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Using automatic snow depth and snow water equivalent data to minimize the error in winter precipitation measurements
Peňáz, Štěpán ; Jeníček, Michal (advisor) ; Jirák, Jan (referee)
The measurement of winter precipitation represents one of the largest uncertainties in the calculation of the hydrological balance. Manual measurement of winter precipitation is time- consuming, costly in terms of personnel and money, and is for this reason not often carried out. The measurement of winter precipitation using a heated rain gauge is in turn affected by wind and partly by the increased evaporation caused by heating. Therefore, automatic snow depth measurement is increasingly used and is becoming more affordable over time. This paper deals with the analysis of automatically measured data from a heated rain gauge, from ultrasonic or laser sensors for snow depth measurements, and from sensors for snow water equivalent measurements in order to find the dependence of new snow density on air temperature and on air humidity. Subsequently, a multiple linear regression equation was derived to calculate the density of new snow, which, together with the new snow accretion, was used to calculate snowfall totals. In addition, alternative winter precipitation was calculated and measured by sensors to calculate the snow water value as well as reference winter precipitation measured by a rain gauge from a manned station. The accuracy of these three precipitation alternatives was assessed using the...
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Modelling of runoff changes due to forest disturbances in the Šumava catchments
Švejdová, Klára ; Jeníček, Michal (advisor) ; Šípek, Václav (referee)
Runoff conditions in river basins are heavily influenced by vegetation cover. Changes in the vegetation linked to forest disturbances significantly affect the water balance of the river basin. These changes can be effectively quantified using hydrological models. Therefore, this thesis aims to describe water balance change in forests disturbed by bark beetles and storms. Three model experiments were simulated using the HBV precipitation-runoff model for Roklanský potok, Ptačí potok and Rokytka catchments in Šumava, Czechia. All these catchments underwent significant forest damage after recent disturbance. First experiment used the split sample test method. Calibration was performed separately for the period before and after disturbance, and then simulated for the whole period. The resulting simulated runoffs notably differ from one to the other, which may be caused not only by deforestation, but also by the effects of climate and the characteristics of individual catchments, which also affect their runoff response. The second model experiment was based on changes in vegetation-dependent parameters (melt factor and snowfall correction factor) and analysis of their effect on the simulated runoff. The results did not reveal significant changes in the monitored runoff characteristics. However, this is...
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Effect of climate change on hydrological extremes in montane catchments
Čermák, Daniel ; Langhammer, Jakub (advisor) ; Jeníček, Michal (referee)
This master thesis deals with the issue of low-flows in mountain catchments in the context of expected climate change. The Zdobnice, Vydra and Mumlava river basins are selected for analysis. In the first part of thesis, the meteorological and hydrological historical data are evaluated. This data are obtained from CHMI (Czech Hydrometeorological Institute). The work also focuses on estimating the possible change in flow rates in the distant future (2100). For these purposes, the conceptual model HBV is used. This model is often used for these types of analyzes due to its robustness. To evaluate the change, twelve alternative scenarios were created. These scenarious were based on the results of global and regional climate models related to each selected river basins. The model was calibrated using the automatic GAP optimization function. Based on the best results, the calibration period is set for the years 1980 - 1998. Climate models suggest increase of temperature in far future by 1.5 ř C - 4.5 ř C. At the same time, according to climate models, we can approximate a total precipitation change by 10 %. Based on climate changes, a shift in the runoff seasonality in the all river basins is evident. Seasonality change is most visible in the Zdobnice river basin. In terms of hydrological drought, an...
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Effect of selected physical-geographical factors on the snow accumulation and snow melt
Pevná, Hana ; Jeníček, Michal (advisor) ; Langhammer, Jakub (referee)
Effect of selected physical-geographical factors on the snow accumulation and snow melt Abstract: This master thesis analyzes the influence of physical-geographical factors on spatial distribution of snow water equivalent, and its evolution. In this work, emphasis is placed on describing the influence of vegetation, aspect and altitude. Measurement was carried out in experimental catchments Zlatý Brook and Bystřice River in western part of the Ore Mountains in winters 2008/2009, 2009/2010, 2010/2011 and 2011/2012. To evaluate the influence of these factors on value of snow water equivalent there was used one of the methods of multivariate statistical analysis - cluster analysis. The research shows that the greatest influence on the distribution and evolution of snow water equivalent in the experimental basins has vegetation and some dependency was proved also between the points of southern exposure. The measurement results demonstrate the suitability of cluster analysis for analyzing the data of point values of snow water equivalent. On the other hand the results showed the main limits of this method, especially the need for a large number of points with different characteristics. The results of measurements and statistical analysis are compared with results published in technical literature. Keywords: snow...
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Land cover changes in Ore Mountains and their possible impact on rainfall-runoff process
Kratochvílová, Petra ; Jeníček, Michal (advisor) ; Královec, Václav (referee)
Land cover changes in Ore mountains and their possible impact on rainfall-runoff process Abstract Land cover changes have occurred since the formation of Earth, but increasingly, these changes mainly in anthropogenic characters, a big problem in many places around the world. It is, therefore, necessary to monitor how land cover changes, and its impact on individual natural processes and use these results of studies in preventing or fix possible consequences of these changes. More and more disciplines are, therefore, also examines this issue. This paper deals with the assessment of land cover change and its impact on rainfall- runoff process, focusing mainly on mountain basin where this influence manifests itself most expressive, both influencing the water balance of the basin, and influence responses to extreme hydrological events. The findings are applied to the upper basin Chomutovka in the Ore mountains where the thesis evaluates changes in land cover on the basis of aerial photos from 1975, 1987 and the present day (2010). Changes are visualized using digital vectorization and color differentiation of areas of individual land cover types, further processed into a map series and subsequently quantified. According to the results are established the major factors of possible rainfall-runoff processes in...
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Modeling the impact of small water reservoirs on flood events
Taufmannová, Alice ; Jeníček, Michal (advisor) ; Daňhelka, Jan (referee)
This paper deals with evaluating the impact of small reservoirs on flood events. The system of small reservoirs represents an effective part of integrated flood protection in the Czech Republic. Its realisation does not require a drastic impact on the environment. The small reservoirs could influence significantly the decrease of flood flows in the mountain catchments. Four small potential uncontrolled reservoirs were implemented to the headwater part of the Rolava river basin (126 km2) in the Ore Mountains. The relief of the Rolava river basin is heterogeneous with the upper headwater part characterised as flat plain and the middle part of the river flowing through a steep valley. The only option of the river to be flooded out during the extreme floods could appear in the lower part of the river basin. The Rainfall-runoff modeling was carried out in the model HEC-HMS (Hydrologic Engineering Center - Hydrologic Modeling System). The advantages of the model are its freeware availability, good arrangement and connection with GIS. The basin model of Rolava was calibrated using the known flood event in September 2007. The verification of the basin model ran on flood event in August 2006. The value of the efficiency criterion between the simulated and measured hydrograph was 0,86 and 0,89, which means successful...
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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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