|
|
Evaluation of runoff formation in catchment using stable isotopes 2H and 18O and water temperature
Hojovec, Daniel ; Vlček, Lukáš (advisor) ; Jeníček, Michal (referee)
The evaluation of the water regime of the springs, or the total runoff in small mountain catchments, is an important aspect in this work for understanding the functioning of the catchment from the point of view of the precipitation-runoff process, and above all for the verification or refutation of the various methods used to evaluate the runoff of the mountain catchment. For the stated purposes, between 2018 and 2020, repeated sampling was carried out from water courses, soil (shallow wells) and precipitation in the Rokytka catchment area. From the obtained data, the ratio of stable isotopes 2 H and 18 O was subsequently determined in the laboratory. We also worked with the data of stable isotopes 2H and 18O provided by the Department of Physical Geography and Geoecology of the Faculty of Natural Sciences of Charles University for the period 2014-2018. All data, together with hydro-meteorological data, were subjected to various analyzes and methods with the aim of evaluating the runoff. The core method of this work was hydrogram separation using a mixing equation working with stable 2 H isotopes and water temperature for 6 events. On the basis of the performed analyzes and hydrographic separations, it was found that the water in the Rokytka přítok during significant rainfall-runoff events is...
|
|
|
Spray Cooling at High Temperatures
Chabičovský, Martin ; Čarnogurská, Mária (referee) ; Hajduk, Daniel (referee) ; Raudenský, Miroslav (advisor)
Spray cooling of hot surfaces is used in the metallurgical industry during continuous casting, hot rolling or heat treatment. The water is sprayed on the cooled surface by the nozzle which transforms the water stream to droplets. The spray cooling of hot surfaces can be characterized as forced convection with the presence of the boiling. This physically complicated process is influenced by many factors, such as impurities and contaminants in the water, water temperature, water flow rate, droplet size, droplet impact velocity, surface temperature, surface roughness or the presence of oxides (scales) on the cooled surface. The dominant factor that affects the heat transfer during the spray cooling is the water impingement density. Other factors have a smaller but also significant effect. This doctoral thesis deals with the influence of the water temperature, surface roughness and the presence of oxides on the intensity of the spray cooling. These factors are investigated by laboratory experiments in which the hot steel surface is spray cooled. Effect of the oxide layer is also investigated by the numerical simulation. The experimental results are theoretically explained and generalized using mathematical methods.
|
|
|
Three-way control valve in industrial environment
Vozár, Viliam ; Čožík, Ondřej (referee) ; Levek, Vladimír (advisor)
This work deals with the design, realization and testing of the system for regulating the temperature of the water in an industrial environment using three-way mixing valve. This system can work autonomously, but also can be controlled by a superior control system. Created temperature regulation can be adjusted and controlled by a computer using control software.
|
|
|
Zhodnocení přežívání a růstu dvou invazivních raků v teplotně suboptimálních podmínkách
MARKOVÁ, Kateřina
Biological invasions of non-native species are one of the most serious threats negatively impairing global biodiversity. The negative influence of these invasions is especially noticeable in freshwater ecosystems also exemplified by the populations of native crayfish species in Europe. Dominance of non-native species of crayfish over native ones is relatively well known and studied, but the interactions between individual non-native invasive species are significantly less explored. As the range expansion and numbers of non-native crayfish species constantly increases, it becomes apparent that the non-native species will dominate in European waters. However, it is not clear which of these invasive species, and under which conditions will perform better. The goal of this bachelor thesis was to create a literature review focusing on factors that negatively influence the population of the native species (mainly the issue of non-native species and crayfish plague which these species often transmit). Consideration was paid to the importance of the water temperature for the crayfish and to the focused species used in the experimental part the marbled crayfish Procambarus virginalis Lyko, 2017 and signal crayfish Pacifastacus leniusculus Dana, 1852. The experiment was focused on the evaluation of survival, growth, damage to the claws, and the maturation of these species at the water temperature of ~16 °C, which is in the optimal range for signal crayfish, but suboptimal for marbled crayfish (yet, within a range presumably allowing its successful reproduction). If these species should meet more frequently in the wild, it is important to understand their relationships.
|
|
|
Study of plasma discharge effect on distilled water pH
KOBRLE, Lukáš
This tesis is concerned with the influence of Gliding arc plasma discharge on the pH of distilled water while using different treatment time and distance between Gliding arc and the surface of distilled water. The theoretical part consists of research into various studies, whose main focus is the practical usage of Gliding arc and the possibilities of its use. The practical part contains the values of the measured quantities, models and graphs illustrating the effects of the process. The conclusion offers a brief summary of the findings and claims, whose correctness needs to be verified in further studies.
