National Repository of Grey Literature 3 records found  Search took 0.01 seconds. 
Heavy snowfall in Czechia and snowfall extremity evaluation
Kolář, Šimon ; Müller, Miloslav (advisor) ; Nedělčev, Ondřej (referee)
The thesis deals with selected heavy snowfall events and evaluation of their extremity in Czechia in the period 2009-2013. Based on a literature search, four methods to assess the extremity of heavy snowfall events are described. In Czechia, the only tool used so far is the highest recorded depth of fresh snow, which represents an indication of point extremities. Another option is to evaluate the size of the area with the depth of fresh snow according to the criteria of the Integrated Warning Service System. The third way is the regional snowfall index (RSI), considering not only the size of the affected area but also the number of population in it. It would also be possible to assess the heavy snowfall events with the help of the weather extremity index (WEI), which would quantify the area distribution of return periods of depth of fresh snow at meteorological stations. In the second part of the thesis, the extremity of four selected events is evaluated using the first three criteria and the differences resulting from the tools used are pointed out. The results of the extremity assessment of individual heavy snowfall events according to different indices show a difference in the results in the extremity assessment for the same event depending on the evaluation index used. We record the maximum...
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...
Effect of canopy interception on snow accumulation at selected alpine localities in the Czech Republic
Nedělčev, Ondřej ; Jeníček, Michal (advisor) ; Falátková, Kristýna (referee)
This bachelor thesis analyzes the impact of canopy interception on snow accumulation. In the first part of the thesis, available literature about interception of snowfall on forest canopy is reviewed. In the second part of thesis, the reader is acquainted with the analysis concerning the effects of forest cover on snow accumulation. The thesis compares snow water equivalent under forest stands with different canopy density, under a disturbed forest due to bark beetle forest with snow water equivalent in adjacent open areas. Snow water equivalent in accumulation period in forest is 28% lower than snow water equivalent in open area. Ratio of snow water equivalent in forest to snow water equivalent in open area during accumulation period does not significantly change. Linear regression was used to describe the relationship between snow water equivalent and canopy density. The findings obtained from the regression show that snow water equivalent decreases with increasing canopy density.

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