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Analysis of snowpack density in mountain catchments in Krušné Mountains and Šumava Mountains
Blšťák, Adam ; Jeníček, Michal (advisor) ; Vlček, Lukáš (referee)
Analysis of snowpack density in mountain catchments in Krušné Mountains and Šumava Mountains Abstract: Mountain catchments are very important sources of fresh water. These areas are characterized with long period of snow cover. The thesis presents analyses of snow density in mountain catchments, focusing mainly on factors and processes influencing its distribution. The data of data recorded in experimental catchments in the Krušné Mountains and the Šumava Mountains through 2010 - 2014 are compared with findings given in different scientific articles and studies. The thesis examines the influence of several factors on snow density. It is first of all the influence of snow depth, as well as the influence of vegetation, the development of density in time, and the development of snowpack density in relation to the snow water equivalent. The results of the research show that snowpack density gradually increases with snow depth. The highest density occurs on open plains and in damaged forests. Density also increases with time. The highest density can be observed towards the end of winter, in March and April. Keywords: snow density, snow depth, snow cover, mountain catchments
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Calculation of melt factors in a forest with different structure and in an open area in a small mountain catchment
Hotový, Ondřej ; Jeníček, Michal (advisor) ; Matějka, Ondřej (referee)
This bachelor thesis focuses on the development of snowpack in connection with effects of different physical-geographical factors, especially with the strong influence of vegetation on components of energy balance of the snowpack, including rainfall and runoff regimes of the area. The main aim of this thesis is to investigate the differences in snowmelt characteristics in an open area, under healthy coniferous forest and under forest infected by the bark beetle (Ips typographus). The snow depth and snow water equivalent data were obtained by field measurements at selected study sites in the experimental basin of Ptačí Brook in the Šumava Mountains during winter 2015/2016. The data were evaluated by simple conceptual method based on degree-day approach (temperature index), which examines the relationship between the snowmelt rate and air temperature. According to vegetation, degree-day factors were defined for each type of area as 1.71 mm řC-1 d-1 for healthy coniferous forest, 2.07 mm řC-1 d- 1 in forest infected by the bark beetle and 2.68 mm řC-1 d-1 in an open area. A simple model is a part of the thesis. It predicts the development of snow water equivalents using melt factors and it was used to evaluate the snow storages during snowmelt in study sites. Furthermore, it showed, that the most...
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Influence of catchment spatial subdivision on the accuracy of the snow accumulation and snowmelt model
Hájková, Barbora ; Jeníček, Michal (advisor) ; Šípek, Václav (referee)
Influence of catchment spatial subdivision on the accuracy of the snow accumulation and snowmelt model Abstract This thesis is focused on influence of catchment spatial subdivision on the accuracy of rainfall-runoff model simulations. A hydrological model HEC-HMS developed by U.S. Army Corps of Engineers was applied in the thesis. Study area includes two experimental catchments; Bystřice River basin and Zlatý Brook basin. Both catchments are located in the Krušné Mountains. The research in catchments has been carried out by the Department of Physical Geography and Geoecology since 2008. The influence of four different horizontal and vertical catchments delineation on runoff simulations was analyzed. The simulations were performed in two two-year periods 11/2008-10/2010 and 11/2010-10/2012. The attention was mainly aimed to snowmelt component of the model, for which temperature index method was chosen. The results of simulations were compared with water stages data measured in catchments outlets and with data from winter field measurements (snow depth and snow water equivalent). The results from both catchments showed that higher accuracy of simulation of the snow water equivalent was reached by dividing the catchments into more elevation zones. However, each of the catchments behaved in different way. The...
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Main controls affecting the occurrence and extremity of rain-on-snow events in the Ptačí potok basin in the Šumava Mts.
