Study on calculation of flow resistance and riverbed slope of the Yellow River
The study of flow bed resistance in alluvial river has a significant impact on flood evolution and riverbed deformation.Therefore,this article first analyzes the correlation between multiple single hydraulic factors,dimen-sionless hydraulic parameters and roughness coefficients using the field test data from the lower reaches of the Yellow River.It concludes that the primary hydraulic factors influencing roughness are water depth,slope,sedi-ment concentration,and longitudinal stability coefficient of the river channel.Subsequently,based on the general expression of Zhang's flow velocity and principles of river dynamics,the study determines indices for water depth and slope,which reflect the effects of physical characteristics such as velocity gradients,riverbed stability,and sediment transport intensity on hydraulic resistance.Then,a formula for calculating riverbed slope and hydraulic energy slope is proposed,which avoids using surface slope values with significant observation errors to directly sub-stitute the hydraulic gradient,thereby enhancing the accuracy of roughness calculations.Finally,a formula suitable for the Yellow River was established,which can be used to calculate the flow resistance with only a few measured parameters.Verified by 3188 sets of measured data from the main and tributaries of the Yellow River,the roughness calculated using this method is quite similar to the measured values,with a correlation coefficient of 0.894 and a relative error of only 16.5％.The method in this paper can provide theoretical support for the calcula-tion of water flow resistance in the Yellow River.
flow resistanceriverbed slopethe Yellow Riverroughnesslongitudinal stability coefficient of river-bed
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