In this paper we present runoff simulations for snow and icemelt for the basins of Rhine-Felsberg, Rhône-Sion and Ticino-Bellinzona. We use high resolution multispectral remote sensing data to map snow and ice cover of selected years. Further, we use GIS based extrapolation techniques to evaluate cloud and forest covered areas with respect to snow cover. We use the deterministic hydrologic model SRM+G to simulate the daily runoff of selected years. Conditions for a norm year in terms of normalized daily values for snow cover depletion, temperature and precipitation for the time period 1961 to 1990 have been established. Based on norm year conditions we did climate change simulations for the scenarios 2030 and 2100, which are characterized by increasing temperatures during winter and summer and increased precipitation during winter. The results show different characteristic behavior for the three basins. The highly glaciated basin Rhône-Sion shows an influence of enforced summer icemelt, the low glaciated Rhine-Felsberg and Ticino-Bellinzona an earlier snowmelt.