Paulusová, Barbora ; Jeníček, Michal (advisor) ; Hotový, Ondřej (referee)
Rain-on-snow events (ROS) are natural phenomena that have the potential to cause serious floods, wet avalanches and slushflows. Due to climate change the spatial distribution and intensity of ROS events is changing. Accordingly, ROS events become more frequent in high-elevation areas as well as in high latitudes, whereas their occurrence at low-elevation and low latitudes is less common. The behaviour of a snow coverduringrainfallandmechanismsofrainwaterpropagationthroughthesnowpackarestill poorly understood. A frequency and correlation analysis of ROS events in the Ptačí potok basin in the Šumava Mts. was conducted. The selected characteristics of the events were calculated from measured climate and streamflow data (2015-2019) and then analysed to examine the influence of individual characteristics on the development of ROS events. Results indicate a significant correlation between the amount of precipitation and the resulting outflow, as well as the influence of other snow and rain characteristics was shown. The time lag of outflow was mainly influenced by snow density. In order to evaluate the impact of climate change on ROS events, climate time series were analysed for the period 1961-2017 and a significant increasing trend in winter air temperature and decreasing trend in snow depth were...
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Melt rates calculation with respect to meteorological conditions
Šťovíček, Vít ; Jeníček, Michal (advisor) ; Hotový, Ondřej (referee)
Meteorological conditions are an important factor affecting the speed of snowmelt. Their impacts have been changing accroding to physical-geographical factors such as elevation, slope of the terrain, slope orientation and vegetation, affecting energy balance of the snowpack. The calculations were made using data from four automatic stations in the Šumava Mountains, namely the Vydra river-basin. These stations measure individual meteorological aspect and snow properties. Based on these data and pre-defined conditions, 136 melting events were selected. The melt factors were calculated based on degree-day approach. Similarly, the melt rates were calculated from the snow water equivalent decrease and snowmelt event duration for each snowmelt event. The correlation and regression analyzes were used to determine the effect of each meteorological factor on the snowmelt speed. The analyses proved the highest dependence of the snowmelt speed on the precipitation amount (the value of the Spearman's rank correlation coefficient rs reached 0.54 for the melt factor and 0.68 for melt rate). There is more substantial difference in the effects of meteorological conditions if we compare the winter season from November to February and the spring snowmelt season from March to May, while the highest snowmelt...
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Changes in snowfall fraction in cold season and their impact on spring runoff in selected mountain catchments
Blšťák, Adam ; Jeníček, Michal (advisor) ; Juras, Roman (referee)
The precipitation falling as rain or snow has different impact on regional water resources and their annual distribution. Shift from solid to liquid form of precipitation following the increase of the surface air temperatures could be important because such change could influence the timing of spring runoff and cause water scarcity in summer. In this study, the spatial and temporal variations of ratio of snowfall to total precipitation (Sf), mean air temperature, day of year of melt-out and winter and spring runoff is analysed. Data were examined for 11 meteorological and 6 hydrological stations in the mountains catchment in Czechia for November-April 1965-2014. Data were analyzed using the Mann-Kendall trend test. Major results show that Sf has been decreasing strongly throughout the whole examined area, with the strongest decrease in the foothill area of the northern mountains of Czechia. Stronger decrease is observed in lower elevations, at the stations with meant air temperature close to melt temperature. Strongest decrease was observed in March and the weakest decrease was observed in December and April, The significant decreases in Sf are associated with large increase in mean winter air temperatures. Due to the increasing mean air temperature in the cold season, the total rainfall is...
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Frequency and trend analysis of rain-on-snow events at selected meteorological stations in the Czech Rebublic
Kakalejčík, Matej ; Jeníček, Michal (advisor) ; Blahušiaková, Andrea (referee)
Rain-on-snow events represent a natural hydro-meteorological phenomenon and their occurrence is often associated with floods. Due to the climate change occurrence, rain-on snow events are also changing. The main goal of diploma thesis is to define spatial and temporal occurrence of rain-on-snow events at 16 selected meteorological stations in the Czech Republic between the years 1966-2012. Spatial occurrence of rain-on-snow events is expressed by number of events per meteorological station. Final number of events varies widely even between the stations with similar altitude. Stations with the highest frequency of rain-on-snow events are located in Jizerské hory between 675 and 780 m a.s.l. Temporal occurrence of rain- on-snow events is expressed by number of events per year and month respectively. Time series of rain-on-snow events were analysed by statistical trends to gain information about changes in occurrence over time. Most of the stations proved no statistically significant trend. There was a trend detected only at four out of 16 stations. Three meteorological stations showed a rising trend, whereas one station signalled a decreasing trend. More complex results were produced by the trend analysis of monthly time series of rain-on snow events. Nine stations yielded at least one month with a...
