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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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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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Simulation of water and heat transport considering preferential flow. Experimental site Na Lizu
Votrubová, J. ; Dohnal, M. ; Vogel, T. ; Tesař, Miroslav
Coupled water and heat transport in soil profile at the experimental site Na Lizu (Volynka headwater catchment, Sumava Mountains, southern Bohemia) is studied. The site is located on a mild slope cov-ered with grass. The soil is Cambisol developed upon biotite paragneiss bedrock. One-dimensional dual-continuum model with semi-separate flow domains representing the soil matrix and the network of preferential pathways (S1D) is employed. Hydraulic parameters of the model are set based on labo-ratory retention curve measurements and in-situ measurements of hydraulic conductivity. Thermal pa-rameters are estimated using methodology of Cote and Konrad (2005). Simulation is conducted for the summer season of 2009. The in-situ monitored precipitation and soil surface temperatures are used as the model upper boundary condition. Model performance was evaluated through comparison with soil water pressure and soil temperatures monitored in situ.
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