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Multi-criteria calibration of a hydrological model using runoff, snow water equivalent and groundwater level data
Hlavatý, Vojtěch ; Jeníček, Michal (advisor) ; Šípek, Václav (referee)
Multi-criteria calibration of a hydrological model (against multiple output variables simultaneously) has in previous research mostly resulted in satisfactory quality and reduced uncertainty in the simulations of all variables considered. However, its importance in the context of groundwater and low flows has rarely been studied. Therefore, a multi- criteria calibration using observed runoff, snow water equivalent and groundwater level data was performed in this study to determine if this approach leads to more accurate simulations, especially for low flows. The HBV hydrological model was calibrated using a genetic algorithm on the case of 14 mountain and sub-mountain basins in Czechia. The accuracy of different calibration variants was evaluated according to objective functions and hydrological signatures. The results show that multi-criteria calibration against the three mentioned variables is a good compromise for correct simulation of all these variables, where the value of objective function for each of them differs only slightly from a calibration more focused on it alone. Considering groundwater in the calibration further increases the simulated baseflow and its variability and refines the simulation of low flows, especially in summer, in terms of deficit volumes, minimum runoff and other...
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Snow drought and its importance for runoff in the context of changes in climatic and snow characteristics
Hlavatý, Vojtěch ; Jeníček, Michal (advisor) ; Nedělčev, Ondřej (referee)
Snow drought, defined as a lack of snow accumulation, is one of the consequences of increasing air temperature, which has a considerable impact on the runoff generation as it provides a substantial part of water supplies in the warm season. However, the attention to snow drought has been paid mainly to North America. Therefore, this work aimed to evaluate the current state of research on this topic and to analyze data from the Churáňov station in the Šumava Mountains. Long-term trends in climatic and snow characteristics in the period 1966-2017 were described using linear regression and Mann-Kendall test and relationships between them were examined by correlation coefficients. Consequently, the occurrences of snow drought were classified using different approaches. According to the results, the main cause of interannual changes in snow storage in the Šumava Mountains was the increasing mean cold season air temperature, causing a decrease in snowfall and thus a reduction in the maximum snow water equivalent, which can be intensified by a decrease in cold season precipitation. This was also indicated by the frequency of different types of snow drought, especially an increase in warm snow-poor seasons, which, considering the predicted climate change, highlighted the importance of this phenomenon....
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