National Repository of Grey Literature 7 records found  Search took 0.01 seconds. 
Runoff formation in polar areas and runoff analysis in two selected catchments in the James Ross Island, Antarctic Peninsula
Vacková, Kateřina ; Jeníček, Michal (advisor) ; Nedělčev, Ondřej (referee)
Runoff in polar areas is strongly influenced by rising air temperature because these regions experience the largest air temperature increases in the world. Rising air temperatures affect permafrost, snow cover and glaciers which are the main components of runoff in high latitude regions. Warming is also causing the shift in precipitation phase from solid (snow) to liquid (rain) as well as changes in annual precipitation its distribution. With reducing extent of the snow and ice cover, the energy balance of the Earth's surface is fundamentally affected as the albedo is reduced, which leads to further warming of the Earth's surface. Changes in snow and ice cover lead to significant positive feedback loops in the climate cycle. This study includes analyses of meteorological and hydrological data measured in James Ross Island during the 2018 austral summer. Meteorological data were measured at eight automatic weather stations, and hydrological data were measured in seven catchments. However, in this thesis the analyses are focused on two selected catchments: the partly glaciated Triangular and the glacier-free Bohemian catchments. The influence of different meteorological variables on the catchment runoff was analysed using correlation and regression analyses. The analyses showed the highest...
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.
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....
Long-term changes in snow depth and snow water equivalent at selected mountain stations in Czechia
Kožíšek, Matěj ; Jeníček, Michal (advisor) ; Nedělčev, Ondřej (referee)
Long-term changes in snow depth and snow water equivalent at selected mountain stations in Czechia This bachelor's thesis deals with the topic of long-term changes of snow cover in the peripheral mountain ranges in the Czech Republic. The first part is a research of foreign and czech literature dealing with changes in the parameters of snow cover depending on climate change and the consequences of these changes on various components of nature. The second part of the work consists of the analysis of climatic data from stations located in the peripheral mountains of the Czech Republic in the period of hydrological years 1980-2014. The mountains included in this research include Šumava (Churáňov, Lenora and Husinec), Jizera Mountains (Bedřichov and Desná), Krkonoše (Harrachov), Orlické Mountains (Deštné and Rokytnice v O. h.) and Moravskoslezské Beskydy (Lysá hora). The statistical Mann-Kendall test is used to evaluate trends. Changes in snow cover have a significant impact on the functioning of many landscape processes and on the life of the population in terms of future water availability and recreation.
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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