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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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Methodology for evaluating the soil properties by using magnetic susceptibility , applicable for the assessment of soil degradation due to water erosion
Kapička, Aleš ; Kodešová, R. ; Jakšík, O. ; Klement, A. ; Petrovský, Eduard ; Grison, Hana
This work has been supported by the Ministry of Agriculture of the Czech Republic (Project No. QJ1230319, “Soil water regime within a sloping agricultural area”). The goal was to propose methodology for using the soil magnetic parameters for accessing soil properties and their spatial distribution within agricultural areas affected by water erosion. Methodology includes: choice of sampling design for target area (optimized based on other auxiliary data) and soil sampling (topsoil), soil sample processing (drying, grinding, sieving, etc.), method of magnetic susceptibility measurements (using Bartington MS2 and Kappametr SM400) and procedure to calibrate models of predicting soil properties from soil magnetic properties. Prediction of the oxidable organic carbon from the mass specific magnetic susceptibility determined in the laboratory is shown here as an example of practical application of this methodology for soil properties assessment in certain soil types. In addition close correlation between volume magnetic susceptibility measured directly in the field and mass specific magnetic susceptibility obtained in the laboratory documents that the oxidable organic carbon may be estimated directly from the field measurements.
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Using the dye tracer for visualization of preferential flow in macro- and micro-scale
Kodešová, R. ; Němeček, K. ; Kodeš, V. ; Žigová, Anna
Study is focused on the visualization of the preferential flow in different soil types and their horizons using the dye tracer experiment. The field ponding dye infiltration experiments were performed in two soil types: Haplic Luvisol and Haplic Cambisol. In addition, the thin soil section were made and micromoprphological images were used to study soil aggregate structure and dye distribution in microscale. Images of the dye patterns (taken in macro- and micro-scales) documented very different nature of the preferential flow in different soil types and also within the soil profiles.
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Fly-ash mobility in sandy material
Kodešová, R. ; Kapička, Aleš ; Fialová, Hana ; Žigová, Anna ; Kočárek, M. ; Kopáč, J. ; Petrovský, Eduard
Fly-ash migration in three sands of various particle size distributions and consequently various porosities was studied in the laboratory. The fly-ash was applied on the top of all sands packed in plastic cylinders followed by pulse infiltrations. Water regime was monitored using the soil water content sensors SM200 and micro-tensometers T5. Kappameter SM400 was used to monitor migration of ferrimagnetic particles-tracers presented in the fly-ash. Undisturbed samples of sands polluted by fly-ash were taken at the end of the experiments to study final fly-ash distribution in section planes and thin sections of sandy material.
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Impact of Pedogenetic Processes on Pore System Development and Consequently on Soil Hydraulic Properties
Kodešová, R. ; Kodeš, V. ; Žigová, Anna
Soil micromorphological properties were studied on soil thin sections to define configuration of soil porous system that is reflected in a shape of soil hydraulic properties. The micromorphological study of soil porous systems discovered multimodality of pore-size distributions and hierarchical pore configuration. Some pore systems were affected by clay coatings. The soil water retention curves also frequently display multimodality. The single-porosity and dual-permeability models in HYDRUS-1D (Šimůnek et al., 2003, 2005) were applied for description of soil hydraulic properties and soil water flow. Results showed a very important impact of multimodality of soil porous systems and effect of clay coatings on water flow process in soil.
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