Mathematical modelling of the dynamics of mountain basin snow cover in Moravian-Silesian Beskydy for operational purposes

Abstract

The objective of this paper is to evaluate the applicability of models and methods available for research to simulate runoff from snowmelt for operational purposes. Both the HYDROG model exclusively used in operational practice in the Czech Republic and the HEC-HMS model were evaluated in this study. In both models has been implemented the temperature index method to meet the given purpose of usage. While the HYDROG model is in fact basic implementation of the temperature index method, the HEC-HMS allows inclusion of other factors into the calculation, which are affecting the studied process, such as the cold content of snow cover, snowmelt above the active surface, thermal deficiency of snow cover, variability of thermal factor. HEC-HMS allows the division of the research area or river sub-basins into altitudinal zones. The upper stream of the Ostravice River was selected as the area of interest. Simulation was carried out on episodes occurring in 2006 and 2009. Although the temperature index method is not widely recommended for simulating the runoff for a time period shorter than one day, the results from both models in the given area proved that using appropriate input data, as well as parameterisation, can result in the values which are accurate enough even in one hour time periods. The value of the Nash-Sutcliff coefficient is larger than 0.5 in almost all cases, which generally indicates a satisfactory behaviour of the models during the simulation. Similarly, the satisfactory results were achieved with other criteria used for assessing the accuracy of modelling. Complementing additional parameters into the temperature index method using HEC-HMS enabled better simulation of snow-melt conditions than the simulation with HYDROG.