Equivalent roughness of gravel-bed rivers
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The relation between the equivalent roughness and different grain size percentiles of the sediment in gravel-bed rivers was determined under the hypothesis that the vertical distribution of the flow velocity follows a logarithmic law. A set of 954 data points was selected from rivers with gravel size sediment or larger, with a non-sinuous alignment and free of vegetation or obstacles. According to the results, the ks roughness is equivalent to approximately 2.4D90, 2.8D84, and 6.1D50. No correlation was detected between the sediment sorting and the sediment mobility index on one hand, and, on the other, the coefficient of proportionality of each grain size percentile.
Is part ofJournal of Hydraulic Engineering, 2008, vol. 134, núm. 6, p. 847-851
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Flow resistance equations without explicit estimation of the resistance coefficient for coarse-grained rivers López Alonso, Raúl; Barragán Fernández, Javier; Colomer, M. Àngels (Maria Àngels) (Elsevier, 2007)The uncertainty and subjectivity inherent in estimating the resistance coeffi-cient is one of the main sources of error in the application of flow resistance equations tonatural channels. Various studies have shown that ...
López Alonso, Raúl; Barragán Fernández, Javier; Colomer, M. Àngels (Maria Àngels) (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (Espanya), 2009)Three models of flow resistance (a Keulegan-type logarithmic law and two models developed for large-scale roughness conditions: the full logarithmic law and a model based on an inflectional velocity profile) were calibrated, ...
Reply to the comment by D.E. Rupp and G.M. Smart on "Flow resistance equations without explicit estimation of the resistance coefficient for coarse-grained rivers" López Alonso, Raúl; Barragán Fernández, Javier; Colomer, M. Àngels (Maria Àngels) (Elsevier, 2007)