National Repository of Grey Literature 7 records found  Search took 0.01 seconds. 
Mathematical model of groundwater flow in the Police basin
Grecká, Marie ; Mls, Jiří (advisor) ; Ondovčin, Tomáš (referee)
The topic of this thesis is a groundwater modelling of the cenomanian sediments in the north area of the Police basin. The text is divided into a part of a characterization of the cretaceous sediments from geological and hydro-geological view based on literature. Another part is about a theory of the mathematical modelling in hydrogeology. The main part is related to the groundwater model of the Police basin. This part contains concept and description of the groundwater modelling in software Feflow, which is based on the finite element method. The results, (of the two variants with slightly different boundary conditions), are compared to the model of the same area from the authors Jakeš et al. (1996), who used another software (Modflow) with a different method of the calculation (the finite difference method).
Mathematical model of groundwater flow affected by circulation wells
Nedvěd, Jakub ; Mls, Jiří (advisor) ; Ondovčin, Tomáš (referee)
In this thesis, I focused on numerical modelling of groundwater flow in the vicinity of groundwater circulation well (GCW). The thesis can be devided to two parts. In the first one, I created a simple numerical model of GCW. I used a cylindrical flow domain because of the radial symmetry of the problem. The task was to find out which parameters have the biggest influence on groundwater flow. It was found that the hydrogeological settings and hydraulic properties have more considerable effect on GW flow than the well construction parameters. Distance between the well screens is the only important construction parameter, other parameters can be neglected. However, we cannot neglect the influence of hydraulic properties of the porous medium. Considering the radius of influence of GCW, the presence of aquitards and anisotropy of layers affect the groundwater flow around the well seriously. These two parameters cause the extension of the radius of influence, which leads to a longer path of the particle of water. The travel time of particles increases too this slows down the remediation. A big influence has also an intensity of natural groundwater flow in the area because it decreases the radius of influence of the well. In the second part I created a numerical model of pilot site Velká Hleďsebe to investigate...
Local hydrogeology of the PLA Blanský les
Čečka, Jan ; Ondovčin, Tomáš (advisor) ; Čurda, Jan (referee)
The protected landscape area of Blanský forest is located in the region of South Bohemia, 12 kilometres south-west from the town of České Budějovice. Its geological environment consists of the granulite massif Blanský forest including a lot of bodies of ultramafic rocks - serpentinised peridotites, then we find gneisses of varied unit of Český Krumlov with many different types of rocks - crystalline limestones (marbles), amphibolites, quartzites and graphitic parts. This bachelor thesis aims to sum up as much hydrogeological data and knowledge about the area as possible. It presents characteristics of the hydrogeological environment like disposition of rocks to transport groundwater due to the influence of weathering, fissured zones and tectonic deformation. In its next part this thesis quantifies the hydraulic properties of present rocks by the number of the order of transmissivity magnitude Y and compares these results from pumping tests with theoretical opinions mentioned above. It also considers chemical and physical properties of qroundwater, the influence of mining and the water resources treatment. There are presented field data from hydrogeological mapping too. As the last part of this thesis, hydraulic and other data from hydrogeological boreholes which have been drilled until this time...
Hydraulic conductivity of sandstone samples
Kobrlová, Alžběta ; Bruthans, Jiří (advisor) ; Ondovčin, Tomáš (referee)
Saturated hydraulic conductivity (k) describing the ability of the porous media to allow flow is defined by Darcy's low. Beside pore space properties it depends on the properties of liquid; therefore it is conventionally determined for water at 15 řC. Values of hydraulic conductivity vary between m/s and m/s for sands and sandstones and rises with increasing grain size and porosity. Hydraulic conductivity can be estimated by empirical formulas or measured by laboratory and field methods. Laboratory determination includes the constant head and the falling head permeameter tests. The constant head permeameter test is suitable for material with values of hydraulic conductivity ranging between m/s and m/s; the falling head test for values between m/s and m/s. Unsaturated hydraulic conductivity is a function of moisture (and pressure head). Retention curve describing the dependence of moisture on pressure head is the basic characteristic of each material. The unsaturated hydraulic conductivity can be calculated from the parameters of retention curve and the value of the saturated hydraulic conductivity using Van Genuchten - Mualem formula (1980). Fine grain rocks with small pores have higher values of hydraulic conductivity than coarse grain rocks in condition of significantly negative values of...
Model of transport in vadose zone in vertisols under semiarid climate.
Weiss, Tomáš ; Ondovčin, Tomáš (advisor) ; Kodešová, Radka (referee)
Vertisols cover a hydrologically very significant area of semi-arid regions, and thus understanding of water flow and solute accumulation is very relevant to agricultural activity and water resources management. Previous works suggest a conceptual model of desiccation-crack-induced salinization where salinization of sediment in deep section of the vadose zone (up to 4 m) is induced by subsurface evaporation due to convective air flow in desiccation cracks. This thesis presents a conceptual model of water flow and solute transport in vertisols, and its numerical implementation. The model uses a single-porosity material but unconventionally prescribes a boundary condition representing a deep crack in soil and uses the unsaturated hydraulic conductivity as one of the fitting parameters. The numerical model is bound to one location close to a dairy farm waste pond, but the application of the suggested conceptual model could be possibly extended to all semi-arid regions with vertisols. Simulations were conducted using several modelling approaches with an ultimate goal of fitting the simulation results to the controlling variables measured in the field: water content, and chloride salinity of pore water. The development of the model was engineered in numerous steps; all computed as forward solutions by...
Use of soluble tracers as possible tool to quantify groundwater recharge
Svobodová, Eliška ; Bruthans, Jiří (advisor) ; Ondovčin, Tomáš (referee)
The objective of this study is to test soluble tracers as potential tool to approximately measure the groundwater recharge. In the first part of the study, the most frequently used methods for the estimation of groundwater recharge especially in arid areas are shortly discussed. Eight experiments with soluble tracers - halite and gypsum - were performed. The purpose of the experiments was to examine whether the conductivity of water flowing through a soluble tracer corresponds to the conductivity of the saturated solution. The results indicate that the conductivity of water flowing through halite is approximately equal to the saturated solution. Unlike halite, gypsum was found to be unsuitable because after drying, gypsum milled to analytical fineness becomes solid mass which does not dissolve any more.
Tidal phenomena in groundwater hydraulics
Ondovčin, Tomáš ; Mls, Jiří (advisor) ; Šembera, Jan (referee) ; Novotný, Oldřich (referee)
Manifestations of the tidal force have been known to humanity since an- tiquity. The oldest extant remarks on the origin of the tidal force are in the Natural History of Pliny the Elder. He also left us remarks on periodic changes of water-level in wells. This phenomenon does not necessarily have to be connected to the proximity of seas. As such, it is a subject of research since the end of 19th century. Exploring the mechanisms with which the tidal force affects the groundwater level requires combining the findings of geology and hydrogeology but also the knowledge of hydraulics and geomechanics of porous media and certain understanding of astronomy. This thesis contribu- tes to the knowledge of the mechanism of tidal oscillations in groundwater measured in a borehole near Teplice nad Metují in Police Basin. It utilizes models based on the knowledge of geological and hydrogeological structure of the surroundings of the borehole. It investigates the relation between the physical properties of porous media and the amplitude and phase of the tidal oscillations and presents solutions of the models.

Interested in being notified about new results for this query?
Subscribe to the RSS feed.