|
|
|
Changes of selected surface water geochemistry parameters in relation to rainfall-runoff regime
Bartůšek, Adam ; Matoušková, Milada (advisor) ; Havlíková, Petra (referee)
This work deals with the study of changes in the geochemistry of surface waters in relation to the rainfall-runoff regime and its transformation. As rainfall-runoff extremes such as long episodes of drought with low flows or, conversely, high flows caused by extreme rainfall events have been increasing in recent years, it is important to understand how these phenomena affect water quality. Therefore, the main objectives of this work are firstly a literature search on the changes in surface water geochemistry during change of climate and precipitation-runoff regime and methods that can be used to quantify these changes, and then the application of some of these methods to the analysis of selected parameters and their changes in the Klíčava catchment. In addition to some climatic characteristics and flow rates, the analysis included basic parameters of geochemistry (flow rate, water temperature), physicochemical parameters (electrolytic conductivity, pH), some nutrients (forms of nitrogen and phosporus) and indicators of organic pollution and stream cleanliness (BOD5, CODCr, TOC and dissolved oxygen). In addition, the status and evolution of concentrations of some herbicide metabolites were briefly assessed. For data analysis, e.g. box plots, Mann-Kendall test, correlation coefficients or linear...
|
|
|
Changes of geochemistry of surface water in selected catchments of the Ore Mountains
Navrátilová, Denisa ; Matoušková, Milada (advisor) ; Benešová, Libuše (referee)
This master thesis focuses on an analysis of surface water chemistry, long-term trends and the impact of drought on changes in concentrations of selected parameters in the upper Svatava, Rolava and Načetínský potok basins located in the Ore Mountains. Research on water quality in mountain spring areas is important, the consequences of various changes can be easily observed there. This work analyses the changes in surface water chemistry and discusses their possible causes, especially the impact of peat bogs and dry episodes. The parameters of water temperature, conductivity, pH, BOD5, COD, TOC, concentration of nitrate nitrogen, total phosphorus, phosphates, sodium, potassium, calcium and iron were investigated for the period 1993-2018. The available data are analysed using evaluation methods according to ČSN 75 7221 as well as box plots, Pearson correlation coefficient, PCA analysis and Mann-Kendall test. The greatest anthropogenic influence exhibited in Svatava, almost all concentrations reached their highest values there. In the Rolava and Načetínský potok basins, the influence of peatlands manifested itself by increasing the concentrations of iron, TOC and COD. The results of trends showed an increase both in pH and in surface water temperature related to an increase in air temperature, on the...
|
|
|
Three-way control valve in industrial environment
Vozár, Viliam ; Čožík, Ondřej (referee) ; Levek, Vladimír (advisor)
This work deals with the design, realization and testing of the system for regulating the temperature of the water in an industrial environment using three-way mixing valve. This system can work autonomously, but also can be controlled by a superior control system. Created temperature regulation can be adjusted and controlled by a computer using control software.
|
|
|
Spray Cooling at High Temperatures
Chabičovský, Martin ; Čarnogurská, Mária (referee) ; Hajduk, Daniel (referee) ; Raudenský, Miroslav (advisor)
Spray cooling of hot surfaces is used in the metallurgical industry during continuous casting, hot rolling or heat treatment. The water is sprayed on the cooled surface by the nozzle which transforms the water stream to droplets. The spray cooling of hot surfaces can be characterized as forced convection with the presence of the boiling. This physically complicated process is influenced by many factors, such as impurities and contaminants in the water, water temperature, water flow rate, droplet size, droplet impact velocity, surface temperature, surface roughness or the presence of oxides (scales) on the cooled surface. The dominant factor that affects the heat transfer during the spray cooling is the water impingement density. Other factors have a smaller but also significant effect. This doctoral thesis deals with the influence of the water temperature, surface roughness and the presence of oxides on the intensity of the spray cooling. These factors are investigated by laboratory experiments in which the hot steel surface is spray cooled. Effect of the oxide layer is also investigated by the numerical simulation. The experimental results are theoretically explained and generalized using mathematical methods.
|
|
|
Surface water temperature modelling to estimate Czech fishery productivity under climate change
Svobodová, Eva ; Trnka, Miroslav ; Kopp, R. ; Mareš, J. ; Spurný, P. ; Pechar, L. ; Beděrková, I. ; Dubrovský, M. ; Žalud, Zdeněk
Freshwater fish production is significantly correlated with water temperature, which is expected to increase under climate change and affect fish growth, productivity, and survival. This study deals with estimating the change in water temperature in productive ponds and its impact on fishery in the Czech Republic. The target fish species were common carp (Cyprinus carpio), maraena whitefish (Coregonus maraena), northern whitefish (Coregonus peled), and rainbow trout (Oncorhynchus mykiss). It was hypothesized that there would be an increasing risk of high water temperature stress for fish. Water temperature calculations based on 3-day means of air temperature were tested in several ponds in three major fish production areas. The verified model was applied to the climate change conditions determined by standardized scenarios derived from the five global circulation models MPEH5, CSMK3, IPCM4, GFCM21, and HADGEM. The results for changed climate indicated limitations for Czech fish farming in terms of prolonged periods with fish temperature stress as well as the increased number of stress periods and increased number of days within these periods. It is very likely that Czech fishery will have to change the fish species farmed in particular productive areas. In particular, higher altitudes are likely to become less suitable for the Salmonidae.
|
guest ::
