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Change of bed roughness by particle separation in the surface layer
Roháčová, Denisa ; Šedivý, Jiří (referee) ; Zachoval, Zbyněk (advisor)
This master thesis is divided into two parts: theoretical and practical one. In the theoretical part there is described hydraulic roughness, velocity distribution in the case of hydraulically rough surface and the process of grain sorting in surface layer. The practical part of the thesis resolves the influence of surface layer on hydraulic roughness of bed, expressed by Nikuradse sand grain size ks. The results are formulas explaining dependence of ks on characteristic grain size dx from grain-size distribution curve and comparison with coefficient ks according to different authors.
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The limits of movement and quantification of bedload amount for gravel-bed rivers
Roušar, Ladislav ; Matoušek, Václav (referee) ; Tůma, Antonín (referee) ; Veselý, Jaroslav (advisor)
Doctoral thesis in detail and comprehensively deals with mechanic of incipient bedload motion for gravel-bed rivers. This study based on theoretical knowledge, experimental researches, numerical models and field survey extends present knowledge concerning with incipient bedload motion and sediment transport at small relative height and hydraulically rough surface bed for turbulent unaerated free surface flow. Incipient bedload motion and sediment transport have been determined for homogeneous and inhomogeneous bed materials. For homogeneous bed material the velocity profiles have been described by different methods in near the bed. Further, hydraulic flow resistance has been evaluated. In the case of inhomogeneous bed material, static armouring and influence of surface layer sorting on hydraulic roughness have been investigated. The correctness of obtained knowledge has been confirmed on the object of nature-inspired river widening. Results shown, among others, that incipient bedload motion does not depend on relative height or final armouring of surface layer to what extend hydraulic roughness is influenced.
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The limits of movement and quantification of bedload amount for gravel-bed rivers
Roušar, Ladislav ; Matoušek, Václav (referee) ; Tůma, Antonín (referee) ; Veselý, Jaroslav (advisor)
Doctoral thesis in detail and comprehensively deals with mechanic of incipient bedload motion for gravel-bed rivers. This study based on theoretical knowledge, experimental researches, numerical models and field survey extends present knowledge concerning with incipient bedload motion and sediment transport at small relative height and hydraulically rough surface bed for turbulent unaerated free surface flow. Incipient bedload motion and sediment transport have been determined for homogeneous and inhomogeneous bed materials. For homogeneous bed material the velocity profiles have been described by different methods in near the bed. Further, hydraulic flow resistance has been evaluated. In the case of inhomogeneous bed material, static armouring and influence of surface layer sorting on hydraulic roughness have been investigated. The correctness of obtained knowledge has been confirmed on the object of nature-inspired river widening. Results shown, among others, that incipient bedload motion does not depend on relative height or final armouring of surface layer to what extend hydraulic roughness is influenced.
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Change of bed roughness by particle separation in the surface layer
Roháčová, Denisa ; Šedivý, Jiří (referee) ; Zachoval, Zbyněk (advisor)
This master thesis is divided into two parts: theoretical and practical one. In the theoretical part there is described hydraulic roughness, velocity distribution in the case of hydraulically rough surface and the process of grain sorting in surface layer. The practical part of the thesis resolves the influence of surface layer on hydraulic roughness of bed, expressed by Nikuradse sand grain size ks. The results are formulas explaining dependence of ks on characteristic grain size dx from grain-size distribution curve and comparison with coefficient ks according to different authors.
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