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Use of conductivity meter LTC to characterize the flow of groundwater in well: Use of artificial well and field monitoring
Rodovská, Žaneta ; Bruthans, Jiří (advisor) ; Procházka, Martin (referee)
My Master thesis is focused on a tracer dilution technique in the well using automatic conductivity logging probes LTC Levelogger (Solinst co. Canada). The main aim of my thesis was to test the application conductivity meters LTC to track the movement of fluids in wells. Different set up were used moving probes with unmodified sensor slit, moving probes with modified sensor slit, probes measuring at fixed points, combined moving and fixed points probes and results were compared. 15 wells in quaternary and 11 wells in Bohemian Cretaceous Basin were measured, some of them repeatedly. The comparison of results indicate that the highest apparent flow velocity have probes with unmodified sensor slit. On the other hand fixed point probes indicate flow velocity, which is 40 - 50% lower at the same wells. The combination of the stable positioned probe LTC and the moving probe LTC has about 40% higher flow velocity than the rate of steady probe LTC placed in the well. The results also indicate that extremely slow velocity values (below approximately 0.02 m/day) can be measured only with LTC probes at fixed points. Modified probe slit was tested in the laboratory in plexi-glass tube using fluorescein and NaCl tracers. Unfortunately the modified geometry of measuring slit does not show distinctively better...
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Study of water flow and geochemical processes in the unsaturated zone of carbonate and salt karst
Kamas, Jiří ; Bruthans, Jiří (advisor) ; Tesař, Miroslav (referee) ; Buzek, František (referee)
Water flow and geochemical processes within the unsaturated zone (UZ) in two distinct types of karst environment were investigated using natural tracers (chemistry, stable isotopes 13 C, 18 O, 2 H, and 3 H, 14 C, 87 Sr/86 Sr). The extent of horizontal flow component and the response of drip water chemistry to recharge events were examined in the Moravian Karst (Czech Republic), while the character of water flow and its chemistry were studied in salt diapirs in southeastern part of the Zagros mountains (Iran). Under the conditions of well-developed epikarst, the horizontal flow component, defined as Hmax/T (Hmax = horizontal migration component, T - thickness of VZ) typically reaches values of 0.1 - 0.6 (Moravian and Slovenian Karst). However, in areas where epikarst was stripped off by glacial or human activity, the proportion of horizontal flow component is far greater (Hmax/T 1.6 - 24). This parameter is vital for the design of water source protection zones above caves. Nitrate mean residence time in 120 m thick VZ of the Moravian karst exceeded 16 years. The VZ above the Ochoz Cave (Moravian Karst) represents a semi-open to open system with respect to soil CO2. Under a high drip rate (high flow), the event water only made 5% of the total. During the year, water degassing and so called prior...
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Hydrogeology of Skorkov and Sojovice waterworks based on data from new water wells
Rybářová, Magdalena ; Bruthans, Jiří (advisor) ; Kůrková, Iva (referee)
The Riverbank Filtration (RBF) water supply system Karany has been affected by increasing NO3- concentrations during recent decades. This thesis deals with flow and chemical composition of groundwater in Skorkov and Sojovice RBF systems, which are the most problematic ones according to their quality in long term. Twelve new groundwater wells (V1- V12) were drilled in study area in 2013. Data derived from the wells were used to improve the conceptual hdrogeological model of the area and I tried to specify information about the origin of nitrate pollution. The Groundwater level logging showed hydraulic connection between the river and the wells situated up to 130 m faraway from the river (V1, V2 andV10), which were also demonstrated by the short- term temperature fluctuations caused by fast penetration of surface water from The Jizera River during higher flow rate to wells. I compiled geological sections which show the geometry of The Quaternary fluvial deposits and groundwater level. The chemical analysis of groundwater showed that it is not possible to differentiate groundwater from the shallow part of The Cretaceous aquifer from the aquifer of fluvial deposits by major chemical components. The result of infiltration experiments showed higher permeability in the environment with grass cover (kv=...
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Frost weathering of sandstones: mechanisms and laboratory experiments
Dvořák, Matěj ; Bruthans, Jiří (advisor) ; Schweigstillová, Jana (referee)
Frost weathering of sandstones: mechanisms and laboratory experiments This thesis studies and compares different mechanisms of frost weathering, and further describes the characteristics of the rock material and the external environment, which affect this process. The effects of frost action were related to sandstones. The thesis consists of a literature review and practical experiments. The literature review indicates, that frost weathering of sandstones is due to their characteristics (higher porosity, grain structure) rather influenced by mechanisms based on water migration through the pore space of freezing rock. Beside the properties of the sandstone material, also the water content, the final temperature of freezing and the rate of the temperature fall are important. The experiments were performed on samples of Cretaceous sandstones (thick-bedded and argillaceous sandstones of Bohemian Paradise) and Carboniferous arkoses of Syřenov formation. Samples were subjected to repeated cycles of freezing at - 20 řC and thawing in distilled water. The weathering progress was monitored by measuring the weight loss and damage description. Selected samples were further compared to samples weathered under the influence of tensile stress (3 kPa). Based on the experiments, the frost resistance (from the most...
