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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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Modelling the impact of seasonal snowpack on summer low flows in mountain catchments
Nedělčev, Ondřej ; Jeníček, Michal (advisor) ; Šípek, Václav (referee)
This thesis analyses the impacts of winter snowpack and subsequent spring and summer liquid precipitation on low flows in the warm season. Meltwater is an important source of groundwater recharge. From groundwater storage streams are donated during summer months. Snow accumulation during cold season is reduced and snowmelt occurs earlier, which is a result of climate change and leads to lower groundwater recharge rates. That is the reason why change in snow cover dynamics affects summer low flows. Main goals of this thesis are to analyse how snow cover affects low flows I warm season and to compare it with impact of spring and summer precipitation. A conceptual runoff model HBV-light has been used to simulate the snow water equivalent (SWE) and streamflow from three mountain catchments. The integrated multi-variable model calibration procedure was used to calibrate the model. The model was used to simulate the snow and streamflow from 1981 to 2014. Besides the mentioned simulation, two hypothetical scenarios have been performed. These two scenarios accounted for reduced spring and summer liquid precipitation. In the first scenario, precipitation after maximum annual SWE was reduced to 75% of the real measured precipitation. In the second scenario, precipitation was reduced to 50% of the real...
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