**1. Introduction**

Sediment transport modeling is a recently still developing topic of morphodynamic investigations. Although researchers elaborate an increasingly accurate description of the sediment motion, there is still no one generally accurately applicable sediment transport model. The selection of the applied appropriate sediment transport method for a given case with even unique morphodynamic features (such as grain size, homogeneity of the bed content, bed slope, bed shear stress, hydraulic flow regime, the measure of armoring, etc.) must be preceded by a careful preliminary examination. There are, however, a large amount of empirically derived bed load transport formulas [1–10]. A comprehensive collection of the most widely applied formulas can be found in the Sedimentation Engineering Handbook [11]. The collection contains the most relevant sediment transport models, such as the ones from Meyer-Peter and Müller [1], from Einstein [2], Ashida and Michiue [4], Parker, Klingeman and McLean [5], surface-based relation of Parker [6], two-fraction relation of Wilcock and Kenworthy [7], surface-based relation of Wilcock and Crowe [8], relation of Wu et al. [9] and of Powell et al. [10]. The summary provides a short description of the hydraulic and sediment conditions of the experiments for which the given bed load formulas are developed (such as grain size, homogeneity of the bed material, bed slope, range of the bed shear stress and the measure of armoring). Although the applicability limits of the formulas are usually not defined in an exact way, they can be indirectly concluded based on the conditions of the benchmark experiments.

Török et al. [12] elaborated on a novel calculation method, which does not represent a new sediment transport model. The method says that by the combined and parallel application of the present models the applicability range can be increased. The laboratory measurements based validation evinced that the novel method can result in significantly more accurate sediment transport calculation [12]. However, the novel method was not yet verified with field measurements based comparative investigation.
