Tracer-basierte Modellkalibrierung von Abflussprozessen in einem vergletscherten Einzugsgebiet in den Alpen.

Glaciers play an important role in the water budget of alpine catchments. Especially for valleys with relatively little annual precipitation and an increasing use of water for agricultural irrigation, it is essential to understand the complex role of rainfall, snow and ice melt contribution to river runoff and groundwater recharge. This study aims to assess the main surface and subsurface contributions to the stream runoff by means of isotopic (δ18O) and electrical conductivity data in a glacierized catchment, in order to get insights about the main hydrological processes governing catchment behavior and to use them to calibrate the parameterization of the distributed hydrological model GEOtop 1.2. Experimental and modeling activities were carried out in the Saldur basin, located in the Eastern Italian Alps (62 km2 drainage area). Observed discharge data of a subbasin (WG3, 11 km² drainage area ) was compared to simulated discharge for a calibration period of 4 days in August 2011. The study highlights the dominant effect of snow melt contribution to surface runoff and groundwater recharge at Saldur basin. First model simulation results show the most important parameters controlling daily runoff variations (lapse rate, snow reflectivity, land surface resistivity, lateral hydraulic conductivity).