Author(s): Sebastian Schwindt; Marwan A. Hassan; Niklas Henning And Teresa Schnellbach
Linked Author(s): Teresa Schnellbach, Sebastian Schwindt, Niklas Henning
Keywords: Sediment transport Morphodynamics Mountain rivers Flume experiments
Abstract: Estimating bedload transport poses challenges due to uncertain boundaries, turbulence, bed structures, and spatiotemporal variation in flow and sediment delivery regimes. Numerous bedload calculation equations rely on semi-empirical assessments of laboratory experiments or field measurements, typically involving cross-section and time averaging of hydro-environmental parameters and the assumption of infinite and constant sediment supply. Although these equations may perform well on the datasets they were trained on, their accuracy decreases when applied to different contexts. Equations established in the 21st century also exhibit uncertainties despite the use of extensive data. To quantify the meaningfulness of typically applied cross-section and time-averaged parameters, this study analyzes statistical attributes of bedload measurements from a generic flume experiment designed to scale to gravel-cobble-bed rivers. It is shown that due to the non-Gaussian nature of the controlled and uncontrolled parameters, a normal distribution-based analysis is not possible. Instead, a nonparametric rank correlation determines the relationships between hydraulic and geometric attributes. The findings indicate that none of the commonly used cross-sectional and time-averaged parameters have a significant correlation (i. e., greater than 0.7) with bedload transport. These results underscore the limited relevance of equations based on local and time-averaged parameters, such as water depth, discharge, and cross-section geometry, in explaining the observed variance in bedload transport.
Year: 2025