Abstract
[1] Runoff generation in Alpine regions is typically affected by snow processes. Snow accumulation, storage, redistribution, and ablation control the availability of water. In this study, several robust parameterizations describing snow processes in Alpine environments were implemented in a fully distributed, physically based hydrological model. Snow cover development is simulated using different methods from a simple temperature index approach, followed by an energy balance scheme, to additionally accounting for gravitational and wind-driven lateral snow redistribution. Test site for the study is the Berchtesgaden National Park (Bavarian Alps, Germany) which is characterized by extreme topography and climate conditions. The performance of the model system in reproducing snow cover dynamics and resulting discharge generation is analyzed and validated via measurements of snow water equivalent and snow depth, satellite-based remote sensing data, and runoff gauge data. Model efficiency (the Nash-Sutcliffe coefficient) for simulated runoff increases from 0.57 to 0.68 in a high Alpine headwater catchment and from 0.62 to 0.64 in total with increasing snow model complexity. In particular, the results show that the introduction of the energy balance scheme reproduces daily fluctuations in the snowmelt rates that trace down to the channel stream. These daily cycles measured in snowmelt and resulting runoff rates could not be reproduced by using the temperature index approach. In addition, accounting for lateral snow transport changes the seasonal distribution of modeled snowmelt amounts, which leads to a higher accuracy in modeling runoff characteristics.
Highlights
[2] Runoff in Alpine regions is largely controlled by snow accumulation, storage, redistribution, and melting
This paper will report about the investigation of the influence of different snow model approaches on modeling runoff dynamics in complex, high Alpine terrain
It is characterized by an extreme topography with mountain ranges covering an altitude from 603 to 2713 m above mean sea level (MSL)
Summary
[2] Runoff in Alpine regions is largely controlled by snow accumulation, storage, redistribution, and melting. Depending on the purpose of the model application, e.g., runoff simulations, flood or avalanche forecasting, glacier mass balance, or small-scale snow physics studies, many snow models have been developed. [4] In distributed hydrological models, index approaches are most commonly used because of their simplicity, robustness, and efficiency It is obvious, that they are not suitable tools to produce reasonable results for snow cover development in complex Alpine terrain on WARSCHER ET AL.: COMPLEX SNOW DESCRIPTIONS IN A HYDROLOGICAL MODEL regional to local scales. Rigon et al [2006] recently developed a distributed hydrological model system to simulate coupled mass and energy fluxes in Alpine catchments. The required data to run the model consist of spatially distributed data sets to describe topography, land use, and soil parameters as well as station measurements of meteorological variables.
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