National Repository of Grey Literature 49 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Dynamics of surface water quality changes in model headwater areas of the Czech Republic
Fraindová, K. ; Matoušková, M. ; Kliment, Z. ; Vlček, Lukáš ; Vlach, V. ; Šajnarová, L.
River headwaters have a high environmental value. Unfortunately, the biogeochemical processes in headwaters in context of different rainfall-runoff conditions and specific land cover have not been fully examined. This study focuses on changes in correlations of 16 biogeochemical parameters related to different types of rainfall-runoff events and land cover condition for eight headwater catchments in Central Europe. Multiple methods as linear regression, Spearman rank correlation, Principal Components Analysis and C/Q hysteresis loops revealed main relationships. Presence of peatlands and waterlogged spruce forests had decisive influence on the biogeochemistry (mainly for CODMn, humins, Fe, P-PO43− TP, and N-NO3−). The strongest positive correlation of organic matter (CODMn) and Fe is represented in a catchment with the largest area of damaged forest (70%), but with a smaller proportion of wetlands (8%). High flow rates influence the release of greater amounts of organic matter and N-NO3−.
Dynamics of dissolved organic carbon in surface water during extreme rainfall-runoff events
Matoušková, M. ; Fraindová, K. ; Bejčková, M. ; Kliment, Z. ; Vlach, V. ; Vlček, Lukáš
The release of a greater amount of natural organic matter (NOM) within climate change is registered in many catchments with peatbog areas. The aim of our research is to study the dynamics of releasing dissolved organic carbon (DOC) into surface water in headwater areas with peatbogs. DOC concentrations are analysed in relation to extreme rainfall-runoff (R-R) events and according to the hydrological preconditions of the basin. These preconditions are described using selected hydroclimatic variables (14 days before the R-R event). The source data comes from stations of the Faculty of Science, Charles University, and the Czech Hydrometeorological Institute. For the evaluation of relations and processes, the Principal component analysis (PCA), hysteresis loops or Pearson correlation coefficient was used. The lag time of DOCmax for Qmax, the dependence of DOCmax and groundwater levels were studied. The influence of flow rate on the decline and ascent phases of DOC\nconcentrations by hysteresis loops and the influence of the number of partial flow maximums on the amount of transported DOC during the R-R event was analysed. Our first results show that great influence on the dynamic of DOC concentration in surface water has the change in groundwater-levels in the peatbog and the outflow amount during the R-R event. The hydroclimatic preconditions of the basin have also a significant influence on the DOC release. Changes in concentrations during R-R events also occurred for other compounds that were studied additionally. Particularly significant was the increase in metals (mainly Fe, Al, Mn) and base cation (K) and decrease in nitrate nitrogen.
Soil and hydrological degradation of wetlands
Panocha, Tomáš ; Vlček, Lukáš (advisor) ; Šefrna, Luděk (referee)
The thesis researches the knowledge about soil degradation and the most important soil degradation processes, including desertification, erosion, the impact of agriculture on soils and soil sealing. It also deals with wetlands as ecosystems at the transition between aquatic and terrestrial systems, their definition and delineation, as well as their decline and recovery, which is very important in climate change projections. The chapter on wetlands also includes a section on international conventions and organisations. The work then focuses on wetland types in the Czech Republic and the soil types most commonly found on them, together with their soil-forming processes and water regimes. Last but not least, the thesis tries to find a link between the degradation of wetland ecosystems in relation to changes in the hydrological regime of the surrounding area and the surrounding soils. Keywords: soil degradation, wetland, wetland definition, wetland restoration, wetlands of the Czech Republic
Time variabilty of soil hydraulic properties and their impact on soil moisture estimation
Šípek, Václav ; Vlček, Lukáš ; Tesař, Miroslav ; Zelíková, Nikol ; Hnilica, Jan
The study was focused on the temporal variability of saturated hydraulic conductivity in an experimental plot covered by spruce forest and investigated benefits of its incorporation into soil water balance model. The results showed that the higher saturated hydraulic conductivity (33.6-44.8 cm hr-1) was observed in summer period compared to lower values (13.2-22.3 cm hr-1) in the winter period. The use of seasonally variabile saturated hydraulic conductivity improved the efficiency of soil water balance model in terms of lower root mean square error between observed and simulated volumetric soil water content by 33.2 %. The Nash-Sutcliffe coefficient rose from 0.34 to 0.68.
