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Groundwaters in vicinity of subway line A
Drábková, Jana ; Bruthans, Jiří (advisor) ; Kůrková, Iva (referee)
The main aim of bachelor's thesis was to process and assess data measured during groundwater monitoring in the surroundings of construction sites of the new subway line A (21/04/2010 - 31/08/2011). The data from 17 monitored objects (subhorizontal mine galeries, springs and hydrogeological wells), which, with few exceptions, drain mainly Cenomanian aquifer (1 object in Orovician shales a 2 objects in Quaternary aquifer). For outflows from galeries and springs, statistics of the following parameters was calculated: discharge, pH, electric conductivity and water temperature. Discharge of all studied objects shows very low time variation. pH is neutral waters and overall, pH values show very low variability. Mean conductivity of studied objects suggests lower to moderate mineralization of waters. Groundwater temperature does not respond significantly to temperature changes at the surface. Marked temporary declines in water table leveal were probably caused by tunnel construction in proximity of the wells. Chemical analyses of groundwater from all 17 objects demonstrated that groundwater in the studied area belongs to the Ca-HCO3 type. Waters from different objects differ in increased concentrations of chlorides, nitrates or sulphates. Water is undersaturated in gypsum. Water is undersaturated in...
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Effect of compression on salt weathering rate of sandstone
Vaculíková, Jana ; Bruthans, Jiří (advisor) ; Schweigstillová, Jana (referee)
The aim of this study was to investigate whether the uniaxial compression have any influence on the rate of salt decay. Tests were performed on several types of rocks, mainly sandstones from the Czech Republic and the USA. The first tests were made on Strelec sandstone blocks that were loaded with a mass of 6-24 kg, slowly saturated by solutions of NaCl, CaSO ₄. H ₂ O and KAl(SO ₄) ₂. 12 H ₂ O and dried at room temperature. Because the weathering rate was too low, another method was used for other rocks. Cubes cut fromrock were compressed by steel frame with a torque wrench to 0.75 Nm, which corresponds approximately to the uniaxial compression of 1.2 MPa. These compressed samples were tested according to a modified standard EN 12370, saturated by solution of Na2SO4 and subsequently dried in an oven. The cycle was repeated until the complete decay of the sample or until the residual weight of samples fall below 10 grams. Weight of the samples was plot over numbes of cycles. Approximately after first two cycles increase in weight due to the salt crystallization within samples was observed. In following cycles the samples begun to lose weight. All compressed samples wistand more cycles than their non-compressed counterparts. The experiment continues to find out how many cycles will the compressed...
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Origin of karst conduits and caves in Jizera Formation in Turnov.
Slavík, Martin ; Bruthans, Jiří (advisor) ; Schweigstillová, Jana (referee)
Aim of this study is to characterize the processes responsible for evolution of open conduits and caves in Jizera Formation near Turnov, in particular to distinguish if the main factor acting in enlargements of conduits is dissolution and the conduit system can be called karst, or if the process is caused by erosion of weakly cemented sandstone without contribution of dissolution. An important part of the study is to introduce the concept of self-organization. Based on results from accelerated simulation of dissolution of twenty rock samples, SEM analysis and drilling resistance, I have proved that rocks in Jizera Formation near Turnov dissolve in an acidic environment and their strength characteristics does not enable direct erosion by flowing water. Samples from localities of "Bartošova pec", "Slepé údolí Podhorčí", "Rozsedlinové ponory pod Drábovnou", "Šetřilovsko", "U Kačeny" and "Semikraska" dissolve, but behavior of samples from "Sudoměř - rybník" and "Sudoměř - Skalský potok" is in an acidic environment very similar to samples from Teplice Formation "Skalní pískovcový výchoz u Podhorčí" and "Valdštejn".