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Karstification of carbonato-silicate rocks: review of literature and leaching experiments
Vojtíšek, Jan ; Bruthans, Jiří (advisor) ; Kůrková, Iva (referee)
The process of karstification doesn't occur only in easily soluble rock, such as limestone and evaporites, but also occurs in other rocks such as quartzites or siliciclastic rocks with carbonate cement. The "ghost rock" karstification is, unlike the classical karstification, two- step process, where the soluble component are dissolved first and subsequently the insoluble components are eroded and flushed away. These processes also occur in the Czech Republic, for example in the Bohemian Cretaceous Basin (BCB). Practical part of this thesis consists of leaching experiments of samples from BCB. Leaching in hydrochloric acid is an accelerated simulation of natural processes of dissolution by acidic solutions. Leaching of the samples in acid led to the decrease of sample strength, sometimes to their desintegration. The samples are probabbly prone to the evolution of karst conduits. Leaching experiments showed that the carbonate content is an important but not the only driving factor in the karstification process.
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Permeability of natural surfaces of Hruba Skala sandstone in rock cities for water vapour and intensity of evaporation
Slavík, Martin ; Bruthans, Jiří (advisor) ; Pavlíková, Milena (referee)
Aim of this study was to describe capillary water and vapor transport in shallow subsurface of Hrubá Skála sandstone in the Bohemian Paradise. I have quantified permeability of Hrubá Skála sandstone for water vapor using "wet cup" method and also capillary water absorption of sandstone drill cores. I have found out general rules of evaporation and rate of evaporation from several sandstone outcrops in real microclimate. Important part of my work was to determine whether surface crust plays some role in studied parameters. Based on my results, permeability of different types of sandstones for water vapor does not vary significantly and surface crust has no effect on rate of water vapor diffusion. Rate of capillary water absorption is reduced by surface crust. Hrubá Skála sandstone is classified as medium or highly absorbing material. I have proved that evaporation from porous medium can be approximated by exponential function. Rate of evaporation is strongly controlled by climatic conditions, especially by relative humidity. Powered by TCPDF (www.tcpdf.org)
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Development of groundwater surface and inflows to the Strelec quarry: interpretation of conduits development in the quarry surroundings
Světlík, Daniel ; Bruthans, Jiří (advisor) ; Kůrková, Iva (referee)
As a result of ground water pumping in the Střeleč quarry there has been developed a depression in ground water surface during recent 30 years impacting an area of approx. 10 km2 . Due to the existence of steep hydraulic gradient in the quarry surroundings subsurface erosion occurs resulting in a development of underground channels. The biggest one developed in the years 2000 - 2002. Its length was 300 m reaching in some place the height of 17 m. During field works in the quarry in the years 2009 - 2010 the only accessible channel was mapped. In the channel two main types of cracks were discovered. On the crossing of these cracks slumping of the sandstone occurs which causes difficulties for the mining company. A hydraulic gradient higher than 5% was determined to be critical for sand transport in the channels and widening the initial conduits into channels. The channel development and releasing of static ground water reserves also influenced chemical composition of ground water emerging in the quarry. In the period of the most intensive channel development in 2001 the ratio of ground water from static reserves on the total amount pumped was 56%. Also in this period the concentration of sulphates in the ground water of the streams in the quarry decreased significantly. In the year 2010 there were...
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Repeated tracer tests under different hydraulic conditions
Paděra, Martin ; Bruthans, Jiří (advisor) ; Kůrková, Iva (referee)
The thesis deals with tracer tests conducted repeatedly at several sites under different flow rates. Number of parameters vary depending on flow rates, such as mean residence time, tracer concentration and recovery, the character of breakthrough curve. I compared results from various sites, including the results of my own measurements to see if it is some general pattern. As it turned out, generalization is not possible. Mean residence time can decrease with increasing discharge in one system, while it increases in the other one. The same can be said about tracer recovery. Both parameters are controlled mainly by geometry of karst conduits, especialy by volume of phreatic and vadose spaces in individual levels above and below the lowest water table in the system Breakthrough curve plays essential role in the description of the karst system. It's character varies depending on the flow rate and allows to characterize the karst system. By it's interpretation, it is possible to detect or locate bifurcation and describe the water distribution into discrete conduits.
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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...
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Sandstone moisture measurement: laboratory and field techniques
Sommerová, Anna ; Bruthans, Jiří (advisor) ; Schweigstillová, Jana (referee)
Summary: In my thesis I reviewed the most used methods for moisture measurements with the focus on sandstone exposures. Concerning direct methods, the gravimetric is used most commonly for the calibration of other methods. Concerning indirect methods I mention radiometric, microwave, resistive and capacity methods. The major part of thesis is dedicated to capacity device TDR (Time Domain Reflektometry), which emits electromagnetics pulses and measures the reflection time at the beginning and the end of the probe. This methodology is nondestructive and is widely used, mainly in pedology. In practical part of Theses I worked with drill cores of sandstone from natural exposures and I detected their mass water content using gravimetric method, their bulk density by laboratory measurements and from those values I calculated volumetric water content. Average value from measured mass water content is 3,3% and from volumetric water content 6,2%. At some localities the moisture content was measured by TDR was measured beside taking drill cores At places where it was possible to compare measurements using TDR with gravimetric method, TDR measurements show usually higher values (in average 1% higher) then gravimetric method. This fact is caused by calibration and accuracy of the device, generally though this TDR...
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