driven changes affect discharge. With many basins around the world depending on meltwater, correct understanding of these changes is vital.