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Study of vadose zone in northern part of Moravian Karst
Gregorová, Anita ; Bruthans, Jiří (advisor) ; Kamas, Jiří (referee)
This study is focused on the flow through the uppermost part of the unsaturated zone in karstified areas. The information about distribution of transit times and chemical reactions taking place in the unsaturated zone is based on isotopic and chemical composition of cave dripwaters, precipitations and water caught by gravitation lysimeters. The water balance was calculated using measurements of intensity of dripwaters and amounts of water caught by lysimeters and rain gauges. The velocity of a hydraulic shockwave between monitored objects was also estimated according to the delay between significant precipitation event and dripwater intensity increase. The field study took place in the Němcova 1 cave in the northern part of Moravian Karst, near the village Suchdol. It was carried out during the hydrological year 2010/2011. The cave is about 13 m under the surface. The information about composition of overlaying rock above the cave was obtained using geoelectrical and electromagnetic measurements. Studied geological environment is built of 0.5 - 1.5 m of soil, 0.5 - 3.5 m of epikarst and a layer of massive limestone as thick as 10 m. About 70 to 90 % of dripwaters have residence time over 4 years. The distribution of transit time of younger water can be described using the exponencial model (well...
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Hydrology of Amateur cave and sinking streams focused on tracer tests
Gregorová, Anita ; Bruthans, Jiří (advisor) ; Vojtěchová, Anna (referee)
This study briefly summarizes methodology of tracer studies in karst areas (the way how they were carried out and their evaluation). Second part of the study specifies geological, hydrogeological and hydrological situation of the area of interest - northern part of the Moravian Karst, surroundings of Sloup - using available literature on that topic. Description of the area was completed with field measurements done by the author. Their results can be used as a basis for possible future surveys.
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Use of radon in hydrogeology
Malečková, Kateřina ; Bruthans, Jiří (advisor) ; Vojtěchová, Anna (referee)
Study is focused on possibilities of radon isotope (222 Rn) as a natural as well as artificial tracer. It contains examples of radon use for hydrogeological, or tectonic research, especially for interactions between groundwater and surface water, contaminants free phase delineation and estimation of residence time of water. The used methodology is described as well. Finally, importance of radon is emphasized given its low financial and time costs and low environmental impact.
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Physical processes leading to failure and entrainment of slightly cohesive material initiated by groundwater seepage
Světlík, Daniel ; Bruthans, Jiří (advisor) ; Mašín, David (referee)
Relatively recently the geomorphologists have realized that beside the overland flow the groundwater flow emerging from porous rock or soil can under specific conditions cause erosion of that material and create land forms. The goal of this theses is to demonstrate the importance of seepage erosion, which on many places on the Earth contributes to the landscape development, and also to describe the physical nature of the erosion processes acting on slightly cohesive material leading to it's entrainment or failure. Special attention is paid to erosion influence of groundwater on stability of streambanks, where in case of suitable hydraulic and geomechanical properties of the material, a perched water table can be developed leading to lateral seepage through a conductive layer and undercutting the bank face.
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Sapping- its field features and studies focused on detail description of the process
Soukup, Jan ; Bruthans, Jiří (advisor) ; Schweigstillová, Jana (referee)
The study discuss about groundwater sapping erosion, whereas is upon process looked from various points of view. In small scale it observes difference between sapping drainage network and network formed by surface runoff. Further forms of the sapping weathering are described and are mentioned examples of sapping valleys from different places around the world. Partially are mentioned actual knowledge in evolution of deep incised valleys on the Mars surface, which are obviously also formed partly by sapping. In the second part, study describes some experiments focused on evolution of sapping valleys in laboratory environment.
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Characterization of karst conduits and flow: Use of tracer tests, recession curves and autocorrelation
Vojtěchová, Anna ; Bruthans, Jiří (advisor) ; Buzek, František (referee) ; Tesař, Miroslav (referee)
5. CONCLUSION In frame of present PhD Theses I performed 8 new quantitative tracer tests and processed 26 of quantitative tracer tests realized in different karst areas of the Czech Republic. Calculations of conduit volume based on tracer breakthrough curve was compared with the real volume of the phreatic loop. The best results were obtained for mean transit time, where tracer-test calculations yielded volumes very similar to the volume obtained by direct filling of the loop. It demonstrates that volume estimation by tracer tests may be quite precise for common natural conduits, but results are strongly affected by the breakthrough-curve parameter chosen by the experimenter. .Spring and river flow hydrographs were studied by tools of statistical mathematics such analyses of recession curves, curves of exceeding and autocorrelation function applied on 77 objects (karst and non-karst springs, resurgences and streams). Ratio of maximum to average discharge is between 1.6 and 65. In general lower values belong to spring hydrographs and higher to superficial streams. There is no possibility to determine origin of the spring (karst spring, non-karst spring, karst spring fed by with sinking streams, karst spring fed by autochthonous recharge only. Coefficients of recession curves were calculated. For every...
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