Runoff from a mainly peat bog basin
Vlček, Lukáš ; Falátková, Kristýna
This research focuses on the basin's hydrological regime, where peatlands make up approximately half of the area. Hydrological processes in the peat bog and the surrounding forest were evaluated using the HBV model. The results show that the peatlands significantly increase the water regime fluctuation of local streams. Moreover, water balance shows a lower cooling effect of tree-less peat bogs than forests on organo-mineral soils. Except for a positive ecological aspect, peatland restoration can have a negative hydrological impact on the surrounding landscape and local streams.
Report on the hydroledological survey in the Černý Důl, Krkonoše Mts.
Šípek, Václav ; Vlček, Lukáš ; Zelíková, Nikol
The report documents results of hydropedological survey in the Černý Důl, Krkonoše Mts. Two experimental sites were selected based on the requirements of National Park Krkonoše with the aim to determine the effect of bark beetle outbreak on the soil water regime. The report contains description of soil hydraulic properties at two plots (healthy and impacted forest) for several soil horizons which will serve as a basis for hydropedological model.\n
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 of natural organic substances within hydrological extremes in headwater areas
Bejčková, Marie ; Matoušková, Milada (advisor) ; Vlček, Lukáš (referee)
Diploma thesis is focused on changes of natural organic matter within hydrological extremes in headwater areas of the upper Vydra. The increace in these concentrations and increased transport to surface waters negatively affect the environmental and social environment. The main aim of this work is to analyse the amount and variability of organic metter in relation to selected runoff events with clarification of these relationship. The change in the amount of concentrations and variability of Dissolved Organic Carbon (DOC) was evaluated with respect to the preconditioning of the catchment (over a period of 14 days) and the influence of hydroclimatic conditions during the episodes. The dependence of each variable on DOC concentrations was also examined. The dependence of parameters (water temperature, conductivity, flow rate, pH, Dissolved Oxygen, Dissolved Organic Carbon concentration) within the campaigns and the subsequent similarity of the profiles were also investigated. The data for this work were provided by the Department of Physical Geography and Geoecology, Faculty of Science, Charles University. The evaluating of relationship and processes was determined, for example, using Principal Component Analysis (PCA Analysis), hysteresis loop or Pearson's correlation coefficient. The greatest...
Water retention in experimental waterbasins with focus on histosols
Vlček, Lukáš ; Šefrna, Luděk (advisor) ; Kliment, Zdeněk (referee)
This thesis is being written within the framework of the project GA UK 2371/2007 "Water retention in spring areas as a tool of integrated anti-floods protection and solution of problems with dryness" at the Institute of Physical Geography and Geoecology. The influence of histosols on retention, especially in the National Park of Šumava, is a delicate topic because of collision of nature protection and valuable biotopes preservation on one hand and countryside utilization for anti-floods protection on the other hand. The thesis follows the bachelor thesis "Water retention of histosols". It includes a detailed pedological analysis of the basins of 'Rokytka' and 'Černý potok'. The result of the thesis is water retention determination in the basins and calculation of overall soil retentive potential. The thesis also addresses the analysis of the influence of organic soil on retentive potential of countryside. Keywords: water retention, histosols
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

National Repository of Grey Literature : 49 records found   1 - 10nextend  jump to record:
See also: similar author names
3 VLČEK, Ladislav
3 Vlček, Ladislav
9 Vlček, Libor
1 Vlček, Lubomír
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