The hydrological cycle in a warmer world: combined effects of changes in snowmelt and evaporation on Rhine discharge evaluated with the new dS2 model

Recent and projected changes in the climate are known to affect the hydrological cycle. Many studies have shown how these climate changes result in differences in for example, evaporation rates, melt of snow and ice, precipitation patterns and seasonality. Since these processes are influencing different parts of the hydrological cycle, the hydrological response as result of changes in climate can be rather complex (Buitink et al., 2019b). In this study, we investigate how the combined effects of changes in melt from frozen water and increased evaporation rates affect the hydrological response in the Rhine basin, using the new dS2 model (Buitink et al., 2019a). It is known that increased temperatures affect both the melt of frozen water and the energy available for evaporation. However, as temperatures will reach melting point earlier in the year, the contribution of meltwater to the total discharge will also peak earlier in the year. Contrary, evaporation will increase without strong changes in the seasonality. Since the Rhine depends for a significant fraction on meltwater from snow and ice during warm and dry summers, this change in timing can have significant impacts on the low flows. This study shows these effects both for the recent changes in climate, but also presents the sensitivity of the hydrological cycle to the changes in the climate.

 

Buitink, J., Melsen, L. A., Kirchner, J. W., and Teuling, A. J.: A distributed simple dynamical systems approach (dS2 v1.0) for computationally efficient hydrological modelling, Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2019-150, in review, 2019a.

Buitink, J., Uijlenhoet, R., and Teuling, A. J.: Evaluating seasonal hydrological extremes in mesoscale (pre-)Alpine basins at coarse 0.5° and fine hyperresolution, Hydrol. Earth Syst. Sci., 23, 1593–1609, https://doi.org/10.5194/hess-23-1593-2019, 2019b.