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Calculation of melt factors in a forest with different structure and in an open area in a small mountain catchment
Hotový, Ondřej ; Jeníček, Michal (advisor) ; Matějka, Ondřej (referee)
This bachelor thesis focuses on the development of snowpack in connection with effects of different physical-geographical factors, especially with the strong influence of vegetation on components of energy balance of the snowpack, including rainfall and runoff regimes of the area. The main aim of this thesis is to investigate the differences in snowmelt characteristics in an open area, under healthy coniferous forest and under forest infected by the bark beetle (Ips typographus). The snow depth and snow water equivalent data were obtained by field measurements at selected study sites in the experimental basin of Ptačí Brook in the Šumava Mountains during winter 2015/2016. The data were evaluated by simple conceptual method based on degree-day approach (temperature index), which examines the relationship between the snowmelt rate and air temperature. According to vegetation, degree-day factors were defined for each type of area as 1.71 mm řC-1 d-1 for healthy coniferous forest, 2.07 mm řC-1 d- 1 in forest infected by the bark beetle and 2.68 mm řC-1 d-1 in an open area. A simple model is a part of the thesis. It predicts the development of snow water equivalents using melt factors and it was used to evaluate the snow storages during snowmelt in study sites. Furthermore, it showed, that the most...
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Analysis of snowpack density in mountain catchments in Krušné Mountains and Šumava Mountains
Blšťák, Adam ; Jeníček, Michal (advisor) ; Vlček, Lukáš (referee)
Analysis of snowpack density in mountain catchments in Krušné Mountains and Šumava Mountains Abstract: Mountain catchments are very important sources of fresh water. These areas are characterized with long period of snow cover. The thesis presents analyses of snow density in mountain catchments, focusing mainly on factors and processes influencing its distribution. The data of data recorded in experimental catchments in the Krušné Mountains and the Šumava Mountains through 2010 - 2014 are compared with findings given in different scientific articles and studies. The thesis examines the influence of several factors on snow density. It is first of all the influence of snow depth, as well as the influence of vegetation, the development of density in time, and the development of snowpack density in relation to the snow water equivalent. The results of the research show that snowpack density gradually increases with snow depth. The highest density occurs on open plains and in damaged forests. Density also increases with time. The highest density can be observed towards the end of winter, in March and April. Keywords: snow density, snow depth, snow cover, mountain catchments
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Snow depth variability at the plot scale: Assesment of topography and vegetation influence
Murdychová, Pavlína ; Jeníček, Michal (advisor) ; Pevná, Hana (referee)
Snow depth variability at the plot scale: Assesment of topography and vegetation influence Abstract This master thesis deals with the evaluation of snow depth variability at the plot scale. It focuses on influence of topography and vegetation factors as slope, exposure, curvature, solar radiation and leaf area index. There is also assesment the impact of the size scale. Measurement was carried out in period of accumulation and snowmelt in winter 2014/2015 in the Krkonoše Mountains on Hanapetrova glade. To evaluate the effect of selected factors on variability of snow depth there was used multiple linear regresion and other descriptive statistical methods. The research shows that the variability of snow depth during the accumulation is greater in forest which is probably due to vegetation. The dependency was not confirmed by regression analysis. Higher variability of snow cover in the forest was also observed in the melting period. The variability of snow cover increased in the forest in general. The results show that the snow depth variability decreasses with increasing grid size. Keywords: snow accumulation, snowmelt, topography, vegetation, multivariate analysis
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