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Pedotransfer functions for estimation of moisture retention curves of medium-heavy soils of South Moravia
Gavlasová, Iva ; Doležal, Petr (referee) ; Kameníčková, Ivana (advisor)
The most important characteristics of each soil is its hydro-physical properties, which include retention curve. Retention curve expresses the relationship between humidity and pressure head. It is course affected by many factors such as grain size and mineralogical composition, humus content, structure and bulk density of dry soil. This thesis deals with direct and indirect determination of one of the basic hydraulic characteristics of the soil, soil moisture retention curve. For laboratory determination of moisture retention curves were used for sand tank and pressure instruments. Measured body retention curves were optimized RETC program.For indirect determination of retention curves were used Pedotransfer function by Wösten et . al .(1998 ) , derived from the European soils and under HYPRES Šútora and Štekauerová (2000). As in the project Wösten et al . (1998), PTF were processed for arable land in the area. The accuracy of both models PTF was assessed by the correlation coefficient R and standard error RMSE. Simple models PTF provide estimates of retention curves with sufficient accuracy for practical use in the locality.
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Determination of soil hydraulic characteristics in the selected location
Stoklásková, Adéla ; Doležal, Petr (referee) ; Kameníčková, Ivana (advisor)
This thesis deals with direct and indirect determination of soil hydraulic characteristics (retention curve and hydraulic conductivity) in the locality of Bohaté Málkovice. For laboratory determination of soil moisture retention curve is used sand tank and pressure relief device. For the indirect determination of soil hydraulic characteristics is used computer software Rosetta, which includes 5 models of pedotransfer functions. For estimatiton of retention curves are applied previously derived pedotransfer function (continuous parametric PTF and point PTF).
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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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Comparison of hydraulic characteristics of cavernous weathering rocks forming tafoni and honeycombs
Studencová, Alžběta ; Bruthans, Jiří (advisor) ; Sněhota, Michal (referee)
Forms of cavernous weathering - tafoni and honeycombs - belong to long-term investigated and discussed phenomena in geology. The reason for the difference in size between few centimetres- long honeycombs and the several-metres-long tafoni has not been yet studied. In my master thesis I compared the hydraulic properties of rocks with developed honeycombs and tafoni. The research consists of field measurements (measurement of suction pressures and capillary water absorption using Karsten tube) and laboratory measurements on tafoni and honeycomb samples (retention curve measurement, capillary water absorption, water vapour diffusion rate and saturated hydraulic conductivity). I have been studing honeycombs from various sites in the Bohemian Cretaceous Basin and tafoni from three different sites: Carbon Arkoses near Kralupy nad Vltavou, Cambrian Sandstone in Petra (Jordan) and Tunnel Spring Tuff in Crystal Peak (Utah). The measurements showed that values of suction pressure are far higher inside tafoni than inside honeycombs. This observation corresponds to different retention curves of studied rocks: steeper retention curve for honeycomb's quartz sandstone than for fine-grained arkosic sandstones to arkoses with tafoni. In the other part of my research I have compared the properties of hydrophobic...
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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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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...
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Pedotransfer functions for estimation of moisture retention curves of medium-heavy soils of South Moravia
Gavlasová, Iva ; Doležal, Petr (referee) ; Kameníčková, Ivana (advisor)
The most important characteristics of each soil is its hydro-physical properties, which include retention curve. Retention curve expresses the relationship between humidity and pressure head. It is course affected by many factors such as grain size and mineralogical composition, humus content, structure and bulk density of dry soil. This thesis deals with direct and indirect determination of one of the basic hydraulic characteristics of the soil, soil moisture retention curve. For laboratory determination of moisture retention curves were used for sand tank and pressure instruments. Measured body retention curves were optimized RETC program.For indirect determination of retention curves were used Pedotransfer function by Wösten et . al .(1998 ) , derived from the European soils and under HYPRES Šútora and Štekauerová (2000). As in the project Wösten et al . (1998), PTF were processed for arable land in the area. The accuracy of both models PTF was assessed by the correlation coefficient R and standard error RMSE. Simple models PTF provide estimates of retention curves with sufficient accuracy for practical use in the locality.
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Determination of soil hydraulic characteristics in the selected location
Stoklásková, Adéla ; Doležal, Petr (referee) ; Kameníčková, Ivana (advisor)
This thesis deals with direct and indirect determination of soil hydraulic characteristics (retention curve and hydraulic conductivity) in the locality of Bohaté Málkovice. For laboratory determination of soil moisture retention curve is used sand tank and pressure relief device. For the indirect determination of soil hydraulic characteristics is used computer software Rosetta, which includes 5 models of pedotransfer functions. For estimatiton of retention curves are applied previously derived pedotransfer function (continuous parametric PTF and point PTF).
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Evaluation of water regime monitoring in Roklan site
Čejková, E. ; Sněhota, M. ; Tesař, Miroslav ; Dohnal, M.
Contribution focuses on soil water regime in the mountainous site Roklan, which is located in the first zone of the National Park Sumava. Spruce monoculture forest in the location was devastated by bark beetle and then left to natural regeneration. The soil hydrological and meteorological monitoring is performed since 2011. Presented paper reports on soil hydraulic properties of the soil from the site. Then, the TDR water contents data collected in the site are compared with the water content data obtained by calculation from the pressure head data using the known water retention curves. The data for two selected rain episodes are presented in detail and results are discussed.
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