The Hydrological Cycle in an Alpine Valley, Data Analysis and Simulation with the GEOtop ModelThis master?s thesis was written within the framework of the research project ?Climate Change in South Tyrol - How Vulnerable Are We?? and describes hydrological conditions of an alpine and partly glacierized catchment in the central Alps, called Matschertal, in South Tyrol.The components runoff and precipitation of the catchment?s hydrological cycle were quantified for the hydrological year 2009/2010.Within the analysis of discharge data, the preliminary discharge curve for the Saldurbach at the water gauge located in the catchment was determined, as well as the runoff regime. Precipitation data were controlled and water amounts of irrigation, which influence one station could be successfully individuated and deleted from data series. Furthermore, for five weather stations quantities of snowfall water equivalent were determined by an empirical approach based onprecipitation, snow depth, air temperature, humidity and radiation data, and added to the precipitation data series.Data gaps in stations could be successfully filled by using data from surrounding stations to interpolate precipitation.The spatially distributed hydrological model GEOtop was used for discharge simulation, as it fulfills the requirements of the research project and it is suitable for alpine catchments like the Matschertal examined in this master?s thesis. The model was calibrated and validated for two flood events in August, 2010.A sensitivity analysis was performed to identify the most relevant parameters for runoff simulations and their effect on peakflow and averaged runoff.Regarding the aims of this master?s thesis, the simulations showed quite good accordance with the observed values.Parameter settings of the effected calibration will be used for further simulations within the research project.