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The application of three temperature-index based models and of one energy balance based snowmelt model was investigated. The snow models were integrated in the spatially distributed hydrological model PREVAH. In this study the hydrological simulations of the alpine catchment of the Dischmabach in Switzerland in the period 1982-2000 have been analyzed. The PREVAH model was driven by hourly interpolated meteorological data. All snowmelt approaches allowed a good simulation of the discharge regime and of the seasonal course of the snowpack. The highest model efficiency was obtained by a radiation based temperature-index approach. A simplified energy balance approach combined with the positive degree-day method showed a very similar performance to the classical positive degree-day approach. The energy balance approach ESCIMO showed a high performance variability from year to year. The dependency of the seasonal water balance with respect to altitude is also discussed in this report. The quality of the spatially distributed reproduction of periods with positive and negative water balance (snow accumulation and snowmelt) is crucial for the correct simulation of the runoff hydrograph. The analysis shows that runoff maximum in the Dischmabach catchment is caused by a superposition of the main snowmelt season in the areas between 2,100-2,800 m a.s.l. and the period with maximum rainfall.
Zappa et al. (Sun,) studied this question.