SnowModVis - Improving the runoff forecast with focus on snow cover modeling and monitoring for optimization hydropower generation of VERBUND Trading GmbH

The VERBUND AG operates the time-continuous conceptual rainfall-runoff model COSERO (Nachtnebel et al., 2009) as part of its forecasting system. The processes considered include snow melting and snow accumulation, interception, evapotranspiration, temporal dynamics of soil moisture, the division of the runoff into the three runoff components, surface runoff, interflow and base runoff, and the routing of surface runoff and channel runoff. Spatially distributed temperature and precipitation data are currently required as input data. Depending on the data situation, COSERO can calculate with variable time steps and be operated in different spatial discretizations or on the basis of HRU's. Snow accumulation and snow ablation are currently calculated using a relatively simple approach, the so-called "day-degree" method (e.g. Martinec, 1960). This has the advantage that they are based only on the input variables of temperature and precipitation. A crucial disadvantage is that the snow melt essentially depends on the available radiation and for this the air temperature is only a limited reliable approximation. Furthermore, the lateral snow transport processes have not yet been implemented in the COSERO model system, which can lead to the fact that the snow masses in the model are on average in too high locations and thus the runoff forecast can be negatively influenced. As part of the offered project, a new snow module is to be developed or adapted, which is based on the energy balance and takes lateral snow movements into account on the subscale. The performance of the overall model may e.g. in order to calculate the inflow into the storage lakes with respect to the computing time, so that there is a trade-off between the quality of the model and the necessary computing times.