National Repository of Grey Literature 121 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
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...
Measuring of winter precipitation and derivation of precipitation time series using snow water equivalent at selected stations in the Sumava Mts.
Valešová, Petra ; Jeníček, Michal (advisor) ; Míka, Dominik (referee)
The measurement of winter precipitation is an important part of many scientific fields, but the same time there are many uncertainties in the measurement that can arise from inaccuracy or poor calibration of sensors, rain gauges and the influence of environmental factors. Measurement inaccuracies can be caused by the influence of wind, evaporation from heated rain gauges or clogging of the rain gauge. The aim of this work is to process data measured by a heated tipping bucket rain gauge, a classical rain gauge and snow water equivalent sensors from selected stations in the Sumava Mountains. These measured data are subsequently processed and, in case of failures, supplemented with data from other stations according to the given principles. Cumulative precipitation series for the hydrological years 2016 to 2022 are then compiled from the data thus supplemented. Key words: precipitation, snow water equivalent, snow depth, measuring of precipitation
Modelling the course of extreme floods in the context of landscape changes and integrated flood protection
Jeníček, Michal ; Langhammer, Jakub (advisor) ; Zezulák, Jiří (referee) ; Szolgay, Ján (referee)
Introduction Floods mean a considerable hazard for mankind. Effective protection against their impact represents one of the basic hydrology and water management tasks. The conception of flood protection came tfuough development reflecting the progress in natural processes description, flood experiences and also improvement in technology possibilities enabling better computation of flood measures effectiveness. Cunently centralized flood protection concept is replaced with íntegrated flood protection concept (Langhammer et al., 2008b; Dumbrovský et al., 2006)' which gives the complex flood protection solution for the whole basin by means of smaller, close{o-natural measures, such as small retention reservoirs. land use change, suitable agrotechnical principles etc. The thesis can be divided into three main parts that form three main pillars ofintegrated flood protection. These pillars are represented by three case studies. First study was made in Blanice River basin. It computes flood extreme changes in condition of changing landscape. Results could lead to positive land cover change which could cause the flood peak decrease. Second study was made in Chomutovka River catchment (Ore Mts.). It quantifies dry retention reservoirs impact on the course of floods by different precipitation extremities. Third study...
Influence of spatial snow distribution on flood course
Kučerová, Dana ; Jeníček, Michal (advisor) ; Langhammer, Jakub (referee)
For the purpose of hydrological forecasting on mountains' and sub-mountains' rivers is important knowledge of distribution of snow water equivalent in the watershed. Submitted thesis therefore deals with comparison of 9 interpolation methods in terms of quality of their forecasting when predicting snow depth and snow water equivalent in watershed Bystřice (127,6 km2 ), which is situated in the northwest of Bohemia in the Ore mountains. Point data of snow depth and snow water equivalent used in interpolation were sampled during an off- road measuring in 17. 2. 2010 at the 14 snow sampling locations. The interpolation methods were: (1) Thiessen's polygons, (2) inverse distance weighting, (3) global polynomial (4) local polynomial (5) radial basis functions, (6) ordinary kriging, (7) cokriging, (8) residual kriging and (9) orographic interpolation. Independent variable-altitude used in the calculation of snow depth and snow water equivalent was used only in the last three listed methods. Predictive ability of interpolation methods was evaluated by using cross-validation and visual comparison of predicted maps. The best prediction ability was provided by residual kriging and orographic interpolation. The geostatistical methods were next in the order. The method of Thiessen's polygons and inverse distance...
Multi-criteria calibration of a hydrological model using runoff, snow water equivalent and groundwater level data
Hlavatý, Vojtěch ; Jeníček, Michal (advisor) ; Šípek, Václav (referee)
Multi-criteria calibration of a hydrological model (against multiple output variables simultaneously) has in previous research mostly resulted in satisfactory quality and reduced uncertainty in the simulations of all variables considered. However, its importance in the context of groundwater and low flows has rarely been studied. Therefore, a multi- criteria calibration using observed runoff, snow water equivalent and groundwater level data was performed in this study to determine if this approach leads to more accurate simulations, especially for low flows. The HBV hydrological model was calibrated using a genetic algorithm on the case of 14 mountain and sub-mountain basins in Czechia. The accuracy of different calibration variants was evaluated according to objective functions and hydrological signatures. The results show that multi-criteria calibration against the three mentioned variables is a good compromise for correct simulation of all these variables, where the value of objective function for each of them differs only slightly from a calibration more focused on it alone. Considering groundwater in the calibration further increases the simulated baseflow and its variability and refines the simulation of low flows, especially in summer, in terms of deficit volumes, minimum runoff and other...
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...
