Comparisons are made of the overall accuracy as well as the accuracy within different ranges of sediment concentration, Froude number, and slope for seven bed‐material load formulas. Four formulas that can compute bed‐material load transport by size fraction are used to determine the particle size distribution of the bed materials in transportation. One‐thousand, one‐hundred‐nineteen sets of laboratory data and 319 sets of river data in the sand size range are used to evaluate and compare the accuracy of these formulas. The overall accuracy of formulas in descending order are those of Yang, Engelund and Hansen, Ackers and White (d50), Laursen, Ackers and White (d35), Colby, Einstein, and Toffaleti formulas when applied to laboratory flumes. The accuracy in descending order when applied to natural rivers are the formulas by Yang, Toffaleti, Einstein, Ackers and White (d50), Colby, Laursen, Engelund and Hansen, and Ackers and White (d35). However, these ratings may vary depending on the values of sediment concentration, Froude number, and slope of the data used in the comparison. The study also indicates that Yang's formula by size fraction can accurately predict the size distribution of bed material in transportation, while Einstein's hiding and lifting correction factors overcorrected the effect of nonuniform size distribution of bed material on total bed‐material transport.
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Yang et al. (1991) studied this question.