Author(s): Luis Ayala
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Keywords: No Keywords
Abstract: Several flow resistance equations that have been proposed for gravel bed rivers, are reviewed and analyzed having as reference field and hydraulic model data obtained from a mountain (Los Andes) reach of the Mapocho river in Santiago, Chile. Existing relations take into account to some degree pavement of non-uniform bed material by introducing a characteristic grain diameter which su pposedly represents the roughness of the paved surface. Tests carried out in the river model show that grain resistance significantly varies with flow and associated bed pavement conditions so that differences between various proposed relations and observed scatter of field data could be attributed to this effect. The use of a bed pavement diameter greater than the median size (e. g. : D＿ (65) ) as representative of the surface roughness seems to account satisfactorily well for pre-existing pavement conditions.
Year: 1991