Extreme cases of snowfall in Czechia
Kolář, Šimon ; Müller, Miloslav (advisor) ; Jeníček, Michal (referee)
The diploma thesis deals with identification and evaluation of extremity by extreme cases of snowfall in Czechia in the period 1961-2019. Identification of extreme events takes on bases from Weather extremity index and maximum depth of fresh snow on weather stations. Extreme events are evaluated with Weather extremity index and Regional Snowfall index in relation to the affected people or with tool of maximum depth of fresh snow. The results of the diploma thesis bring a more comprehensive climatological view of the relatively hitherto neglected issue of the extremity of this winter hydrometeorological hazard in Czechia, but also of the causative synoptic situations leading to these extreme events. The results show a close connection of the point extremity by the events to higher and mountainous locations, which is related to the intensifying windward effect of precipitation. Important from this point of view is the area of the Moravian-Silesian Beskids, which is characterized by the highest number of extreme events, during which the height of the national maximum depth of fresh snow was recorded here. An example of an extreme event was 14th October 2009, when up to 65 cm of depth of fresh snow fell on station Lysá hora in a single day. In the case of area extremity, the link to lower and medium...
Analysis of main controls of runoff events in the Sumava Mts. caused by rain-on-snow
Šťovíček, Vít ; Jeníček, Michal (advisor) ; Juras, Roman (referee)
Rain-on-snow (ROS) events are hydrometeorological phenomena when a sufficient combination of rainfall and snowmelt can generate floods, snow avalanches or landslides. As average air temperature gradually increases, the trend of ROS events occurring earlier in spring and at higher altitudes can be expected to continue. Snowmelt during ROS events is controlled by the snowpack energy balance and is influenced by several factors, especially meteorological conditions, and initial conditions of the snowpack. The calculations were made using data from four automatic stations in the Šumava Mountains, namely the Vydra river basin. Based on these data and pre-defined threshold conditions, 105 ROS events were selected. Resulting components of the energy balance, climatic, snow and outflow characteristics were mutually correlated, and their influence on ROS events was determined. The analyses showed that during ROS events, the most important source of energy for melting were turbulent fluxes, i.e., latent, and especially sensible heats. According to the monthly averages, they accounted, at almost all observed stations, for at least 40% (and up to 60% in December), of the total energy available for snow melting. Another important energy flux was shortwave radiation, whose fraction increased with the progress of...
Modelling the impact of potential restoration of small reservoirs on the hydrological regime at the upper Vydra River basin.
Purm, Marek ; Vlček, Lukáš (advisor) ; Jeníček, Michal (referee)
The presented diploma thesis deals with the implementation of the SWAT eco- hydrological model at the upper Vydra basin in Šumava. In the first simulation, the model was built without inserted extinced small water reservoirs. In the second simulation, the effect of the possible inclusion of the small water reservoirs on the transformation of peak flows and the mitigation of low flows during dry periods is studied. To achieve the desired results, the SWAT model was used. This model is still not widely used in our territory. Model calibration was performed using the SWAT-CUP semi-automatic calibration software. Through the conducted research, it was found that in the case of the inclusion of some reservoirs, there is a slight reduction in peak flows and an improvement in low flows during dry periods. The influence of the inclusion of the reservoirs in the final profile of the basin of interest in Modrava is less apparent. The results also include a option with the five times greater volume of the reservoirs. The presented results and their discussion could provide more detailed information about the inclusion of today's defunct reservoirs in the runoff regime in the upper Vydra basin. Key words: SWAT, SWAT-CUP, horni Vydra basin, small water reservoir, hydrological modelling
Changes in groundwater recharge and base flow in mountain catchments in Czechia due to changes in snow storages
Kožíšek, Matěj ; Jeníček, Michal (advisor) ; Šípek, Václav (referee)
Changes in groundwater recharge and base flow in mountain catchments in Czechia due to changes in snow storages The diploma thesis deals with the topic of replenishing groundwater reserves due to the melting of snow cover. The main motivation is the importance of the topic for understanding the changes in the hydrological regime caused by decreasing snow cover and small number of research papers on this topic. The aim of the work is to find the relationships between changes in snow cover and groundwater recharge and runoff parameters in the warm part of the year. The main part of the thesis is work with the HBV model. The parameters of underground water reserves and the size of the basic runoff are modeled using climate data and snow water value data from selected mountain basins of the Czech Republic. The Mann-Kendall test and Theil- Sen linear trend is used to evaluate trends in data. The relationships between individual parameters, expressed by Spearmann correlation tests are also examined. The impact of climate change and the associated increase in air temperature was reflected in all runoff and groundwater parameters. Trends were observed at the annual and especially the monthly level. The impact of climate change and the associated increase in air temperature (0.24 to 0.4 řC/decade) was...

National Repository of Grey Literature : 121 records found   1 - 10nextend  jump to record:
See also: similar author names
1 Jeníček, M.
Interested in being notified about new results for this query?
Subscribe to the RSS feed.