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Design of methodology for determining roughness coefficient of open channels
Smelík, Lukáš ; Havlík,, Aleš (referee) ; Šoltész,, Andrej (referee) ; Uhmannová, Hana (advisor)
Determination of immeasurable parameter, the Manning’s roughness coefficient, is a complex problem of open channel hydraulics for more than 200 years. Now it doesn’t exists a method for determining an exact value of 1D roughness coefficient for computation water levels in watercourses. Doctoral thesis is focused for comparing different approaches to determine a roughness coefficient, especially for empirical equations. It were sought empirical equations, which are suitable for wide spectrum of water stages, types of bed material, channel shapes and channel dimensions. Selected equations were sorted on the base of two methods by the best values of medians and standard deviations of measured and computed values of roughness coefficients. Furthermore, it were compared qualities of roughness coefficient determination by tables, by photographic catalogs, CES software and by Cowan’s method, which has been extended and recalibrated. The computed values of roughness coefficients by those four methods were compared with values from own measurements in 27 locations in watercourses near of Brno and Frýdek-Místek. Also it were compared the grain size curves determined by sieving, by Wolman’s method and by Subjective estimation. Doctoral thesis is marginally focused for beginning of sediment movement, roughness coefficient of bedforms (dunes), grass and trees.
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