Estimation of Gravel-Bed River Flow Resistance

Abstract

Numerous formulations have been proposed linking friction factors to the gravel-bed river downstream hydraulic geometry. Data from 280 rivers show that existing gravel-bed power and semilogarithmic formulations fail to correctly predict the friction factors. A new gravel-bed semilogarithmic formulation is developed using nonlinear statistical tools. It considers the influence of the relative roughness, the Froude number, the sediment mobility parameter, and a cross-sectional form factor. The best fit is achieved by modifying the adjustment parameter and the interior of the logarithmic term of the universal velocity distribution equation.